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1. DOE SW 41286 1 OSTI ID 5295 COILED TUBING SAFETY MANUAL Topical Report January 1999 By OST Walter Crow April 1999 Work Performed Under Contract No 75 97SW41286 MONAZA BNO Westport Technology Center Houston Texas National Petroleum Technology Office U S DEPARTMENT OF ENERGY Tulsa Oklahoma DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government Neither the United States Government nor any agency thereof nor any of their employees makes any warranty expressed or implied or assumes any legal liability or responsibility for the accuracy completeness or usefulness of any information apparatus product or process disclosed or represents that its use would not infringe privately owned rights Reference herein to any specific commercial product process or service by trade name trademark manufacturer or otherwise does not necessarily constitute or imply its endorsement recommendation or favoring by the United States Government or any agency thereof The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government This report has been reproduced directly from the best available copy Available to DOE and DOE contractors from the Office of Scientific and Technical Information P O Box 62 Oak Ridge TN 37831 prices available from 615 576 8401 Available to the publ
2. Foreward This document addresses safety concems regarding the use of coiled tubing as it pertains to the preservation of personnel environment and the wellbore The scope of this document is not intended to fully replace a standard practice manual or give full detail of all safety procedures The main contribution of this document is to provide further depth to the broad scope of these basic practices to enhance the effectiveness of the industry The practices discussed in this document pertain to a normally pressured and low pressure wells on land or on fixed platforms caissons in open waters Westport Technology and the authors of this document make no representation warranty or guarantee by publishing this material and hereby expressly disclaim any liability or responsibility for loss or damage resulting from its use or for the violation of any federal state or municipal regulation with which this publication may be in conflict Acknowledgement Coiled tubing has been a technology available for over thirty years however the application and use has expanded signifi cantly over the past 8 years due to improved materials better handling and transportation equipment The expanded use has improved procedures and reliability though varied between company and business sectors A number of companies will benefit from access to the information contained in this manual and will be able to more reliably apply this technology to control cost
3. Coiled Tubing Technology Operations Service Practices March 13 16 1995 Graham R A Schlumberger Dowell Planning for Underbalanced Drilling with Coiled Tubing The Feasability Study and Computer Modeling SPE 46042 Coiled Tubing Roundtable April 15 16 1998 Gudmonstad Marianne Statoil and Hovden Magne Odfjell Well Intervention Snubbing on the Gullfaks Field Long Tubing Patch Installed in Horizontal Gravel Pack Coiled Tubing and Well Intervention Technology Feb 9 11 1998 Hall Jack and Ben M Wijngaard Slickline Power Unit on Coiled Tubing Provides Innovative Solution for Setting a Nippleless Lock in a Multilateral Completion SPE 47847 Hall Jack Halliburton World Wide Ltd Slickline Power Unit on CT Provides Solution for Setting Nippleless Locks in Multilateral Completions Coiled Tubing and Well Intervention Technology Feb 9 11 1998 Hardy Jack Imperial Snubbing Services Innovation and Design Changes Allow Snubbing Unit to Drill Faster and Cheaper Coiled Tubing and Well Intervention Technology Feb 9 11 1998 Hartley Michael Larry Harford Transocean Petroleum Technology Giorgio Girola and Carlo Bascjenis Agip Teap Coiled Tubing Drilling Ragusa Field Continuous Improvements on A 3 well CTD Campaign Coiled Tubing and Well Intervention Technology Feb 9 11 1998 Haver Nelson Drexel Coiled Tubing Products Inc System Injects Cable onto Coiled Tubing Coiled Tubin
4. Samsonsen B B G Jacobsen T Skagestad and S Kerr Drilling and Completing a High Angle Well With Coiled Tubing Technology SPE 48941 Sas Jaworsky Alex Il SAS Industries Inc and Troy Reed Reed Analytics amp Consultants Fluid Hydraulics Behavior in CT Operations A Nodal Analysis Approach Coiled Tubing and Well Intervention Technology Conference and Exhibition Feb 4 6 1997 l Sas Jaworsky Alex Il SAS Industries Update of API Coiled Tubing Standards Activities Coiled Tubing and Well Intervention Technology Conference and Exhibition Feb 4 6 1997 Sas Jaworsky Alexander Il SAS Industries Inc API Committee 5 Overview of Recommended Coiled Tubing Practices Coiled Tubing Technology Operations Service Practices March 13 16 1995 Sas Jaworsky Alexander and Jerry G Williams Conoco Potential Applications and Enabling Capabilities of Composite Coiled Tubing Coiled Tubing Technology Operations Services Practices March 29 31 1994 Sas Jaworsky Alexander Clarence G Steube and Phillip A Coleman Conoco Inc Convergence Initiative for Coiled Tubing An Operator s Perspective Coiled Tubing Technology Operations Services Practices March 29 31 1994 Schamp J H Mobil International Drilling Services and P V R Suryanarayana Mobil E amp P Technical Center Job Tracking Using Local Friction Profile to Minimize Risk in CT Operations SPE 46032 Coiled Tubing Roundta
5. the previous value and unlock and open the tubing slips Proceed with normal operations 5 11 O Ring Leaks If an O ring or chevron seal between the BOP stack and the stripper fails always close the tubing rams first The coil depth and leak severity should be considered when determining the next step a b O Stop the coil and note the current string weight set the slips on the coil Set the tubing rams and manually lock Bleed off the lubricator Back off the quick union where the O ring is leaking and walk the injector head up the tubing by operating the injector as if running the coil in the hole slowly while raising the trolley hoist to help support the total injector head and guide arch weight Repair the O ring with a standard O ring patch kit or if a spare O ring is already on the lubricator roll it down into place Walk the injector head back down and make up the quick union Coiled Tubing Safety Manual Flow the well to decrease the WHP Pressure test the new O ring to a value comparable to the current wellhead pressure Set the string weight to the original setting Unlock and open the slips Equalize across the tubing rams and open them Pull out of the hole to change out the patched O ring If a spare O ring was rolled into place continue with CTU work 6 0 Equipment Layout and Site Preparation a One of the best methods to minimize risk and reduce cost of an op
6. Disassembly and Inspection Section 4 1 5 Page 14 On site After rebuild BOP in shop During rig up During rig up Pre job pressure test after each disassembly Depending on severity of service this should be performed each job Maximum time 12 months or after each incident Periodically during operation especially BOP system pressure Type of Test Pre Job_ Daly Weekly Monthly Shear rams to be tested with highest grade of CT to be used On site for 7 day operations On site for 7 day operations or after each incident 30 day max between inspections or after each incident Coiled Tubing Safety Manual Bleed Line a Bleed Line Fiuid Return Tank 1 Stab the coiled tubing into the injector head insure proper alignment of the guide arch to the injector head Improper alignment can severely damage the coiled tubing and injector chains Inspect the stripper bushing to insure there is the proper clearance between it and the coiled tubing as defined by the manufacturer Function test the stripper Connect the hydraulic hoses to the weil control stack and perform a function test of each ram independently Visually insure each ram control actually functions the proper ram and that each one fully retracts Position the two way sealing valve optional pipe ram and flow tee on top of the well Function test the pipe ram and visually inspect the
7. The following options may exist to retrieve the coil w Continue circulation if possible b Work the coil in the opposite direction from the way you were going when it was discovered the coil was stuck If a few feet of progress is made in that direction begin working the coil back the other way Try working the coil down a few feet then try the up direction again Gradually increase the overpull or set down weight in each cycle rather than going to maximums all at once c Often times coil circulation is lost to the surface due to the solids buildup If circulation can be attained across the solids build up consider pumping a high viscosity sweep to help string the solids out The goal is to string out the solids to reduce the friction load so the coil can be moved A sand arch around the coil has tremendous gripping power d Avoid working the coil over the gooseneck with high coil pressure as this drastically reduces the number of cycles that can be performed before suffering permanent coil fatigue ballooned pipe Check the coil history to get an idea how much the coil which is currently across the gooseneck has been worked on other jobs Take careful note of any prior fishing jobs or stimulations where the coil has been reciprocated many times e Try to increase the differential hydraulic pressure across the solids bridge by flowing the well harder increasing gas lift or surging the well while continuing to work the
8. w Kili the well if it is not already dead b Release the stripper element pressure and remove the stripper elements and retaining bushings c Pick up the coiled tubing slowly to determine the top of the collapsed pipe d Attempt to pull the collapsed portion of pipe through the injector very slowly while adjusting the chain pressure to the orientation of the collapsed pipe Spool the collapsed pipe onto the reel e While pulling out of the hole slowly watch for the transition section to undamaged pipe f Reassemble the stripper assembly and finish pulling out of the hole g Replace coiled tubing and determine the cause of collapse before entering the well again 5 2 2 Collapse with Coiled Tubing Deep in the Well a Kill the well if it is not already dead b Release the stripper element pressure and remove the stripper elements and retaining bushings c Pick up the coiled tubing slowly to determine the top of the collapsed pipe d Run back into the hole with the coiled tubing until the undamaged portion of the pipe is across the well control stack components e Close the pipe and slip rams and manually lock f Relax the injector chains to verify that the slip rams are holding stripper If the collapsed portion does make it into the stripper Page 8 g Cutthe coiled tubing above the injector Coiled Tubing Safety Manual Open the injector chains Remove the injector from the coiled t
9. WeCem AS and Knut Pedersen Saga Petroleum Therma Set Resin for Pressure Isolation of a Depleted Production Zone in a CTD Sidetrack Coiled Tubing and Well Intervention Technology Feb 9 11 1998 Divers Denis Transocean Petroleum Technology Hydraulic Workover Unit for Multiwell Platform Operalons Coiled Tubing and Well Intervention Technology Conference and Exhibition Feb 4 6 1997 Doermus Denis Dowell Schlumberger Coiled Tubing Drilling Update 94 Coiled Tubing Technology Operations Services Practices March 29 31 1994 Doremis Denis Schlumberger Dowell Drilling Directional Wells with Coiled Tubing Coiled Tubing Technology Operations Service Practices March 13 16 1995 Dorman Thomas G Chevron USA Terry Matte Western Sand Control and Gregg Stout Western Research and Engineering Single Trip Gravel Pack System Used Effectively on a Highly Deviated Well Coiled Tubing Technology Operations Services Practices March 29 31 1994 Evertsen Steffen Smith Red Baron and Knut Pedersen Saga Petroleum Window Milling and Isolation Test of Stacked Multilateral Wellbores Through Concentric 5 7 x 9 5 8 Casing Coiled Tubing and Well Intervention Technology Feb 9 11 1998 Falk Kelly Nowsco Well Services Sand Cleanout Technology Using Concentric Coiled Tubing Coiled Tubing Technology Operations Service Practices March 13 16 1995 Fowler Hampton and Perry Courvil
10. coil If fluid can be injected consider pumping in gas or nitrogen down the tubing coiled tubing annulus to form a gas cap Then surge the well down the wing valve to apply a high upward differential pressure across the problem debris again while working the coiled tubing If fluid can be injected down the coiled tubing tubing annulus this can be used in conjunction with working the pipe Avoid pumping at pressures close to the collapse rating of the coiled tubing h Always keep track of coiled tubing cycles over the gooseneck Do not work the pipe excessively if no progress Page 10 mh Q is being made Work to change the down hole conditions to increase the chances of freeing the pipe Then resume working the pipe again i Once progress is made always continue circulating while working the pipe back up the hole slowly j Consideration can be given to spotting acid across the problem debris if you feel it is even partially acid soluble k A minor mechanical movement can be achieved without the use of jars by removing one of the three pump suction valves from the triplex pump to induce hydraulic jacking through the coiled tubing The pulses created can contribute to solving both mechanical or friction stuck coiled tubing However this option should be used with caution due to the inherent cycling effects imposed on the coiled tubing at surface If the coil cannot be retrieved I If there is a tool stri
11. grade and maximum thickness of coiled tubing to be used Flanged connections and ring gaskets should meet API Spec 16A Section III Band C Quick connections are only appropriate for use on the bottom of the stripper in low normally pressured wells When quick connections are used an additional o ring is advised to be placed above the connection which can be rolled on in the event the original o ring is cut Some ram components have been known to shear fracture during a function pressure test and have fallen into the wellbore during operations The body of the rams themselves should be inspected periodically for integrity The inside bore of the well control stack should be visually inspected after a function test of all rams to insure that they have actually retracted as shown by the indicator pins A function test should be made individually for each ram to note that the appropriate ram has been actuated to prevent accidentally switching hoses during rig up Flow tees should have a flange connection on the outlet Threaded connections do not effectively support the weight which is inherently applied to this section of the riser Some well flowbacks will bring back sand from the wellbore which can erode the returns line A visual and or ultrasonic inspection should be performed to insure the surface piping is suitable for the operation High coiled tubing rig ups above the wellhead can translate high bending forces with rela
12. kill procedure through the kill line down the coiled tubing left hanging in the slips to eliminate the surface pressure When the well is dead pull out of the hole and repair or replace the coiled tubing string Note If there is acid in the coil it should be displaced to the wellbore with water while pulling out of the hole Coiled Tubing Safety Manual 5 6 Leak in the Coiled Tubing Downhole This condition is characterized by a decrease in pump pressure that could be caused by a leak in the coiled tubing connector or bottom hole assembly or a leak in the coiled tubing itself Either case can lead to a fish being left in the hole and jeopardize the completion a Stop pumping and observe the pressure on the coiled tubing b If there is no pressure on the annulus then pull out of the hole while pumping slowly and repair or replace the coiled tubing or the downhole component of the tool string which caused the problem c If the leak is found to be in the coiled tubing while pulling out of the hole and it cannot safely continue to pull out of the hole the well has to be killed 57 Buckled Coiled Tubing Between the Stripper and Injector Close the slip rams and manually lock them Close the pipe rams and manually lock them c Close the shear rams and manually lock them Cut the coiled tubing d Pick up the coiled tubing 2 feet and close the blind rams e Pull the coiled tubing out of the hole and if necessa
13. operations and 50 fatigue de rating of the weld is recommended e To effectively control the quality of each weld periodic test welds should be done each 30 60 days by the individual welder and inspected by the coiled tubing manufacturer For completeness the non destructive test and evaluation should accompany each weld during its review by the manufacturer In this manner both the weld and the inspection process can be scrutinized for procedure and judgement Each welder should originally be certified by the coiled tubing manufacturer and use this process to maintain the required skills level Alternatively the coiled tubing manufacturer can provide skilled welders as a planned event but is impractical for most field operations e The welds will be much more adversely affected by fatigue cycling than the base material Therefore they should be cut out and re welded long before the life of the coiled tubing has been reached tis not recommended to weld coiled tubing of diameter greater than 1 75 OD for use in well entry The forces on the welded areas have greater associated risk for large diameter pipe when cycled through the drum guide arch and injector head l Corrosive Fluid History If the CT has been stored for an extended period without proper purging and protection then internal corrosion is likely After an acid job it is recommended that the reel be flushed with a neutralizing solution caustic soda or soda ash
14. site to facilitate better grip Use material such as sodium chloride potassium chloride sand etc If the well is under control and there are no mechanical problems then open the pipe rams and slip rams Change the stripper element if necessary Pull out of the hole slowly to determine if the end of the coiled tubing can be pulled inside of the production tubing Pull completely out of the hole to inspect the coiled tubing completely for external damage that may have been caused by the slips or chains during descent 9 Uncontrolled Ascent Out of the Well Apply additional pressure to the stripper assembly and simultaneously close the pipe rams Increase the velocity of the chains in the same direction as the pipe to closer match the speed of the coiled tubing falling into the well This will help relieve the loss of friction between the chains and the pipe Attempt to increase the injector s inside chain pressure to stop the uncontrolled movement of pipe If these attempts are unsuccessful put the injector motors in neutral and close the slip rms Once the pipe motion is halted close the pipe rams and slips if not already closed Pump the hydraulic cylinders open on the injector chain skates Inspect the chain blocks and remove any debris Reset the inside and outside chain pressures to the proper settings If the well is under control and there are no mechanical problems the
15. transport solids Temperature pressure and contamination with hydrocarbons can affect the ability of these products to perform their intended function Xanthan or guar polymer gels are adversely affected by high temperature and hydrocarbon contamination whereas nitrified foam is affected by temperature pressure and hydrocarbon contamination As the fill is removed to the level of the perforated interval hydrocarbons can begin to contaminate the foam or gel without any indication at surface As the gel viscosity decreases or the foam quality is lost the solids settling velocity increases and can stick the coiled tubing Returns to the Flowline Some operators have made it a policy to take retums directly to a flowline instead of an open tank to minimize potential environmental impact or personnel injury due to escaped gas hydrogen sulfide In this situation itis critical to have a method to monitor returns and sand content continuously to respond to lost returns and solids settling The on site production test separator or a sand separator will serve this function The advantage of this option is to limit the amount of surface equipment and an added measure of safety in the returns flowback The disadvantage is that returns fluid content quality and sand concentration are difficult to sample effectively Inline flowmeters will be susceptible to damage from small amounts of sand contained in the retums tubing out of the hole Page 5 Co
16. tubing or down the coiled tubing production tubing annulus If pumping down the CT PT annulus limit the pressure below the collapse rating of the coiled tubing d Displace the well to heavier fluid to provide increased buoyancy e Additional buoyancy can be achieved by displacing the coiled tubing to nitrogen Note that collapse pressure conditions have increased when changing the fluid gas displacement of the wellbore and coiled tubing f Mechanical movement can be induced without the use of hydraulic jars in the tool string See Notes at the end of Section 4 3 5 3 2 Mechanically Stuck If the weight indicator load does not decrease after applying a tensile load of up to 80 of pipe tensile yield rating it is likely that the coiled tubing is mechanically stuck Attempt to lower the coiled tubing into the well to determine if it is actually stuck at that point or if it is unable to pass through a restriction or upset in the completion pipe If the coiled tubing can be moved downward then determine the following a If the pipe or tools could have been bent or buckled by setting down excessive weight or running into an obstruction b Review the well sketch for any obstructions or restrictions Page 9 that may present problems for movement of coiled tubing or downhole tools c Mechanical movement can be induced without the use of hydraulic jars in the tool string See Notes at the end of Section 5 3
17. valves should be run unless reversing operations are anticipated The check valves prevent flow up the CT in the event that a leak develops at surface It is also generally a good idea to run a hydraulic disconnect Ensure that the BHA does not have any square shoulders that could hang up when POOH pulling out of the hole Coiled tubing failures can occur while snubbing into high pressure wells approximately 1500 psi or greater Negative weights combined with operator error and weight indicator malfunction can result in crimped CT in large lubricators or between the stripper and the injector chains Injector pressure should be selected to balance between potential for damaging the coiled tubing if an obstruction is encountered and the possibility of being blown out of the hole if the chains lose the ability to grip the pipe Running speeds should be dependent on well conditions and operator experience Recommended maximums are 100 fpm into the hole and 150 fpm out of the hole slowing down at any restrictions Lower values can be used depending on well conditions and or company policy It is recommended to pump at least minimum rate while in the hole to keep the coil full With the CT overbalanced relative to the tubing the fluids will drain A dry coil with checks in place can then be subject to collapse Page 4 Coiled Tubing Safety Manual 3 3 Well Operations 3 3 1 Initial Coiled Tubing Entry Coiled tubing well
18. 9 31 1994 Stewart Hamish Camco Intemational Inc and Graham Medhurst Coflexip Stena Offshore A Decade of Subsea Well Intervention Coiled Tubing and Well Intervention Technology Feb 9 11 1998 Stricklin David and Mike Smith Cudd Pressure Control Inc Concentric Workovers in a Well Recovery Operation Coiled Tubing and Well Intervention Technology Conference and Exhibition Feb 4 6 1997 Teel Mark E editor World Oil Coiled Tubing Handbook Gulf Publishing Houston Texas 1993 Thomeer Bart Dowell and Sammy Gauthier Conoco Coiled Tubing Services Review of Coiled Tubing Completion Trends Coiled Tubing Technology Operations Service Practices March 13 16 1995 Thompson J M P C Lewis Sid Scott CYMAX and S H Fowler Halliburton Energy Services Full Body Quenched and Tempered Coiled Tubing Theory vs Field Experience Coiled Tubing Technology Operations Services Practices March 29 31 1994 Tippon Steven M University of Tulsa and Paul A Brown Dowell Schlumberger Monitoring Coiled Tubing Fatigue Life Coiled Tubing Technology Operations Services Practices March 29 31 1994 Coiled Tubing Safety Manual Page 27 Tipton Steven M and James R Soren Jr Mechanical Engineering Department The University of Tulsa and Radovan D Rolovic Schlumberger Dowell The Influence of Tubing Rotation on its Mechanical Behavior Coiled Tubing and Well Intervention Te
19. Coiled Tubing Safety Manual Sola Sonny Transocean Petroleum Technology Coiled Tubing Rig Features Unique Configuration Coiled Tubing and Well Intervention Technology Conference and Exhibition Feb 4 6 1997 Sola Sonny Transocean Petroleum Technology The New Generation Coiled Tubing Drilling Rigs CDRO The Future s Ultimate Drilling Machine Coiled Tubing and Well Intervention Technology Feb 9 11 1998 Sorrell Dean and Ron Miller Shell Western E amp P Inc Coiled Tubing CO Gas Lift Evaluated in West Texas Coiled Tubing and Well Intervention Technology Conference and Exhibition Feb 4 6 1997 SPE Reprint Series No 38 Coiled Tubing Technology Society of Petroleum Engineers Richardson Texas 1994 SPE ICoTA Proceedings Coiled Tubing Roundtable 15 16 April 1998 Stanley R K Quality Tubing Inc Results from NDE Inspections of Coiled Tubing SPE 46023 Coiled Tubing Roundtable April 15 16 1998 Stanley Roderic K Quality Tubing Inc Failures in Coiled Steel Tubing Coiled Tubing and Well Intervention Technology Conference and Exhibition Feb 4 6 1997 Stanley Roderic K Quality Tubing Inc Result from NDE Inspections of Coiled Tubing Coiled Tubing and Well Intervention Technology Feb 9 11 1998 Stephens Rodney K and James L Welch BP Exploration Prudhoe Bay Coiled Tubing Remedial Straddle slats Coiled Tubing Technology Operations Services Practices March 2
20. Texas Iron Works Multilateral Branch Drilling Through Tubing Using CT Plans for Snorre Field TLP in Norway North Sea Coiled Tubing and Well intervention Technology Conference and Exhibition Feb 4 6 1997 Pelling Bob Lasmo and Peter Scott Transocean TCP Perforating on Coiled Tubing Using Gun Coiled Tubing Technology Operations Service Practices March 13 16 1995 Penny Rusty Arco Update on Electric Submersible Pump Completion Run on Coiled Tubing Coiled Tubing and Well Intervention Technology Conference and Exhibition Feb 4 6 1997 Plummer Mark J Mark A Peavy Oryx Energy Co and Jay Cooke Santa Fe Minerals Inc Through Tubing Gravel Packs Gulf of Mexico Case Histories Coiled Tubing Technology Operations Services Practices March 29 31 1994 Pourjavad Mohsen EEM Engineering Rolf Bratli and Knut Pedersen Saga Petroleum Finite Element Modeling as a New Design Tool for CTD Branch Design Applied for Snorre Field North Sea Coiled Tubing and Well Intervention Technology Feb 9 11 1998 Procyk Alex Pall Well Technology and George King Amoco Exploration and Production Technology Group Sand Analysis for Screens in Non Gravel Packed Applications Coiled Tubing and Well Intervention Technology Conference and Exhibition Feb 4 6 1997 Qiu Weiyong Baker Oil Tools Stefan Miska University of Tulsa and Leonard Volk BDM Petroleum Technologies Effect of Coiled Tubing Initial C
21. all lubrication orifice so lubrication can be done right at the stripper This has the advantage of placing the lubrication where it is needed and the disadvantage of not being able to visually verify adequate lubrication 5 10 1 Small Stripper Leaks If a small leak develops the stripper pressure can be increased until it stops Do not allow even a small leak to continue because it will cut the elements and become more severe If the leak cannot be stopped by stripper hydraulic pressure and the coil cannot be pulled out the stripper should be changed out immediately Coiled Tubing Safety Manual 5 10 2 Stripper Replacement a O Qa o ca Note the current string weight set the slips on the coil and either slack off coil weight or pick up depending upon whether current weight is positive or negative from 3000 5000 Ibs to be sure the slips are holding Manually lock in the slips Set the tubing rams and be sure the rams are holding by bleeding off above them Manually lock the rams Bleed off the pressure in the well control stack through the kill line Change out the stripper as per the manufacturer s procedure Energize it to the proper pressure setting based on the wellhead pressure The stripper can be pressure tested by pumping through the kill line Equalize the lubricator pressure with the wellhead pressure Unlock and open the tubing rams Set the string weight to
22. and manually lock b Close pipe rams and manually lock c Apply the reel brake if it is not fail safe applied d Maintain circulation if required e Repair or replace he power unit and resume operations 5 2 Collapsed Coiled Tubing Coiled tubing will collapse whenever the differential pressure exerted against the OD exceeds the collapse limit of the pipe This limit is also determined by the tensile load applied to the coiled tubing at the time and the overall condition of the pipe A collapse condition generally occurs just below the stripper assembly and is often detected by a sharp increase in pump pressure while pumping down the coiled tubing When coiled tubing collapsed it will flatten resembling a thin oval cylinder with the center touching This increase in OD is usually greater than the wear bushing ID in the stripper assembly and the collapse will usually be halted at the assembly be cautious of discharged pressure as the stripper element will not effectively seal on the pipe Note Pipe should be checked periodically with calipers to determine the ovality while running in or pulling out of the hole Pipe with greater than 3 ovality should be derated or retired to prevent collapse during operations The maximum acceptable is 6 which should not be run Tubing integrity monitors can also be used to verify the condition of coiled tubing during operations 5 2 1 Collapse with Coiled Tubing Shallow in the Well
23. ated with Inner String Liner Cementing Concept Coiled Tubing and Well Intervention Technology Feb 9 11 1998 Brookley T J Bird and C Garrett Sun Drilling Products Corp Use of Drilling Fluid Additives to Improve Drilling and Remedial Operations with Coiled Tubing Coiled Tubing Technology Operations Services Practices March 29 31 1994 Brown Paul Drexel Coiled Tubing Products Inc Calculate Coiled Tubing Fatigue in Real Time Using Computer Software Coiled Tubing Technology Operations Service Practices March 13 16 1995 Buge Phil Baker Huges INTEQ Update on Fit For Purpose Coiled Tubing Drilling Units Coiled Tubing and Well Intervention Technology Conference and Exhibition Feb 4 6 1997 Burch Douglas W Gerald Loring and Randall Lagendyk Hydraulic Well Control Inc Snubbing Quick Rig Up Provides Economic Alternative for Well intervention Coiled Tubing and Well Intervention Technology Conference and Exhibition Feb 4 6 1997 Chambers Michael J BP Exploration Anchorage Laying Sand Plugs with Coiled Tubing Coiled Tubing Technology Operations Services Practices March 29 31 1994 Chambers Mike J BP Alaska Gregg S Sanders and R H Lane Arco Alaska Gas and Water Shutoffs Using Polymer Gel Temperature Modeling and Coiled Tubing Placement in Alaska and the North Sea Coiled Tubing Technology Operations Service Practices March 13 16 1995 Chitty G H MG Nitr
24. ated in the program design Conduct a pre job meeting with the contractor personnel Determine equipment needs including any possibilities for contingency operations b The subsurface safety valve SSSV should be pulled if it is a wireline retrievable type If it is not retrievable with wireline it should be isolated to prevent closure during the job It can be isolated with a check valve that is placed in line with on or near the wellhead The check valve should allow the hydraulic supply to remain connected in case there Coiled Tubing Safety Manual is a slow seal leak downhole The pressure in this line will increase due to thermal expansion and the check valve assembly should include a bleed to prevent over pressuring the valve seals A gauge run to TD total depth with the largest drift possible is usually made by wireline prior to running coiled tubing The gauge run should include a tubing end locator TEL if an accurate TD is desired Compare the gauge run TD tag to the TD referred to in the program and see if there is a significant difference and whether it will effect the program procedure d Contingency plans should be in place Hazard reviews should be conducted for all non routine operations Refer to API RP 5C7 recommended practice for CT operations Appendix C Emergency Response and Contingency Planning e Rig ups should be in compliance with the BOP Requirement in Section 3 and Section 6 8 Wel
25. ble April 15 16 1998 Sehnal Zdnek Bjorn Ostebo and Kjell Rorhuus Dolphin HWC Extending The Limits of Hydraulic Workover Technology Coiled Tubing and Well Intervention Technology Conference and Exhibition Feb 4 6 1997 Selby B A Halliburton Energy Services N Strinivasan B Donnely IRI Intl Corp R A Vincent and J Wilke Halliburtone Energy Services Hybrid Coiled Tubing System for Offshore Re Entry Drilling and Workover SPE 39374 Coiled Tubing Roundtable April 15 16 1998 Selby Bruce Halliburton Energy Services Horizontal Sidetrack of Existing North Sea Well Coiled Tubing Technology Operations Service Practices March 13 16 1995 Sjonberg Gier Transocean ASA Coiled Tubing Drilling Successful Drilling Offshore in the North Sea Coiled Tubing and Well Intervention Technology Conference and Exhibition Feb 4 6 1997 Smith Bruce ARCO Operational Issues and Experience of Combining CT Unit with a Rotary Drilling Rig Coiled Tubing and Well Intervention Technology Conference and Exhibition Feb 4 6 1997 Smith lan Transocean Well services Ltd and Russsel Jordan Pentex Oil Onshore UK Coiled Tubing Drilling Coiled Tubing Technology Operations Service Practices March 13 16 1995 Smith Ted Halliburton Energy Services Snubbing Unit Enables Foam Wash Sand Removal Coiled Tubing and Well Intervention Technology Conference and Exhibition Feb 4 6 1997 Page 26
26. bore to insure it fully retracts Coiled Tubing Safety Manual 4 Tree Connection Diagram 1 Typical Equipment Layout lt And Preliminary Steps of Pressure Test Page 15 Page 16 Bleed Line 1 Position the coiled tubing injector head and BOPs over the well 2 Perform system pressure test as per Section 4 3 This shows the kill line attached for the rig ups that require it Coiled Tubing Safety Manual Diagram 2 Equipment Rig Up And Pressure Test Stripper assembly Ram type weil control components Ram type well control component Coiled Tubing Safety Manual Page 17 Bibliography Abdulkadir R and S Krueger Halliburton Energy Services Inc and D Aunger and J McMullen PanCanadian Petroleum Coiled Tubing as an Alternative to Service Rig Completions for Multifractured Horizontal Wells in the Westrose Gas Fields in Alberta SPE 46037 Coiled Tubing Roundtable April 15 16 1998 Adams Larry Chevron USA Midland Evaluation of Large Diameter Coiled Tubing for Subsurface Tubular Installations Coiled Tubing Technology Operations Service Practices March 13 16 1995 Ali Nazir Tucker Drilling Services Short Radius Roatary Steerable Drilling Coiled Tubing and Well Intervention Technology Feb 9 11 1998 Angell Paul P BP Alaska Objectives and Results of Horizontal CT Workovers Coiled Tubing and Well Intervention Technol
27. chnology Feb 9 11 1998 Toler Scott Stewart amp Stevenson High Capacity Injector Head for Large OD CT and Jointed Tubing Coiled Tubing and Well Intervention Technology Conference and Exhibition Feb 4 6 1997 Townsend Steve George King and Ernie Onyia Amoco EPTG Drilling Evaluation of a Through Tubing Whipstock System to Exit Both 7 in and 9 5 8 in Casing Strings Using Coiled Tubing Coiled Tubing and Well Intervention Technology Conference and Exhibition Feb 4 6 1997 Wesson W R Rob Cudd Pressure Control Coiled Tubing Pipelines and Flowlines Update 94 Coiled Tubing Technology Operations Services Practices March 29 31 1994 l Williams Brock BP Update on use of CT Self Propelled Hybrid Workover Rig in Arctic Service Coiled Tubing and Well Intervention Technology Conference and Exhibition Feb 4 6 1997 Yang Y S Maurer Engineering Inc V A Avkov Halliburton Energy Services D E Smith Well Service Technology A S J R Martin Qualtiy Tubing Inc and J Wu Chevron Petroleum Technology Coiled Tubing Fatigue Damage on Floating Vessels SPE 46252 Coiled Tubing Roundtable April 15 16 1998 Zheng A S Schlumberger Dowell An Improved Model for Collapse Pressure of Oval Coiled Tubing SPE 46003 Coiled Tubing Roundtable April 15 16 1998 Page 28 Coiled Tubing Safety Manual
28. colm Piutman Baker Oil Tools Fishing Coiled Tubing Coiled Tubing Technology Operations Service Practices March 13 16 1995 Liaaen Nils Rogaland Research Update on Coiled Tubing Research Activities and Projects Coiled Tubing Technology Operations Service Practices March 13 16 1995 Lord D J and J G Brinkhorst Shell UK E amp P T J Robertson Schlumberger Dowell and R H Martin Schlumberger Anadrill Coiled Tubing Drilling on the North Cormorant Platform SPE 46046 Coiled Tubing Roundtable April 15 16 1998 Lord David Jan Brinkhorst Bill Townsley and Philip Bogaert NFU Shell Expro Shell Expro s First Application of Coiled Tubing Drilling Coiled Tubing and Well Intervention Technology Conference and Exhibition Feb 4 6 1997 Martinez Alec and John Martinex Production Assocs Coiled Tubing Velocity Strings Expanding the Cases SPE 46030 Coiled Tubing Roundtable April 15 16 1998 Coiled Tubing Safety Manual Page 23 Matland Ester Knute Arne Jacobsen Johan Kolsto Statoil and Steve Howarth Maritime Well Service Halliburton Coiled Tubing Alliance Planning and Execution of Tubing Milling with Coiled Tubing Coiled Tubing Technology Operations Service Practices March 13 16 1995 l McCoy Terry Halliburton Energy Services and mark Negley Ames Magnetics Inc Estimation of QT 800 Fatigue Lifetime throught the Use of Magnetics SPE 46014 Coiled Tubin
29. d wasn t sufficiently cleaned up afterwards d Friction reducers can lower the circulating pressures encountered during a job and will ease the normal strain of operating conditions The choice of reducers should be evaluated for the type of job performed Formation damage can be an issue with these additives and may affect the performance of corrosion inhibitors e CT safety factors Tensile Generally 70 80 but is dependent on the overall risk level of the program Burst Stay below 4000 psi circulating pressure in order to minimize pipe fatigue Depending on the CT size and yield strength higher pressures can be used under extreme circumstances The maximum allowable static pressure should not be higher than the maximum test pressure and is typically no more than 4500 psi When in static conditions consider the burst loading along the entire length of the string Collapse Collapse rating is a function of tensile load and CT ovality It is necessary to refer to stress ellipse diagrams which account for tensile loads however ovality is not considered Ovality can dramatically reduce the collapse resistance API RP5C7 RP for Coiled Tubing Operations in Oil and Gas Well Services has recently published collapse de ratings for ovality Table 6 Remember that the worst case collapse conditions aren t always at the surface A BHA bottom hole assembly diagram with all fishing dimensions should be made prior to RIH Dual check
30. derations iis siscscarctexcansisteeratetticanaticcunss Ada ateniemsgioee danas eee 2 3 2 Coiled Tubing Considerations csssssssssssssccssessssssssorssossssersssscorssoneesssssressenensossssessseerees 3 Fie HISO Ne 3 Location and De Rating of Field Butt Wells cccccccsssscsesesscsssessseeeseescsseasseseseeseees 3 Corrosiove Fluid History Luske Gnaeus 3 Surfaces Damage suasit 4 3 3 Well Operations urtene eee ea 5 3 3 1 Initial Coiled Tubing Entry saadan 5 302 Be i Per E AA TE A ERN 5 Lost Circulation and Bridges eesssensssesssesssresssrssssessrressersseennssressonsneosrreunrnsnneserosrensres 5 Horizontal Well Cleanouts A Special Problem ennsesvvrevvvevnnenervrnensvrrvsvernsenenerernernner 5 Fluid Viscosity Degradation ccccscscsscsesesssesesssssssscsesesssessesessssrsesseereesseeesssscaeseseneetaees 5 Returns to the Flowline Luse 5 Section 4 Pressure Testing ua SSD EE EGGE 6 4 1 Blowout Preventers s s sessesseseesseesnssossenressonrosenresnresennrressestentoranenrsronsstoutstenttseenentores ind 4 1 1 General Pre Job Inspections oeornservvrnrerevnerernrrrrrserenenevrnsrrverevanenesevevsveverenersesesesrernssnnen 6 212 FOO ENN 6 4 1 3 Pressure Testorn itunean ninan a aaa ai 6 4 1 4 Minor Disassembly and Inspection esessesesoesresersssnenseseeessorsrissurnnsarssseensreesnssensuenssreeras 6 4 1 5 Disassembly and Inspection ccccscscssssssssss
31. ence and Exhibition Feb 4 6 1997 Beynon Douglas Sonoma Corp New Bi Directional Clean Out Tool for Cleaning Obstructions Using CT Coiled Tubing and Well Intervention Technology Feb 9 11 1998 l Blount C G L L Gantt D D Hern M B Mooney and B E Smith ARCO Alaska D Quinn Schlumberger Anadrill and E B Larson Schlumberger Dowell Development Update of an MWD Directional Drilling Package for 2 4 Opernhole Tiny Tools SPE 46016 Coiled Tubing Roundtable April 15 16 1998 Coiled Tubing Safety Manual Page 19 Blount Curtis G and C M Mel Hightower ARCO Alaska Advancements in Coiled Tubing Drilling and Completions at Prudhoe Bay Coiled Tubing Technology Operations Services Practices March 29 31 1994 Blount Curtis G Arco Alaska Though Tubing Completion and Zonal Isolation of Coiled Tubing Drilled Drainholes Coiled Tubing Technology Operations Service Practices March 13 16 1995 Blount Curtis ARCO Alaska Inc Drilling with a 2 3 8 in Collar OD MWD System Coiled Tubing and Well Intervention Technology Conference and Exhibition Feb 4 6 1997 Bond Andrew J Arco Alaska and BP Alaska authors Latex Acid Resistant Cement and Various New or Existing Placement Techniques Coiled Tubing Technology Operations Service Practices March 13 16 1995 Braddick Britt O TIW Corp and Knut Pedersen Saga Petroleum New Design Thru Tubing Retrievable Whipstock Integr
32. entry will be easier if WHP is reduced below 1800 psi by pumping fluid into the well immediately prior to the RIH If this is not possible or practical evaluate the ability to grip the coiled tubing with the injector chains to prevent being blown out of the hole As coiled tubing becomes pipe heavy this possibility decreases Maximum applied weight at the end of the coiled tubing should not be higher than 3000 pounds to prevent permanently buckling the coiled tubing in wells that are vertical or nearly vertical In deviated wells this figure may increase depending on the tubing force analysis and helical buckling tendency 3 3 2 Cleanouts On average this is the most common use for coiled tubing in the industry The preservation of the wellbore for the purpose of this discussion pertains to preventing stuck pipe and requires nearly complete transport of the solids to surface To achieve this the circulated fluid has to be pumped at a rate capable of overcoming the settling tendency of the solid particles obstructing the wellbore Several factors can affect solids transport Lost Circulation and Bridges Removal of a sand solid bridge can create a temporary Situation of lost circulation This may allow the solids which have been brought only part of the way to surface to fall freely and stick the coiled tubing Continuous movement of the coiled tubing will physically distribute the sand to prevent stuck pipe Itis important to contin
33. eration is to perform a wireline gauge run prior to running coiled tubing in a well Fluid and nitrogen pump discharge and pressure release valves should be directed away from normal personnel work areas Fluid pans should be used under all pieces of equipment Wellbore returns should be routed to surface tanks away from combustion sources or taken directly to a permanent flowline Sand or other solids should be disposed of in an environmentally approved method to prevent future contamination Typically solids will be washed to remove the hydrocarbons before being stored in a container for disposal Care should be taken to monitor solids for radioactivity to determine any special disposal needs Liquid nitrogen tank and hoses should be protected from leaking which could affect platform decking and structural support Surface hydraulic master valves should be isolated with a lead fusible cap to prevent closing unless in the event of a fire 1 Downhole hydraulic safety valves should be isolated at surface with a check valve mounted in line on near the wellhead This will prevent inadvertent closure in the event of loss of hydraulic system pressure or if the valve seals have a slow leak Page 13 Appendix 1 Pressure Testing Time Table from Section 4 General Inspection Section 4 1 1 Function Test Section 4 1 2 Pressure Test Section 4 1 3 Minor Disassembly Section 4 1 4
34. f the coil still above the BOPs pressure through the coil to 400 psi and close the blind ram or the top set of blind shear rams Bleed the pressure off from above the ram The WHP should read 400 psi and the lubricator pressure CTP should read zero Hold the low pressure test for 5 minutes Open the blind ram or the top blind shears and pressure through the coil to 4000 psi close the rams and bleed off the pressure above the them The WHP should read 4000 psi and the lubricator pressure should read zero If the WHP drops but the lubricator pressure remains zero the swab valve is leaking c Equalize the pressure across the blind rams and open the blinds Check the shear rams or the lower set of blind I shear rams with the same procedure d Run the coil into the BOP stack and lightly tag the closed swab valve gate and pick up 1 foot Ensure that coiled tubing is across the pipe rams and that the right size of pipe rams are in the BOP s Close the pipe rams Pressure up through the coil to 400 psi The coil pressure should read 400 psi and the lubricator pressure above the pipe rams should remain at zero If the lubricator pressure remains zero but the coil pressure bleeds off the swab valve is leaking This may be able to be corrected by greasing the valve but may require a two way sealing valve to be installed below the BOPs e Increase the pressure to 4000 psi for the high pressure test The coil should remain at 4000
35. g Roundtable April 15 16 1998 McMechan Roger PetroCanada Resources and Dave Crombie Nowsco Well Services Drilling Completing and Fracturing a Gas Well with Coiled Tubing Coiled Tubing Technology Operations Services Practices March 29 31 1994 Melvan J BP Exploration Consultant Coiled Tubing Fill Clean Outs Coiled Tubing Technology Operations Services Practices March 29 31 1994 Misselbrook John Nowsco Well Services Coiled Tubing Drilling for Underbalanced Well Finishing Coiled Tubing Technology Operations Service Practices March 13 16 1995 Moak Tony W Terry Prater Ensearch Exploration Inc Randall Lagendyk and Brent E Olsen HWC Inc Through Tubing Snubbing Workover on a Subsea Well Under Pressure Coiled Tubing and Well Intervention Technology Feb 9 11 1998 Moore Brian Nowcam The Mechanics of Coupling Completion Equipment to Coiled Tubing Coiled Tubing Technology Operations Services Practices March 29 31 1994 Myklebust Jens Kjell I Torgerson JM Consult and Knut Pedersen Saga Petroleum The First Remote Operated Pipe Handling System for CTD Liner Installation Coiled Tubing and Well Intervention Technology Feb 9 11 1998 Newman Ken Drexel Coiled Tubing Products Inc Hybrid Coiled Tubing Snubbing Unit Drilling and Completions Coiled Tubing Technology Operations Service Practices March 13 16 1995 Newman Ken Drexel Phil D
36. g Technology Operations Service Practices March 13 16 1995 Head P F XL Technology Ltd T J Hanson Enterprise Oil Plc M Yuratich TSL Technology Ltd and D R Turner XL Technology Ltd Electric Coiled Tubing Drilling The First Steps Toward a Smart CT Drilling System SPE 46013 Coiled Tubing Roundtable April 15 16 1998 Head Philip XL Technology Ltd ESP Deployment on Coiled Tubing with Intemal Power Cable Coiled Tubing Technology Operations Service Practices March 13 16 1995 Hern Dave Arco Alaska Coiled Tubing Window Milling Techniques Coiled Tubing Technology Operations Service Practices March 13 16 1995 Herring Barry Quality Tubing On and Offshore Flowline Pipeline Coiled Tubing Installations Coiled Tubing Technology Operations Service Practices March 13 16 1995 Hightower C M Mel ARCO E amp P Technology An Operator s Coiled Tubing Drilling History Coiled Tubing and Well Intervention Technology Conference and Exhibition Feb 4 6 1997 Page 22 Coiled Tubing Safety Manual Hightower C M Mel ARCO E amp P Technology An Operator s CT Drilling History Coiled Tubing and Well Intervention Technology Feb 9 11 1998 Hoyer Carel Nowsco Well Services Coiled Tubing Straddle Packer Stimulations Coiled Tubing Technology Operations Service Practices March 13 16 1995 International Coiled Tubing Association 1997 Coiled Tubing We
37. gain 5 3 Coiled Tubing Stuck in the Hole When the pipe is unable to be moved freely with a force of 80 of the tensile yield the pipe is stuck due to one of two reasons Friction sticking is due to a tortuous wellbore or buckled production tubing Mechanical sticking can be the result of solids accumulation around the coiled tubing or downhole tools becoming lodged in the completion 5 3 1 Friction Stuck Coiled Tubing Preventing friction stuck coiled tubing begins in the job planning by identifying wellbore paths that have areas of Coiled Tubing Safety Manual dogleg severity DLS that can inhibit the free movement of pipe Normally a relatively high DLS 10 15 deg 100 can be tolerated if it exists in an isolated area However if they are widespread in the completion even a moderate DLS can frictionally stick the coiled tubing The drag weigh forces can be modeled to determine if there will be a problem While performing the operation frequent weight checks each 500 will help identify a problem before it becomes severe This can also be a problem in dual or triple completions even if there is no obvious DLS problem a Apply 80 of the tensile yield to the pipe and maintain that force for a minimum of 30 minutes b If possible continue to maintain circulation by pumping at low rate pressure to minimize the coiled tubing pressure c Pump friction reducing additives such as polymer gel diesel or beads down the coiled
38. ic from the National Technical Information Service U S Department of Commerce 5285 Port Royal Rd Springfield VA 22161 DISCLAIMER Portions of this document may be illegible in electronic image products Images are produced from the best available original document DOE SW 41286 1 Distribution Category UC 122 Coiled Tubing Safety Manual By Walter Crow April 1999 Work Performed Under Contract 75 97SW41286 Prepared for U S Department of Energy Assistant Secretary for Fossil Energy John Ford Project Manager National Petroleum Technology Office P O Box 3628 Tulsa OK 74101 Prepared by Westport Technology Center 6700 Portwest Dr Houston TX 77024 Table of Contents Section 1 Well Control Equipment ccccsscssssessssessssssecsssesssseseessseasesesescseseessssessacssseteceesnerssnacavseseeases 1 1 1 Blind RAMS eTa rran e E eras tame to sein N A NRN 1 1 2 Shear RIMS EE RE EE SE EE aai 1 1 3 Slip RMS EEE EE E E RN EE 2 1 4 Pipe RAMS ie eon aaea a T T A AE N NREN 2 1 5 Downhole Check Valves sesnessnnesosssrnssresssnnssssosssrsersusressunosorsatusonsrinsransrensacnsresursaeeseres 2 1 6 TWO WAY Sealing Valve eden 2 Section 2 Well Control Equipment for Hydrogen Sulfide cesesssessssessesssesssecssessesssecesecsesesesssceeaeeeeees 2 Section 3 Guidelines for Planning Coiled Tubing Operations 00 0 cccssesessescssssesessseeseseessesesseesesesessesesesens 2 3 1 General Consi
39. iled Tubing Safety Manual 4 0 Pressure Testing Inspection Requirements Procedure The generally accepted procedure is to pressure test with non flammable non energized fluids It is not recommended to pressure test with nitrogen gas Leaks detected in this type of environment are slow to bleed down and have the potential for injury to personnel Please refer to the chart in Appendix 1 for time related reference of the following pressure testing guidelines 4 1 Blowout Preventers 4 1 1 General Pre Job Inspection a Check hoses for wear kinks worn spots and general condition b Confirm configuration of rams i e blind shear pipe slip ram placement c Check BOP system operating pressure d Confirm proper hydraulic fluid summer winter is in use e Check that all isolation valves are open 4 1 2 Function Test a Should be performed before each job b Close and open each ram Record time required to function Be sure pipe rams are functioned on pipe and not empty bore c Maximum allowable function time is 30 seconds If longer than 30 seconds is required then the test is considered a failure and the unit should be returned to the shop until repairs are made 4 1 3 Pressure Test a Should be performed weekly b Test each ram from below to 200 psi and to the rated working pressure of the BOP or X mas tree whichever is lower c Pipe rams should be tested to lesser of BOP X mas tree or collap
40. inhibited and then purged with nitrogen A cap with a valve should be placed on both ends to prevent loss of the nitrogen blanket It Page 3 is not sufficient to flush with diesel after an acid job since this will not effectively dilute the acid or stop it from spending itself on the coiled tubing There are a wide variety of acid corrosion inhibitors whose temperature limit will affect the concentration to be used An added measure of protection can be achieved by pumping a small volume of inhibitor through the coiled tubing prior to well entry Surface damage Surface marks can reduce fatigue life by 50 or more Chain alignment and wear of the gripper blocks can cause this type of damage Itis critical that the tubing guide arch is properly aligned with the centerline that the coiled tubing takes through the injector chains Most coiled tubing unit manufacturers suggest that this be done with approximately 1000 of coiled tubing in the hole when itis pipe heavy It is not sufficient to make this alignment with a solid bar while the injector is on the ground and being connected to the guide arch This is typically difficult to do during operations since the injector head is difficult to access after it is rigged up and the job is in progress c Does the CT need to be pigged or drifted prior to RIH Determine if the coil had been welded recently and pigged afterward Or cement was pumped through the coil recently an
41. l Control Equipment of API RP 5C7 f Refer to API RP 500B to ensure that all electrical codes are adhered to O 3 2 Coiled Tubing Considerations a Run predictive models to determine weight and CT forces String weight is dependent on the length of CT wellbore geometry WHP Wellead Pressure fluids in the CT and tubing and stripper psi Run simulations for all of the anticipated conditions While RIH Running in the hole check actual weights against simulations If there are significant differences determine the reason before proceeding further b Coiled Tubing Condition Fatigue History If there are high cycle areas itis suggested to check coiled tubing ovality while RIH This can be done with a set of calipers and measuring the diameter in the x and y axis of the coil e A simplified way of measuring coiled tubing life is by tracking cumulative footage in one direction across the tubing guide arch Some operators have adopted the Coiled Tubing Safety Manual policy of changing out the coiled tubing reel after a cumulative footage of 450 000 to 500 000 running feet has been reached e Computer programs are also available to track coiled tubing life and can be used for predicting tubing forces e Either method will require assumptions to be made for derating the coiled tubing for the type of operations performed Location and De Rating of Field Butt Welds Strict QA QC must be adhered to during the welding
42. lding Specifications for Tube to Tube Welds Johnson Ashley Schlumberger Cambridge Research and David Eslinger and Henrik Larson Schlumberger Dowell An Abrasive Jetting Scale Removal System SPE 46026 Coiled Tubing Roundtable April 15 16 1998 Johnston Colin Baker Hughes INTEQ Evolution and Development of Fit for Purpose CTD Rigs Coiled Tubing and Well Intervention Technology Feb 9 11 1998 Larimore David R Gary Z Fehrmann and Russell Bayh lil Halliburton Energy Services Case Histories Advancements in Slickline Technology Provide Cost Efficient Well Intervention Coiled Tubing and Well Intervention Technology Conference and Exhibition Feb 4 6 1997 Latos Gordon Nowsco Well Service Performance and Economy in Downhole Jetting Coiled Tubing Technology Operations Services Practices March 29 31 1994 Leising L J and I C Walton Schlumberger Dowell Cuttings Transport Problems and Solutions in Coiled Tubing Drilling SPE 39300 Coiled Tubing Roundtable April 15 16 1998 Lemp Stephen P Cliff Webe and Bart Thomeed Dowell Downhole Sensors for Coiled Tubing Stimulations Coiled Tubing Technology Operations Services Practices March 29 31 1994 Leslie Charles BP Exploration Aberdeen Coiled Tubing Drilling Operations in BP s West Sole Field Coiled Tubing Technology Operations Service Practices March 13 16 1995 Leslie Charlie BP Exploration and Mal
43. le Halliburton Energy Services A Coiled tubing Recompletion Technology Overview Including Repair Patches Concentric Installations and Circulating Gravel Packs Coiled Tubing Technology Operations Service Practices March 13 16 1995 Fowler Hampton Halliburton Energy Services Coiled Tubing Completion Opportunities Equipment and Considerations for Running Larger Diameters Coiled Tubing Technology Operations Services Practices March 29 31 1994 Fowler S H FibersparSpoolable Products Inc and M Feechan and S A Berning Halliburton Energy Services Applications Update Advanced Composite Coiled Tubing SPE 460543 Coiled Tubing Roundtable April 15 16 1998 Gantt Lamar L and Bruce E Smith ARCO Alaska Advancements in the Coiled Tubing Cement Squeeze Process at Prudhoe Bay Coiled Tubing Technology Operations Services Practices March 29 31 1994 Coiled Tubing Safety Manual Page 21 Gantt Lamar Arco Alaska North Slope Coiled Tubing Drilling Experience Including Workover Rig Assist and MWD Coiled Tubing Technology Operations Service Practices March 13 16 1995 Gary Susan Schlumberger Dowell Methodology for Designing Coiled Tubing Wellbore Cleanouts Coiled Tubing Technology Operations Service Practices March 13 16 1995 Gordon Doug Shell Western E amp P Inc SWEPI and Willem van Adrichem Shlumberger Dowell High Pressure Coiled Tubing Unit for South Texas
44. luded in the equipment inventory and the well control equipment This will serve as an additional barrier above the swab valve of the wellhead Many swab valves may have a slow leak and are not designed to hold pressure from above This may complicate and extend the pressure test procedure Additionally this valve should be capable of cutting the coiled tubing with its gate and still effect a pressure seal 2 0 Well Control Equipment for Hydrogen Sulfide Service Well control equipment should comply with API Recommended Practice 53 Section 9 when the equipment may be exposed to fluids from hydrogen sulfide gas zones that could result in the partial pressure of hydrogen sulfide exceeding 0 05 psia in the gas phase at the maximum anticipated pressure l Also liberated hydrogen sulfide gas in the returns may require routing them directly to the flowline and production facilities Hydrogen sulfide detection monitors should be located near the returns pit in two locations depending on wind direction to facilitate detection 3 0 Guidelines for Planning Coiled Tubing Operations 3 1 General Considerations a Review the well file and other pertinent data to identify any aspect of the completion or the well history that will affect the coiled tubing entry A current completion schematic is critical Identify the objective and prepare contingency plans The success of any operation depends on input from all personnel involved and should be incorpor
45. n open the pipe rams and slip rams Change the stripper element if necessary Page 12 i Reduce the hydraulic pressure on the stripper element and pick up the coiled tubing enough to inspect the areas of pipe held by the slips j Determine whether it will be necessary to repair replace that section of coiled tubing prior to resuming the pipe extraction Be extremely cautious while checking the area of pipe held by the slips since the pipe may be weakened and may fail with high surface pressure present k Continue to pull out of the hole and close the master valve Determine the cause for the uncontrolled movement of pipe prior to entering the well again Replace or repair the coiled tubing string as required If the coiled tubing is blown out of the stripper assembly close the blind rams and master valve as quickly as possible 5 10 Stripper Leaks Stripper leaks are a common occurrence and are affected by many factors such as stripper hardness coil smoothness effectiveness of the coil lubrication system and the stripper pressure that is used Without adequate lubrication strippers can completely grip the coil while going in the hole This can cause coil failure between the stripper and the injector head chains The standard coil lubrication procedure used to consist of lubricating the coil with diesel at the spool To reduce the environmental impact of dripping diesel on the ground the stripper housing can be and fitted with a sm
46. ng that can be released pump a ball to release the hydraulic disconnect if it is determined that the BHA is getting hung up m Kill the well cut the coiled tubing at the surface and run a free point tool to determine the depth to the stuck point Follow normal fishing procedures to remove the coiled tubing 5 3 3 Mechanically Stuck without Circulation a Pump the kill weight fluid down the coiled tubing Ifitis not possible to pump down the coiled tubing attempt to pump the kill weight fluid down the annulus at pressures below the collapse pressure of the coiled tubing b Cut the coiled tubing at surface and run a free point tool Follow normal fishing procedures 54 Leak in Riser or Connections Below the Well Control Stack a This is usually manifested by a drop in pump pressure It is advisable to verify the source of the problem before continuing with the job to minimize the potential problems b Displace the coiled tubing with water or another kill weight fluid This will help prevent oil gas entry into the coil Begin pulling out of the hole and continue pumping kill fluid through the coiled tubing This will minimize the environmental Coiled Tubing Safety Manual impact of fluid spray If possible use a covering to help contain the spray as the hole is brought above the well control stack When the end of the coiled tubing reaches the well control stack close the master valve and
47. ogen Services Canadian Air Drilling Services Ltd Corrosion Issues with Underbalanced Drilling in H2S Reservoirs SPE 46039 Coiled Tubing Roundtable April 15 16 1998 Coats Alan Greg Clawson Preeminent Energy Services Tim Sargent and Joe Zimmerman Samedon Coiled Tubing Resin Sand Control in a Gulf of Mexico High Pressure Gas Well Coiled Tubing and Well Intervention Technology Conference and Exhibition Feb 4 6 1997 Conrad A B D W Morrison and Rufus Mullins Halliburton Energy Services Effective Management of Coiled Tubing Workstrings SPE 46034 Coiled Tubing Roundtable April 15 16 1998 Coronado M P Baker Oil Tools Development of an Internal Coiled Tubing Connector Utilizing Permanent Packer Technology SPE 46036 Coiled Tubing Roundtable April 15 16 1998 Page 20 Coiled Tubing Safety Manual Courville Perry and Vladimir Avakov Halliburton Energy Services Coiled Tubing String Management Coiled Tubing Technology Operations Services Practices March 29 31 1994 Crow Walter Crow Consulting and Perry Hill BP Exploration Concentric Sandscreen Repair of a Horizontal Completion Failure A Case History Coiled Tubing Technology Operations Service Practices March 13 16 1995 Crow Walter Tucker Energy Services Risk Analysis and Project Evaluation for Remedial Operations Coiled Tubing and Well Intervention Technology Feb 9 11 1998 Dahl Jorgensen Einar
48. ogy Feb 9 11 1998 Angell Paul BP Exploration Anchorage Low Cost Coiled Tubing Gas Lift and Compact Platform BOP Deck CT Unit installations Coiled Tubing Technology Operations Service Practices March 13 16 1995 Avakov Vladimir A and Jerry C Foster Halliburton Energy Services Coiled Tubing Life Strain Reliability Function Coiled Tubing Technology Operations Services Practices March 29 31 1994 Avakov Vladimir Halliburton Energy Services Collapse Data Analysis and Coiled Tubing Limits SPE 46004 Coiled Tubing Roundtable April 15 16 1998 Badrak R P Prescision Tube Technology High Strength Coiled Tubing SPE 46052 Coiled Tubing Roundtable April 15 16 1998 Bartlet Paul BP Exploration Alaska Using Through Tubing Whipstocks for CT Sidetracks Coiled Tubing and Well Intervention Technology Feb 9 11 1998 Baugh Benton F Radoil Tool Co Extended Reach Pipeline Blockage Remediation Coiled Tubing and Well Intervention Technology Conference and Exhibition Feb 4 6 1997 Bedford S A BP Exploration and P Divers Transocean Well Services Coiled Tubing Operations in Northern North Sea Magnus Field Coiled Tubing Technology Operations Services Practices March 29 31 1994 Beynon Douglas and Daniel Thompson Sonoma Corp Performance Comparison of Impact Drill Jars with Conventional Downhole Motors Coiled Tubing and Well Intervention Technology Confer
49. onfiguration on Buckling Behavior in a Hole of Constant Curvature SPE 46009 Coiled Tubing Roundtable April 15 16 1998 Qiu Weiyong Prediction of Contact Force for Drill Pipe Coiled Tubing SPE 51092 Quigley M S and L R Stone CTES L C The Benefits of Real Time Coiled Tubing Diameter Measurements SPE 46040 Coiled Tubing Roundtable April 15 16 1998 Ravensbergen John and Andrew Campbell BJ Services A Perforating Deployment System ford Coiled Tubing Coiled Tubing and Well Intervention Technology Conference and Exhibition Feb 4 6 1997 Robberechis Hilde Conoco Specialty Products Inc and Curtis Blount ARCO Alaska Inc A New Generation of Drag Reducer Additives for Hydrocarbon Based CT Applications Coiled Tubing and Well Intervention Technology Conference and Exhibition Feb 4 6 1997 Romagno Roy A CalResources Inc and Dave Ewert Halliburton Energy Services Onshore Califomia Coiled Tubing Drilling Coiled Tubing Technology Operations Service Practices March 13 16 1995 Rosen P M A Rosen Inspection Technologies Remote Coiled Tubing Operation Monitoring SPE 46038 Coiled Tubing Roundtable April 15 16 1998 Rosen Patrik Rosen Inspection Technologies Progress in Onshore and Offshore Coiled Tubing Inspection and Monitoring Coiled Tubing Safety Manual Page 25 Coiled Tubing and Well intervention Technology Conference and Exhibition Feb 4 6 1997
50. p ram f Pipe ram g Flow tee and 2 5000 psi valve h Riser sections optional depending on rig up configuration i Two Way Sealing Valve optional Notes The blind and shear ram can be combined into a single component as well as the pipe and shear ram e The kill line will not be used to take returns from the wellbore Instead a flow fee should be mounted below the BOP stack for flowback The master valve of the wellhead should never be closed to gain access to a well If a swab valve is leaking it should be repaired prior to rigging up coiled tubing equipment Optionally an additional two way sealing valve can be added to the wellhead Ideally this valve should be capable of cutting the coiled tubing with minimal hanging weight All connections from the wellhead to the BOP stack should be flanged connections The BOP should be mounted as close as practical to the wellhead Wellheads which have threaded connections such as multiple completions should consider changing out the tree prior to the coiled tubing workover if at all possible In the eventit is impractical to change out this type of wellhead two considerations are suggested First use a platform style base to rest the weight of the coiled tubing which will minimize side loading by the sway of crane support or independent legs Second incorporate a two way sealing valve immediately above the swab valve that has demonstrated capability to cut the size
51. psi and the lubricator above the pipe rams should read zero f Equalize across the pipe rams and then open them g Function test the slips and record opening and closing times The opening closing times of all the BOP rams should also be recorded during the pressure testing A Closing time greater than 40 seconds is not acceptable all the rams usually close in 5 15 seconds times are longer in very cold conditions Page7 NOTE Be careful when pressure testing that the coil is not subjected to a collapse pressure This is especially true when check vaives are installed The bottom part of the coiled tubing should be visually inspected after the pipe ram pressure test fo insure that it has not collapsed Additionally after step e of the BOP test it is convenient to test the check valves if they are installed in the string Bleed the pressure below the pipe rams to 2000 psi and then bleed off the CTP and see if the WHP follows The CTP should be bled to around 100 psi and blocked in Watch to see if the CTP builds and the WHP drops If the BOPs function and pressure test OK then install the fusible cap on the surface safety valve SSV and run in the hole RIH 5 0 Emergency Procedures In each of the following conditions when a ram is closed it should also be locked manually to prevent accidental opening in the event of a hydraulic system pressure failure 5 1 Power Pack Failure a Hang off coiled tubing in slips
52. r disassembly 4 2 Accumulator a Sizing of Accumulator bottle system The Accumulator bottle system should be sized to provide twice the necessary volume to open and close each ram in the BOP stack without lowering the Accumulator pressure to less than 200 psi above pre charge pressure b Recommended pre charge and BOP operating pressure The BOP operating pressure should be 2500 3000 psi with pre charge pressure of 1000 psi c Accumulator operation and safety recommendations All Accumulator bottles should have valves for isolating Coiled Tubing Safety Manual individual bottles from Accumulator system in event of leaks or damage Guards removable should be installed over the pre charge connections of Accumulator bottles Gauge and necessary connections for checking pre charge pressure should be kept on unit Checking pre charge pressure Isolate Accumulator system from hydraulic system and closing unit Drain hydraulic fluid from bottom of Accumulator bottles to hydraulic reservoir Install gauge in top of bottles and check pre charge pressure Pressure should not be lower than 950 psi or greater than 1100 psi Isolation Valve There should be an isolation valve between the Accumulator system and the main hydraulic source that can be closed to allow for testing of the Accumulator bottles Qa D 4 3 Remote Hydraulic System Tie In a Each unit shall have an easily accessible point to tie in an auxiliary hydra
53. rake Hydra Rig and Rick Palmer Texas Oil Tools New Developments in Coiled Tubing Equipment Coiled Tubing Technology Operations Services Practices March 29 31 1994 Nirider Lee Marathon Oil Co Coiled Tubing Completions A Marathon Oil Co Overview Coiled Tubing Technology Operations Service Practices March 13 16 1995 Ostvang Knut John Haukvik Statoil A S Terje Skeie MWS and Jorgen Hallundboek Welltec World s First Successful Horizontal Wireline Operation Coiled Tubing and Well Intervention Technology Conference and Exhibition Feb 4 6 1997 Ostvang Knut Oddbjorn Kopperstad and Roger J Tailby Statoil Planning Implementation and Analysis of Coiled Tubing Operations in Ultra Long Reach Wells Coiled Tubing Technology Operations Services Practices March 29 31 1994 Papadimitriou Steve Stwylan Inc and R K Stanley NDE Information Consultants Inspection of Used Coiled Tubing Coiled Tubing Technology Operations Services Practices March 29 31 1994 Pearson Jim Dowell Schlumberger and Paul Starck Maersk Oil amp Gas First Boat Based CT Operations in the North Sea Coiled Tubing and Well Intervention Technology Feb 9 11 1998 Page 24 Coiled Tubing Safety Manual Pedersen Knut Svein Orstland Ivar Spilling Rolf Bratlie Saga Petroleum ASA Tony Hargreaves Dowell Paul Lonsdale Anadrill Jim Crawford The Red Baron and Brit Braddick
54. replace repair the leading riser section Watch for the possibility of the coil not being able to pass the stripper bushing This is a sign of severe damage and will require killing the well and cutting the coil If itis unsafe to pull out of the hole with surface pressure present kill the well Resume pulling out of the hole Once the leak has cleared the well control stack revert to the section Leak in the Coiled Tubing Above the Stripper 55 Leak in the Coiled Tubing Above the Stripper Very high compressive loads can be achieved when first Starting to RIH with coiled tubing so extreme care should be taken to prevent crumpling the coiled tubing Stop moving the coil and shut down the pump Inspect the hole Ifitis a pinhole or if there is only minimal leakage or flow continue to pull out of the hole Placing the leak onto the drum will help contain the spill If the hole is large and leaks significantly it may not be possible to continue spooling the coiled tubing If the check valves hold pressure the damaged section of the coiled tubing can be cut and reconnected to continue spooling If the check valves do not hold or if they have not been used pick up off bottom set the slips and cut the coiled tubing with the shear rams Note Use the lower blind shear rams if there are two sets in the well control stack Pick the coiled tubing up above the upper blind shear ram and close the rams Initiate a
55. rrsenrnenrnrr 10 55 Leak in the Coiled Tubing Above the Stripper 0 0 ccscssscscscssssccesscetsessssceesessesesenesees 11 5 6 Leak in the Coiled Tubing Downhole cccessesssecscsssssocsesecsseseessserserescenssesescsesesessers 11 5 7 Buckled Coiled Tubing Between the Stripper and Injector o sorarrrervrrrorrearrrrererrsvnrnnns 11 5 8 Uncontrolled Descent of Coiled Tubing ccessessesessssessestecessesesecsssnssssessesssecscereneess 11 5 9 Uncontrolled Ascent out of the Well ccssssssecssssssessensesssssecessseaserescsecsssscacereececesesears 12 5 10 SUPPER SARS Lasse A A en 12 5 10 1 Small Stripper Leaks eee 12 5 10 2 Stripper Replacement ssseessssseesseroessassrreessnersusernssssonsnesssneossnorieonsnersssreossersoreaneesrenss 12 S 8 a eTa o LAS EOE T E EEA 13 Section6 Equipment Layout and Site Preparation isesnsernrererevvrvrvvrrvnrnernrvrnrrrnerersersressenersverssererenne 13 Appendix 1 Pressure Testing Time Table from Section 4 seseecenscnnsnsnsssenansassanccrecesennenensennnassssnsesses 14 Diagram 1 Equipment Layout and Preliminary Steps of Pressure Test ccccsssesscssssssesesessesessseeeeens 15 Diagram 2 Equipment Rig Up and Pressure Test smevvrnvrvvrerovrrenvrsreerrersvenserenersesenersersressvsenereresensser 16 PAGAL EEE dela costa dade aepaliras EN 17 Bbledrepuvavv2v5v44454v44r ev 19 28 Coiled Tubing Safety Manual Page iv
56. ry kill the well to retrieve Ua 58 Uncontrolled Descent of Coiled Tubing a Apply additional pressure to the stripper assembly and simultaneously close the pipe rams b Increase the velocity of the chains in the same direction as the pipe to closer match the speed of the coiled tubing falling into the well This will help relieve the loss of friction between the chains and the pipe Attempt to increase the injector s inside chain pressure to stop the uncontrolled movement of pipe c Once the pipe has stopped falling through the chains slowly reduce the chain speed and come to a complete stop d Close the slip rams and manually lock them e Once the pipe has stopped close the pipe rams and inspect for damage to the chains or pipe f Observe pump pressures and circulation rate to determine Page 11 OQ X 5 ko hon a if there is any damage to the bottom of the coiled tubing such as a crimp kinks or buckling Pump the hydraulic cylinders open on the injector chain skates Inspect the chain blocks and remove any debris Reset the inside and outside chain pressures to the proper settings Verify the proper alignment and spacing between the chains If necessary replace the chains or individual gripper blocks as necessary to prevent damage to the coiled tubing while pulling out of the hole If no additional chains or gripper block inserts are available the chains can be material on
57. s Westport greatly appreciates the U S Department of Energy National Petroleum Technology Office in Tulsa for sup porting this project The ultimate success will be measured through the transfer of this information to the industry especially with the help of the Petroleum Technology Transfer Council PTTC through their valuable services to the industry We would like to express our thanks to the number of production operators service companies and individuals who contrib uted their valuable time data and experience to making this document Finally Westport wishes to acknowledge the efforts of Carl Cron who was the original project manager Carl passed away in 1998 during its development It was Carl s vision that recognized the need for this manual and his strong persuasion that convinced a number of companies to contribute their information and ideas for this project Executive Summary This document is provided to establish a general set of safety guidelines for coiled tubing intervention in low and normally pressured wells It is not intended to serve as an operations manual to accomplish the myriad of activities possible with this device Rather this manual hopes to add value for the production operator and service company by outlining the safety basics augmented by operational experience to preserve the well being of personnel and to preserve the environment and invest ment in each well The content assumes a certain amount of familiari
58. se rating of pipe used for testing d Test hydraulic cylinders with hydraulic fluid to BOP operating system pressure Monitor opposing hydraulic chambers for leakage Page 6 4 1 4 Minor Disassembly and Inspection a Time related inspection Should be performed at tubing change out or every 30 days whichever is less BOP should be broken open and ram packers ram seals bonnet gaskets slips and shear blades visually inspected and replaced if wom or damaged Slips and shear blades should be replaced if evidence of wear flat spots pitting or corrosion is noted Equalizing valve seals and packing should be changed b Incident related inspection Should be performed each time shear rams or slip rams are used to hold or cut pipe Shear blades or slip inserts whichever were used should be replaced Ram packers ram seals and bonnet gaskets should be inspected and replaced as needed c Pre job pressure test should be performed after each disassembly 4 1 5 Disassembly and Inspection a Time related Inspection Should be performed every 12 months and should include complete disassembly of all BOP components All seals and packing should be inspected and replaced if evidence of wear or damage is noted b Incident related inspection Should be performed on the affected BOP component any time leakage is detected between hydraulic chambers or well test fluid leaks through weep hole c Pre job pressure test should be performed afte
59. sssessssssssenssersessesssssesessseccasssessssessssesesasenseeas 6 4 2 KOMEN ae NTE 6 4 3 Remote Hydraulic System Tie In csessssssssssecssssessssssesseserssessesssessesescetsecsssuessssscseseeens 7 4 4 General Requirements uuupsenranjennen Gauda huntanaGevaddds dest 7 4 5 Daily FESTE EST ewan RUAA 7 Page iti Coiled Tubing Safety Manual 46 Weekly BOP Function Pressure Test cccssssssssssessesssssseeseseessesesesscssssssssecssensssressscavens Section 5 Emergency Procedures jis ceccccscvessisctecevessvistguecccvsssnsssdsaaen dundee tecascaaewisvapsaiovseveticwuast sunataanannsesiee 8 5 1 Power Pack FANE Lane 8 5 2 Collapsed Coiled Tubing pec sceses puscuesasenccanndynyveacheedhetau ayarts nsertertdsadeocesecei Rmuataben evntulenses 8 52 1 Collapse with Coiled Tubing Shallow in the Well ieseeesesrvrvevsrversrorvrnrorevervrsrsevevsssrvener 8 5 2 2 Collapse with Coiled Tubing Deep in the Well ccccessssesscsessesessssessssesesteresesseerersees 8 5 3 Coiled Tubing Stuck in the Hole ds acqsisarecscaads oaridedeatisdccinsieea Sitar ohenaenseacnatentes 9 591 Friction Stuck Coiled Tubing ciisicseseetesese3i ete etusmacanssivensennseas Gees 9 5 3 2 Mechanically Stuck 2 ass Gade 9 5 3 3 Mechanically Stuck without Circulation cc cscsesesesesssseseessecseesessesesssnscsessessessseseesenens 10 5 4 Leak in Riser or Connections Below the Well Control Stack mmsensrvrovrvresrr
60. the ram seal 1 5 Downhole Check Valves This is an optional item for use in the bottom hole assembly However if it is included two valves should be used in conjunction or a dual valve for redundancy in the event of seal failure Also consideration should be given to the potential plugging tendency of various types of valves Flapper type valves are less likely to plug because of greater cross sectional flow area However spring type valves usually have greater success in controlling wellbore fluid entry into the coiled tubing because of greater strength of the springs used in their construction lt should be noted that a flapper check valve will normally not act as a positive seal in most cases Valve construction and maintenance greatly affect the potential to serve this purpose Consideration should be given to valve type used if there will be greater operational risk from parted collapsed or broken coil These possibilities are always present to varying degrees in every operation but should be weighed against the ability of the valve to provide a positive seal Generally a downhole check valve is used for all operations when reverse circulation will not be performed lf a check valve is not used a contingency plan should be prepared to handle the escape of wellbore fluids gases at surface in the event of a coiled tubing failure 1 6 Two Way Sealing Valve Although this valve is not mandatory itis strongly suggested to be inc
61. tively minor movement from the injector head even when supported by a crane or platform A periodic check of the Christmas tree bolts is advisable to insure they have not worked loose during prolonged operations 1 1 Blind Rams Blind rams should be able to provide an effective seal from wellbore pressure below when the BOP bore is unobstructed Equalizing valves should be used when opening the ram with differential pressure to prevent damage to the ram seal 1 2 Shear Rams Shear rams will be able to perform at least two cuts of the specified coiled tubing size at the rated working pressure of the well control stack A function test of the shear rams should be made every 120 days The condition of the blades should be verified after each cut A test should be performed when using conductor cable or concentric tubing 1 3 Slip Rams Slip rams will be capable of being used at the rated working pressure of the well control stack to hold the coiled tubing when the pipe has a positive downward weight up to the value of minimum tensile pipe yield They should also be capable of holding the pipe when there is negative weight snubbing mode to a value of 50 of the minimum tensile pipe yield 1 4 Pipe Rams Pipe rams should be able to provide an effective seal from wellbore pressure below for the appropriate size of coiled tubing Equalizing valves should be used when opening the ram with differential pressure to prevent damage to
62. ty with operations by the managers superintendents engineers and field personnel for whom this document was written As per normal the personnel involved with operations should have well control training and equipment operations experience The manual is not intended to address coiled tubing operations in high pressure environment or coiled tubing drilling This document has used some of the information outlined in API Recommended Practice 5C7 as well as the vast operational experience of some operators and their lessons learned There are a number of quality documents which have served to make this well intervention method a high quality dependable and unique solution Westport Technology is committed to expanding the educational experience of the industry through this document workshops and other manuals like the Coiled Tubing Squeeze Cementing Best Practices Coiled Tubing Safety Manual Page v Coiled Tubing Safety Manual 1 0 Well Control Equipment Ref API RP 5C7 The well control equipment will be used for primary well control and should be configured from the top to bottom as follows a Stripper or annular type presenter An annular preventer can also be installed below the Blowout Preventer BOP stack depending on the operation BOP blowout preventer Stack to consist of b Blind ram Optionally use a blind shear combination c Shear ram Optionally use a blind shear combination d Kill line e Sli
63. ubing and set it off to the side i Attach a full tube clamp to the coiled tubing directly above the well control stack j Connect the crane or travelling block to the clamp and open the pipe and slip rams k Slowly pull the coiled tubing out of the well to the maximum height of the crane or block Attach a collapsed tube clamp to the coiled tubing directly above the well control stack and cut the tubing above the bottom clamp Connect the crane and pull the collapsed coiled tubing out of the well m Continue alternating pulling clamping and cutting the coiled tubing until all of the collapsed section has been removed from the well and the transition section to undamaged pipe is located above the well control stack Ensure that there is enough competent pipe above the well control stack to thread the coiled tubing through the Stripper and injector n Close the slip rams and remove the clamp o Install and secure the injector onto the coiled tubing Apply hydraulic pressure to the inside chains and switch the injector to the extraction mode Open the slip rams p Either connect the end of the coiled tubing to the other section of coiled tubing on the reel with a connector or install a valve onto the end of the coiled tubing and begin a new wrap on the reel q Reinstall the stripper bushings and elements r Finish pulling out of the hole and replace the reel Determine the cause of collapse prior to entering the well a
64. ue to reestablish circulation Also the rate of penetration and control of the accumulated solids in the wellbore will help minimize the chance of sticking the coiled tubing Therefore a set penetration rate should be followed independent of how soft the fill might be A short trip should also be incorporated in the process to help remove the jetted solids Acalculation should also be made to monitor the total suspended solids at any given time to prevent accidental increase above the amount that can be supported by the fluid Visually monitoring returns at surface is extremely helpful in identifying lost returns and responding by pulling the coiled Horizontal Well Cleanouts A Special Problem Solids are only required to settle the diameter of the completion before a bedding plane develops One effective method to prevent becoming stuck in the horizontal section during a cleanout is to jet a limited interval usually no more than 50 feet and follow immediately with a short trip until the wellbore deviation decreases to 40 or less Sand entry into this type of completion can be a sign of significant mechanical damage that could result in free flowing sand and or allow the coiled tubing to exit the completion For this reason it is advisable to use slim hole assemblies to perform the cleanout Fluid Viscosity Degradation Viscosity enhancement of water based fluids or foam is a common practice to improve their ability to suspend and
65. ulic source in the event of a total hydraulic system failure 44 General Requirements a All personnel on unit should be familiar with operation maintenance and repair of Blow Out Preventers Accumulator and Closing Unit b An Instruction Operation Manual with schematic drawings for the BOP stack in use on that unit and a record book of BOP tests and repairs should be kept on the unit 45 Daily Pressure Test a With the end of the coil above the BOPs pressure up to 400 psi through the coil for the low pressure test This will apply pressure to and test the surface lines coil pack off BOPs lubricator and the tree connection Hold for 5 minutes and inspect all connections for visible leaks When the low pressure test is OK increase the pressure to 4000 psi for the high pressure test and hold for 10 minutes Again look for leaks and a pressure decline If a significant pressure decline is seen but no leaks are visible the swab valve is leaking A two way sealing valve may be needed to be placed below the BOPs since many wellhead valves Coiled Tubing Safety Manual are not designed to hold pressure from above Bleed off the pressure when the testis OK This pressure test should be performed before running in the hole on all jobs and as a first step during the weekly BOP pressure test 4 6 Weekly BOP Function Pressure Test a Perform step 1 above Record the function and pressure test information b With the end o

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