SEDIMENTOLOGICAL CORE ANALYSIS OF THE UBEFAN-4 G6 RESERVOIR NIGER DELTA TO DETERMINE ENVIRONMENT OF DEPOSITION

ABSTRACT

The aim of this study is to reconstruct the environment of deposition of the Ubefan-4 core, located in Niger Delta, with latitude 5°35’0’’ and longitude 5°19’0”. From the geological description of the Ubefan-4 core, the G6 reservoir has been made out to consist mainly of three genetic elements as follows: (a) Fluvial facies consisting of planar cross-bedded, poorly sorted sandstones and flat-bedded, coarse, conglomeratic sandstones, interbedded with massive muds; (b) Flat-bedded and cross-bedded medium to fine, fairly well sorted, intensely bioturbated sandstones identified as foreshore facies with lagoonal and back barrier muds. (c) Wave ripple cross-laminated, fine, well sorted, shale intercalated and bioturbated sandstones deposited in the shoreface environment. These facies constitute the lithic fill of a valley incised during a temporary base level drop within an overall transgression in the mid Miocene. Floored by a fourth order sequence boundary, the channel was progressively filled by back stepping fluvial, through tidal/estuarine and lagoonal to shoreface parasequences.