Seismic amplitudes and spectral attribute analysis in reservoir characterisation, \u2018MUN\u2019 onshore Niger delta field

J M Munyithya,T Dagogo,M O K’Orowe,C N Ehirim

doi:10.1007/s13202-020-00917-1

Abstract

Integrating seismic amplitudes and spectral attribute analysis has successfully mapped, validated and characterised hydrocarbon-saturated channel sands by high-amplitude low-frequency anomaly. The aim of the study was targeted at using these novel geophysical tools to improve characterisation of tertiary clastic reservoir in the field. These attributes were extracted along H4 seismic horizon and analysed independently for structure, lithology and hydrocarbon saturation. The result of the analysis shows that both attributes complimented each other in mapping the hydrocarbon-saturated reservoir channel sands. However, the spectral attributes in combination with spectral-based Red, Blue and Green (RGB) colour blending attribute map reveal finer and subtle details of the channel structure and stratigraphy which hitherto were not apparent in the seismic amplitude maps. The channel sands trend NE–SW, broadening towards the southwest and bounded by major growth faults to the northeast and southwest, respectively. It is thick to the southwest and thins to the northeast. By-passed hydrocarbon prospect was delineated to the northeast of the existing wells, and as such, infill wells can be drilled in these areas to recover hydrocarbons.

Highlights

Reservoir characterisation is fundamental in assessing the prospectivity and economics of a given hydrocarbon reservoir
Previous studies have independently demonstrated the effectiveness of seismic reflection amplitudes and spectral attribute analysis as direct hydrocarbon indicators (DHI), mapping of stratigraphic units and structures and evaluation of reservoir properties (Partyka et al 1999; Marfurt and Kirlin 2001; Othman et al 2016; Ehirim and Akpan 2017)
Seismic amplitude is encumbered by ambiguity due to acquisition footprints, processing and imaging errors, surface conditions and geologic factors, which can lead to amplitude interpretation pitfalls during reservoir characterisation if not validated (Houk 1999; Harilal 2010)

Summary

Introduction

Reservoir characterisation is fundamental in assessing the prospectivity and economics of a given hydrocarbon reservoir. Characterisation entails identifying, mapping and estimating petrophysical, structural, stratigraphic and geometric reservoir properties for effective development and exploitation of hydrocarbons from well and seismic data. This process is complicated by the quality of data, geology and interpretational methods adopted in analysing data. These results in the prediction of error-bound reservoir properties, leading to the drilling of less performing or dry wells and subsequently, poor returns on investment. Seismic amplitude is encumbered by ambiguity due to acquisition footprints, processing and imaging errors, surface conditions and geologic factors, which can lead to amplitude interpretation pitfalls during reservoir characterisation if not validated (Houk 1999; Harilal 2010)

Objectives

Methods

Discussion

Conclusion