Top-hole formation pore pressure assessment at deepwater well sites using a geotechnical approach

Geotechnical investigations are routinely performed in site characterization studies for offshore infrastructure development. Until present, little consideration has been given to the application of geotechnical methods to pore pressure assessment in the top-hole section of deepwater sediments. Laboratory geotechnical tests including one-dimensional consolidation tests and index property measurements on intact cores collected from pilot holes drilled at prospective well sites have the ability to provide a rigorous characterization of the normal compaction trend and in-situ porosity, which are critical in evaluations of overpressure associated with a compaction disequilibrium mechanism. This paper presents key considerations pertaining to interpretation of results from geotechnical tests in the context of top-hole formation pore pressure assessment at deepwater settings. Examples of top-hole pore pressure regime evaluation at two hypothetical deepwater wellsites are used to depict particularities related to development and interpretation of normal compaction trend describing stratigraphic sequences associated with various depositional mechanisms, likely to be encountered within the top-hole section of deepwater sediments.