Dual Permeability Modeling of Flow in a Fractured Geothermal Reservoir
A three dimensional fracture system synthesis and flow simulation has been developed to correlate drawdown characteristics measured in a geothermal well and to provide the basis for an analysis of tracer tests. A new dual permeability approach was developed which incorporates simulations at two levels to better represent a discrete fracture system within computer limitations. The first incorporates a discrete simulation of the largest fractures in the system plus distributed or representative element simulation of the smaller fractures. the second determines the representative element properties by discrete simulation of the smaller fractures. The fracture system was synthesized from acoustic televiewer data on the orientation and separation of three distinct fracture sets, together with additional data from the literature. Lognormal and exponential distributions of fracture spacing and radius were studied with the exponential distribution providing more reasonable results. Hydraulic apertures were estimated as a function of distance from the model boundary to a constant head boundary. Mean values of 6.7, 101 and 46 {micro}m were chosen as the most representative values for the three fracture sets. Recommendations are given for the additional fracture characterization needed to reduce the uncertainties in the model.
- Research Organization:
- Idaho National Engineering and Environmental Laboratory (INEEL), Idaho Falls, ID
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AS03-80SF11459; AS07-84ID12529
- OSTI ID:
- 887093
- Report Number(s):
- SGP-TR-93-12; TRN: US200618%%139
- Resource Relation:
- Conference: Proceedings, Eleventh Workshop Geothermal Reservoir Engineering, Stanford University, Stanford, California, January 21-23, 1986
- Country of Publication:
- United States
- Language:
- English
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