裂缝性地层中水平井压裂裂缝起裂新模型

对裂缝性地层中的水平井进行水力压裂时，井筒附近的天然裂缝会对压裂产生影响。现有压裂裂缝起裂压力计算模型所考虑的影响因素各有侧重，且尚未考虑井筒附近天然裂缝产生的诱导应力场对起裂压力造成的影响。本文基于弹性力学及岩石力学理论，综合考虑了井筒周围天然裂缝的诱导应力、压裂液渗滤效应、岩石温度变化、封隔器影响等因素，建立了一个适用于裂缝性地层中的水平井压裂裂缝起裂压力计算模型，且计算简便便于推广。本文根据实例计算分析了天然裂缝影响起裂压力的各个因素，并进行了对比。计算结果表明，一定条件下井筒周围天然裂缝对起裂压力影响明显，采用以前的起裂压力计算模型误差较大。

A New Model of Fracture Initiation of Horizontal Well Fracturing in Fractured Reservoirs

Natural fractures near the wellbore will impact on horizontal well fracturing in fractured reservoirs. The existing pressure calculation models of fracturing initiation emphases some factors, but all had not yet considered the impact of the natural fractures near the wellbore, which change fracturing initiation pressure. Based on the theory of elasticity and rock mechanics, considering the natural fractures around the wellbore, effects of fracturing fluid percolation, temperature variations of rock and impact of packer, a pressure calculation model for horizontal well fracturing in fractured reservoir is established, which is easy to calculate and promote. To find the factors of natural fractures which impact on the fracturing initiation pressure, a computational analysis is made. The results show that under certain conditions, natural fractures around the wellbore make a significantly impact on the fracturing initiation pressure. So, an error will appear when using former calculation model to calculate fracturing initiation pressure of horizontal well fracturing in fractured reservoirs.