Abstract:

Geochemical characteristics of source rocks, biomarker characteristics of source rocks and crude oil saturated hydrocarbons, stable carbon isotope characteristics of source rock extracts or crude oil and their family components are researched based on source rock samples of Permian Lucaogou and Tiaohu formations, as well as crude oil samples of tuff in Malang Sag of the Santanghu Basin in Xinjiang. The sources of the crude oil in the tuff are made clear in this paper. It indicates that the second member of Lucaogou Formation has the best quality. There are significant differences among soluble organic matter biomarkers of various sets of source rocks, mainly in Pr/Ph, gammacerane content, β-carotane content and peaks of steranes of ααα20RC₂₇, ααα20RC₂₈ and ααα20RC₂₉. Crude oils of tuff in Tiaohu Formation are characterized by low Pr/Ph, high gammacerane content, high β-carotane content, and dominated by ααα20RC₂₉(upward type of steranes of ααα20RC₂₇,ααα20RC₂₈ and ααα20RC₂₉). Also there is light stable carbon isotope of crude oils and their family components. The oil-source correlation shows that the crude oil of the tuff reservoirs is mainly from source rocks of the second member of Lucaogou Formation, and is also from the reservoirs’ organic matters.

Key words: biomarker, stable carbon isotope, oil-source correlation, tuff, Tiaohu Formation, Malang Sag