Pressure Analysis of a Well with an Inclined Asymmetric Hydraulic Fracture

Habte, Azeb Demisi (2009-12-08)


Hydraulic fracturing is an effective well stimulation technique which is introduced in the 1950s and widely used in the oil and gas industry. Most of the works about hydraulic fracture assumed that the fracture is symmetric and either vertical or horizontal. But, several field and laboratory observations show very complex fractures, inclined, multi-segmented, asymmetric, and the presence of multiple fractures. The purpose of this study is to investigate the pressure behavior of a uniform flux hydraulic fracture which is both inclined and asymmetric. This objective is achieved by using transient pressure and pressure derivative plots. Three cases are investigated, (a) the fracture is asymmetric along the horizontal direction (X-axis), (b) the fracture is asymmetric along the lateral direction (Yaxis), and c) the fracture is asymmetric along both lateral and horizontal directions (X and Y axes). Three flow regimes, Linear Flow Regime, Early-Radial Flow Regime, and Pseudo-Radial Flow Regime are observed when the asymmetry is not significant and for small θw and hD . As the asymmetry increases the behavior of the fracture also shows changes. For a fracture with high asymmetry, Biradial flow regime is observed. As the asymmetry becomes significant the uniform flux fracture solution shows similar behavior to infinite conductivity fracture. Type curve matching technique was developed in this study using pressure and pressure derivative curves. This type curve matching procedures can be used to obtain the following reservoir parameters: fracture half length, inclination angle, formation permeability and the pseudo-skin factor which is caused by fracture inclination. Transient pressure analysis of an inclined asymmetric uniform flux fracture using conventional techniques and detailed explanations, tables, figures and numerical examples are included in this paper.