Integration of Rock Properties Crossplot and Petrophysics for Enhancement of Litho-Fluid Discrimination and Compartmentalizationto Reduce Uncertainty and Mitigate Hydrocarbon Exploration Risk. ‘A Case of ‘NICK' Field, Onshore Niger Delta’.

Abstract

The main components of reservoir rocks are hydrocarbons and immiscible water in varying ratios. It is essential to precisely identify, characterize, and divide the fluids in these reservoirs into distinct groups according to the characteristics of their rock properties to conduct a successful hydrocarbon exploration. For this reason, petrophysics and rock physics analysis were combined on the "NICK" field in the onshore Niger Delta. Through precise litho-fluid discrimination in the field, this study seeks to improve field hydrocarbon production, lower uncertainty, and mitigate risks related to hydrocarbon exploration. The suites of well logs (Gamma-ray neutron, bulk density, sonic, and resistivity logs) from three wells—NICK-1, NICK-3, and NICK-6—make up the data used. Gamma-ray log signatures were used to identify and correlate lithologies throughout the field. Potential reservoirs and fluid content were identified and delineated by high resistivity and adequate neutron-porosity log signatures. Hydrocarbon-bearing sands were recorded at low values of elastic attributes (acoustic impedance, rigidity, incompressibility, and others), which were computed to aid in the characterizations. Two potentialreservoirs’ Sands A and B delineated, constituted the correlated pay zones observed in three wells across the field at depths ranging from 1986.24 to 2599.82m. Petrophysics results generally revealed fair to good porosities of (11-25%) for easy accumulation of hydrocarbon. Permeability ranged from 210- 809mD for Sand A and 27 – 887mD for Sand B, showing that there are suitable permeabilitiesfor fluid movement/migration within the reservoirs. Cross plot of Lambdarho versus Murho, Lambdarho versus Velocity Ratio, and Velocity Ratio versus Acoustic Impedance gave four distinct clusters for litho-fluid zones identification given as gas-sand, oil-sand, brine-sand, and shale. This study has assisted in better characterization and distinguishing of the litho-fluid details for enhancement of hydrocarbon production in the field.