Investigation of lateral continuity of bituminous sands in parts of the eastern dahomy basin, nigeria

Investigation of the bituminous sand in parts of the eastern Dahomy basin was conducted to establish its lateral continuity across the area. The study area cuts across Irele and Odigbo Local Government Areas of Ondo State and Ovia-West Local Government Area of Edo State, Nigeria. Five core holes (BTW–1, BTW–2, BTW-3, BTW-4, and BTW-5) each of diameter 75mm were bored using mechanical rig. BTW-1 and BTW-2 are located at Ayadi village and Ajana-Ejidokun in irele and Odigbo Local Government Area of Ondo State respectively while BTW-3, BTW-4 and BTW-5 are located within Ibru Farm in Ovia-West Local Government Area of Edo State. Seven different lithologic units (Lateritic Topsoil, Sand, Shaly-sand, Shale, Limestone, Bituminous sand and Basement) were identified. The average overburden thickness in the study area is 14.8m while the average depth to the basement is 34m. Wells BTW-3, BTW-4 and BTW-5 encountered basement at shallow depths of 30m, 42m and 30m respectively indicates reduction in depth to basement towards north-eastern sector of the study area. The average Correlation of the holes revealed two bituminous horizons encountered by wells BTW-2, BTW-3 and BTW-4 while wells BTW-1 and BTW-5 encountered one bituminous horizon. The average thickness of the first bituminous horizon is 1.7m while that of the second bituminous horizon is 3m. Results of the study have established lateral continuity of the bituminous sand across the area but with reduced thickness towards Ovia-West Local Government Area of Edo State, Nigeria.