Finding out the influence of bedding on fracture law of tight sandstone is of practical significance for objective evaluation of fracture law of tight oil and gas reservoir.In this paper,three-point bending loading is carried out on tight sandstone SCB samples in different bedding directions,and digital image correlation(DIC)technology is used to record the surface displacement,strain evolution and crack growth of the samples,so as to obtain the crack growth evolution of sandstone.The research shows that the development of fracture of tight sandstone includes five stages:defect compression,elastic compression,failure failure,rapid fracture and slow fracture.On the whole,the plasticity of tight sandstone is significant.The transverse displacement of tight sandstone is maximum when the bedding orientation is 0° and 90°,which indicates that the fracture opening is large and the fracture is pure tension fracture form,which is favorable for the high diversion fracturing of deep tight oil and gas reservoir.At bedding Angle of 45°,the displacement is the smallest and the strain is the largest in the X-axis direction,indicating that the sample is shear fracture,and the rock matrix on both sides of the fracture is seriously deformed,which restricts the flow of oil and gas fluid into the matrix pores.It is found that the bedding fabric affects the crack extension orientation,and the fracture deflection Angle increases first and then decreases with the increase of the bedding angle.The angle between the fracture and the maximum load direction is the largest when the bedding angle is 45°.The characteristics of dynamic evolution law of fracture of tight sandstone are of practical significance to the evaluation and design of fracturing stimulation effect of tight sandstone reservoirs.
万方数据
维普
