基于岩芯非弹性应变恢复量测定的深孔三维地应力测试方法

 虽然存在各种地应力测试方法，但并没有一个比较完善的方法测量较大深度条件下主应力的大小和方向。所以，在以科学研究为目的的钻井工程中，最好能够结合钻孔法和岩芯法得到三维地应力的大小和方向。叙述一个新颖而且有效的岩芯地应力测试法——非弹性应变恢复量测定法的基本原理、实验技术和基本操作程序；并给出其在科学钻探工程中的一个具体应用实例。测试结果表明，非弹性应变恢复量测定法对于测试三维地应力的主方向和估测主应力的大小有较大的实用价值。特别是在某些较大深度钻井的条件下，如在应力释放法及水压致裂法都无法实施，或者需要一些其他测试方法来补充一些不足或来增添其测试结果的可信度的时候，此方法的应用价值更高。

A CORE-BASED METHOD TO DETERMINE THREE-DIMENSIONAL IN-SITU STRESS IN DEEP DRILLING WELLS:ANELASTIC STRAIN RECOVERY TECHNIQUE

There is no foolproof method by which the magnitudes and orientations of three-dimensional in-situ stresses can be reliably measured at great depths,although various field and laboratory measurement techniques have been proposed. In the case of scientific deep-drilling wells,therefore,it is desirable to combine borehole methods with core-based methods to obtain a complete three-dimensional in-situ stress. Here,the principles,testing techniques,and procedures for a new and effective core-based stress measurement method called anelastic strain recovery (ASR) technique are described;and then its application to a scientific deep-drilling project is shown. The measurement results reveal that the method is suitable for determining the orientations of the principal stresses and for estimating their magnitudes in deep drilling wells where other methods such as the over-coring technique and hydraulic fracturing tests are difficult or impossible to be conducted,or are needed complementary data to enhance the reliability of the stress measurements.