Geochemical characteristics of crude oil and oil-source correlation of Well Tucan 1, Tuquan Basin, Inner Mongolia

Light crude oil was found at the depths of 1684.5~1698.2m of the Middle Jurassic Wanbao Formation in Well Tucan 1, which was deployed in the southern part of Mangniuhai depression in Tuquan Basin. The oil discovery reveals a better new field of oil and gas exploration in the area. The molecular geochemical characteristics and stable carbon isotopic group components of the crude oil and the main hydrocarbon source rocks were analyzed in the paper. The crude oil is light and high wax oil. The maturity parameters of C31-hopane and C29-sterane isomerization show that the crude oil is a mature crude oil. N-alkanes occur as single and front peak type. Pristines occupy absolute advantage compared with phytane (Pr/Ph>2.5). The content of C29-sterane is much higher than C27-sterane. The content of gammacerane is low. These features indicate that the oil organic matter was mainly derived from terrestrial higher plant in a partially oxidized sedimentary environment. The crude oil came from the coal shale of Jurassic Wanbao Formation.