Evaluation of Facies Architecture and Depositional Environment of G-Field in the Greater Ughelli Depobelt of the Niger Delta Area, Nigeria

K.O Okengwu,G.C Soronnadi-Ononiwu

doi:10.4314/jasem.v25i10.2

Abstract

This study utilized well logs and core data to evaluate facies architecture and depositional environment of G-field in the Greater Ughelli Depobelt of the Niger Delta area in Nigeria. The study revealed five lithofacies unites, namely, Bioturbated Sandstone Facies (BSF), Coarse to Pebbly Sandstone Facies (CPSF), Mudsone Facies (MF), Very Fine Grained laminated Sandstone Facies (FGLSF), and Wavy- to Flaser-Bedded Facies (WFbF). The lithofacies were grouped into Two (2) Facies Assemblages that where established from the five mentioned lithofacies A-E. The Facies Assemblages are Open-marine Facies Association, Brackish-water Marginal-marine Facies Association and Tidal Flat Association. Gamma Ray (GR) logs within the cored interval defined an aggrading deposit. These assemblages were used to infer the various environments responsible for the deposition.

Highlights

The lithostratigraphy of the Tertiary Niger Delta is divided into three major units: Akata, Agbada and Benin formations, with depositional environments ranging from marine, transitional and continental settings respectively. (Figure.3 and Table 1)
Oomken (1974) in his study, examined the sediments in the Terrestrial and Submarine parts of the modern delta and grouped them into three major lithofacies using lithological characteristics and other sedimentary features. These lithofacies are grouped into sandstone, heteroliths and mudstone
1) Open-Marine Facies Association: It is an area of low energy so it consist of fine grained sand interspersed with thin layers of mud, moderate to intense bioturbation and burrowing

Summary

MATERIALS AND METHODS

Description of Study Area: The study area, “G Field” is located within the Greater Ughelli Depobelt It lies between longitude 5.14°E and 5.28°E and latitude 5.14°N and 5.26°N (Figure 1) on the onshore part of the Northwest Niger Delta. The Akata, Agbada and Benin formations overlie stretched continental and oceanic crusts (Heinio and Davies, 2006) Their ages range from Eocene to Recent, but they transgress time boundaries. Oomken (1974) in his study, examined the sediments in the Terrestrial and Submarine parts of the modern delta and grouped them into three major lithofacies using lithological characteristics and other sedimentary features. These lithofacies are grouped into sandstone, heteroliths and mudstone. >50% mud R (rooted) deformed - M (mudstone F (fossiliferous) slumped, dominant) O (organic-carbonaceous) slide, micro

AND DISCUSSION

Conclusion

REFRENCES