Stress Magnitude Measurements to Mid-Crustal Depth in the KTB Borehole

限制地壳中应力的大小是岩石圈力学的广泛问题的基础。西德KTB项目在10公里深处进行钻探和取心，这是首次有机会测量大陆地壳发震深度的地应力大小。传统的应力测量技术不能用于KTB主井眼或大多数其他深井眼。因此，该项目旨在开发一种新的综合应力测量策略，最终用于KTB井眼和其他深孔（如苏联存在的深孔）的10公里深度。在制定和实施建议的压力测量策略方面，有四项主要活动：详细观察井眼裂缝和热裂缝，发展足够全面的井眼破坏理论，对岩心进行全面的实验室测试，并利用套管射孔水力裂缝进行最小主应力测量。这项研究是与卡尔斯鲁厄大学的Karl Fuchs教授和鲁尔大学-波鸿的Fritz Rummel教授合作完成的。岩心样本的实验室强度测量将与美国地质调查局的詹姆斯·拜尔利博士合作完成。

Constraining the magnitudes of stresses in the earth's crust if fundamental to a broad range of problems of lithospheric mechanics. The plan to drill and core to 10 km depth by the KTB project of West Germany represents the first opportunity to measure in situ stress magnitudes at seismogenic depth in continental crust. Conventional stress measurement techniques cannot be employed in the KTB main borehole, or most other deep boreholes. Thus, this project is aimed at development of a novel integrated stress measurement strategy for eventual use to 10 km depth in the KTB borehole and other deep holes, such as those that exist in the Soviet Union. There are four main activities associated with developing and implementing the proposed stress measurement strategy: Making detailed observations of breakouts and thermal fractures in the borehole, development of sufficiently comprehensive theories of borehole failure, conducting comprehensive laboratory tests on core and making least principal stress measurements utilizing hydraulic fractures through perforations in the casing. This research is being done in collaboration with Prof. Karl Fuchs of the University of Karlsruhe and Prof. Fritz Rummel of Ruhr University-Bochum. Laboratory strength measurements of core samples will be done in collaboration with Dr. James Byerlee of the U.S. Geological Survey.