New insights into Subsurface Architecture of Gongola Basin: it’s Implication for Exploration Failure and Future successes in part of Gongola Basin, Upper Benue Trough, NE Nigeria

Abstract Globally, more than 50% exploration failure are attributed to subsurface structural architecture and the recent exploration success in the Kolmani river-2 well validates the presences of favorable stratigraphic framework (petroleum system elements) for hydrocarbon discovery in the Gongola basin. However, no study has attempted to relate subsurface structural architectures to over 2 decades marginal success of the Kolmani River-1 Well and the absence of hydrocarbon (failure) in the Nasara-1 or Kuzari-1 wells in this basin. Therefore, this research evaluates the role of subsurface architectural disposition on the marginal hydrocarbon discovery (gas) and failure (dry well), and attempts to identify potential prospects for more detailed studies through the integration of gravity, radiometric, remote sensing data and high resolution aeromagnetic data over parts of the basin. Surface remote sensing digital elevation model reveals the study area is a highly undulating terrain that exhibits a generally elongated structure trending mostly in the NE-SW and closely E-W direction. The basin has a basement depth of about 8.9 km with a major bedrock depression (a half basin). The Kolmani-1 and Nasara-1 wells are located at the border and outside this depression, respectively. The lineaments exhibit a zero (0o) degree tilt angles to form close to the edges of bodies, and define source structural discontinuities such as faults and geologic contacts that can serve as potential spill points for the migration of hydrocarbon out of a trap or reservoir or into adjacent formations. The distribution of radiometric elements supports the assertion of hydrocarbon generation, and the presence of structural control features such as faults, fractures and folds that can act as pathways for the migration and accumulation of hydrocarbon within the Gongola Basin. The mapped magnetic aureoles at the basement topography indicate that the petroleum system in the area is chiefly controlled by the major depression observed at the central western part of the basin. This implies that the greatest potential hydrocarbon prospects lie within that depression Based on this premise, the positioning of the Kolmani-1 Well on a magnetic aureole at the margin of the depression accounts for its marginal success of 33 Bcf of gas, while the location of Nasara-1 Well outside the depression may explain why it is a dry hole. Future hydrocarbon prospects within the Gongola Basin are recommended to be targeted at Aureoles A5, A6, A7, A11, A14 and A15, subject to further confirmation through 2D and 3D seismic surveys