STUDIES OF FLOW PROBLEMS WITH THE SIMULATOR SHAFT78
In recent years, a number of numerical simulators for geothermal reservoirs have been developed. The general purpose of these is to aid reservoir engineers in (i) determining characteristic parameters of reservoirs (most important among those being the reserves of fluid and heat), and (ii) simulating the performance of reservoirs upon production and injection. The various simulators differ in the approximations made in the underlying physical model (e.g., dependence of rock and fluid properties upon thermodynamic variables), in the geometrical definition of the reservoir (one-, two-, or three-dimensional, regular or irregular shape); in the choice of thermodynamic variables, and in the mathematical techniques used for solving the coupled mass and energy transport equations. Criteria for desirable performance of numerical simulators depend in part upon the particular problems to be investigated. Different problems will often differ in the required level of detail to be resolved, and in the optimum balance of speed and accuracy of computation. Much can be learned about two-phase flow in porous media from model studies for idealized systems. Such studies can be performed with less-than-three-dimensional model and algorithms which are based on regular grid spacings will be perfectly acceptable. For modeling natural geothermal reservoirs, on the other hand, it is important that irregular three-dimensional geometries may be handled easily. In comparison with other two-phase simulators which have been discussed in the literature, the main distinctive feature of SHAFT78 is that it uses an integrated finite difference method (IFD). We solve finite difference equations that are obtained by integrating the basic partial differential equations for mass and energy flow over discrete surface and volume elements. This method is as easily applicable to irregular geometries of actual reservoirs as it is to idealized, regular geometries; yet the relative simplicity of the finite difference method is retained in the theory and algorithms. The purpose of this paper is to give a brief review of the basic concepts associated with SHAFT78 and the IFD approach, and to present comparisons of SHAFT78 calculations with some analytical solutions. The comparisons include both single-phase and two-phase water problems and demonstrate the accuracy and calculational stability of the algorithm.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- Earth Sciences Division
- DOE Contract Number:
- DE-AC02-05CH11231
- OSTI ID:
- 1022108
- Report Number(s):
- LBL-8515; TRN: US201216%%77
- Resource Relation:
- Conference: Fourth Geothermal Reservoir Engineering Workshop, Standford University, Stanford, CA, December 13-15, 1978
- Country of Publication:
- United States
- Language:
- English
Similar Records
Geothermal reservoir simulations with SHAFT79
SHAFT78: a two-phase multidimensional computer program for geothermal reservoir simulation