Evaluation of Hydrocarbon Generation Potential of the Mesozoic Organic-Rich Rocks Using TOC Content and Rock-Eval Pyrolysis Techniques

This paper investigates the hydrocarbon generation potential of the Mesozoic organic-rich rocks of Dorset area in the Wessex Basin. The objectives of this study are to sample the organic-rich rock outcrops from the Dorset area of southern England and to assess the quality of these organic-rich rocks by organic geochemical analyses. A total of eight outcrop samples of organic-rich rocks collected from six Mesozoic stratigraphic intervals along the coastline of Dorset were analyzed using total organic carbon (TOC) content analysis and Rock-Eval Pyrolysis technique. The analytical results of the studied outcrop samples revealed that they have high total organic carbon (TOC) contents, suggesting that there exist conditions in the Mesozoic that favoured organic matter production and preservation. There is a variation in the kerogen types and this may be attributed to the relative stratigraphic positions of the outcrops within the basin. The Rock-Eval results indicated that the Blue Lias, the Kimmeridge Clay Formation, the Oxford Clay, and the Nothe Clay contain predominantly Type II kerogen with a capacity to generate oil and gas; the Gault Clay contains mainly Type III kerogen and is gas-prone with poor to fair or lean generative potential; and the Purbeck Black Shale comprises Type I kerogen and is oil-prone with high organic matter content and hence has excellent generative potential.