--> --> Deposition and Diagenetic Analysis of a Core from the Upper Wolfcamp of the Southern Delaware Basin

AAPG Southwest Section Annual Convention

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Deposition and Diagenetic Analysis of a Core from the Upper Wolfcamp of the Southern Delaware Basin

Abstract

The Wolfcamp Series in the Southern Delaware Basin of West Texas is a Permian aged mix of siliciclastics and carbonates deposited through pelagic sedimentation, turbidity currents, and mass wasting in a deep-water environment. A potentially more isolated depositional system was present in the study area than in the rest of the Southern Delaware basin during Wolfcamp time. The Central Basin Platform to the east, and Waha and Coyanosa structural features to the west and south form a mini basin in northern Pecos County. Isolation resulted in lithologies with less siliciclastic input compared to other studies in the Southern Delaware Basin. Using a core from the Southern Delaware Basin, the reservoir characteristics of the upper Wolfcamp are being analyzed. Eight different lithofacies were observed in the core. Two of the more siliclastic lithofacies have the best reservoir characteristics. Based on observed depositional features, stacking patterns, chemostratigraphic proxies, log character, and thin section observations, it is hypothesized that a channelized submarine fan system was active off the Central Basin Platform during Upper Wolfcamp deposition in the study area. An overall coarsening upward package is interpreted as the system was prograding out into the basin. Levee deposits, lobes, and channel fill deposits are present in the cored interval. Diagenesis is complex, with multiple stages and several paragenetic sequences observed throughout the core. Different lithologies have experienced varying degrees of diagenesis. The carbonate clasts inherited diagenetic features from the source area and record events during late diagenesis in the basin. Mudstones contain mineralized fractures and other diagenetic phases acquired during late diagenesis. The diagenetic study is ongoing.