Mapping of thin sandstone reservoirs in bisol field, Niger delta, Nigeria using spectral decomposition technique

Abstract

This study focuses on using spectral decomposition (SD) technique to characterize complicated reservoirs to understand the structural and stratigraphic variations in the interpreted horizons from Bisol field. The purpose of this study is to use geophysical and well logging data sets to map the thin-bedded sandstone reservoirs and prospect zones within the multiple reservoirs in Bisol field, Niger Delta. The interpretation of faults and horizons was carried out on the seismic section, which was further used to produce the structural maps. Seismic attributes such as trace and variance were used to enhance the truncated structures from the seismic section, while the produced spectra were used to delineate the stratigraphy and thickness of the thin-bedded reservoirs. Thin sandstone reservoirs were identified from well logs and consequently mapped on the seismic section. Fast Fourier Transform workflow was successfully used to image the stratigraphic features in the study area. Three horizons (S1T, S2T and S3T) were delineated from the seismic section, and four reservoirs were mapped and correlated across the wells. Frequency analyses from the seismic sectional view revealed some thin pay sandstone reservoirs, which were characterized by high amplitude. Three new probable zones (Prospect A, B and C) of hydrocarbon accumulation were identified using the SD technique.

Keywords

• Fast Fourier Transform
• Spectral decomposition
• Thin sandstone reservoirs
• 3D seismic
• Well logs