Estimating the Pressure-Transient Response for a Horizontal or a Hydraulically Fractured Well at an Arbitrary Orientation in an Anisotropic Reservoir

Abstract

Summary This article presents a method for finding the equivalent isotropic system for a horizontal well or a hydraulically fractured well at an arbitrary azimuth in an anisotropic reservoir. The equivalent isotropic system can then be used to calculate the pressure response of the original system. The horizontal well solution is compared with previous solutions reported in the literature. The general hydraulically fractured well case has not, to our knowledge, been presented before. This study confirms the observation by Yildiz and Ozkan1 that small deviations (up to 20°) from the optimal azimuth for a horizontal well do not have a major effect on the pressure response. Because this solution is obtained by finding an equivalent isotropic system, this study also confirms the observation by Earlougher2 that an anisotropic system cannot be identified from a single-well test.