Tab Input Streams is used to add, delete or edit input streams. To define a new stream click on the Add button. The Stream name field will be filled with the string INSTR- followed by a number reflecting the total number of streams defined. The Stream name field cannot be edited by the user. The Composition field will show the default choice of PRIMARY. By default the Primary mole fraction field will show the value of 1.0 and be disabled. The primary composition entered on the most recently defined composition form is echoed on the composition grid. The composition grid is disabled for edits by default. The following table shows the ways in which the composition may be specified for an input stream and the controls involved.
User's Guide WinProp Process Flow • 133 Type How to select or enter Status of primary
mole fraction text box
Status of composition grid
Composition entered as primary feed under the last composition form
Select PRIMARY from the composition drop down list
Disabled Disabled
Composition entered as secondary feed under the last composition form
Select SECONDARY from the composition drop down list
Disabled Disabled
Composition obtained by mixing primary and secondary feed compositions entered on the last composition form
Select MIXED from the
composition drop down list. This will enable the primary mole fraction text box. Enter the mole fraction of the primary feed stream in this box
Enabled Disabled
User defined composition Select USER INPUT from the composition drop down box. This will enable the composition grid. Enter values directly on this grid
Disabled Enabled
Enter the flow rate, pressure and temperature in fields labeled Flow rate, Pressure and
Temperature respectively. The flow rate can be specified on a molar or volumetric basis. The
default is molar rates. Use the menu labeled Flow Units to select Molar or Volumetric basis. If SI units are being used then the molar rates should be kmol/time and volumetric rates in m3/time whereas for Field units the molar rates are in lb-mole/time and volumetric rates are in ft3/time. The final required piece of information is the name of the unit to which the input stream is directed. Enter the name of the unit or select from one of the units already defined through the drop down combo box labeled Input to. If the name of the unit is entered then this unit will be automatically created as a splitting unit. The user can set the properties of this unit subsequently by locating the appropriate record on tab 2, Process Units.
To move between the defined input stream records click on the VCR type navigation arrows on the data control labeled Input Stream on the left bottom corner of the tab. The fields for a particular record can be edited by first loading the record via the data control and then entering new values on the corresponding text boxes such as flow rate etc. The changes will be saved by moving to a new record or by clicking on the OK button To delete an existing input stream use the data control to locate the record and then click on the Delete button. To save changes made on the tabs on the form press the OK button. The Cancel button will close the form without saving any of the changes.
134 • Process Flow User's Guide WinProp Tab Process Units is for managing process units. To delete an existing unit use the VCR type navigation keys on the data control labeled Units to locate the desired unit and then click on the
Delete button. Any Input to field of input streams referencing the deleted unit will be cleared
to the null string. If the deleted unit was cited as the destination of one or more output streams from other unit(s) then those destination fields will be cleared to the empty string as well. To add a unit click on the Add button. This will result in a new record with the default name of
UNIT- followed by a number representing the total number of units defined to that point. The
unit type selected will be a SPLITTER by default. The Pressure and Temperature fields as well as destination fields will be left blank to be filled by the user. The user has one
opportunity to edit the name field. Once the unit name text box is highlighted and then the focus lost the unit name cannot be edited. Alternatively, by moving to another record the unit name field cannot be edited subsequently. To enter the destinations of the output streams click on the button labelled Destinations…. This will open an appropriate dialog box depending on the unit type. For a splitting unit, for example, there can be a maximum of 10 output streams. The user is required to enter the destination of each of these streams and the fraction of the total flow assigned to each stream. If the user enters a new unit name in the destination combo box then that unit is created automatically by the program.
Tab Product Streams is for specifying the reporting conditions for predefined product streams such as OIL and GAS. There are 3 other predefined product streams in addition to
OIL and GAS; these are named PR-STR3, PR-STR4 and PR-STR5. The user can reference
any or all of these product streams in specifying the destination of an output stream from a particular unit. When a product stream is chosen as a destination, the corresponding record will be written to the data file. The block of keywords will be something like this:
*STREAM 'OIL' *PRESSURE 20.0 *TEMPERATURE 50.0
The user cannot delete or add a product stream record. The reporting conditions can be specified individually for a given product stream. Locate the appropriate product stream using the navigation arrows on the data control labeled Product Streams and edit the pressure or temperature values appearing in the respective text boxes.
User's Guide WinProp Black-Oil PVT Data Generation • 135
Black-Oil PVT Data Generation
Overview
This option can be used to generate the PVT data for simulation studies with CMG’s black- oil simulator IMEX as well as other commercially available black-oil simulators. In the latter case, some of these simulators implement the Extended Black-Oil Formulation. In addition to the standard black-oil parameters an additional parameter, the condensate gas ratio, often denoted as Rv is added to account for oil component vaporization in the gas phase at reservoir conditions. WinProp can generate PVT data for the extended black-oil model. Unlike models for CMG’s own simulator IMEX the data is presented in a “generic” format. The keywords do not exactly correspond to a specific simulator.
The calculations should be done once an EOS model is obtained for the oil, generally through characterization of the heavy end followed by regression to match the available data. The PVT data is written out to a file with the root name corresponding to the input-data-file and with the extension (.imx). For example if the input file name is test.dat, the PVT data file will be test.imx. If the PVT data is designed for IMEX then it may be referenced as an include file in an IMEX data set or opened with ModelBuilder. If the PVT data is targeted at some other simulator then the information in the .imx file may require editing prior to use in the specific simulator of choice.
A total of thirteen different fluid component models may be specified with IMEX. At present, WinProp can be used to generate six of those models, namely Black-Oil, Pseudo-
miscible with chase gas, Pseudo-miscible without chase gas, Gas-Water, Gas-Water with Condensate and Volatile Oil. Please refer to the IMEX user guide for more information on
these fluid models.
For PVT data aimed at one of IMEX’s models, the following information is written out to the output file:
1. The *PVT *BG|*EG|*ZG 1 keyword and associated table (1 is always written out for the table number) are written for the oil models. The columns of this table are pressure, gas-oil ratio, oil formation volume factor, gas formation volume factor | gas expansion factor | gas Z-factor, oil viscosity and gas viscosity. For the pseudo- miscible option with chase gas, the solution gas always remains in solution. The solution gas-oil ratio is fixed and input through a field on the Solvent tab (writes out keyword *GORINT). The bubble point pressure versus solution gas-oil ratio curve in the table belongs to the chase gas. This is NOT taken into account when values are written to the PVT table. The total amount of solution gas is the value
136 • Black-Oil PVT Data Generation User's Guide WinProp given by *GORINT and the dissolved chase gas given by the Rs vs. bubble point pressure curve.
For the Gas-Water model, a *PVTG *BG|*EG|*ZG table is written. The columns of this table are pressure, gas formation volume factor | gas expansion factor | gas Z-factor and gas viscosity.
For the Gas-Water with Condensate table, the *PVTCOND *BG|*EG|*ZG table is written with columns: pressure, gas-oil ratio, condensate-gas ratio, oil formation volume factor, gas formation volume factor | gas expansion factor | gas Z-factor, oil viscosity and gas viscosity. For this option, a series of *BGUST|*EGUST|*ZGUST and *VGUST tables are also written, giving the formation volume factor and viscosity of the gas at saturation pressures lower than the corresponding mixture pressures given in the *PVTCOND table. BOT tables are not generated for this option, as the oil is assumed to be saturated at all times.
For the Volatile Oil option, either the PVTCOND or PVTVO table can be written. Using the PVTCOND table with associated *BGUST|*EGUST|*ZGUST and VGUST tables allows non-linear behavior of undersaturated gas to be modeled. Using PVTVO allows a simpler linear treatment of undersaturated gas properties by specifying only saturated gas and dry gas formation volume factors and viscosities. The *PVTCOND table specification is the same as for the Gas-Water with Condensate model, including use of *BGUST|*EGUST|*ZGUST and VGUST tables. The *PVTVO *BG|*EG|*ZG table is written with columns: pressure, gas- oil ratio, condensate-gas ratio, oil formation volume factor, gas formation volume factor | gas expansion factor | gas Z-factor, oil viscosity, gas viscosity, dry gas formation volume factor | dry gas expansion factor | dry gas Z-factor and dry gas viscosity. *BOT tables are allowed with either table type for the volatile oil option. The units for these properties are indicated in the output file and are the same as in
IMEX. Field, SI and modified SI units are supported.
2. Water phase properties are optional. The keywords written out are *REFPW, *BWI, *CW, *VWI, *CVW and *DENSITY *WATER.
3. Gas phase density at surface conditions, *DENSITY *GAS or *GRAVITY *GAS. 4. Oil phase density at surface conditions, *DENSITY *OIL. Pressure dependence of
oil viscosity, *CVO. Oil compressibility at the original oil bubble point pressure *CO, or *BOT tables for the undersaturated oil may be output. Not required for the gas water option.
5. For the pseudo-miscible fluid models a *PVTS *BS table. The entries of the table are pressure, solvent water ratio, solvent expansion factor, solvent viscosity and mixing parameter between solvent and oil. The solvent density is written out with the keywords *DENSITY *SOLVENT. The mixing parameter between solvent and gas is written out with the *OMEGASG keyword. If the pseudo-miscible model with chase gas is chosen then the initial solution gas-oil ratio is written with keyword *GORINT.
User's Guide WinProp Black-Oil PVT Data Generation • 137 To generate the PVT data for the IMEX black-oil model the following information is required:
1. Composition of oil and, if the swelling curve is to be generated, the gas
composition. These are entered on the Composition form. Oil is entered as the primary fluid and gas is the secondary fluid. Note: For gas water option enter the gas composition as the primary fluid on the composition form.
2. The reservoir temperature and a guess for the saturation pressure of the original oil. These are entered on tab 2 of the Black-Oil PVT Data form. For gas water option only the reservoir temperature is required.
3. At least one pressure step for the differential liberation experiment on the grid with the label No. of pressure levels on tab 3, Pres. levels. For gas water option, these are pressures at which properties gas formation volume factor and gas viscosity are to be calculated. The differential liberation experiment is not performed for the gas water option.
4. The number of separators excluding the stock tank and the operating conditions on tab 3. A maximum of 8 separators may be specified. For gas water case only the standard (stock tank) conditions are required.
5. If the swelling curve is to be generated then the composition of the injection gas is entered on the Composition form as the secondary fluid. If the solution gas is to be used for swellling calculation, then select the appropriate option button on Tab 5, “Gas Properties” under the frame labelled “injection gas composition for swelling test”. On the grid labeled No. of swelling experiments on tab Pres. levels enter the mole fraction of the gas, initial guess for the saturation pressure of the oil/gas mixture and the saturation pressure flag. For gas water option these data are not required.
6. Water phase properties may be input by the user directly on tab 4 or alternatively estimated from built in correlations. This data is optional.
7. For the pseudo-miscible options the solvent composition can be the secondary fluid on the Composition form or values entered on tab Solvent properties. The oil solvent mixing ratio as a function of pressure is entered on the grid provided on this tab. These values are echoed as column 5 of the *PVTS table. The remaining entries of this table, that is the solvent water ratio, the solvent expansion factor and solvent viscosity will be calculated by the program. Note: add the water component from the library for the solvent solubility in the aqueous phase calculations. Enter a composition of zero for the water component. The fields for entering the solvent gas mixing parameter and the minimum solvent saturation are on tab Solvent properties. If the pseudo-miscible with chase gas option is selected then the initial solution gas- oil ratio text box on this tab is enabled and a value is required.
8. For the Gas-Water with Condensate option, the method for calculating oil phase properties (Bo and GOR) must be selected on the Oil properties tab. Oil phase properties can be obtained by flashing a sample of the oil phase at each depletion pressure through the user defined separators (Method of Whitson and Torp) or alternatively from material balance equations (Method of Coats).
138 • Black-Oil PVT Data Generation User's Guide WinProp For PVT data aimed at an extended black-oil model, the following information is written out to the output file:
1. The *PVTO keyword and associated table. Typical output is shown below.
*PVTO
** solution pressure, oil oil ** GOR(2) psia FVF(1) vis,cp ** --- 0.2606 515.00 1.2279 0.16615 Saturated 1115.00 1.2158 0.17475 1915.00 1.1996 0.18621 2715.00 1.1834 0.19768 3515.00 1.1673 0.20914 5000.00 1.1372 0.23043 6034.82 1.1163 0.24526 6500.00 1.1069 0.25192 0.5045 1115.00 1.3730 0.14572 Saturated 1915.00 1.3503 0.15714 2715.00 1.3275 0.16856 3515.00 1.3048 0.17998 5000.00 1.2626 0.20118 6034.82 1.2332 0.21595 6500.00 1.2199 0.22259 0.8261 1915.00 1.5462 0.12408 Saturated 2715.00 1.5150 0.13452 3515.00 1.4839 0.14497 5000.00 1.4262 0.16436 6034.82 1.3859 0.17787 6500.00 1.3678 0.18394 1.1532 2715.00 1.7100 0.10950 Saturated 3515.00 1.6720 0.11872 5000.00 1.6015 0.13582 6034.82 1.5523 0.14774 6500.00 1.5302 0.15310 1.4574 3515.00 1.8505 0.10135 Saturated 5000.00 1.7735 0.11634 6034.82 1.7198 0.12679 6500.00 1.6956 0.13149 1.6255 5000.00 1.8713 0.10344 Saturated 6034.82 1.8290 0.11189 6500.00 1.8100 0.11568 1.7044 6034.82 1.8751 0.10689 Saturated 6500.00 1.8590 0.11031 1.7399 6500.00 1.8768 0.10845 Saturated
The columns of this table are the gas-oil ratio (GOR), pressure, oil formation volume factor, and oil viscosity. For each GOR value the first row shows the saturated fluid values. For a GOR of 0.186 mscf/stb for example, the saturation pressure is 515 psia, the formation volume factor equals 1.1689 and the viscosity is 0.16615 cP. Second and subsequent rows of data for a given GOR define the undersaturated curves for the oil formation volume factor and viscosity as a function of pressure as specified in column 2.
User's Guide WinProp Black-Oil PVT Data Generation • 139 1. PVTG (gas phase properties) and associated table. Typical format is shown below:
*PVTG
** pressure, solution, gas gas ** psia CGR(4) FVF(3) vis,cp ** ---
515.00 0.000597 5.73365 0.01262 Saturated 0.000000 5.73597 0.01263 Dry gas 1115.00 0.001038 2.37473 0.01441 Saturated
0.000597 2.37631 0.01441 Under saturated gas 0.000000 2.37845 0.01440 Dry gas
1915.00 0.005019 1.27344 0.01926 Saturated
0.001038 1.28264 0.01905 Under saturated gas 0.000597 1.28366 0.01903 Under saturated gas 0.000000 1.28504 0.01900 Dry gas
2715.00 0.020711 0.90464 0.02658 Saturated
0.005019 0.92026 0.02516 Under saturated gas 0.001038 0.92444 0.02481 Under saturated gas 0.000597 0.92491 0.02477 Under saturated gas 0.000000 0.92555 0.02472 Dry gas
3515.00 0.057092 0.75257 0.03598 Saturated
0.020711 0.75975 0.03208 Under saturated gas 0.005019 0.76457 0.03045 Under saturated gas 0.001038 0.76597 0.03004 Under saturated gas 0.000597 0.76613 0.02999 Under saturated gas 0.000000 0.76634 0.02993 Dry gas
5000.00 0.186452 0.69119 0.06067 Saturated
0.057092 0.64409 0.04474 Under saturated gas 0.020711 0.63417 0.04032 Under saturated gas 0.005019 0.63060 0.03844 Under saturated gas 0.001038 0.62977 0.03797 Under saturated gas 0.000597 0.62968 0.03792 Under saturated gas 0.000000 0.62956 0.03785 Dry gas
6034.82 0.265054 0.69762 0.07772 Saturated
0.186452 0.66087 0.06746 Under saturated gas 0.057092 0.60205 0.05014 Under saturated gas 0.020711 0.58698 0.04532 Under saturated gas 0.005019 0.58085 0.04326 Under saturated gas 0.001038 0.57933 0.04274 Under saturated gas 0.000597 0.57916 0.04268 Under saturated gas 0.000000 0.57894 0.04261 Dry gas
6500.00 0.300389 0.70479 0.08562 Saturated
0.265054 0.68800 0.08103 Under saturated gas 0.186452 0.64996 0.07045 Under saturated gas 0.057092 0.58755 0.05249 Under saturated gas 0.020711 0.57093 0.04747 Under saturated gas 0.005019 0.56402 0.04533 Under saturated gas 0.001038 0.56230 0.04479 Under saturated gas 0.000597 0.56210 0.04473 Under saturated gas 0.000000 0.56185 0.04464 Dry gas
140 • Black-Oil PVT Data Generation User's Guide WinProp 2. The columns of this table are the pressure, the condensate gas ratio, the gas
formation volume factor and viscosity respectively. The first row corresponds to saturated values. Subsequent rows show the properties of the mixture of saturated gas and dry gas. These combinations are done such that the mixtures correspond to condensate gas ratios that are specified at lower pressures. For example at a pressure of 1800 psia there is one row for undersatured gas with a CGR of 0.00104 stb/mscf which is the CGR ratio at the previous pressure value of 1100 psia. 3. The stock tank densities of the oil, gas and water phase as well as the water phase
properties.
To generate the PVT data for the extended black-oil model the following information is required: 1. Composition of oil and, if the swelling curve is to be generated, the gas composition.
These are entered on the Composition form. Oil is entered as the primary fluid and gas is the secondary fluid. The injection gas composition can alternatively be chosen to be the solution gas. The selection is made on Tab 5 “Gas Properties”.
2. Selection of the PVT Experiment. For black-oils, differential liberation
corresponds the best to the depletion process occurring in the reservoir. For light oils differential liberation or constant volume depletion may be chosen. For gas condensates the constant volume depletion experiment is appropriate. The PVT experiment provides samples of the gas and oil phase which are then flashed through the user defined separators to obtain the oil and gas properties. This choice is made on Tab 1 of the Write BLACK-OIL PVT data form.
3. Selection of the method for calculating oil phase properties. Oil phase properties can be obtained by flashing a sample of the oil phase at each depletion pressure through the user defined separators (Method of Whitson and Torp) or alternatively from material balance equations (Method of Coats). This choice is made on Tab 1 of the form.