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NESC0893 SHAFT79.

SHAFT-79, 2 Phase Flow in Porous Media for Geothermic Energy System

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1. NAME OR DESIGNATION OF PROGRAM:  SHAFT79.
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2. COMPUTERS
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Program name Package id Status Status date
SHAFT-79 NESC0893/01 Tested 20-NOV-1981

Machines used:

Package ID Orig. computer Test computer
NESC0893/01 CDC 7600 CDC 7600
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3. DESCRIPTION OF PROBLEM OR FUNCTION

SHAFT79 (Simultaneous Heat And  Fluid Transport) is an integrated finite difference program for computing two-phase non-isothermal flow in porous media. Although designed for simulating production and injection in geothermal reservoirs, it is, or can be readily modified to be, applicable to other two-phase problems. SHAFT79 solves coupled mass and energy balance equations based on the following major assumptions: the physical system is a system of porous rock saturated with a one- component fluid in liquid and vapor form; all rock properties, except porosity, i.e., density, specific heat, thermal conductivity, and absolute permeability are independent of temperature, pressure,  or vapor saturation: and liquid, vapor, and rock matrix are at the same temperature and pressure at all times. Capillary pressure is neglected.
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4. METHOD OF SOLUTION

The solution method is an explicit-implicit integrated finite difference approach which allows a flexible geometric description because it does not distinguish between one-,  two-, or three-dimensional regular or irregular geometries. The non- linear finite difference equations are solved using the Newton- Raphson method. In SHAFT79 a fluid table is used to provide the equilibrium thermodynamic properties of the fluid filling the void space - temperature, pressure, vapor saturation, heat conductivity,  liquid and vapor viscosities, densities, specific interval energies  - as functions of fluid density and fluid specific internal energy.  All thermodynamic information including derivatives is obtained from the fluid table by bivariate interpolation.
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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

SHAFT79 has been developed only for systems of water and rock. The fluid table covers most of the equation of state of water substance in the temperature  range of 5 to 400 degrees C and the pressure range of 0.5 to 220 bar, which is adequate for most geothermal applications.
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6. TYPICAL RUNNING TIME

Typical problems require about 10 to 25 CP seconds on a CDC7600.
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7. UNUSUAL FEATURES OF THE PROGRAM:
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8. RELATED AND AUXILIARY PROGRAMS

The fluid table is generated by executing two auxiliary programs included in the package, WATER and  PROPER. WATER computes and tabulates the steam table equations as given by the International Formulation Committee (IFC,1967). PROPER  numerically inverts these tables into functions of viscosities and densities and appends parameters other than temperature, pressure and vapor saturation. The tabulation is done in such a way that interpolation does not occur across the saturation line, where derivatives change in discontinuous fashion.
SHAFT79 is one of a set of five geothermal codes. The others are: ANALYZE for multiwell, multirate well test parameter determination (NESC Abstract 891); CCC for one-phase conduction, convection; and compaction (NESC Abstract 892); TERZAGI for isothermal fluid flow and subsidence (NESC Abstract 894); and WELBORE for steady and transient geothermal wellbore flow (NESC Abstract 895).
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9. STATUS
Package ID Status date Status
NESC0893/01 20-NOV-1981 Tested at NEADB
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10. REFERENCES

- K. Pruess, J.M. Zerzan, R.C. Schroeder, and P.A. Witherspoon,
  Description of the Three-dimensional Two-phase Simulator SHAFT78
for Use in Geothermal Reservoir Studies, Paper SPE-7699, presented    at the Fifth Symposium on Reservoir Simulation, Denver, Colorado,
  1979.
- K. Pruess, G. Bodvarsson, R.C. Schroeder, P.A. Witherspoon, R.
  Marconcini, G. Neri, and C. Ruffilli,
  Simulation of the Depletion of Two-phase Geothermal Reservoirs,
Paper SPE-8266, presented at the 54th Annual Technical Conference,    Society of Petroleum Engineers, Las Vegas, Nevada, 1979, also
  printed as,
  LBL-9606, August 1979.
- K. Pruess, R.C. Schroeder,
  Geothermal Reservoir Simulation with SHAFT79,
  5th Geothermal Reservoir Engineering Workshop, Stanford,
  California, 1979,
  LBL-10066.
NESC0893/01, included references:
-  K. Pruess et al.:
    SHAFT-78, A Two-phase Multidimensional Computer Program for
    Geothermal Reservoir Simulation. LBL-8264 (November 1979).
-  K. Pruess and R. C. Schroeder:
    SHAFT-79, USER'S MANUAL. LBL-10861 (March 1980).
-  NESC Note 81-35 (May 9, 1981).
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11. MACHINE REQUIREMENTS:  725,000 (octal) words of storage are required
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12. PROGRAMMING LANGUAGE(S) USED
Package ID Computer language
NESC0893/01 FORTRAN-IV
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13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:  SCOPE2.1.
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14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

The
SHAFT79 program uses subroutine MA28A and associated routines from the U.K.A.E.A. Harwell Subroutine Library to solve a general sparse  n x n system of linear equations. These routines, included as part of the package with Harwell's permission, are not in the public domain and extraction for other use is not permitted.
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15. NAME AND ESTABLISHMENT OF AUTHOR

             K. Pruess* and R.C. Schroeder
             Lawrence Berkeley Laboratory
             University of California
             Berkeley, California 94720
* Contact
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16. MATERIAL AVAILABLE
NESC0893/01
File name File description Records
NESC0893_01.001 SHAFT-79 FORTRAN SOURCE 5599
NESC0893_01.002 FLUTAB3 LIBRARY DATA 18297
NESC0893_01.003 BRIGHAM & MORROW HALF-WATER HALF-STEAM 24
NESC0893_01.004 NATURAL HYDROTHERMAL CONVECTION SYSTEM 109
NESC0893_01.005 GARG'S RADIAL FLOW 118
NESC0893_01.006 WATER FORTRAN SOURCE 273
NESC0893_01.007 WATER SAMPLE INPUT 5
NESC0893_01.008 PROPER FORTRAN SOURCE 1734
NESC0893_01.009 PROPER SAMPLE INPUT 364
NESC0893_01.010 ISOT1 FILE 4937
NESC0893_01.011 OGRE FORTRAN SOURCE 1014
NESC0893_01.012 TEST CASE OUTPUT1 380
NESC0893_01.013 TEST CASE OUTPUT2 883
NESC0893_01.014 TEST CASE OUTPUT3 1223
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17. CATEGORIES
  • H. Heat Transfer and Fluid Flow
  • R. Environmental and Earth Sciences

Keywords: finite difference method, geothermal systems, reservoir engineering, simulation, thermodynamic properties, two-phase flow.