Seismic-Consistent Reservoir Facies Modelling; A Brown Field Example from Deep Water Niger Delta

Abstract

Abstract Reservoir models often tend to be simple and do not always represent typical reservoir property variations and sometimes complex communication patterns typically encountered in deepwater turbiditic systems (amalgamated, laterally-offset stacked channel complexes and lobate systems). Consequently, such models prove unreliable for development planning and long term production forecast. To address this, seismic facies, which are derived from 3D inversion and subsequent classification studies, are often used either as a background trend or direct quantities in static model building process to guide both lateral and vertical reservoir grid population away from well control points. In this paper, we discuss a methodology for the integration of well data (reference data) and seismic reservoir facies probabilities (auxiliary data) to build a seismic-consistent static reservoir model in a deep-water field, deep offshore Niger Delta. The methodology captures both vertical and lateral variations in reservoir quality seen on well logs (after up-scaling) and seismic-derived reservoir properties inferred from 3D and 4D seismic. Furthermore, we discuss the challenges (fault shallow effect, amplitude degradation across fluid contacts, etc.) and pitfalls (inversion uncertainties, clustering/classification uncertainties etc.) of seismic-driven reservoir facies modeling and their impacts on the reservoir history matching process. Additionally, we discuss potential corrective measures to address some of these challenges, thereby enhancing the consistency of seismically-derived reservoir facies. The paper concludes with the validation of the geologic model with the use of 3D seismic loop-back process.