定向井压裂射孔方位优化及应用研究

低渗储层采用定向井水力压裂是油气田增储上产和降本增效的重要措施和手段。射孔是压裂前打开储层的首要工序，射孔质量好坏直接影响定向井产能的发挥程度。为了降低储层起裂压力、减少砂堵风险，需要进行定向井压裂射孔方位优化。考虑原地应力、套管水泥环诱导应力、射孔孔眼诱导应力、井筒注液诱导应力和流体渗流诱导应力综合叠加，基于张性破坏准则，建立了基于最低裂缝起裂压力（FIP）的定向井压裂射孔方位优化模型；并进一步通过室内物理模拟，验证了模型的可靠性与合理性。模拟结果表明，FIP在360°射孔方位内周期性变化，存在两个最小和最大FIP点，并且随着井筒方位角的增加而增加，最小FIP逐渐增加，最大FIP逐渐减小；不同井斜角和方位角的最小FIP对应的射孔方向相差较大，斜井的最佳射孔方向应同时考虑井斜角和方位角的综合影响；水平主应力差和施工排量等因素对确定最佳射孔方位影响不大；并且在SXM气田X井进行了现场应用，优化的最佳射孔方向角为20°和205°，其对应的最小起裂压力为45.5 MPa。从而降低施工难度，为低渗储层射孔方位优化技术提供借鉴。

Research on Optimization and Application of Fracturing Perforation Orientation in Directional Wells Based on Minimum Initiation Pressure

Hydraulic fracturing with directional wells in low permeability reservoirs is an important measure to increase production and efficiency and decrease cost in oil and gas fields. Perforation is the first procedure to open a reservoir before fracturing. The quality of perforation directly affects the productivity of directional wells. In order to reduce the fracturing pressure of reservoir and the risk of sand plugging, the perforation azimuth of directional wells fracturing is optimized. Different from previous studies, this paper considers the combined superposition of original ground stress, casing cement ring induced stress, perforation hole induced stress, wellbore injection induced stress and fluid seepage induced stress, and establishes an optimization model for directional well fracturing and perforating azimuth is established based on the minimum fracture initiation pressure(FIP) prediction and the tensile failure criterion. The reliability and rationality of the model are verified by the comparison of indoor physical simulation and theoretical model calculation results. The simulation results show that (1) FIP changes periodically in 360°perforation azimuth, there are two minimum and maximum FIP points, and with the increase of wellbore azimuth, the minimum FIP gradually increases, and the maximum FIP gradually decreases; (2) the perforation directions corresponding to the minimum FIP at different inclination angles and azimuths are quite different, and the optimal perforation direction for inclined wells should take into account the comprehensive effects of the inclination and azimuth angles at the same time; (3) factors such as horizontal principal stress difference and construction displacement have little effect on determining the optimal perforation orientation. The optimal perforation direction angle is 20°and 205°, and the corresponding minimum FIP is 45.5 MPa. Thus, it reduces the construction difficulty and provides reference for the perforation position optimization technique of low permeability reservoir reconstruction.