Compressibility Analysis and Geomechanical Characterization for CO2 Sequestration and Storage for Advancement of Health and Environment Protection: A Case of ‘JXT’ Field, Niger Delta, Nigeria

Abstract

CO2 sequestration and storage are parts of the approaches to mitigate the effect of global warming through the reduction and stabilization of CO2 emitted in the atmosphere. In the Niger Delta, several depleted and abandoned wells can be utilized as geologic storage for CO2 to assist economic growth and environmental protection This study aimed at identifying suitable reservoirs for CO2 storage to prevent it from leaking to the surface. Logs from two wells from the 'JXT' field, onshore, Niger Delta were used for the studies. Petrophysics computation and Rock physics analysis such as Geomechanics, fluid sensitivity, and compressibility were carried out. Potential reservoirs were delineated and correlated, elastic parameters were generated from pseudo logs, cross plotted for comparison, and evaluated for physical strength. Fluid sensitivity was carried out using Gassmann's equation to understand dry rock sensitivity to fluid changes. Finally, a compressibility study was done to measure the drained and undrained properties of each reservoir and its resistance to compressive forces. Results of the petrophysical analysis for the three potential reservoirs (A, B, C) delineated revealed values ranging from a high thickness of reservoir (20-109m), moderate porosity (17-23%), and good permeability (128-1251mD). The geomechanical analysis for the two wells shows the range of values for Young modulus (E) as (20.5-27.5GPa), bulk modulus (k) as (21.3-25.3GPa), Shear modulus (µ) as (8.01-11.2GPa) and Poisson ratio (σ) as (0.25). Results from the compressibility analysis indicated the average drained and undrained compressibility for both wells as (0.048GPa-1, 0.044GPa-1) and (0.044GPa-1, 0.044GPa-1) respectively. Conclusively, the results indicated that the ‘JXT’ field is suitable for CO2 storage and can be considered to reduce the emission of this greenhouse gas into the atmosphere and aid positive global climate change.