Abstract

Onshore Gulf Coast salt domes offer redevelopment opportunities if new ideas/leads can be developed through a better understanding of the impact of salt dome growth history on hydrocarbon accumulation. The exploration discipline concept (Baie and Gallagher, 2008) provides a rigorous framework for generating the ideas/leads needed to redevelop some piercement-type salt domes. West Columbia Salt Dome was chosen because: (1) it has a 120 year history of exploration and production with hundreds of wells drilled and more than 100 million barrels of oil produced, (2) it is one of ten Texas Gulf Coast salt domes with identified Heterostegina reef material (Het Lime) present, and (3) the historical distribution of production seems anomalous. Prolific production was from the north, northwest, and southeast segments of the dome, while lesser production came from the east side and no commercial production from the southwest quadrant. By using several of the concepts found in the exploration discipline paper, an initial review of available data revealed that the distribution of the Het Lime indicates that early salt tectonism formed a broad northeast-southwest oriented swell during the Oligocene, which led to the erosion of thick, previously deposited Frio and older sandstones and underlying shales. This left a bathymetric high and a significant unconformity at the seafloor, upon which hundreds of feet of Het Lime accumulated over an area many times larger than the current expression of the later piercement phase. Thus at West Columbia, and probably at nine other salt domes with Het Lime present, salt had at least two distinct and very different periods of movement: salt swell development accompanied by erosion and redeposition of sedimentary sections, and later piercement of salt with-in the initial area of broad uplift as defined by the Het Lime distribution. These events each occurred during the likely time of initial generation and migration of hydrocarbons from the middle Wilcox, impacting their resulting distribution.