Nonisothermal Effects During Injection and Falloff Tests

Summary Numerically simulated pressure transients during injection and falloff tests are analyzed to develop methods for obtaining the correct permeability/thickness of the reservoir and the skin factor for the well. The results show that to analyze correctly the pressure transients governed by a moving thermal front, the fluid-property values must correspond to the temperature of the injected fluid. For pressure falloff tests and for injection tests conducted in a well cooled by previous injection or drilling, however, the physical properties of the in-situ reservoir fluids must be used. The application of conventional isothermal methods for calculating skin values from injection and falloff data will give erroneous results. A new method is presented for calculating skin values from injection and falloff data that accurately corrects for nonisothermal effects. Examples are given to illustrate this analysis method. The technique is applied to the analysis of injection test data from a well located in the East Mesa geothermal field in southern California.