页岩气水平井段内多簇压裂暂堵技术的数值模拟研究及先导实验

Numerical simulation study and pilot test of multi-cluster fracturing and temporary plugging technology in the horizontal hole section of shale-gas horizontal wells

水平井段内多簇射孔技术已成为页岩气压裂工艺发展的新方向,暂堵转向技术能有效提高射孔孔眼开启效率,是一种有效的辅助手段。为了给页岩气水平井压裂工艺参数优化提供技术支撑,基于数值模拟的方法优化了"单段5簇射孔+投球暂堵转向"工艺的相关参数,并在昭通国家级页岩气示范区YS112HX-1水平井开展了"段内多簇+暂堵转向"先导性试验;最后,结合微地震监测、微形变监测以及压力恢复试井分析等技术进行了压后综合评价。研究结果表明:(1)投球时机为注入压裂液量为900 m3时对应的时间,投球数量为所需封堵孔眼数的1.0~1.2倍,暂堵球直径不小于13.5 mm;(2)微地震、测斜仪和试井结果一致,单段5簇射孔+投球暂堵转向压裂对比常规3簇射孔压裂裂缝复杂度要更好,虽然HX-1井基质区渗透率较低,但高渗区渗透率更高,改造效果更好;(3)试井解释HX-1井裂缝半长不超过100 m,与数值模拟的裂缝半长存在着一定的误差,试井结果可以反过来对数值模拟参数进行优化;(4)采用"段内多簇+暂堵转向"技术的HX-1井压后返排具有见气时间早、井口压力大、日产气量高的特点。结论认为,该研究及试验成果对于页岩气水平井压裂工艺参数优化具有指导意义。

Multi-cluster perforation technology in the horizontal hole section has become a new development direction of shale gas fracturing process,and temporary plugging and diverting technology is its effective auxiliary means,which can effectively improve the perforation opening efficiency.In order to provide technical support for optimizing the process parameters of shale-gas horizontal well fracturing,this paper optimized the related parameters of"5-cluster perforation in single stage and ball-sealer in-stage diversion"process through numerical stimulation.Then,the pilot test of"multi-cluster in single stage and temporary plugging and diverting"was carried out in Horizontal Well YS112 HX-1 of Zhaotong National Shale Gas Demonstration Area.Finally,post-fracturing comprehensive evaluation was performed by using the technologies of micro-seismic monitoring,micro-deformation monitoring and pressure buildup test analysis.And the following research results were obtained.First,the balls shall be dropped the moment the injection volume of fracturing fluid reaches 900 m3,the number of balls shall be 1-1.2 times the number of perforations,and its diameter shall not be less than 13.5 mm.Second,micro-seismic,inclinometer and well test results are accordant.Compared with the conventional fracturing of 3-cluster perforation,the fracturing of 5-cluster perforation in single stage and ball-sealer in-stage diversion is better in fracture complexity.The matrix permeability in Well HX-1 is lower,but the permeability of the high-permeability area is much higher,so the stimulation effect is better.Third,according to the well test interpretation,the half fracture length in Well HX-1 is shorter than 100 m,which is deviated from the numerical simulation result.The well test result can be conversely used to optimize the numerical simulation parameters.Fourth,after the technology of"multi-cluster in single stage and temporary plugging and diverting"is applied in Well HX-1,the flow back presents the characteristics of early gas breakthrough,high wellhead pressure and high daily gas production.In conclusion,the research and test results are of guiding significance to the process parameter optimization of shale-gas horizontal well fracturing.