Pressure Analysis of a Well With an Inclined Hydraulic Fracture in a Naturally Fractured Reservoir

Abstract

Hydraulic fracturing has been an effective technique to stimulate damaged wells or wells producing from low-permeability formation. It has been established that the orientation of a hydraulic fracture is perpendicular to the direction of the least principal stress in the formation. Thus, most pressure transient analysis techniques are based on the assumption that the fracture is vertical. However, it is now generally agreed that the direction of the least principal stress is not always parallel or perpendicular to the plane of the formation. For this reason it is very likely that some hydraulically fractured wells have inclined fractures. Objectives of study: (1) Provide background to justify the conclusion that the direction of least principal stress might be at an orientation different from parallel or perpendicular to the bedding plane of the formation. (2) Develop a technique, based on the pressure derivative concept, for interpreting pressure transient tests in wells with an inclined hydraulic fracture. Three cases are possible: (a) the fracture is symmetric in both lateral and horizontal directions, (b) the fracture is asymmetric in only one of the directions, and (c) The fracture is asymmetric in both directions.