Petrophysical properties and spectral insights of selected reservoirs in the Niger Delta

Abstract

The study location consists of subtle hydrocarbon-harbouring reservoir structures often bypassed using traditional seismic with petrophysics interpretation, and the current research integrates spectral analysis in reservoir characterisation to produce more detailed results missing within the LOLO oilfield. Petrophysics, seismic interpretation, and spectral decomposition were utilised to evaluate the hydrocarbon potential. Selected reservoir horizons were mapped between 2.35 and 2.55 s based on event strength and continuity. A network of progressive fault planes was delineated from reflection characteristics. Unlike most parts in the Niger Delta, this study uniquely combines petrophysical data with spectral decomposition across multiple frequency bands (12 Hz, 27 Hz and 50 Hz), a technique rarely applied in this region, while employing RGB blending to visualise subtle geological features and delivering a more refined interpretation of fault-assisted traps and stratigraphic variations to enhance hydrocarbon prospectivity. The lithology is composed of an alternation of sand and shale units. The reservoirs designated C5, C6, D2, and D5 extend across the wells (LOLO-006, LOLO-007, LOLO-010, and LOLO-013). The delineated zones of interest have an average net sand thickness of between 4 and 325 ft, net to gross in the range of 0.28–0.89, an average effective porosity in the range of 0.24–0.28 (24–28 %), permeability ranging from 609 to 2225 mD, and hydrocarbon saturation ranging from 0.59 to 0.71 (59–71 %). These reservoirs were considered to be of good economic value. The probable hydrocarbon-harbouring structure in the area is a faulted anticlinal structure. Spectral decomposition analysis revealed subtle fault-assisted structures whose misinterpretation could lead to bypassed hydrocarbon-bearing units and reduced recovery, whereas accurate identification supports efficient drainage and optimised field exploitation. The findings strengthen the existing hydrocarbon exploration database for the study area and offer valuable insights for ongoing and future investigations.