Organic Matter of Agbada Formation, Niger Delta, Nigeria

ABSTRACT The status of the Agbada Formation as a major source rock for oil and gas in the Niger delta is debatable. An organic matter survey of the formation in three exploratory wells (Makaraba-26, Abiteye-13, and Okan-25) shows that on the average amorphous organic matter constitutes 63% of the kerogens, whereas terrestrial organic matter (woody remains, spores, and pollen) and recycled (coaly) organic matter make up 30% and 7%, respectively. Pyrolysis data indicate essentially Type III kerogen for the Agbada shales. Thermal alteration index (TAI) and pyrolysis data show that the kerogens are mature in the three wells. We estimate that about 2,000-4,000 ft (600-1,200 m) of mature Agbada shales are present in the western part of the Niger delta. Results of organic carbon determinations show that the Agbada shales contain moderate to high amounts of organic matter, which could have sourced some of the oils found in the Makaraba, Abiteye, and Okan fields. Although this view is valid for the western part of the Niger delta, the situation in the other parts of the delta might be different.