Stratigraphic Interpretation and Reservoir Modeling of Deepwater Slope Canyon Systems – Erha and Erha North Fields

Jeremy J. Willson, Christopher A. Hedlund, Rikus De Mooij, Timothy M. Davies, David M. Marschall, and Sidney M. Weaver
Shell International E&P, Houston, TX

Detailed stratigraphic interpretation of deepwater slope canyon turbidite systems at Erha and Erha North fields have formed the basis of reservoir models and reservoir connectivity analysis. The Erha and Erha North discoveries, located in Deepwater Nigeria block OPL209, consist of Mid to Late-Miocene turbidite reservoirs in a slope canyon setting, draped over a north-south oriented shale-cored high. Since the initial Erha discovery in 1999, an ongoing independent technical evaluation by Shell has complimented work by the operator, ExxonMobil. Early Erha appraisal wells indicated a large single accumulation on the western flank of the high and at least two fault compartments on the eastern flank, each with individual fluid contacts and pressures. Along with the channelized nature of the reservoir, these appraisal results suggested reservoir net-to-gross and connectivity as major uncertainties with the Erha development. The moderate to poor quality seismic data over much of the field reduced confidence in seismic connectivity based approaches to constraining reservoir continuity, and dictated an alternative approach to predicting connectivity within these systems. An integrated evaluation, from regional seismic interpretation to detailed log and core facies interpretation, was used to elucidate stratigraphic architecture, and formed the basis for static reservoir models of both fields.