涪陵页岩气田二期产建区块相比一期地质构造复杂、地层产状变化大,水平井AB靶点垂差较大,为了准确求取该区域地层实际产能,评价压裂工艺改造效果,通过开展大垂差水平井流体扫描成像产剖测试,对比大垂差水平井不同试气井段测试结果,分析不同段簇产气、产水特征规律。研究结果表明对于AB靶点垂差超过200 m时,水平段受井筒积液及“回流”效应影响较大,产气贡献率较大的段簇主要集中在试气井段的上半段。综合井筒轨迹与水平最小主应力夹角对压裂改造的影响,提出对于大垂差水平井采用分段开采方式以及调整水平井轨迹顺地层构造进行部署;同时,对顺地层构造水平井提出“变黏度+变粒径+变排量”针对性措施工艺,确保调整后气井的改造效果,为涪陵页岩气田二期产建顺利完成提供坚实保障。

Compared with the phase I production capacity construction project, the phase II of the project is facing complex geological structure, variation attitude of stratum, large vertical difference between target A-B of horizontal well and so forth.In order to acquire the real productivity accurately and evaluate of fracturing effectiveness, by performing flow scanner image (FSI) in large altitude difference of horizontal shale gas well, the results shows a sharp contrast of different test section production profile.Further research shows if the vertical differences surpass 200 meters, the gas production clusters with higher contribution rate mainly concentrated in the shallow layer half of the test gas section, the liquid loading and backflow effect of gas well is obvious.Considering the impact of included angle of bore trajectory and minor principal stress on fracking, it is proposed that the method of production by stage and horizontal well deployment along with stratum structure be adopted for horizontal well with large vertical difference.Meanwhile, the measures ofvariable viscosity, variable particle diameter and variable displacementare taken for the horizontal wells of the stratum structure to ensure the effect of the adjusted shale gas wells.