3-D Seismic Structural Interpretation of High Field Offshore Western Niger Delta

S.S Adebayo,O.W Osisanya,E.O Agbalagba,O.E Oyanameh,A.I Korode,T.S Fagbemigun

doi:10.4314/jasem.v25i8.4

Abstract

Seismic Structural interpretation of subsurface system is a vital tool in mapping source rocks and good trapping system which enhances good understanding of the subsurface system for productive drilling operation. This study is geared towards mapping the structural traps available within the hydrocarbon bearing zones of the “High field” with the use of well log and 3D seismic data. Seven horizons (H1, H2, H3, H4, H5, H6 and H7) were identified on well logs using gamma ray log and resistivity logs. Nine (9) faults were mapped on seismic sections across the field, two (2) of which are major growth faults (F1 and F2), two (2) synthetic faults (F3 and F7) and five (5) antithetic faults (F4, F5, F6, F8 and F9). Rollover anticlines which are structural closure and displayed on the depth structural maps suggest probable hydrocarbon accumulation at the down throw side of the fault F1. Structural interpretation of high field has revealed a highly fault assisted reservoir which depicts the tectonic setting of Niger Delta basin.

Highlights

Niger Delta has a distinctive structural and stratigraphic zonation
This study is channelled towards mapping the structural traps available within the hydrocarbon bearing zones of the study area using 3D seismic data and well log which will lead to a better understanding of the subsurface geology of the study area, which enhance location of productive wells
The Niger Delta clastic wedge formed along a failed arm of a triple junction system that originally developed during breakup of the South American and African plates in the late Jurassic, (Burke, 1972; Whiteman, 1982)

Summary

Introduction

Niger Delta has a distinctive structural and stratigraphic zonation. Regional and counter-regional growth faults, developed in an outer-shelf and upperslope setting, are linked via a translational zone containing shale diapirs to a contractional zone defined by a fold-thrust belt developed in a toe-ofslope setting (Hooper et al, 2002). Subsurface configurations must be understood in detail to effectively delineate the structures that are favourable for hydrocarbon accumulation (Coffen, 1984) This is because hydrocarbons are found in geologic traps, that is, any combination of rock structure that will keep oil and gas from escaping either vertically or laterally. Adeoye and Enikanselu (2009), generated structural maps that revealed fault assisted closures at the centre “Extreme” Field, South-western Niger Delta using Seismic and Borehole data, which correspond to the crest of rollover anticlines and possibly served as the trapping medium. Growth fault triggered by contemporaneous deformation of deltaic sediment are the common structures in the Niger delta (Merki, 1972; Evamy et al, 1978)

Methods

Results

Conclusion