INFLUENCE OF PRESSURE ON POROSITY–PERMEABILITY RELATIONSHIP IN SOUTHERN NIGER DELTA, NIGERIA

Well logs data comprising of comprising of gamma ray, spontaneous potential, density and neutron logs from four oil wells were analysed for determining the influence of pressure on porosity–permeability relationship in the study area. Porosity values were deduced from well log whereas permeability and pressure values were computed using empirical equations. The average porosity, permeability and pressure values for the four wells range from 0.1% to 30.9%, 34.9mD to 306.4mD, 61926.9psi to 109928.1psi respectively. The lithostratigraphic correlation section of the wells revealed a sand – shale sequence which is a characteristic of a typical Niger Delta formation. The results of this work show that three reservoirs (sand A, sand B and sand C) were identified and correlated across the four wells, each reservoir sand unit spread across the wells and differs in thickness ranging from 8ft to 155ft, with some unit occurring at greater depth than their corresponding unit. The analysis of the wells show that wells OTIG9 and OTIG11 have better reservoirs indicating high potentiality and productivity due to their more porous and permeable nature, reflecting well sorted coarse grained sandstone and linearity in the relationship between porosity, permeability and pressure. The reservoir of well OTIG7 is the least porous but most permeable, thus is highly productive but less potential. The reservoir of OTIG2 has moderate potentiality and good productivity, hence is said to have average production capacity. The results of this work can be used as an evaluation tool for reservoir engineering activities, structural engineering, well stability analysis, blowout and lost circulation prevention