Petrographic and Diagenetic Evaluation of Carbonate Reservoir Quality: A Case study of the Lower Congo Basin, offshore Democratic Republic of Congo

The Lower Congo basin’s Albian – Early Cenomanian Pinda group is the most productive carbonate reservoir within the West African margin basins. However, the understanding of its diagenetic features is very limited. Core samples obtained from the Democratic Republic of Congo offshore section of the formation were petrographically analysed to image the sedimentary facies along with diagenetic processes and links to reservoir quality. The sedimentary facies obtained indicate a dominant lagoon sedimentation within the oolitic – siliciclastic ramp. Diagenetic processes detected include micritization, dolomitization, dissolution, cementation, and compaction. Diagenetic links to reservoir quality within the facies is established in the dominant occurrence of moldic pores which have been occluded either by calcite or dolomite cement, leaving three facies with poor reservoir quality. The facie exempted from this class possesses a fair reservoir quality linked to microporosity within its sandstone domain. These observations should serve as important considerations for future reservoir characterization studies within the Pinda group.