Four-dimensional in-situ stress simulation before and after energy replenishment in shale oil reservoirs and research on complex fracture propagation law in infill wells
Aiming at the problems of low production degree and abundant remaining oil in the horizontal well area of Chang 7 oil-bearing layer in the An 83 well area,taking into account the heterogeneity and anisotropy of shale oil reservoir geomechanical parameters,natu-ral fractures,etc.,a set of the coupling mechanism simulation method of in-situ stress field and seepage field was established,traditional reservoir seepage simulation with geomechanical simulation were combined,and through fracturing construction parameters,on-site well testing data,microseismic monitoring data,etc.,the four-dimensional in-situ stress simulation before and after reservoir energy replen-ishment and study of the propagation law of complex fractures in infill wells were conducted.The results show that the reservoirs in this area are high in Young's modulus and low in Poisson's ratio,and are prone to fracture;large-scale fracturing can form complex frac-tures,which are basically multi cluster fracture bands with a length of about 250 m and a width of about 80 m;water medium energy re-plenishment can play a uniform energy replenishment effect,and the effect is better than gas medium;when the old well is replenished to 80％of the original pressure,the fracturing fractures are fully reformed and the fractures expand evenly,5 000 m3 of energy replenish-ment fluid is optimal for a single well in old wells;when the 300 m infill well replenishes energy to 120％of the original formation pres-sure,the fracturing after fracturing is sufficient,and the optimal amount of energy replenishment fluid for a single well is about 25 000 m3.The simulation analysis method has important guiding significance for the simulation of the in-situ stress of the same type of reser-voir and the study of the fracture propagation law.
shale oilreservoir energy replenishmentfour-dimensional in-situ stress simulationfracture propagation lawcoupling of in-situ stress field and seepage field
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