GROWTH OF A HYDRAULIC FRACTURE IN THE SIDETRACKED BOREHOLE

Abstract

Initially developed as one of the most successful methods for stimulating hydrocarbon production, hydraulic fracturing (HF) has gradually found its application in related fields, such as underground mining. At the same time, the importance of controlling the crack propagation path increases, since the design of in-mine hydraulic fracturing is a complex technological task due to the influence of mine workings and other inseam boreholes. When performing HF for the purpose of degassing a coal-bearing massif, there is a problem of forming a longitudinal crack in the plane of the coal seam. Such a crack makes it possible to most effectively cross natural fractures and increase the production rate of methane. To do this, HF is carried out in closely spaced parallel boreholes with the formation of a single plane of filtration. However, the approach has a significant drawback: for successful implementation of the method, the distance between wells must be sufficiently small. In this paper, a method for creating a crack in a borehole with a sidetrack is considered and numerically investigated. Sealing of the fracturing interval is performed above the sidetracking point, which acts as a stress concentrator and promotes the onset of crack growth. As a result, a longitudinal crack propagates in the plane formed by the borehole and the sidetrack. The influence of the stress field, the properties of the medium, the free surface, as well as the direction and angle of the sidetrack on the path of the crack is studied.