Initiation and propagation of cracks in problems of petrothermal energy

One of the challenges in using petrothermal energy is creating a fractured reservoir. The depth of formations suitable for exploitation is higher than that of formations for which hydraulic fracturing operations are usually carried out in hydrocarbons production. Therefore, the study of hydraulic fracturing features at great depths can be useful for petrothermal energy. The paper compares the pressures required for the initiation and propagation of a hydraulic fracture for a reservoir located at a depth of 5 kilometers and characterized by a strong contrast in compressive stresses. Fully 3D model is used to simulate fracture propagation and obtain propagation pressure. The initiation pressure is calculated based on the elastic equilibrium equations the solution. It is shown that the initiation pressure may greatly underestimate the pressure required for fracture propagation.