Evaluation of Reservoir Sand using Petrophysical Analysis in ‘Jat’ Field, Niger Delta Basin Nigeria

Abstract

The research aims at evaluating delineated reservoirs in ‘Jat’ Field, Niger Delta, Nigeria to know their quality by using their petrophysical properties through a mathematical relative indexing method. The work employed results from well log analysis to describe the reservoir properties of the delineated reservoir sands in the study area and relatively rank them. Three reservoirs, namely RES 1, RES 2 and RES 3 were delineated and correlated in the SW-NE direction across four wells. Their reservoir properties (lithology, gross thickness, net pay, net to gross (NTG), porosity, permeability, hydrocarbon saturation) were determined. The average determined porosity, permeability, NTG and water saturation with respect to each reservoir from RES 1 to RES 3 were 30%, 28%, 29%; 1082 md, 2110.75 md, 1205.75 md; 762%, 82%, 78%; and 48.25%, 54.25%, 51% respectively. The reservoir quality assessment and ranking were carried out by categorizing the reservoir properties as linear (those associated with thicknesses like gross thickness, net thickness and net pay) and non-linear (properties other than those associated with thickness like porosity, permeability, hydrocarbon saturation) using a mathematical relative indexing method while prioritizing the non-linear properties over the linear properties. Result shows that all the can be exploited for hydrocarbon production with RES 1 being the main target for production.