Long Axis Orientation In Elongated Roreholes And Its Correlation With Rock Stress Data

Abstract

Several detailed studies of borehole elongation, as measured with 4-arm dual caliper systems, have been made for specific geographic areas of North America. These studies have shown that a correlation exists between the orientation of elongation and the orientation of known principle horizontal stress. However, borehole elongation alone may not be a reliable indicator of unequal horizontal stress. Some guidelines are presented to assist the user of such data in distinguishing potential stress-related elongations from those of other causes. A compilation of data from other authors in addition to newly acquired data is compared to existing rock stress measurements in several areas in the U.S. The resultant correlation shows excellent agreement in orientation, and supports major continental scale trends as well as regional differences. 21 references.