PetraSim Examples: Five-Spot Geothermal Injection and Production
Contents
1. NT a gt ttt t t REDUCE TIME STEP AT 87 1 4 C 87 2 ST 0 415996E 07 DT 0 312500E 01 DX1 125042E tt tt EOS CANNOT FIND PARAMETERS AT ELEMENT Ds tttt t t REDUCE TIME STEP AT 88 1 4 tttt 4 4 EOS CANNOT FIND PARAMETERS AT ELEMENT a t t t t REDUCE TIME STEP AT C 88 1 C 88 1 ST 0 415996E 07 DT 0 390625E 00 DX1 0 000000E C 89 1 ST 0 415996E 07 DT 0 781250E 00 DX1 0 000000E tt tt EOS CANNOT FIND PARAMETERS AT ELEMENT E CONVERGENCE FAILURE ON TIME STEP 90 WITH DT 0 STOP EXECUTION AFTER NEXT TIME STEP REDUCE TIME STEP AT C 90 1 90 1 ST 0 415996E 07 DT 0 390625E 00 DX1 0 000000E END OF TOUGH2 SIMULATION RUN ELAPSED TIME 1 155 SE vr Log of DT z cL cL 22 ae 4020 eo ne acco 100 4 Time Step 4 j j Sim Time 48 15 days End Time 36 50 yrs Max TS 200 Sim Time 48 15 days End Time 36 50 yrs Max TS 200 DT 0 39s Run Time 2 00s Remaining 42 37 yrs Cose DT 0 39s Run Time 2 00s Remaining 42 37 yrs So in the previous example we were able to run with injection and production but in this example the solution failed This provides a good example of the critical importance of physically meaningful PetraSim Examples boundary conditions in TOUGH2 Specifying a constant production rate is not a realistic boundary conditio2. Produce well and click Properties Click on the Flow tab In the Production section click to clear the Mass Out check box In the Production section click to select the Well on Deliv check box In the Productivity Index box type 2 0E 12 based on calculation described in the TOUGH2 User Manual A a a a In the Pressure box type 8 6E6 the initial pressure in the model For Gradient select Well Model Click the Print Options tab Click to select the Print Time Dependent Flow and Generation Data check box ND 10 Click OK to save changes and close the dialog PetraSim Examples Save and Run with Well on Delivery Conditions The input is complete and you can run the simulation Save your model and run the simulation 1 On the Analysis menu click Run TOUGH2 The Simulation Complete dialog will notify you when the end time has been reached Click OK to dismiss the notification and click Close to exit the Running TOUGH2 dialog View 3D Results To open the 3D Results dialog 1 On the Results menu click 3D Results By default the display will show isosurfaces corresponding to pressure for the first output step To show temperature isosurfaces for the last time step 1 Inthe Scalar list click T 2 Inthe Time s list click the last entry t 1 15183E9 To show scalar data on a slice plane Click Slice Planes In the Axis list click Z In the Coord box type 305 Click Close PHBI To remove isosurfaces and sho
3. g gPHUNDERHEAD 403 Poyntz Avenue Suite B Manhattan KS 66502 USA 1 785 770 8511 www thunderheadeng com PetraSim Examples Five Spot Geothermal Injection and Production using Polygonal Cells and Wells 2010 Table of Contents Five Spot Geothermal Injection and Production using Polygonal Cells and Wells cccceeeeee PV SING sec cig eraser EE EAE A ears ast ee ste EEO tare E E EEO A EOE CPE AVe IVICS I Vee ticrsotatartnscrtensesmiuetsececsenses tds sancnssancesuavetnecesee E EOI VY GOW at CS r E SANS Os IN eae neat see E E dienes cians cage A E E E Save and Run with Well on Delivery Conditions cccecccccsseccccessececeesececeeececeeeseceeaunecessuneses VEW DRE UR e E E acts noasanesntis nt pan neo phenenters aves aaron ane tect eenorere WHEW TMC IS COI PIOUS aan E teaueenestenttenracusesnanueentoueesen View Well Flow Time History PlOts ccccccccsssececceseccecesececseececeeeceeseeseceseeeceeseneceeeeenecessunesss PetraSim Examples Five Spot Geothermal Injection and Production using Polygonal Cells and Wells We will repeat the previous example but this time using a different mesh and wells to define the injection and production Open the Five Spot Geothermal Production and Injection model and save it to a new folder This will preserve all the parameters not related to the mesh that we already defined in the previous model Add Wells To add wells 1 Onthe Model menu click Add We
4. he injection well in the polygonal mesh Because the cell that contains the injection well has a small volume in the polygonal mesh it cools much more rapidly than the larger cell in the rectangular mesh When finished you can close the Cell History dialog View Well Flow Time History Plots The total flow from the well can be plotted by On the PetraSim Results menu click Well Plots In the Variable list click Flow Rate kg s In the Well Name list click Produce 1 On the View menu click Range Click to clear Auto Range In the X Max box type 5 0E6 Click OK a ae a The resulting plot is shown below PetraSim Examples 5 a Well Results C PetraSim 2010 Examples Five Spot Poly Wells five spot poly wellssim T aE File View a Flow Rate kg s 5 0605 1 0606 1 5606 20606 25606 3 0606 3 5606 4 0606 4 5606 5 0E06 Variable Flow Rate kg s Well Name Inject 0 Figure 4 Flow at output well Figure 4 shows how the production flow rate is initially zero and then increases until it matches the injection flow The initial two phase state of the model that provides compressibility so that although injection is constant there is a time delay as the production increases to the steady state value
5. ll Inthe Name box type Inject 3 Inthe Ordered Well Coordinates table type these values yy o0 3 Click OK to create the well 5 Repeat this for the production well Use the name Produce and the following coordinates x _fy _ z___ soo 5000 oo Create Mesh To C re a te a p O y go n a Vo ro n O mMm e S h z f 22 fe PetraSim C PetraSim 2010 Examples Five Spot Voronoi five spot voronoi sim Sex File Edit Model Properties Analysis Results View Help ReW X OR RG CBOlGE ire BOB K lt gt BX amp amp APBD amp Hi fct color by tayer 1 Onthe Model menu click Create Mesh 2 For Mesh Type select Polygonal 3 Click OK to create the mesh Your mesh should be refined near the wells Figure 1 When a new mesh is created the previous cell specific properties names and sources sink data are erased Cell Count 105 TOUGH EOS1 Edit Well Flow Rates Figure 1 Polygonal Voronoi mesh showing To define the injection rate refinement near wells 1 Inthe Tree View right click on the Inject well and click Properties 2 On the Flow tab in the Injection section select the Water Steam check box 3 Inthe Rate box type 7 5 4 Inthe Enthalpy box type 50000 corresponding to about 6 C PetraSim Examples 5 Click the Print Options tab 6 Click to select the Print Time Dependent Flow and Generation Data check box 7 Click OK to save changes and cl
6. n In a real well we cannot specify any desired production rate In a real well the production rate depends on the fluid conditions and material properties of the reservoir and the geometry and conditions of the production well By specifying a fixed production rate we have attempted to remove mass at a higher rate than physically possible As shown below the pressure in the production cell goes to zero and the equation of state is no longer valid Cell Time History BHE File View Primary Data P P a Variable 9 0E0E P Pa Y Cell Name Id Inject 0 1 Produce C 6 0E06 Mark Style i Sa o 5005 10E06 15E06 20606 25E06 30606 35E06 40E06 45E06 Diamond v Time The reason the pressure goes to zero is that the production cell size in the polygonal model is smaller than in the uniform rectangular grid We are trying to remove the same total flow rate from a smaller cell Since the flow area to the well is smaller this requires a greater pressure drop into the cell lowering the pressure in the production cell until an unphysical state is reached in the model A better approximation of a real well can be made using the Productivity Index see p 64 of the TOUGH2 user manual Using the Productivity Index the flow into the well is proportional to the pressure difference between the well and containing cell To define the production well using the Productivity Index In the Tree View right click on the
7. ose the dialog To define the production rate In the Tree View right click on the Produce well and click Properties On the Flow tab in the Production section select the Mass Out check box In the Rate box type 7 5 Click the Print Options tab Click to select the Print Time Dependent Flow and Generation Data check box M a Ye Click OK to save changes and close the dialog Save and Run The input is complete and you can run the simulation Save your model and run the simulation 1 On the Analysis menu click Run TOUGH2 The solution will start and then Halt Prematurely Click OK to Py Simulation Halted Prematurely Click to view output file close the Error dialog i C PetraSim 2010 Examples Five Spot Voronoi five spot voronoi out In the Running TOUGHZ2 dialog click on the Graph tab This display will show how the time step increased and then became small before halting Next click on the Log tab This displays the error messages from the TOUGH2 output file The critical message that will cause convergence failure is EOS CANNOT FIND PARAMETERS AT ELEMENT 3 Use the Find function and it will show that cell 3 is the cell that contains the production well r r Running TOUGH2 Running TOUGH2 a Time Step Size ttt REDUCE TIME STEP AT 86 1 4 C 86 2 ST 0 415996E 07 DT 0 625000E 01 DX1 250063E tt t tt EOS CANNOT FIND PARAMETERS AT ELEME
8. w only slice data 1 Click to clear the Show Isosurfaces check box The resulting visualization is shown below PetraSim Examples r 3D Results File Results View r E 2 32223E07 5 27135E07 1 11696E08 _ T deg 0 1 90339E08 3 21411E08 300 5 83555E08 8 45699E08 Scalar T degC zj Vectors FLOH W per m Show Isosurfaces Scalar Show Vectors Vector Properties Show Slice Planes Figure 2 Temperature contours at end of solution for analysis using Productivity Index and Voronoi cells Comparing Figure 2 to the previous results shows that there is not a pressure and temperature drop at the production well when using the Productivity Index When finished you can close the 3D Results dialog View Time History Plots To view time history plots 1 Onthe PetraSim Results menu click Cell History Plots 2 Inthe Variable list click T deg C 3 Inthe Cell Name Id list click Inject 1 The resulting plot is shown below PetraSim Examples bf Cell Time History File View Primary Data T deg C Variable T deg C v 300 0 Cell Name Id Inject 0 1 250 0 Produce 0 3 150 0 100 0 9 2 Mark Style 0 0 2 008 4 0608 E8 8 0608 1 0609 1 2509 ime Figure 3 Temperature history of injection cell using polygonal mesh Comparing Figure 3 with the previous example shows again the effect of the small cell near t
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