Numerical simulation of three-dimensional induced stress in hydraulic fracturing of giant thick conglomerate oil reservoirs
Under the development model of three-dimensional well pattern in giant thick conglomerate reservoirs,the interference of the first fractured well to subsequent adjacent wells during multi-well fracturing is relatively great.However,the current solution method of induced stress distribution caused by the fracturing opening is unclear,which leads to the decrease of the accuracy of fracture propagation morphology simulation,and affects the integrated fracturing scheme designs and fracturing effects of the well group.To address this problem,based on the linear elasticity theory,a three-dimensional complex fracture opening induced stress model was established using the displacement discontinuity method.The stress field distribution after hydraulic fracturing under the condition of a three-dimensional well pattern in giant thick conglomerate was simulated,and the fracturing mode of horizontal wells was optimized based on actual well groups.The results show that when one fracture is opened,the maximum value of minimum horizontal principal stress increases by 3.3 MPa compared to the initial value,the maximum horizon-tal principal stress increases by 1.4 MPa,and the horizontal stress difference decreases.The induced stress generated by fracture opening is positively correlated with fracture width,and induced stress increases with the increase of fracture width.Simulation results of the actual well group indicates that the stimulated reservoir volume(SR V)of interlayer alternat-ing zipper fracturing is 1 825×104 m3,and the SRV of same-layer sequential fracturing is 1 360×104 m3.Subsequent fractures at the same location of the interlayer alternating zipper fracturing are more affected by the superposition of induced stress during the initiation and propagation process of fracturing,resulting in higher fracture complexity and lager SRV.
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