Application of Geological and Geophysical Data to Characterise E8000 Reservoir in Afenmai Field of Niger Delta Basin, Nigeria

Abstract

Afenmai Field is a partially assessed discovery within the Central Depobelt of eastern Niger Delta Basin in Nigeria. It occupies 242 km surface area and presently has eight wells, giving it an average well density of one well per 31 km . Improved assessment of the discovery is required to upgrade the field to development drilling status. As a contribution to improving the assessment, this study characterised the E8000 sand, which bears hydrocarbon in Well 007. The data utilised comprised information on subsea vertical depth to top and base of sand and shale units, foraminifera content, geophysical logs, checkshot data, fluid contact depths, and 3D seismic volume. Sequence stratigraphic concept was employed to analyse the sand and shale units, foraminifera content, and geophysical logs. The E8000 sand was mapped through the 3D seismic volume, and a depth- structure map was produced. The map reveals a major structure building synthetic fault in the middle of the field. The fault runs approximately east —west in the eastern part of the field and northwest- southeast in the western part. The sand is a lowstand systems tract with a roll-over anticlinal structure that forms a three-way closure with a crestal synthetic fault. The reservoir pay occupies about 4.5 km areal extent, with opportunities for drilling four development wells along the east-west axis of the closure. Opportunities exist for drilling a minimum of three development wells southwards of Well 007. Approximately 4000 - 5000 root mean square amplitude value characterise hydrocarbon in the reservoir. A prospect is generated within the eastern part of the of the major structure building fault's upthrown block.