Formation Evaluation Using Integrated Petrophysical Data Analysis of Maboro Field Niger Delta Sedimentary Basin, Nigeria

Abstract

This study investigates the petrophysical characteristics of the Maboro-Field sand reservoir in the Niger Delta Basin to understand the reasons for its poor hydrocarbon production. Hydrocarbon exploration remains crucial due to the significance of hydrocarbons as primary energy sources. Formation evaluation, encompassing lithology identification, well-log correlation, and petrophysical parameter estimation, was employed to assess the reservoir quality. The analysis involved gamma ray, resistivity, neutron, and density logs from three wells, coupled with 3-D seismic data interpretation using the variance attribute method. The study identified four primary lithologies: sandstone, shale-rich sandstone, sand-rich shale, and shale. Porosity, water saturation, and net pay thickness were evaluated, revealing that CO-01 and CO-03 wells have zones with commercial quantities of hydrocarbons, while CO-02 showed limited potential. Variations in gamma ray signatures indicated lateral continuity of the sand reservoirs, with thirteen hydrocarbon-bearing sands delineated. The 3-D seismic data indicated favorable structural deposition for hydrocarbon accumulation. The findings highlight the varying quality of the reservoirs, with some zones showing high porosity and hydrocarbon saturation, while others were affected by high shale volume and poor porosity. The volumetric analysis estimated the stock tank oil initially in place (STOOIP) and gas initially in place (GIIP), indicating significant gas reserves in several reservoirs. The study demonstrates that petrophysical analysis, integrating well log data and seismic interpretation, effectively identifies productive zones and provides insights into the reservoir's potential for hydrocarbon production.