Application of Pressure Transient Analysis in Steam Injection Wells

Abstract

ABSTRACT The determination of the swept volume in a steam displacement process provides an early means to evaluate the project's progress. By determining the volume occupied by steam, and knowing the cumulative volume of steam injected, the heat losses from the injection interval and the ensuing heat efficiencies can be estimated. These parameters dictate the performance efficiency of the displacement project. Getty Oil Company has run pressure falloff tests in several steamflood projects located on the west side of the San Joaquin Valley. The first project tested had undergone nine months of continuous steam injection, with little apparent increase in oil production or wellhead temperatures in the displacement wells. The test data was analyzed using the theory presented in Eggenschwiler, et al.'s1 work and Walsh, et al.'s3 analytical procedure. The initial results are very encouraging and more-or-less consistent with the previous theoretical studies, implying that this type of testing can be a valuable tool for early evaluation of the viability of a steamflood project, with a minimal shut-in time and expense. Several more falloff tests were run in displacement projects having more history, temperature observation wells, and better control of reservoir properties. These tests were run to verify the analysis procedure and determine steamflood characteristics in projects designated as commercial successes. A simple numerical study using a thermal model was also used to further analyze the principles of the underlying theory and demonstrate the applicability of this particular simulator to pressure transient problems. The results of the numerical study are included.