关键词: 岩石, 水力压裂, 近场动力学, 裂隙扩展, 数值模拟

Abstract: In this study, the rock fracture propagation is simulated based on the ordinary state-based peridynamics, and a numerical model of rock hydraulic fracturing is proposed by means of real-time tracking of newly generated fracture and applying pressure to simulating the interaction between fracturing fluid and fracture surface. According to the digital image processing technology, the Zhang-Suen thinning algorithm is applied to extracting the skeleton of hydraulic fracture network, and a quantitative method of hydraulic fracture network is presented by using the statistical method to calculate the morphological parameters. Finally, the process of hydraulic fracture propagation and the evolution of fracture network morphological parameters are studied considering the effects of loading rate, in situ stress condition and elastic modulus. The results show that when the loading rate is small, the main fracture expands towards the direction of the larger in situ stress, and the fracture branch is not obvious. Increasing the loading rate can increase the average width and density of fractures, promote the opening degree and number of fractures, enhance the complexity of fracture network, and improve its permeability. When the horizontal and vertical in situ stresses are the same, the major fractures intersect. With the increase of vertical in situ stress, the horizontal fractures are restrained, the major fracture propagates along the vertical direction, and the total length and density of fractures increase. The increase of elastic modulus of rock mass can reduce the propagation of fracture branches and simplify the fracture network.

Key words: rock, hydraulic fracturing, peridynamics, fracture propagation, numerical simulation