Stratigraphic and Antecedent Geological Controls on Modern Analogues of Potential Hydrocarbon Reservoirs within a Back Barrier Island Lagoon System: West Galveston Bay
The purpose of this ongoing study is to investigate the facies architecture of the modern day western half of the West Galveston Bay (WGB) system with the goal of delineating deposits that would provide modern analogues for hydrocarbon reservoirs and stratigraphic traps. WGB is the microtidal back barrier lagoon of Galveston Island. Our study area is the western half of the bay, proximal to San Luis Pass, a large tidal inlet through which the tidal prism of WGB flows. WGB is divided into an eastern and western half, with a large oyster reef dividing the two halves. The oyster reef marks the tidal basin divide between east and west half of the bays with the eastern half of the bay being part of the tidal prism of Bolivar Roads and the western half being part of the proximal San Luis Pass tidal prism. Tidal inlets along the Texas coast tend to be situated over older incised valleys. Recently acquired CHIRP seismic lines reveal at least two incised channels running through the study site, one going under the western end of Galveston Island and the other under San Luis Pass. Potential modern analogues for reservoirs include the flood tidal delta sands, fluvial sand deposits at the base of the incised channels, oyster reefs within the bay and the oyster reef constituting the tidal basin divide. Bay fill mud would not only provide ideal stratigraphic traps, but with total organic carbon contents as high as 5% may also constitute in situ source rocks. Antecedent controls include the incised valleys, the overall surface and dip of the Pleistocene surface and the tidal basin divide. Results of a coring campaign will be used to further analyze these potential reservoir analogues, source rocks, and seals.
AAPG Datapages/Search and Discovery Article #90189 © 2014 AAPG Annual Convention and Exhibition, Houston, Texas, USA, April 6–9, 2014