Al-Hikmah University Central Journal
DETERMINATION AND DISTRIBUTION OF FORMATIONS THICKNESS IN BAGA/LAKE SUB-BASIN USING SEISMIC IMAGING AND WELL DATA, CHAD BASIN NIGERIA
Abstract
The Borno Basin is located in North-Eastern Nigeria, formed in the Early Cretaceous.
Deposition of sediments in the basin occurred during rifting. The sediments are mainly
lacustrine shales and sandstones. This work was undertaken by the integration of 3D seismic
interpretations and the well data analysis of eight wells fairly distributed in the study area to
determine the thickness of the formations within the sub-basin. Da-1 well used in this study
was subdivided into stratigraphic units based on the regional stratigraphic subdivision of the
Chad basin and was later correlated with other wells using the similarity of observed log
responses. Density and sonic logs were used to generate synthetic seismograms for seismic to
well ties. Five horizons were interpreted, representing the tops of the formations on the 3D
seismic data covering the block, average velocity function with a maximum residual of 0.48%
was used for the time to depth conversion in all the generated maps. There is a general
thickening of sediments from the west to the east and the estimated thicknesses of the various
Formations in the Baga/Lake sub-basin are; Chad (400-750 m), Kerri-Kerri (300-1200 m),
Fika (300-1000 m) and Gongila (100-1300 m). The thickness of the Bima Formation could
not be established because the deepest well terminates within the Formation. This is a
modification to the previous and widely referenced studies of over fifty decades that based the
estimation of formation th