--> Using Wellbore Images in Sequence Stratigraphy, Atwater Valley 89: An Intraslope Basin in the Gulf of Mexico, by R. S. Thibodeaux and R. J. Davis; #90986 (1994).

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Abstract: Using Wellbore Images in Sequence Stratigraphy, Atwater Valley 89: An Intraslope Basin in the Gulf of Mexico

Renee S. Thibodeaux, Robert J. Davis

In intraslope basin environments, wellbore images aid in resolving features critical to sequence stratigrapic interpretation that are not easily recognized on traditional dipmeter plots. Wellbore images provide a relatively quick and easy way of determining and removing structural dip so that sedimentary structures can be analyzed for depositional characteristics. Integrated into a sequence stratigraphic study, wellbore images supply strong supportive evidence which leads to a more confident interpretation of systems tracts present around the borehole.

Formation Microscanner (FMS) images and well logs from Atwater Valley 89 were examined on an interactive workstation. Conventional dipmeter data have been used to interpret depositional environments and transport deposits. Unlike dips calculated from dipmeters, wellbore images supply actual images of surfaces, and dips picked by hand from wellbore images allow for assignment of an origin to the surface represented by the dip (eg. fault, bed boundary, unconformity). Structural dip elucidated from wellbore images suggests that while the dip remained fairly constant through the early Pleistocene Epoch, the azimuth migrated from NNE to NNW. This migration is evidence for a possible lateral migration of fan lobes within a slope fan complex occurred. Integration of the nonstructural dips an features with all other data (seismic profiles, gamma-ray profiles, paleontology, and core descriptions) led to amore confident recognition of sedimentary environment critical to the sequence stratigraphic interpretation.

This study has shown that wellbore images and subsequent image dipmeter plots, when integrated into a sequence stratigraphic framework, can lead to better understanding of systems tracts and reservoir distribution in salt deformed intraslope basins environments.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994