利用古地磁学研究岩心古水流的方法与应用——以延长油田西南部延长组为例

Method of paleomagnetism to study directions of core paleocurrent and its application:Taking Yanchang Formation in southwest Yanchang Oilfield as an example

古水流向对于油气的勘探与开发具有重要意义。古地磁方法是研究岩心古水流向的一种手段。文中在利用古地磁方法进行钻井岩心重定向的基础上,分析磁化率长轴方位,进而达到确定古水流方向的目的。以延长油田西南部延长组钻井岩心研究为例,首先通过热退磁分离黏滞剩磁进行岩心定向,再进行磁化率测试,计算分析最长轴方位,进而得到古水流方向。结果表明,该区储层砂体的展布方向为NW—SE,亦有来自NE—SW向和近EW向。同时,这一结果还验证了古地磁分析古水流方法的可靠性,为油气田的勘探开发提供了依据。

The redirection of drilling cores is studied using paleomagnetism, and the method and application of magnetic fabric is used to quantitatively determine the paleocurrent. By using the viscous remanence and original residual magnetism separated by thermal demagnetization, the drilling cores are redirected with low temperature component resultant vector. The anisotropy of magnetic susceptibility of rock is analyzed and tested to study the rock depositional environment information and establish the palaeocurrent direction and the direction of sand body distribution. At the same time, this method is used to study the cores from six wells of southwest Yanchang Oilfield. The results show that the distribution direction of reservoir sand bodies in this area is NW-SE,also having NE-SW and nearly E-W. The operation of this method that the redirection of cores and the direction analysis of paleocurrent is simple, quick and less expensive, Study of Yanchang Formation verifies the feasibility and reliability of the method application.