When multiple-fracture broken one by one, there are certain interference among them. Due to the dif ferent properties of fracturing fluid, injection rate, broken fracture number and fracture location, the initial fractu ring pressures are also various. Focused on the calculation problem of the initial fracturing pressure for the staged fracturing in Changqing Oilfield, the influencing factors such as borehole pressure, initial earth stress distribution, the filtration effect of the fracturing fluid, the inducing stress of current hydraulic fractures and so on are compre hensively considered. Based on the superposition principle and elastic mechanics theory, the calculating model of the total stress field mathematical while staged fracturing for horizontal well is established to analyze the initially fractured laws. The theoretical calculation of the eachfracture initial fracturing pressure for one of fractured horizon tal well is well matched with that of field measurement in a certain block of the oilfield. The model can not only qualitatively study the influence trend of the former broken fractures on the later ones, but can quantitatively com putting the breakdown pressure values of each-fracture, so it can soundly guide the design of fracturing operation.%当多条裂缝依次压开时,裂缝间存在着相互干扰,随着压裂液性质、注液量、压开裂缝条数和裂缝位置的不同,裂缝的起裂压力也不同.针对长庆油田分段压裂水平井裂缝起裂压力计算问题,综合考虑了井筒内压、原始地应力分布、压裂液渗滤效应、现有水力裂缝的诱导应力等影响因素,根据叠加原理及弹性力学理论,建立了水平井分段压裂总应力场计算模型,分析了水力裂缝的起裂规律.计算了实际油田区块1口压裂水平井的各条裂缝起裂压力,理论计算值与现场实测值吻合较好.该计算模型不仅能够定性研究先压裂缝对后续裂缝起裂压力的影响趋势,而且能够定量计算出各条裂缝破裂压力值,进而用来指导压裂施工设计.
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