Deepwater slope valley reservoir architecture and connectivity, Brazil

Abstract

A detailed interpretation was undertaken to improve the description of connectivity and reservoir distribution for a field in the Campos Basin, Brazil. The Miocene reservoir was deposited in a deepwater, channelized turbidite fairway in a slope valley setting. Static pressure data acquired after production start-up indicated communication across the reservoir, but the values varied significantly, implying that the efficiency of communication varies. High-quality 3D seismic in combination with production and well data led to a hierarchical interpretation, from channel element to complex-set scale, which defined key stratigraphic and pressure surfaces. Integration of a high-repeatability 4D monitor survey showed that the 4D response changed at stratigraphic boundaries. The 4D data tied to production indicate that an aquifer is traveling along the base of the reservoir in discrete channels. The use of 4D depth shift data increased confidence in the waterfront interpretation in areas without production data. Aggradational channel complexes in the upper part of the reservoir show baffling at the margins of channel complexes down to the channel element scale. The channel elements are also likely baffled on the margins with greater connectivity downward into the lower, amalgamated unit. The lower unit shows greater lateral continuity in 4D signal, consistent with pressure data that indicate larger depletion over greater distances than the overlying aggradational complexes where producer wells are located. In summary, mapping of reservoir architecture and identification of key stratigraphic surfaces from 3D have reduced uncertainty in reservoir distribution and connectivity. Integration of 4D seismic and production data has provided confirmation of connectivity through the identification of waterfronts and unswept areas of the reservoir.