This paper provides a case study in the reservoir description of a fractured carbonate by a multi-disciplinary team. It illustrates how the synergistic interaction of team members during data analysis and model building resulted in: 1) the identification of previously unrecognized links between several reservoir characteristics; 2) produced a superior reservoir model; and 3) increased the likelihood of successful development.

The significant role fractures played in the connectivity, and hence the productivity of the reservoir, became obvious early in the study. A multi-disciplinary team approach allowed for the study of the fracture system utilizing full range of scales, from microscopic to regional. Team members analyzed cuttings, core, wireline logs, well tests and 3-D seismic. Due to the interaction of team members during data analysis and model building, previously unrecognized links between static and dynamic reservoir characteristics were identified.

It was recognized from the study of cuttings and core that microfractures provide reservoir-quality porosity and permeability in the Cretaceous deepwater carbonates of Yum Field. Further, the fractures are concentrated in dense, siliceous/cherty lime mudstone and wackestone facies. Log analysis supports these findings and shows these reservoir zones to be correlatable, high density-low gamma intervals. Analysis of well test data suggests the presence of discrete reservoir zones within the Cretaceous carbonate succession. Interpretation of 3-D seismic allows for delineation of the structural framework.

In summary, identification, characterization, and delineation of fractured intervals within the deepwater carbonate succession resulted in a preliminary 3-D model of both the static and dynamic properties for the Cretaceous reservoir of the Yum Field which, through reservoir simulation, will provide a predictive tool for development planning.

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