HYDROCARBON PROSPECTING OVER ‘OK’ FIELD, NIGER DELTA USING PETROPHYSICAL AND SEISMIC ATTRIBUTES ANALYSIS

Abstract

Reservoir evaluation of  “OK” field in southwestern offshore Niger Delta was carried out with a view to identify the lithological units and quantify the hydrocarbon within the reservoir using an interplay among petrophysics, seismic and structural analyses. To achieve these aims, the work involved analysing and interpreting  seismic attributes and the geometry of the identified reservoir sands which consequently led to the determination of the reservoir characteristics. It was deduced that the lithological units were shales and sandstones which occur as an intercalation and with a rhythmic structure. The shale to sand ratio increased with depth. Two hydrocarbon-bearing reservoirs were delineated on well logs namely; reservoir R₁ and R₂. Hydrocarbon saturation and porosity estimates in the reservoirs; R₁ and R₂ were very high varying between 0.6 and 0.75 and 0.21 to 0.27 respectively. Amplitude analysis showed that most structural highs coincided with zones of anomalous amplitude (seismic anomalies). In terms of structure, 3-D structural interpretation revealed that“OK” field is characterized by a rollover anticline, with a closed trapping mechanism for the D series and fault/dip trapping mechanism in the E series. Hence the reservoir units within the field are porous and with substantial hydrocarbon  that were well trapped.