复杂构造区页岩气水平井高钻遇率井轨迹优化技术——以永川南区开发实践为例

Trajectory optimization technology of shale gas horizontal wells in complicated structure area——A case of the development practice of Yongchuan southern area

为了提高优质储层钻遇率,特别是针对断缝发育、地震预测误差大、靶窗范围小的复杂构造区,形成了以三维地质模型建立为基础,结合入靶方式选择和特殊构造井轨迹优化方案,采用随钻伽马与元素录井的综合导向技术,确保了优质储层钻遇率显著提高。结果表明1)在构造复杂区应选择上靶窗入靶模式;2)钻遇局部隆起、凹陷、断层等特殊构造,为确保工程施工,在追求高钻遇率的同时应适当放弃部分优质储层钻遇率;3)纵向上借助GR曲线及元素Ca,Si,Mg和Fe的变化明显性、横向展布稳定性及工程可调控性,分级确定标志层;平面上根据地层的倾角变化、钻遇特殊构造确定重点关注点;4)采用随钻伽马与元素录井的综合导向来准确判断钻头在地层中的位置,及时做出调整,确保水平轨迹钻遇率。以上成果认识,对后续复杂构造区的井眼轨迹控制具有指导意义。

In order to improve the quality of reservoir drilling rate,especially for fracture development,earthquake prediction error and small target window range of the complicated structure area,formed on the basis of 3D geological model is established,combined into the choice of target and special tectonic characteristics of well trajectory optimization scheme and adoption of gamma and element with drilling mud logging comprehensive guidance technology,to ensure the high quality reservoirs drilling rate significantly increased.The results show that:1)The target entry mode of upper target window should be chosen in complicated structural area;2)When drilling into special structures,the drilling rate of some high quality reservoirs should be properly abandoned;3)Longitudinally,the marker layer was determined according to the GR curve,the variation of elements Ca,Si,Mg,Fe,the stability of transverse distribution and the engineering controllability;On the plane,the key points are determined according to the dip angle change of the strata and the special structure drilled;4)An integrated gamma-while-drilling and elemental logging guide was used to prepare and determine the position of the bit in the formation.The results provide guiding significance for the subsequent well trajectory control of complex structural zones.