Geochemical Correlation of Crude Oils in the Northwestern Niger Delta, Nigeria

By

Chidi Eneogwe¹, Olusegun Edundayo²

(1) CTOP-NIGERIA, San Ramon, CA (2) University of Ibadan, Ibadan, Nigeria

 Sixty-six oils from eleven offshore and onshore fields in the northwestern Niger Delta, Nigeria were analyzed for their biomarker and isotopic composition. Biomarker and isotopic source parameter distributions grouped the oils into three oil families. Family A oils, located in the onshore swamp to the transitional area received charges from predominantly Upper Cretaceous or younger age marine source rocks deposited in a sub-oxic to oxic depositional environment. Family B oils occur in the near offshore area and are derived from Tertiary age source facies that received mixed terrigenous and marine organic matter. Family C oils, which dominate the offshore area, were derived from Tertiary age source rocks typical of deposition in oxic near shore or deltaic settings receiving significant terrestrial organic matter. Biomarker maturity parameters reveal the onshore (swamp) oils were generated at the peak of the oil generating window, while the transitional to offshore oils were expelled at the early stage of oil generation.