利用黏滞剩磁进行水平地应力定向的试验研究
Experimental Research on Horizontal In-Situ Stress Orientation Determination through Viscous Remanent Magnetization
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摘要: 为了快速准确地对地层水平地应力进行定向,指导页岩气的水力压裂开采,研究利用岩心的黏滞剩磁定向方法。该方法可以克服一般古地磁定向的不足,在不考虑地层年代和复杂构造运动的情况下还原岩心在地层中的原始方位。利用热退磁手段分离出黏滞剩磁,对岩心进行定向,并对取自重庆涪陵地区某页岩气井多个层位的岩心进行了古地磁测试。结合声发射Kaiser效应测得的地应力资料,对测试结果进行处理,得到取心层位最大水平主应力的方位角,与先期地震资料的结果进行比较,二者具有较好的一致性。研究结果表明,利用黏滞剩磁进行水平地应力定向的方法是可行、而且有效的。Abstract: In order to determine the orientation of horizontal in-situ stress conveniently and accurately,and provide help in hydraulic fracturing of shale gas,a technique called Viscous Remnant Magnetization (VRM) was investigated.Compared with conventional methods,VRM can help to provide the determination of core orientation without considering the deposit age and tectonic movement of the formation.In the experiment,the procedure of thermal demagnetization was introduced in detail to extract VRM for core orientation determination from a shale gas well in Fuling of Sichuan basin.Combining the results of Kaiser effect,the orientation of maximum horizontal stress was obtained.It indicated that results from VRM were basically consistent with those from seismic data.So it is feasible and effective to utilize VRM horizontal in-situ stress orientation determination.