Channel Complex Fills in the Distal Palaeogene Wilcox Play (GoM): Spatial Organization and Conceptual Model

Abstract

The Wilcox Play in deep-water Gulf of Mexico contains large hydrocarbon in-place volumes. The reservoir represents Late Paleocene to Early Eocene siliciclastic deep-marine sediments deposited in a passive margin system, with generally high NTG and low permeability (avg.<10mD). Appraisal and development wells have revealed strong complexities of the reservoir, with clear implications for field development and exploration. Wells have shown that all the Wilcox fields are more compartmentalized (stratigraphic and tectonic) than originally considered, posing significant challenges related to efficient drainage strategies, identification of critical risks during prospect maturation, and addressing uncertainty in volume estimates. The study area is located on the outer trend, Walker Ridge (GoM). Wireline log responses from 16 wells were calibrated to core interpretation and outcrop well data from several analogues. Understanding of sedimentological processes and facies analysis has allowed interpretation of a wide range of architectural elements (AEs), including channel fills, levee deposits, lobe deposits, and shale drapes. These AEs group into several tens of meters thick units, representing complexes and sets of complexes, separated by thick mudstone intervals dominated mostly by hemipelagites. Complex sets may show a progradational pattern, with a basal lobe complex overlain by a channel complex, and reflecting an overall basinward shift in facies. Thickness frequency distribution of AEs shows that channel complexes are particularly abundant in the lower stratigraphy; the basal boundary is an erosional surface with maximum estimated erosion of about 30 m. The channel complexes interpreted from core are dominated by amalgamated sandy channel-fills with average thickness of 10 m, which are laterally offset and vertically stacked forming units up to 80 m thick (avg. 28 m). Correlations, fence diagrams, architectural element and bed analysis have revealed the internal anatomy of the Wilcox stratigraphy. This work highlights the presence, complexity and spatial organization of basin-floor channel complex fills, and contributes to a better understanding of play fairways, reservoir connectivity/compartmentalization, and property distribution.

AAPG Datapages/Search and Discovery Article #90291 ©2017 AAPG Annual Convention and Exhibition, Houston, Texas, April 2-5, 2017