Salt-Sediment Interaction: A Quantitative Analysis of Depositional Systems in from Evolving, Salt Controlled Mini-Basin, Gulf of Mexico

Chris Leppard¹, Tore M. Løseth¹, and Gyrd O. Sundsbø^2
1Research Centre, Hydro Oil & Energy, Bergen, Norway
²Hydro Gulf of Mexico LLC., Houston, TX

Miocene deepwater plays of the northern Gulf of Mexico are characterised by an interplay of salt controlled mini-basin development and complex deep-water depositional systems. However, the development of allochthonous salt cover in these mini-basins hinders the sub-salt seismic imaging, and seismic attribute analysis that is required to understand these depositional systems - particularly their temporal and spatial distribution relative to the evolving salt. Therefore, in order to gain an understanding of the scale, location and temporal evolution of these deep-water depositional systems within an evolving mini-basin regime an analogous study is required.

The mini-basin selected for this analogue study is located in the northern Gulf of Mexico in a similar setting to the target plays, where the absence of an allochthonous salt cover permits the use of advanced multi-volume seismic attribute techniques to extract quantitative data relating to sediment fairways into and through the mini-basin, in particular the scale, geometry, location and stacking patterns of these depositional systems. Two types of sediment fairways feeding into the mini-basin were identified; 1, Major fairways, highlighted by the presence of a stable entry and exit point over time, and 2, Minor fairways, represented by fixed sediment entry points at narrow (salt-controlled) conduits that periodically feed sediment into the mini-basin, and out towards the major fixed exit point. Depositional elements observed within these fairways include a mixture of confined and unconfined isolated channels, channel complexes, channel levee systems, frontal splays, perched fans, over-bank fans and sheet-like deposits. The quantitative measurements of both scale and location of the depositional elements extracted from these data allow the sub-salt play area models to be populated to a higher degree of confidence.

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas