Sedimentological and stratigraphic analyses as a guide for reservoir quality prediction and distribution: a case study of X1 and X2 reservoirs in Koca field, Niger delta

• Main Author: Kelechi Victoria Njoku
• Format: Article
• Language: English
• Published: SpringerOpen 2020-02-01
• Series: Journal of Petroleum Exploration and Production Technology
• Subjects: Sequence stratigraphy; Conceptual depositional model; 3D static modelling; Reservoir quality
• Online Access: https://doi.org/10.1007/s13202-020-00844-1

Abstract The basic architecture of reservoir models is heavily impacted by the stratigraphic interpretation. The estimation of in-place hydrocarbon volumes and recoverable hydrocarbon volumes will rely on the accuracy of predicting and distributing reservoir quality away from well control. In this paper the interpretation of sedimentological and stratigraphic analyses is used to define reservoir geometry, lateral continuity and determine technique needed for 3D static modelling. The objective of this study is to use a sequence stratigraphic framework and depositional model to predict the characteristic fabric of X1 and X2 reservoirs in unknown portions of the field. Log motifs from four wells (Koca-01, Koca-02, Koca-03 and Koca-04) and core report from a nearby well Z07 were used to classify facies types. Biostratigraphy data from Koca-01 were used to identify key stratigraphic markers. A sequence stratigraphic framework of the facies was built and correlated across the field. This interpretation was further used to build a conceptual depositional model that best represented the environment of deposition for these reservoirs. Results show the major facies associations as distributary channels and shoreface sands. X1 and X2 reservoirs are interpreted to be progradational sands within a highstand system tract. Correlation shows good sand connectivity and distribution of gross reservoir thickness in 2D. The depositional model in this paper was used in 3D static models to improve geometric characterization in 3D static modelling.