Method of producing self-propping fluid-conductive fractures in rock

摘要

A fracture that conducts fluid within the confines of an underground rock formation without the need for particulate proppant materials to hold opposing fracture faces apart is created by a method in which a long portion of a hole drilled into the formation has its axis slanted with respect to the directions of the principal stresses, and is pressurized rapidly over its entire length with fluid, preferably by detonating an explosive therein. A hypothetical fracture plane is defined as that plane containing the axis of the hole which is under the least compressive normal stress. When the orientation of the hole axis is such that there is a substantial shear stress on the hypothetical fracture plane, but the normal stress thereon does not greatly exceed the minimum principal stress, the fracture created lies close to the hypothetical fracture plane, and is conductive to fluids. The fracture is conductive because it is held open by the misfit between the opposing faces which arises from the shear displacement of the faces that occurs when the existing shear stress is released by the formation of the fracture.