European stress: contributions from borehole breakouts

Abstract

Before about 1986 European measurements of rock stresses were sparse. The development of the borehole breakout method has facilitated a dramatic increase in the geographical distribution of rock stress orientations. These are derived from data collected routinely for other purposes by the oil, coal and gas industries over many years. Borehole breakouts can be interpreted in term s of the orientation of the stress field in boreholes as a function of depth, with the findings related to known stratigraphical boundaries, tectonic structures, fault and fracture occurrences, and to other geological and geophysical stress indicators. Geographical and depth distributions of stress on local and regional scales are beginning to provide the necessary base from which broad interpretive stress field models can be constructed.