Seismic, Petrophysical, and Rock-Physics Assessment of Geological CO₂ Storage Potential of Kuro Field, Niger Delta

Abstract

This research focuses on the application of geophysics in analysing and evaluating reservoir properties from seismic and well data for potential subsurface geological storage and monitoring of emitted CO2. The study area is the Kuro field, Greater Ughelli, Niger Delta, and the objectives of this study include effectively placing and utilising geophysics throughout the life cycle of CCS to demonstrate that geophysics plays a fundamental role in site selection and characterising CO2 storage reservoirs; evaluating reservoir storage capacity; monitoring and verifying injected CO2 over time; and quantifying and reducing the risk of possible CO2 leakage. This work integrated 3D geological modelling, seismic interpretation and petrophysical analysis to assess the potential for CO2 storage in the field. Structural interpretation showed a significant horst structure surrounded by major normal fault structures, forming an efficient structural trap for retaining injected CO2, together with competent seal formations, specifically a thick shale formation, that can effectively contain CO2. Petrophysical analysis demonstrated that the reservoir has low shale volume, high effective porosity, low water saturation and adequate permeability favourable for CO2 injection. Rock physics analysis assisted in inverting the elastic properties obtained from seismic data to estimate the saturation of CO2 in the reservoir during injection and retention. Modelled reservoir properties revealed significant heterogeneity but considerable capacity to store CO2. The permeability of the reservoir is estimated at 100-600 mD, with an average of 300 mD. Based on calculations using the pore volume of the grid, density of CO₂, formation volume factor, and storage efficiency coefficients, the estimated capacity for CO₂ storage is 23.6 – 48.5 million tonnes. A spatial analysis of the reservoirs indicated that the central and northwestern portions of the reservoir are the most suitable areas for injection of CO₂ because of their relatively high porosity and net pay thickness.