Integration of Well-Test Deconvolution Analysis and Detailed Reservoir Modelling in 3D-Seismic Data Interpretation-A Case Study

摘要

This paper demonstrates how a combination of seismic data interpretation, advanced well test deconvolution analysis and detailed reservoir modeling helped address the concern of reservoir compartmentalization in the E-M field located offshore South Africa and thus significantly improve the history match. The reservoir is heavily faulted and many of the faults have no throw across them suggesting possible communication throughout the reservoir. Several simulation efforts in the past have failed to reconcile the connected hydrocarbons initially in-place estimated from material balance and those calculated volumetrically leading to unsubstantiated assumptions in order to attain a reasonable history match. The paper draws on the strength of an integrated petroleum engineering study that included detailed fault mapping on the re-processed 3D seismic dataset. The latter was guided by the outcomes of recent deconvolution well test analyses and a revised geological model over the entire field. As a result of this study, a new structural and stratigraphic model that satisfactorily explained the historical production performance of the reservoir was proposed. The field is located on a large tilted fault block, dominated by extensional structures with top reservoir locally truncated by the lower cretaceous synrift unconformity (1At1). The primary reservoir is synrift (pre-1At1) shallow marine and fluvio-deltaic sandstone within an upper shallow marine interval (USM). The new stratigraphic model recommends that, in addition to the extensive faulting, the reservoir stratigraphy may also be compartmentalised by field wide horizontal shale barriers. These shale barriers have prevented access to all the hydrocarbons by the existing production wells and presents opportunities for infill drilling in the reservoir.