Integrating Well Log and 2-D Seismic Data to Generate Inverted Acoustic Impedance for Stratigraphic Validation in Part of Upper Benue Trough (Gongola Basin), Nigeria.

Abstract

Integration of 2-D seismic and well log data of Gongola Basin was carried out to
delineate the subsurface stratigraphy and define the basin structure beneath
Gongola Basin in North-Eastern Nigeria. The 2D seismic interpretation revealed
undulating basement topography, while structural analysis identified three
predominant fault trends—NWSE, NESW, and NNW-SSE—forming horst and
graben features in the region. Interpreting the gamma log from the well log suit, we
identified and delineated subsurface stratigraphy in this area. The analysis
uncovered a sequence of sandstone and shale, leading to the identification of four
stratigraphic horizons—labelled as A, B, C, and D. These horizons are presumed to
correspond to Gombe sandstone, Pindiga, Yolde, and Bima sandstone formations,
respectively. The analysis also revealed the stacking patterns of individual
sedimentary formations and their paleoenvironments of deposition
asProgradational and aggradational.Moreover, the seismic inversion was carried
out and the resulting model was calibrated with a well log from Kolmani-1. The
time-depth relationship between the sonic log and seismic data was determined by
tying a well with an intersecting seismic section and the inverted acoustic
impedance was generated. The analysis of inverted acoustic impedance models also
reveals four major stratigraphic units. The AI also reveals within these rock units the
presence of some micro lithologicunits which may be a result of the intercalation of
shale and sandstone. As in well interpretation, this analysis also reveals a sequence
of alternating units of sandstone and shale which further validates the stratigraphy
sequence beneath the area.