DEVELOPMENT OF BOREHOLE ACOUSTIC EMISSION SONDE TO DETERMINE CRACK DIRECTION OF HYDRAULIC FRACTURING

在用于应力测量的水力压裂中，由于压裂而产生的裂缝的方向遵循最大压应力的方向。为了识别方向，通常在水力压裂后将探头移除，然后将另一个探头插入钻孔并获得裂缝的痕迹。因此，当钻孔变深时，该方法花费大量时间。为了解决这一问题，我们提出了一种通过测量水力压裂过程中的声发射事件来确定裂缝方向的方法。我们开发了一个测试探头安装四个AE传感器的横截面垂直于探头的轴。利用该探头，探讨了确定裂纹方向的可行性。研究结果表明，该探测器可以在实际中使用，但需要进行一些改进。

In hydraulic fracturing for stress measurement, the direction of cracks due to fracturing follows the direction of the maximum compressive stress. To identify the direction, the sonde is usually removed after hydraulic fracturing, and then the other sonde is inserted into the borehole and traces of the cracks are obtained. Thus, this method takes a lot of time when a borehole becomes deep. To solve the problem, we get an idea to measure AE (Acoustic Emission) events accompanied with hydraulic fracturing and determine the crack direction. We developed a test sonde mounting four AE sensors in a cross section normal to the axis of the sonde. Using the sonde, the feasibility in determination of the crack direction is investigated. It is found that the sonde could be used practically with some improvements clarified from this investigation.