PETROLEUM SYSTEM ANALYSIS

PETROLEUM SYSTEM ANALYSIS

Analysis of petroleum systems of a large area, such as the West African continental margin, requires handling large datasets. Geographical Information Systems (GIS) is an ideal software tool for such a massive undertaking. In this paper, we demonstrate a GIS application in identifying potential petroleum exploration targets in offshore West Africa. Prospective areas are identified based on our understanding of the key elements for oil and gas accumulation to occur, especially the distribution of source rock and reservoir rocks. Using a GIS approach, various exploration and production (E&P), geological, geographical and cultural data and attributes can be visualized and superimposed with geological interpretation. Mapping of various petroleum systems elements help us identify the more favourable exploration trends or prospective areas.From our GIS and petroleum system analyses, the most prolific source rocks in the West African Province were identified as the syn-rift Early Cretaceous (Neocomian to Aptian) organic shales and marls. In Lower Congo Basin this include the Bucomazi Formation which contains Type I kerogen with an average Total Organic Carbon (TOC) of 5 weight percent. In Kwanza, the producing source rocks is the early syn-rift section that contains thick, organic-rich, lacustrine shales with abundant Type I kerogen. Potential reservoir in the Lower Congo Basin includes the pre-rift Jurassic Lucula Sandstone and Toca Formation carbonate rocks. The Cuvo Formation in Kwanza Basin which is equivalent to the Chela Sandstone in Congo is a potential reservoir that is deposited in fluvial and lacustrine environments.