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O'BRIEN, J. J., South Dakota State University, Brookings, SD, and IAN LERCHE* and Z. YU, University of South Carolina, Columbia, SC

ABSTRACT: Measurements Under Salt Sheets in the Gulf of Mexico: Observations and Inferences

Four wells in the offshore Gulf of Mexico have penetrated through four different salt sheets and into the underlying formations. Interpretations of sonic and density logs, together with mud weight variations, imply highly overpressured regimes below each of the four salt sheets. Models of the development with time of sediments and salt sheets show the estimates of timing and magnitude of this buildup of overpressure.

Investigations of both horizontal and tilted sand sheets, together with sheets having a sub-salt thief sand, provide estimates of (1) thermal focusing by the highly conductive salt, (2) timing and magnitude of pressure buildup and bleed off in formations underlying the impermeable salt sheet, and (3) porosity retention by formations below the salt.

Importance of salt sheets as an impermeable seal for hydrocarbon retention and high porosity due to overpressure development are significant to exploration assessments in the Gulf of Mexico.

AAPG Search and Discovery Article #90989©1993 GCAGS and Gulf Coast SEPM 43rd Annual Meeting, Shreveport, Louisiana, October 20-22, 1993.