Benchmarking short-time Fourier transform against discrete Fourier transform for stratigraphic feature mapping: insights from the TMB field, Niger delta

This study benchmarks Short-Time Fourier Transform (STFT) against Discrete Fourier Transform (DFT) for mapping stratigraphic features in the TMB Field, Niger Delta, a prolific petroleum province where high-resolution reservoir characterization directly impacts field development decisions. Interpretations of wireline logs (Gamma Ray, Sonic, Resistivity) of Well 06 and 3D post-stack seismic logs (SEG-Y format) resulted in establishing a sand reservoir interval (6300-6384 ft) converted to two-way time (2.440-2.468 s) through checkshot calibration. Spectral decomposition was implemented in MATLAB with systematic optimization of the STFT window parameters (4 ms, 8 ms and 16 ms Gaussian windows) and the final choice was made based on quantitative resolution metrics. Amplitudes across 10 time slices (4 ms sampling) through the reservoir interval showed changes in the amplitude which highlighted the formation fluid changes and sequence boundary. Direct comparison shows that STFT having optimized 8 ms window gives high-quality localization of stratigraphic features than DFT especially in identifying subtle channel geometries (meandering channel found at 4-6 Hz bandwidth) which are then smothered in DFT by spectral averaging. Frequency attributes are used to discriminate lithologies: sand bodies exhibit dominating frequencies between 20-30 Hz and those of shales 40-50 Hz, as would be expected between acoustic impedances of unconsolidated Tertiary sediments. The study sets quantitative performance standards for classical spectral decomposition in the TMB Field, and it offers a reproducible standard against which to compare subsurface stratigraphic delineation and backgrounds enhancing an advanced time-frequency approach (synchro squeezing transforms, machine learning strategies). The open-source implementation and workflow documentation of MATLAB makes it transparent and allows its extension to comparative studies. Findings indicate that optimized STFT is adequate to perform operational stratigraphic mapping in resource-limited contexts, providing operational implications to delimit the reserves and determine the placement of wells in the Niger Delta and other similar mature basins.