Lithofacies, bio-sequence stratigraphy and paleoenvironment of the cretaceous-neogene at the BG-1 well, offshore Eastern Dahomey Basin, Nigeria: implications for future exploration and development efforts

Abstract

Late Cretaceous-Miocene foraminiferas were recovered from the BG-1 well in the offshore Eastern Dahomey Basin. Four (4) lithostratigraphic units comprising Ogwashi-Asaba, Upper Araromi, Lower Araromi and Afowo Formations have been delineated and assigned based on the textural characteristics of the sediments. Forty-nine (49) foraminiferal species were identified, with a total count of 47 calcareous species (96%) comprising both planktonic and benthic forms and two arenaceous forms (3%). Seven (7) foraminiferal zones were recognised and dated from the Upper Cenomanian to Late Miocene age. The Globotruncana aegyptica zone, marked by the disappearance of the Maastrichtian forms at 3060 ft, coincided with the appearance of the Early Paleocene benthic forms such at the Anomalinoides umboniferus- Anomalinoides midwayensis zone. The Cretaceous-Paleogene (K-Pg) boundary was recognised at 3060 ft. Seven MFSs and SBs dated from the Upper Cenomanian and Upper Miocene ages were identified in the sequence stratigraphic analysis. The stacking patterns of the lowstand and highstand systems tracts reveal the interplay of progradational and aggradational parasequence signatures of siltstones and sandstone lithologies. The paleodepositional sedimentary packages of the BG-1 well are recognised from the Inner-Neritic to Bathyal environment. The sequence stratigraphic integration of lithofacies and foraminifera assemblages in this study has created a model of the distribution of the elements in the hydrocarbon system of the offshore Eastern Dahomey basin. Therefore, this study will underscore the critical role of sequence biostratigraphy in enhancing the accuracy and efficiency of exploration and development efforts in the hydrocarbon industry.