Single Well Pressure Transient Testing in Prudhoe Bay, Alaska

Abstract

ABSTRACT This paper presents the results of the application of a mixed-boundary pressure transient testing model to Prudhoe Bay wells. The proposed model considers a constant pressure upper boundary and a no-flow lower boundary. Reservoir anisotropy and partial penetration were considered in the model. These boundary conditions simulate the pressure transient testing in the Prudhoe Bay unit of the Alaskan North Slope where the oil column of the Sadlerochit formation is overlain by a huge gas cap. A set of type curves for gas cap dominated data analysis is presented. These type curves should complement those presented by Kuchuk and Kirwan for no-flow upper and lower boundaries. A correlation for predicting the beginning of the constant pressure boundary effect is provided. This correlation can be used to estimate the period to record analyzeable early-time data during the design of a pressure transient test. Also, it is a useful tool for validating the results of type curve analysis of data obtained from gas cap dominated transient tests. Examples of pressure buildup tests conducted in the Western half of the Prudhoe Bay unit are analyzed. The results obtained are used to discuss the problems of single well pressure transient analysis in gas cap dominated reservoirs.