| The interpretation of pressure buildup tests involving multiphase flow is an active research field in which conventional analysis techniques may produce misleading results. Pseudopressure and pseudotime transformations were recent techniques to consider the effects of changing fluid properties with pressure and with time throughout the reservoir.;During this study, multiphase and single phase pressure buildup tests were analyzed from Yowlumne oil field in Bakersfield, California, after developing a three-phase, two-dimensional variable bubble point reservoir simulator. The analysis method was to history match the observed buildup performance of the field test using the numerical simulator. A successful match indicates a consistent reservoir description as suggested by the geologists and the engineers, and proper interpretation of pressure buildup tests under multiphase flow conditions. The research also presents some guidelines on how to conduct such a study including data requirements, benefits and recommendations.;Unusual pressure buildup behavior were identified due to changes in fluid properties within a wells drainage area during the shut-in period. Such behavior can be misinterpreted as a reservoir heterogeneity, displaying similar characteristics. Possible explanations of unusual buildup behavior are given in heterogeneous cases with partial penetration and permeability anisotropy. Analysis of multiphase tests via the history matching approach provides the absolute permeability and a reliable evaluation of damage or stimulation around the wellbore, which can not be estimated with classical techniques.;The approach requires a well kept data bank which covers reservoir rock and fluid properties, well completion, injection/production and pressure transient test reports. An integral part of the study is geological description of the reservoir and well log analysis, which provide net pay thickness, saturation and porosity values for the simulation data set.;The method utilized is useful to organize all available information as a consistent whole, which is helpful not only for reservoir description, but also for pressure transient test analysis in complex situations. |
