Experimental study on fracturing features in naturally fractured reservoir

The natural fracture system of reservoir was simulated.The fracture geometry under the influence of natural fracture,features of pressure curves and the leak off mechanism were analyzed by using a series of large size tri-axial experiments.The experimental result shows that the propagating patterns of the main fractures include the multiple branch fracture and radial net-fracture.In the same natural fracture system,the main fractures with multiple branches are primary under high differential stress,and the pressure curve of fracturing fluctuates frequently.The propagating pattern of the main fractures has the features of one dimensional leak-off.The radial net-fracture propagation pattern is primary under low differential stress and has two dimensional leak-off and smooth pressure curve.The mini-fracturing ground stress was estimated,and the coefficient of error mainly caused by the natural fractures was defined.The average value of error is 0.42 under the simulated condition of current natural fracture system.