Analytical Study of Unconventional Tight Gas Resource Potential and Development Analogues for the Songhai Formation, Sokoto Basin, Zamfara State, North West Nigeria

Unconventional tight gas resources in sedimentary basins of northern Nigeria are virtually unexplored, and the Songhai Formation in the Sokoto Basin represents a plausible tight gas target based on analogy with Cretaceous tight gas developments in comparable intracratonic basin settings in Africa. This study analytically evaluates the tight gas resource potential of the Songhai Formation using available geological and geophysical data and develops production strategy analogues from comparable international tight gas plays. Core and cutting sample data from three Sokoto Basin boreholes were compiled to characterise Songhai Formation matrix permeability (0.02 to 0.4 millidarcy), porosity (6 to 14 percent), and gas shows documented during drilling. Methane adsorption capacity measurements indicate a minor sorbed gas contribution of less than 15 percent of total gas in place, classifying the resource primarily as tight free gas rather than a shale gas system. In-place resource estimates using volumetric methods with probabilistic porosity and saturation inputs yield a P90 to P10 range of 0.4 to 2.1 trillion cubic feet in the evaluated structural and stratigraphic fairway. Analogous tight gas developments in the Karoo Basin of South Africa and the Rift Valley basins of East Africa are reviewed for hydraulic fracturing programme design insights applicable to the Sokoto Basin pressure and temperature regime. An economic threshold analysis identifies the minimum gas price required to achieve 10 percent IRR as 4.2 USD per thousand standard cubic feet. Keywords: tight gas, Songhai Formation, Sokoto Basin, Zamfara State, unconventional resource.