Analysis of injection tests in liquid-dominated geothermal reservoirs
The objective was to develop procedures for analyzing nonisothermal injection test data during the early phases of injection. In particular, methods for determining the permeability-thickness of the formation, skin factor of the well and tracking the movement of the thermal front have been developed. The techniques developed for interpreting injection pressure transients are closely akin to conventional groundwater and petroleum techniques for evaluating these parameters. The approach taken was to numerically simulate injection with a variety of temperatures, reservoir parameters and flowrates, in order to determine the characteristic responses due to nonisothermal injection. Two characteristic responses were identified: moving front dominated behavior and composite reservoir behavior. Analysis procedures for calculating the permeability-thickness of the formation and the skin factor of the well have been developed for each of these cases. In order to interpret the composite reservior behavior, a new concept has been developed; that of a ''fluid skin factor'', which accounts for the steady-state pressure buildup due to the region inside the thermal front. Based on this same concept, a procedure for tracking the movement of the thermal front has been established. The results also identify the dangers of not accounting the nonisothermal effects when analyzing injection test data. Both the permeability-thickness and skin factor of the well can be grossly miscalculated if the effects of the cold-region around the well are not taken into consideration. 47 refs., 30 figs., 14 tabs.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 5635919
- Report Number(s):
- LBL-17953; ON: DE85011989
- Resource Relation:
- Other Information: Thesis
- Country of Publication:
- United States
- Language:
- English
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