Fracture/Fault Pattern Delineation in Gulf of Mexico

Rao Yalamanchili
Fugro Robertson Inc, Houston, TX

Fracture/Fault pattern maps are one of the tools useful for explorationists to locate hydrocarbon prospects. Depth and lineament maps are generated from gravity and magnetic data on a regional scale using Euler deconvolution technique. Based on this study, it appears that the Euler depth maps are good at revealing the boundaries of major geological provinces and the lineament maps are good at identifying the fracture/fault trends. The mapped lineaments define all classes of fracture/fault patterns in the western Gulf of Mexico region. The dominant trends in the lineament maps show approximately NE-SW and NW-SE directions. Some of these northwest-southeast trends are well correlated with the Matagorda, Galveston, Brazos and Sabine transfer faults. Character changes in fault structure and stratigraphy are evident across transfer faults. These transfer faults control the distribution of shale and salt basins as well as the hydrocarbon bearing basins in the Gulf of Mexico region. The mapped lineaments in the shelf area correlate with the Miocene faults, which are parallel to the synrift basement graben structure. These faults also serve as conduits for the migration of hydrocarbons into shallower reservoirs. As several of the mapped lineaments correlate with published geological fault trends, the other lineaments may be indicators of new insights in this area. Some of these fault trends may very well represent the structural and stratigraphic discontinuities in the geologic horizons. The mapped lineaments may either reflect the nature of the underlying crustal and synrift structures and/or the overlying the sediments. Since hydrocarbon production in the Gulf of Mexico shelf and slope basinal areas are closely associated with the locations of the transfer faults, the mapped fracture/fault trends may reveal some new insights for hydrocarbon plays.