Screening and Ranking of Chad Basin for CO₂ Sequestration Potential in Nigeria

Sedimentary basins are suitable to different degrees for CO₂ geological sequestration as a result of various intrinsic and extrinsic characteristics. This paper preliminarily screened and ranked the Chad Basin of Nigeria sector based on Bachu (2003) ranking and screening criteria adapted which includes factors such as tectonic setting, basin size and depth, geology, hydrogeology, hydrocarbon potentials, climate, geothermal, existing resources and industry maturity. For each criterion i (i = 1…5) used for the evaluation of basin suitability, monotonically – increasing numerical function f_i is assigned, which are continuous or discrete, to describe a value placed on a specific class j for that criterion. The lowest and the highest functions of this functions characterize the worst and best class in terms of suitability for that criterion, i.e. f_i,1 = min (f_i), where and f_i,n = max (f_i); where (n = 3, 4 or 5). The criteria relate to either the containment security, the volume of storage capacity achievable, or considering the economic or technological feasibility. The results shows that Chad basin has Rk score value of 0.53 against the f_{i, n} = max (f_i) value equal to 1 as highest value of the function characterize the best in terms of suitability for the criterion in which this ranking are based on. Regional screening and ranking of the entire basins are recommended while detailed local site characterisation of the basin is needed to assess its overall suitability for CO₂ sequestration potentials, since countries like Cameroon, Central African Republic, Niger, Chad, and Nigeria shares the basin on regional level