Assessment of the Spectral Decomposition Techniques in the Evaluation of Hydrocarbon Potential of “BOMS” Field, Coastal Swamp Niger Delta, Nigeria

Abstract

This study employs the different approaches of the spectral decomposition techniques to evaluate the hydrocarbon potential of the reservoir and analyse to determine the most efficient spectral decomposition technique with better resolution using the “ BOMS ” Field, coastal swamp depobelt Niger Delta, Nigeria. A good number of drilled wells have failed both in the Niger Delta Basin and other basins due to a poor understanding of the reservoir properties in advance of drilling and identifying the best approach will help to minimize this risk. Seismic and well logs data together with the Hampson Russel 10.3 software were used for the study. The target reservoirs were identified from the suite of well logs at the horizons with low gamma ray, high resistivity, and low acoustic impedance between TVD (ft) of 10,350 - 10,450 ft. The analysis of the amplitude spectrum of the seismic data revealed that the distortion of interest lies between 5 - 60 Hz. Seismic data were then spectrally decomposed into several frequencies such as low frequency (15 Hz), mid-frequency (31 Hz), and high frequency (46 Hz) where distortions were observed. Time- frequency slices of 15 Hz and 23 Hz provided clearer events (potential hydrocarbon sand) indicated by high amplitude envelope (2200 - 2400) and amplitude anomalies. While the amplitude dropped in the mid-frequency (31 Hz), the high amplitude envelope and the high energy completely disappeared in the high (46 Hz) time-frequency slice. A comparison of the Short- time Fourier transform and the Basic Pursuit algorithm revealed that the Basic Pursuit provided a better resolution of the reservoir characteristics than the former. The Red, Green and Blue (RGB) colour blending model indicated that the channel was consistent with the low-frequency section and amplitude anomaly.