Production from a Geothermal Reservoir (EWASG)
Contents
1. 1 For the Simulator Mode choose TOUGH2 2 For the Equation of State EOS choose EWASG 3 For the Model Bounds enter the values from Table 1 Table 1 Model boundary dimensions Axis Min m Max m yY oof 10 Zz 5000 00 Click OK to close the New Model dialog and create the model Specify the Solution Mesh The solution mesh must be specified in two steps First the Z divisions must be specified per layer Then the mesh can be created using the Create Mesh dialog Specify Z Divisions We must first specify one Z division for the default layer To do so we will open the Edit Layers dialog On the Model menu select Edit Layers In the layers list in the left hand pane select the Default layer In the right hand pane select Regular for Dz In the Cells box type 1 u a E In the Factor box type 1 0 Click OK to apply the changes and close the Edit Layers dialog Create the Mesh We will now create the radial solution mesh using the Create Mesh dialog To open the dialog on the Model menu select Create Mesh For the Mesh Type select Radial For the Divisions select Regular In the Radial Cells box type 100 In the Factor box type 1 03705 ae E Click OK to create the mesh We have selected Radial Mesh as the mesh type This means that a 2D cylindrical RZ mesh will be created in which X corresponds to cylindrical R Z corresponds to cylindrical Z and the Y coordinate corresponds to cyl2. 8 In the Property Dependence on Salinity list select Full Dependence See eet ee Ye eN O In the Brine Enthalpy Correction list select Michaelides m e m e Select the Include Vapor Pressure Lowering checkbox Do NOT select Molecular Diffusion e e W N Click OK to close the Global Properties dialog Material Properties To specify the material properties use the Material Data dialog On the Properties menu click Edit Materials or click amp on the toolbar In the Name box type POMED In the Density box type 2600 0 In the Porosity box type 0 05 In all three Permeability boxes X Y and Z type 50e 15 In the Wet Heat Conductivity box type 2 0 In the Specific Heat box type 1000 0 Click Apply to save the changes So a a ee a ne In addition to the physical rock parameters we also need to specify the relative permeability and capillary pressure functions for this material These options can be found in the Additional Material Data dialog To open this dialog click the Additional Material Data button To specify the relative permeability function Select the Relative Perm tab In the Relative Permeability list select Corey s Curves In the Sj box type 0 3 In the S box type 0 05 a Ye The default capillary pressure none is correct for this example Click OK to exit the Advanced Material Data dialog Click OK again to save your settings and exit the Material Data
3. dialog Initial Conditions The initial state of each cell in the model must be defined To specify global initial conditions that will be used as the default for all cells in the model on the Properties menu click Initial Conditions or click i gt on the toolbar To set the initial conditions ee Ye Select the Two Fluid Phases P Xsm Sg T state option In the Pressure box type 6 0E6 In the Temperature box type 275 55 In the Gas Saturation box type 0 45 In the Salt Mass Fraction box type 0 3 Click OK to close the Default Initial Conditions dialog Define Reservoir Production In this model fluid is produced from the inner cell 1 oO ON OU A In the 3D View click the Front View button H on the toolbar or rotate the model until the front is visible Use the Zoom Box tool to zoom in on the left side of the model until the left most cell is visible Using the 3D Orbit Navigation tool gt right click the left most cell and from the context menu select Edit Cells as shown in Figure 2 Inthe Cell Name box type Production Click the Sources Sinks tab In the Production section select the Mass Out check box Inthe Rate box type 65 Click the Print Options tab Select the Print Time Dependent Flow and Generation BC Data 10 Click OK to close the Edit Cell Data dialog 52 PetraSim Untitled File Edit Model Properties Analysis Results View Help ReH X DSSAB OR CDOG GE B
4. 0E 00 R Rit m 2 s Figure 6 Results for comparison with TOUGH2 manual References 1 Pruess Karsten Oldenburg Curt and Moridis George TOUGH2 User s Guide Version 2 0 Berkeley CA USA Earth Sciences Division Lawrence Berkeley National Laboratory November 1999 LBNL 43134 10
5. AB lt gt RPP Ss Asie SW celcoorjey Layer Y Find MamedjPrint Cells ExtraCells Edit Cells Select Mesh Column s Select Mesh Layer s Y Show Only Selected Cells Hide Cells Above Hide Cells X Show All Cells Cell Count 100 TOUGH EWASG Figure 2 The cell to be selected Solution Controls We will now define the solution control options 1 On the Analysis menu click Solution Controls or click C on the main toolbar 2 Inthe End Time box type 2 0E6 approximately 23 days 3 Inthe Time Step list ensure that Single Value is selected 4 Inthe Time Step box type 1000 This is the initial time step 5 Select Enable Automatic Time Step Adjustment 6 Click OK to exit the Solution Controls dialog Output Controls By default the simulation will print output every 100 time steps We can increase the frequency of the output in the Output Controls dialog ae ee es On the Analysis menu click Output Controls or click E on the main toolbar In the Print and Plot Every Steps box type 10 Next to the Additional Print amp Plot Times click the Edit button In the Additional Print Times table type 50E5 This will force a solution printout at this time Click OK to exit the Additional Print Times dialog Click OK to exit the Output Controls dialog Save and Run The input is complete and you can run the simulation If you haven t already you may want to save your model in a ne
6. H family of codes can be found at http www esd lbl gov TOUGH2 Printed copies of the user manuals may be obtained from Karsten Pruess at lt K_Pruess lbl gov gt The original development of PetraSim was funded by a Small Business Innovative Research grant from the U S Department of Energy Additional funding was provided by a private consortium for the TOUGHREACT version and by the U S Department of Energy NETL for the TOUGH Fx HYDRATE version We most sincerely thank our users for their feedback and support Production from a Geothermal Reservoir EWASG Description This example is Problem 12 Production from a Geothermal Reservoir with Hypersaline Brine and CO2 EWASG described in the TOUGH2 User s Manual 1 This problem examines production from a hypothetical geothermal reservoir with high salinity and CO2 Fluid withdrawal causes pressure to drop near the production well Boiling of reservoir fluid gives rise to dilution of CO2 in the gas phase and to increased concentrations of dissolved NaCl which begins to precipitate when the aqueous solubility limit is reached As the boiling front receded from the well solid precipitate fills approximately 10 of the original void space causing permeability to decline to approximately 28 of its original value The mesh uses a 1D radial geometry Create an EWASG Model We will first create a new model using the EWASG EOS From the File menu select New to open the New Model dialog
7. Settings warkentin My Documents Test ewasg_geothermal geothermal sim File Results View 2 0E06 Scalar 5G Vectors FLOH W per m C Show Isosurfaces Scalar G Scalar Properties C Show Vectors Vector Properties Show Slice Planes Slice Planes C Color Slices by Cell Figure 3 3D representation of the saturation of gas Close the 3D Results window View Cell History Plots You can view time history plots with the Cell History dialog On the Results menu click Cell History Plots or click 4 on the main toolbar The Cell History dialog will be displayed In this window you can display time history data using a plotting parameter and a list of cells For example to view the gas saturation in the Heat Source cell 1 Inthe Variable list select SG 2 Inthe Cell Name list select Production Figure 4 shows the time history plot of SG at the production cell The user can export this data for plotting in spreadsheets 52 Cell Time History C Documents and Settings warkentin My Documents Test ewasg_geothermal geothermal sim File View Primary Data Variable v Cell Name Id 0 0 2 0605 4 0605 6 0E05 8 0E05 1 0E06 1 2E06 1 4E06 1 6606 1 8E06 2 0E06 Time Mark Style Figure 4 The cell history plot for gas saturation in the production cell Close the Cell History window Line Plots PetraSim also supports line plots where you define a line i
8. ed using these tools Users are warned that PetraSim is intended for use only by those competent in the field of multi phase multi component fluid flow in porous and fractured media PetraSim is intended only to supplement the informed judgment of the qualified user The software package is a computer model that may or may not have predictive capability when applied to a specific set of factual circumstances Lack of accurate predictions by the model could lead to erroneous conclusions All results should be evaluated by an informed user Throughout this document the mention of computer hardware or commercial software does not constitute endorsement by Thunderhead Engineering nor does it indicate that the products are necessarily those best suited for the intended purpose Acknowledgements We thank Karsten Pruess Tianfu Xu George Moridis Michael Kowalsky Curt Oldenburg and Stefan Finsterle in the Earth Sciences Division of Lawrence Berkeley National Laboratory for their gracious responses to our many questions We also thank Ron Falta at Clemson University and Alfredo Battistelli at Aquater S p A Italy for their help with T2VOC and TMVOC Without TOUGH2 T2VOC TOUGHREACT and TOUGH Fx HYDRATE PetraSim would not exist In preparing this manual we have liberally used descriptions from the user manuals for the TOUGH family of codes Links to download the TOUGH manuals are given at http www petrasim com More information about the TOUG
9. g Gg HUNDESHEAD 403 Poyntz Avenue Suite B Manhattan KS 66502 USA 1 785 770 8511 www thunderheadeng com TOUGH2 Example Production from a Geothermal Reservoir EWASG PetraSim 5 Table of Contents ACKNOWIedSemMEnES an a ee ee iv Production from a Geothermal Reservoir EWASG cscsccscsccscescsceccscsccccsccccsccscscescscsscscsseccsseccsceses 1 BES ClO NO Morene nternet 1 Create an EWASG Model smeenk 1 Sec the Saluton MEN ee ie une 1 SPECI Z DIV ONG ee nd ae Eee DER Eee ae ee 1 eae O NO ee ee ee 2 GIODal PO BCS zes een ee ee ee er unapseuatestuaueanorenesto 2 Material Proper ES ereere ee ee re 3 LAME WS OGIO LIONS een A ee A are aba EE E E E 4 Define Reservoir PrOoQueliOn nn een ee 4 SOIULOMEON OIS een AE eas ew ecevecavsoudaguntsievseearseieavstanssacossentsedsdodssunsavesaueencesgaren 5 DRT OU SG IME ONS te ee ee ee re 5 SAVE NOOI este ee eine neden een 5 VIEW DRS a ee re een 6 View Cel History PIOUS ee ee ee een 7 KISP 1 evaleanctasgectenecoiee trav onan E A E E E AE EE BEN 8 References E EE E E TA 10 Disclaimer Thunderhead Engineering makes no warranty expressed or implied to users of PetraSim and accepts no responsibility for its use Users of PetraSim assume sole responsibility under Federal law for determining the appropriateness of its use in any particular application for any conclusions drawn from the results of its use and for any actions taken or not taken as a result of analyses perform
10. indrical Theta which is not used 100 cells extend in the R direction with an X Factor of 1 03705 This means that each cell is 1 03705 times the size of the previous cell in the R direction These were chosen to give a first cell length of 2 0 m which is the value used in the TOUGH2 example See the PetraSim User Manual for instructions on how to calculate the appropriate factor The resulting mesh is displayed in Figure 1 Click the Front View button on the toolbar or rotate the model until the front is visible 52 PetraSim Untitled File Edit Model Properties Analysis Results View Help Bed X ODESAR OBR CBSMAGE ak B i lt gt i h A 5 A JRS m B am Cell Color By Layer A1000 0 1 0 0 0 Cell Count 100 Figure 1 The resulting model Global Properties Global properties are those properties that apply to the entire model We will make changes to some of the EOS options including activating molecular diffusion To edit global properties you use the Global Properties dialog On the Properties menu click Global Properties or click on the main toolbar In the Global Properties dialog select the Analysis tab In the Name box type Geothermal Production Brine and CO2 In the Global Properties dialog select the EOS tab Select Non Isothermal In the Type of NGG list select CO2 For Dependence of Permeability on Pore Space select Tubes in Series In the phi box type 0 8 In the G box type 0
11. n 3D space and the data is interpolated along the line To make a line plot 1 First open the 3D results view On the Results menu click 3D Results or click Ed on the main toolbar On the File menu click Line Plot In the Point 1 coordinate boxes X Y and Z type 5 0 0 5 and 250 0 respectively In the Point 2 coordinate boxes X Y and Z type 1000 0 0 5 and 250 0 Click OK to close the Line Plot dialog This will open a Line Plot window In the Variable list select P Pa In the Time list select 2 0E06 the last time a a Se SS gt The plot is shown in Figure 5 You can export this data to a comma separated value file for import into a spreadsheet 52 Line Plot C Documents and Settings warkentin My Documents Test ewasg_geothermallgeothermal sim File View Primary Data Variable P Pa Time 5 0E04 5 4E04 2 26E05 5 46E05 8 66E05 1 218E06 1 858E06 2 5E06 0 0 1000 2000 3000 4000 500 0 6000 7000 800 0 9000 10000 Mark Style Distance A B Circle2 Figure 5 Line plot of pressure Close the Line Plot window Data saved using the line plot are shown in the same format as in the TOUGH2 user s manual in Figure 6 The calculated results compare well with the manual results Gas saturation Solid Saturation 0 6 Dissolved Natl Pressure 0 5 0 4 Pressure Bar 0 3 Saturation Mass fraction 0 2 0 1 0 0 100505 100E 04 100E 03 100E 02 100E 01 1 0
12. w directory For example 1 On the File menu click Save or click El on the main toolbar 2 Create a new folder named ewasg_geothermal and in the File Name box type geothermal sim 3 Click Save To run the simulation on the Analysis menu click Run TOUGHZ2 or click on the main toolbar During the solution a graph will display the time step size View 3D Results To view the 3D results for a simulation on the Results menu click 3D Results or click Ed on the main toolbar The data for the current simulation will be automatically loaded and displayed To show gas saturation contours for the last time step 1 In the Time s list select the last entry 2 0E6 2 Inthe Scalar list select SG 3 Click to clear the Show Isosurfaces checkbox To add a slice plane on which contours will be displayed click Slice Planes For this example we will show one slice plane To configure the slice plane In the Axis list select Y In the Coord box type 0 5 Select the Scalar check box Click Close oN To orient and view the model with mesh 1 Click the Front View button on the toolbar or rotate the model until the front is visible 2 Onthe View menu click Show Mesh The view can be zoomed and panned by holding the Alt and Shift keys respectively and dragging the mouse After moving the view to the upper left corner of the model the resulting contour plot is shown in Figure 3 52 3D Results C Documents and
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