Reservoir characterization and the possibility of compartmentalization in the Kalloni Field, Niger Delta, Nigeria

The work examined the petrophysical characteristics of fault-bounded sand tops of the Kalloni oil field as theyaffected the sealing capacity and possibility of having compartments. The methods applied were lithostratigraphiccorrelation, seismic interpretation, and evaluation of the reservoir sealing tendencies. A total of twenty-three (23)faults were picked from the 3D seismic volume and 2 major reservoir units were recognized from the suit of welllogs. Structural modelling of the sand units (C6000 and C13000 reservoirs) showed intra-reservoir faults that couldresult in flow restrictions. The sands were seen sandwiched between shale beds having a good spread with a relativeshale thickness of 150-300ft measured depth. The results of the petrophysical analysis showed the C6000 andC13000 sands had a net-to-gross of 0.5, an average volume of shale of 0.4, an average porosity of 28.5% and anaverage permeability of 2,100mD. The results of the fault analysis showed a shale gouge ratio (SGR) of 0.5 - 0.8 onthe fault planes. The stratigraphic juxtapositions showed sand-against-sand as well as sand-against-shale. Theanalysis of the reservoir configuration showed that the shales largely contributed to the sealing having served as thecaprock sequence. A hydrocarbon column height of 266.6ft was estimated in the reservoir C6000 sand while thehydrocarbon column heights of 269.5ft and 333.54ft were estimated on separate stratigraphic crests in the C13000sand. The significance of these results points to the possibility of having compartments in the field.