A Hydrology-Mechanical-Chemical Coupling Mathematical Model and Numerical Simulation of Hydraulic Fracturing in Salt Deposit

Due to its dissolvability to water, the hydraulic fracturing process of resolvable deposit such as salt rock, is different from that of ordinary rocks, it is a complicated coupled course of hydraulic fracture and mineral dissolution. Through detailed theoretical analysis, in this paper, a solid, fluid, and mass transfer coupled mathematical model of hydraulic fracture and dissolution of resolvable deposit is established in this paper, and some numerical simulations were also conducted simultaneously on the basis of the established model. The results of numerical simulation indicate that resolvable deposit fractures during fracturing in the typical way of wing-fracture, with an penny-shaped opening, and the relation between fracture aperture versus expanding distance and fracturing time was founded. Furthermore, it was found that the fluid pressure in the fracture and the expanded velocity of the fracture both decrease gradually as a result of the influence of mineral dissolution during fracturing. These results indicated that the mineral dissolution is an important influential factor in the hydraulic fracture of resolvable deposit. Besides, the values of numerical simulations and the results of practical test in situ were well inosculated, thus the rationality and the dependability of the established coupled mathematical model were demonstrated.