Geological Characterisation of Depleted Oil and Gas Reservoirs for Carbon Sequestration Potentials in a Field in the Niger Delta, Nigeria

摘要

The injectivity, containment and storage capacity of sandstone reservoirs in afield in the Coastal Swamp depobelt of the onshore eastern Niger Delta were evaluated usingwireline logs and seismic data to assess their potentials for carbon dioxide storage andgeosequestration. The reservoir formation consists of multilayered alternating beds of sandstoneand shale cap rocks. Active seismicity and fracturing intensity are low and growth faults providethe reservoir sealing mechanisms. Three reservoirs were delineated at depths between 3319 mand 3539 m which will keep injected CO2 in a supercritical state. The reservoir depth of atleast 800 m, porosity and permeability of more than 10 percent and 20 mD, and a caprockthickness of at least 10 m, in addition to geothermal gradients of 13.46 to 33.66 ºC /km are theideal conditions for the efficacy of storage. Comparison of the derived reservoir and sealproperties such as porosity, permeability, thickness and depth with the minimum recommendedsite selection criteria shows that the reservoirs are potential candidates for carbongeosequestration with a total theoretical storage capacity of 147MM tons.