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

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

Screening of Polyalthia longifolia and Aloe vera for their phytoextractability of heavy metals in tropical soil of the Niger Delta

The work focuses on the screening of Polyalthia longifolia and Aloe vera for their phytoextractability of heavy metal in soil of the Niger Delta. 5kg of soil was polluted with 100 mg of Zn, Fe and Pb each replicated 9 times. Each set was separated into 3 subgroups. The subgroups were phytoextracted with Polyalthia longifolia and Aloe vera alongside a control (no phytoextraction) respectively. After 12 weeks, the concentration of Lead, Iron and Zinc in soils, roots and shoots was determined. Results showed that the two plants have phytoextraction ability with reductions in Zn, Fe, and Pb in the phytoextraction soil . Metal transfer factor was PB: Aloe vera (0.881) > P. longifolia (0.315); Zn: P. longifolia (0.614) > Aloe vera (0.606); Fe: Aloe vera (0.812) > P. longifolia (0.774). Translocation factors for the two plants were in the order: Zn: P. longifolia (0.79) > Aloe vera (0.36); Fe: P. longifolia (0.63) > Aloe vera (0.05); Pb: P. longifolia (0.57) > Aloe vera (0.23). Since the translocation factors were < 1, the plants can be classified as non- hyperaccumulators for these metals.