Integrated Reservoir Modelling Workflow for Deep Water Turbiditic Reservoirs - An Angola Case Study

Angolan deep water offshore is one of most prolific area for hydrocarbon exploration and production. The main discoveries are in high sinuosity turbiditic channels of Miocene and Oligocene age, deposited in slope valley corridors. The large amounts of sediments sourced from the African margin and the high energy level of the depositional environment create numerous discontinuities at regional and local scale, producing complex sedimentary structures (Anka et al. 2009). The heterogeneities inside the reservoir impact the connected volumes and reservoir fluid path. The paper describes a reservoir modelling workflow developed to simulate the reservoir architecture and analyse the uncertainties related to reservoir connectivity for a small oil field offshore Angola. Fluid path discontinuities above and below the corridor scale were split and managed with an innovative approach. A deterministic geological concept for the channel complex valleys was established to drive the seismic interpretation. Individual slope valley corridors mapped on the seismic provided the framework for the reservoir architecture and the facies simulation. Sub-corridor discontinuities were subsequently treated in a probabilistic way generating multiple realizations closing the data uncertainty gap. The result of this integrated workflow provides a reliable reservoir model appropriate for field development planning and reservoir management.