Geotechnical Characterization of Gulf of Mexico Clay

With increasing development in the oil and gas industry, exploration and production are continuously moving deeper off the continental shelf and onto the continental slopes. The hazard of submarine slope failures increases in these locations, potentially leading to damage to offshore structures. Thus there is a need to study and understand properties of offshore marine clays with particular attention to slopes. Submarine failures can be much larger than subaerial ones and typically occur on very gentle slopes that do not fail on land. It is particularly important, therefore, to focus on marine clays because of the possible differences in the response of these soils compared to other clays. This study was undertaken in order to better understand the geotechnical characteristics of a submarine clay deposits from the Gulf of Mexico. The paper presents the results of triaxial testing performed on undisturbed samples of Gulf of Mexico clay. Background information is given about the clay, the sampling program and the laboratory testing program. A SHANSEP approach was used for Ko consolidated-undrained (CKoU) triaxial compression and extension tests. The consolidation tests provided most of the pre-consolidation pressure values used to establish the stress history at the test site and the variation of Ko with OCR. The undrained shear phase provides detailed information on the undrained shear strength, effective stress failure envelopes and stress path characteristics.