Evaluation of Fault Compartmentalization and Seal Integrity of an Onshore Field in the Niger Delta Basin, Nigeria

A static model approach was used to investigate the sealing property and trend of the XAS reservoir within the Onshore Niger Delta Basin, utilizing a method that was aimed at identifying sealing faults that might have compartmentalized oil and gas accumulations. Field correlation was established, which facilitated the prediction of facies variation within the reservoir and allowed for constructing a more representative static model. The model proposed five resolvable genetic units to be interpreted. Two main reservoir flow units were also identified from the model. Structural compartmentalization was assessed by measuring the shale-gouge ratio (SGR), fault permeability, and fault zone thickness of the sand-on-sand juxtapositions of the relevant intrareservoir faults. The in-place volume of oil calculated was 1312 × 10⁶ STB, and the GIIP was determined to be 805 × 10⁶ Bscf. The fault juxtaposition analysis recognized areas of interest where faults were juxtaposed above the oil-water contact (OWC). The SGR, fault thickness, and permeability of the fault within the juxtaposed zones indicated that while the faults are not likely to have compartmentalized the reservoir into distinct pressure compartments, they had the potential to operate as fluid flow baffles across the faults