--> Mass Transport Complexes in the Northern Gulf of Mexico and Their Implications for Hydrocarbon Exploration

AAPG ACE 2018

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Mass Transport Complexes in the Northern Gulf of Mexico and Their Implications for Hydrocarbon Exploration

Abstract

This study investigates Pliocene mass transport complexes (MTCs) in an understudied, hydrocarbon-rich region of the north-eastern Gulf of Mexico. The ongoing research utilizes a dataset of 635 km2 of high-quality 3D seismic, along with wireline logs and biostratigraphic data. This study aims to: (1) characterize external and internal geometries of the MTCs, (2) determine the role of glacioeustatic cycles and halokinesis on their formation, and (3) evaluate the nature of association between channel-levee complexes and MTCs.

Preliminary results suggest that a large shelf-attached MTC, presumably formed during a low sea-level stage, is inter-tongued with localized MTCs that were initiated by rapid salt mobilization. With the help of quantitative seismic geomorphology techniques, mapping of the mass wasting events suggests that topographic constriction due to salt-induced bathymetrical highs greatly influenced the morphologic parameters of the MTCs. The lower part of the shelf-attached MTC is characterized by a thicker, more chaotic deposit indicative of confined flows, whereas the upper part is characterized by a thin, sheet-like deposit indicative of unconfined flows. We suggest that the resulting topography created by the deposition of the MTCs likely influenced the development and spatial-distribution of the channel-levee complexes that regionally overlie them. MTCs in the study area display chaotic, low amplitude and semi-transparent reflectors, and coincide with wireline-log intervals of high gamma values, suggesting a predominantly muddy lithology. However, potential “surprise sands” (e.g., anomalously high-amplitude reflectors) were observed encased within MTCs. Given the extensive regional coverage and channel-levee association of MTCs, it is inferred that these deposits would be successful components of stratigraphic traps for hydrocarbons. By examining different types of MTCs and related processes in a geologically complex province, this research contributes to the understanding of seal vs. reservoir rock development and distribution in the study area.