Cross plotting of Rock Properties for Fluid and Lithology Discrimination using Well Data in a Niger Delta Oil Field

Abstract

The cross plotting of rock properties for fluid and lithology discrimination was carried out in a Niger Delta oil field using well data from a given oil field. The data used for the analysis consist of suites of six wells. The reservoir was evaluated using gamma ray logs, volume of shale, resistivity and neutron porosity for well-02 and well-06. Sand lithology showed low gamma ray, high resistivity and low acoustic impedance. Cross plotting was carried out and the plots with most outstanding results were Vp/Vs versus AI, λρ Versus Vp/Vs, μρ against Density and λρ versus μρ. For the two wells considered, two reservoirs were observed, one   reservoir was observed in well - 02 at a depth of 4600 ft to 5050 ft .and a reservoir was also observed for well - 06 at a depth of 10240 ft to 10600 ft. Crossplotting of rock properties discriminated the wells into lithologies of sand and shale which is typical of Niger Delta. The crossplot also discriminated the fluids into gas, brine and oil. This study has been able to discriminate hydrocarbon reservoirs using well logs in the field of study.

Keywords: Hydrocarbon, Reservoir, Well – Logs, Crossplotting, Lithology