Abstract:

Oil source correlation is one of the important methods to trace new oil layers and guide exploration. Based on analysis of geochemical behaviors of oil produced from Wengu 2well, correlation of crude oil and potential source rocks has been made through comparing carbon isotopes and biomarkers in combination with the regional geologic setting.As for the crude oil in Wengu 2well, hydrocarbon content is high,while nonhydrocarbons + asphaltenes content is low in its group components; the δ¹³C in the components and whole hydrocarbon is light;the main peak's carbon is nC 17; and gammacerane and oleanane are abundant. Oil-source correlation indicates that the Wengu 2well buried hill reservoir belongs to young source rock and old reservoir rock type,and the Paleogene mudstone is the main source rock.The crude oil and the extract from Paleogene dark-colored mudstone have very similar δ¹³C value and distribution,and both of them have high gammacerane and oleanane contents. The extract from coal-measure source rock and simulated oil have large δ¹³C value, low gammacerane content and no oleanane,significantly different from the crude oil in Wengu 2well.

Key words: crude oil, geochemistry, carbon isotope, biomarker, oil-source correlation, Paleogene, Dongpu depression