Mechanics and direction of hydraulic fracturing
Use of the in situ principal stresses greatly simplifies the problems of hydraulic fracturing. For one thing, it reduces the number of stresses to 3, thus simplifying the mathematics. Besides, this choice is in harmony with laboratory observations of fracture propagation perpendicular to the least principal stress. In addition to underground stresses, hydraulic stress is also influenced by the mechanical properties of the formation rock. In this discussion, it is assumed that the formation to be fractured is isotropic, homogeneous, and brittle-elastic. The initiation of hydraulic fractures is synonymous with the rupture of rock adjacent to the borehole wall. This rupture can occur only if the induced stresses exceed the strength of the formation. During fracturing treatments, fracture initiation is identified by a sudden drop in borehole fluid pressure accompanied by an increase in the injection rate. Continued injection of fluid after fracture initiation will result in its extension. The fracture will propagate in such a way that it will require the least possible amount of energy for its extension.
- Research Organization:
- Halliburton Services
- OSTI ID:
- 6706191
- Journal Information:
- Pet. Eng.; (United States), Journal Name: Pet. Eng.; (United States) Vol. 45:11; ISSN PENGA
- Country of Publication:
- United States
- Language:
- English
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