Transient Pressure Analysis of a Horizontal Well With Multiple Inclined Hydraulic Fractures Using Type-Curve Matching

Abstract

Abstract Horizontal wells with multiple hydraulic fractures have become a common occurrence in the oil and gas industry, especially in tight formations. Published models assume the hydraulic fractures are vertical and symmetric. However, recent studies have shown that fractures are asymmetric and inclined with respect to the vertical direction and the axis of the wellbore. This paper introduces a new technique for interpreting the pressure behavior of a horizontal well with multiple hydraulic fractures. The hydraulic fractures in this model could be longitudinal or transverse, vertical or inclined, symmetrical or asymmetrical. The fractures are propagated in isotropic or anisotropic formations and are considered as having different dimensions and different spacing. This technique, based on pressure and pressure derivative concepts, can be used to calculate various reservoir parameters, including directional permeability, fracture length, skin factors, and angle of inclination. The study has shown that early radial flow might develop when the spacing between fractures is significantly long. This paper also suggests new applications for the well test analysis in the hydraulically fractured reservoirs. These applications are focusing on: 1) Evaluating the performance of the fractures, 2) Determining whether one or more hydraulic fractures do not perform properly as designed (closed) and 3) Locating the malfunctioning fractures. A type curve matching technique has been applied using the plots of the pressure and pressure derivative curves. A set of type curves, which will be included in the paper, have been generated for the inclined transverse and longitudinal hydraulic fractures associated to the horizontal wells with different inclination angles from the vertical direction. A step-by-step procedure for analyzing pressure tests using these type curves is also included in the paper for several numerical examples.