Numerical simulation of fracture propagation guided by radial well assisted preflush acid fracturing
In this paper,a fracture propagation model of radial well assisted preflush acid fracturing was established based on the extended finite element method and the two-scale continuum model theory.The term"deflection factor"was introduced as the quantification criterion to analyze the influence of various factors on the fracture morphology,and the main control fac-tors were identified by using the gray correlation analysis method.The simulation results show that the radial well has a sig-nificant guiding effect on the fracture propagation of the preflush acid fracturing.The fracture starts and expands for a certain distance along the radial well,and then gradually deflects to the direction of the maximum horizontal principal stress.Smaller azimuth of the radial well,horizontal in-situ stress difference and elastic modulus of rock and longer length of the radial well can cause smaller deflection factor and better guiding effect.The most important influence factor is the horizontal in-situ stress difference.For instance,when the azimuth of the radial well is 15°,the fracture can propagate 14.32 m along the ra-dial well,and deflect to the direction of the maximum principal stress finally.In this case,the radial well has the best guid-ing effect,and the deflection factor is 0.005.
radial wellpreflush acid fracturingfracture propagationextended finite element methodtwo-scale continuum model
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