Physical Properties of Shallow Sediments in Late Pleistocene Formation, the Ursa Basin, Gulf of Mexico, and Their Implication for Generation and Preservation of Shallow Overpressures

Nguyen Thi Thanh Binh and Tomochica Tokunaga
IODP EXP. 308 Shipboard Scientific Party, University of Tokyo, Japan

Understanding the origin of abnormally high fluid pressures within sedimentary formations in the continental slope of the Gulf of Mexico is critical for evaluating hydrogeological processes and for assessing drilling risks in this area. IODP Exp. 308 drilled 8 holes and conducted in-situ temperature and pore pressure measurements together with core sampling. Laboratory experiments to measure porosity and permeability of the Pleistocene sediments in the Ursa Basin were conducted during and after expedition. Then, the porosity-effective stress and porosity-permeability relationships were used for our simulation. Results from basin simulation showed that compaction disequilibrium and existence of sheet sands mainly controlled shallow overpressures and lateral flow in the Ursa Basin.

AAPG Search and Discover Article #90066©2007 AAPG Hedberg Conference, The Hague, The Netherlands