On Estimation of Horizontal Well Effective Lateral Length and Reservoir Properties from Well Test Data

Abstract

Abstract One of the ways suggested in the literature to estimate effective reservoir properties when drilling horizontal wells is by pressure transient testing. Various analytical solutions published provide the interpretation path for analyzing such tests. Our study shows that using the analytical tools to estimate horizontal wells could be subject to significant errors if there are uncertainties about the effective length of the lateral. In this study, we examined situations where horizontal wells were designed given certain reservoir properties and the inverse estimation of parameters, using currently available analytical tools, showed significant errors. This is attributed to the nonlinear nature of analytical equations which result in multiple combinations of answers. In actual cases, analytical equations may be insufficient to represent complex real horizontal well trajectories. We show multiple examples using the direct modeling of horizontal wells and demonstrate the non-uniqueness of solutions obtained from analytical models when there are uncertainties about the effective lateral length.