Study on Fracture Interference for Volume Fracturing

摘要

As the main exploitation mean of low permeability reservoirs,multistage fracturing plays a significant role in horizontal well.However,due to the multi-stage fracturing technology lack of focused research on crack interaction phenomenon,limiting its further development.In this paper,considering the basis of rock and soil mechanics,flow mechanics theory,the fluid-solid coupling and combining with extended finite element method(XFEM)to simulate the fracture propagation of 2-4 vertical cracks for simultaneous fracturing in horizontal well.Based on the fracture morphology,optimizing the number of fractures,cluster spacing and segment spacing by comparing the crack width of deflection point with the crack width of injection point.The simulation results are applied in field for verification.The study results are as follows:Selecting 2-3 cracks per segment can efficiently satisfy the requirement of production;the optimal cluster spacing of simultaneous fracturing for two fractures is 20-30 m;the optimal cluster spacing of simultaneous fracturing for three fractures is 30-40 m;the optimal segment spacing is 30-40 m.The results suggested as above illustrate that the more the number of fractures,the better the effect of multistage fracturing is not correct.Meanwhile,the reasonable fracture spacing can effectively reduce the negative impact of crack interaction phenomenon.The research method and optimal parameters proposed in this paper provides a theoretical basis for practical production in horizontal well.