Structural Styles and Depocenter Delimitation in Yowi Field: Impacts on Trap Formation and Prospect Identification

Abstract

Three-dimensional seismic volume and well-log data from the Yowi Field, shallow offshore eastern Niger Delta, were used to evaluate structural styles, depocentre configuration, trap development and prospect distribution within this study area. The study area contains fault-related closures within a structurally complex petroleum system where growth faults and associated rollover anticlines influence hydrocarbon entrapment. Faults were interpreted on extracted 3D structural smoothing and variance-edge attribute sections, while the N5.1 horizon was correlated and traced along a negative trough seismic loop to generate time and depth structure maps. The interpretation identified thirty-six (36) faults, including synthetic faults, antithetic faults and incipient collapsed-crest structures. Four faults were classified as major structure-building growth faults. These growth faults initiate at about -400 milliseconds, extend to about -2500 milliseconds, show maximum growth development between -900 and -1500 milliseconds, and exhibit growth cessation beyond -3000 milliseconds. The structural framework delimits the field into three major depocentres, with a structural saddle separating two culminations. Several 3-way anticlinal fault-assisted closures occur on both the footwall and hanging wall of the growth faults, forming seven closures, including five undrilled and two drilled closures. These closures represent possible sites for hydrocarbon entrapment and provide a basis for prospect identification in the field.