Analysis of Buildup Tests With Short Producing Time

Abstract

Summary Pressure buildup data with short producing time are often difficult to analyze. Although the semilog method, known as the Horner1 method, can be used, the drawdown type curve should not. Thus it is difficult to determine whether the semilog plot actually includes the correct straight line. In this paper, a new log-log graph specially designed for a pressure buildup test with short producing time is suggested. This graph allows the user to determine easily the type of flow regime (linear, bilinear, or radial). Consequently, it can be used to detect the presence of the correct semilog straight line. The new graph can also be used to calculate the formation permeability or fracture conductivity in a fashion similar to the semilog method. The analytical models used to develop the new technique are presented. The models consider both well-bore storage and skin effect. A field example is presented and discussed. Use of the new technique to analyze a buildup test with short producing time is presented and briefly compared with the existing techniques.