archives@tulane.edu / Minibasins, i.e., small basins that can be up to 8 km in depth and a few tens of km in diameter, often form in regional salt basins and on salt-rich passive margins. As salt walls grow through time, brittle strain localizes in zones directly above the salt walls leading to complex fault arrays surrounding the minibasins. These fault arrays provide insight into the relative movement of minibasins and the local deformation field, which influences the hydrocarbon exploration around them. Using high-resolution bathymetry and 2D reflection seismic data, we have examined fault systems and their interaction with salt walls around the Lyons minibasin in the Gulf of Mexico, offshore USA. This analysis shows that the geometry of salt walls varies and controls the development of faults form in the overlying sedimentary layer. The wide plateau-like salt wall creates a mechanical constraint that restricts the development of faults vertically and laterally. The narrow ridge of the salt wall has less mechanical restriction and allows faults to grow in displacement. Deformation is more localized above the narrow ridge of salt wall. This study suggests that the intricate fault patterns around minibasins result from multi-phase deformation caused by the variation of salt flow within the salt walls. Initially, minibasin subsidence expels salt upward and outward. After the minibasins is welded, the regional slope enhances the lateral flow and allows salt to flow around welded minibasins. During this stage, the lateral flow of salt is constrained by the salt wall orientation. Moreover, this study demonstrates a new approach that provides an additional perspective to understand the evolution of minibasins and their interaction, which is a limitation of 2D modeling studies. / 1 / Thi Quan H. Pham

This work examines several volume attributes extracted from 3D seismic data with the goal of seismic facies classification and lithology prediction in intraslope minibasins. The study area is in the Keathley Canyon protraction (KC), within the middle slope of the Northern Gulf of Mexico (GOM). It lays within the tabular salt and minibasins province downdip of the main Pliocene and Pleistocene deltaic depocenters. Interaction between sedimentation and mobile salt substrate lead to the emergence of many stratigraphic patterns in the intraslope minibasins. Interest in subsalt formations left above salt formations poorly logged. Facies classification using Artificial Neural Network (ANN) was applied in those poorly logged areas. The resultant facies classes were calibrated and used to predict the lithology of the recognized facies patterns in an intraslope minibasin, away from well control. Three types of facies classes were identified: Convergent thinning, convergent baselaping and bypassing. The convergent baselaping are found to be the most sand rich among all other facies.