Salt Geology and New Plays in Deep-Water Gulf of Mexico

Chowdhury, Abu N.¹, Laura Borton¹ (1) TGS Nopec, Houston, TX

In deep-water Gulf of Mexico, two pre-stack depth migration projects were undertaken recently to better image the deep-water salt and sub salt geology. The P-45 survey area, stretching from Port Isabel to the west and Atwater Valley to the east, comprises approximately 100,000 line kilometers of 2D seismic data. It was pre-stack depth migrated and is currently being used for a deep- water interpretation project integrating approximately 1100 wells, including 300 biostratigrahic wells. In the Mississippi Canyon area, approximately 900 OCS blocks (4.8 km x 4.8 km each) of 3D seismic data was pre-stack depth migrated. More than 80 salt penetration wells were integrated in the Mississippi Canyon salt model interpretation project.

The pre-stack depth migrated data identify autochthonous and allochthonous salt and associated archetypes. The salt bodies show predominantly northwest-southeast structural grain depicting the regional sedimentary depositional dips. The autochthonous Jurassic Louann (mother) salt, Jurassic sediments and the overlying Cretaceous and Paleogene sequences are well manifested in the data sets. The new Paleogene/Mesozoic play is typically characterized by broad rollover structures created by the loading of sediments, deflation and withdrawal of the mother salt and subsequent collapse of the sediments. The good imaging of the sedimentary section and folded structure below the salt helps delineate the new Paleogene/Mesozoic play, which has proven successful in many parts of the P-45 area, but is yet to be tested in Mississippi Canyon.