MECHANICAL AND PETROPHYSICAL PROPERTIES OF NORTH-SEA SHALES

One of the problems when evaluating potential borehole stability probl ems in the drilling of hydrocarbon exploration and production wells is the lack of relevant data to describe the lithologies. This relates i n particular to the shales, since these constitute most of the overbur den and are also the most troublesome. This paper presents a set of da ta from a variety of deeply cored shales from the North Sea. The shale s have been extensively characterised ann span a wide range of both pe trophysical and mechanical properties, depending on, for example, buri al history and diagenesis. Special characteristics of shales have been tested and described, including pore size distribution, permeability, anisotropy and temperature dependence. Appropriate procedures for sam ple handling, testing and interpretation have been developed or modifi ed from other related sciences. (C) 1998 Elsevier Science Ltd. All rig hts reserved.