Geochemical characteristics and origin of crude oil and natural gas in different areas of Wenchang-A Sag,Pearl River Mouth Basin,South China Sea  

作　　者：Xiaoyan FU Shijia CHEN Jungang LU Mingzhu LEI 

机构地区：[1]Exploration and Development Research Institute of PetroChina Southwest Oil and Gas Field,Chengdu 610051,China [2]School of Geoscience and Technology,Southwest Petroleum University,Chengdu 610500,China [3]Hainan Branch of China National Offshore Oil Corporation Ltd.,Zhanjiang 524000,China

出　　处：《Frontiers of Earth Science》2024年第4期714-731,共18页地球科学前沿(英文版)

基　　金：Funding for this research came from the Southwest Petroleum University 2021 Graduate Research and Innovation Fund(No.2021CXYB27);the National Natural Science Foundation of China(Grant Nos.41872165 and 42072185);the development mechanism of high-quality source rocks and hydrocarbon accumulation regularity in the Zhusan Depression(No.CCL2020ZJFN0226).

摘　　要：Complex hydrocarbon distributions characterize the Wenchang-A Sag.Systematic study of the geochemical characteristics of crude oil,natural gas and source rocks and their genetic relationship is still needs to be completed.The Rock-Eval,kerogen maceral,vitrinite reflectance,saturated hydrocarbon gas chromatography-mass spectrometry,natural gas components,carbon isotopes,and light hydrocarbon were performed.1)Crude oil is classified based on four factors:wax content,the presence of C27 diasteranes,the regular steranesαα20RC27-αα20RC28-αα20RC29,and the bicadinanes characteristics.Class I crude oil has high wax and C27 diasteranes.For Class II crude oil,the regular steranes are in‘L’-shaped distribution,and the content of bicadinanes is shallow.Class III crude oil has soft wax and C27 diasteranes,and regular steranes in the reverse‘L’-shaped distribution,with a high peak degree of bicadinanes.For Class IV crude oil,regular steranes are in‘V’-shaped distribution,with high peak bicadinane.2)Class I crude oil comes from source rocks in area C.Class II crude oil comes from source rocks in areas D and E.Class III crude oil comes from areas A,and B.Class IV crude oil comes from source rocks in area A.3)The source of natural gas in Group I is hydro propylene,and natural gas in Group II is humic.Natural gas in Group III is mixed.Groups I and II are kerogen cracking gas,and group III is a mixture of crude oil secondary cracking gas and kerogen cracking gas.Natural gas in Groups I and II mainly come from local source rocks,and Group III has mixed source characteristics.In the future,oil exploration can continue in Areas C and D,and more favorable areas for gas exploration are Areas C,D,and E.

关 键 词：organic geochemistry/origin/geochemical characteristics/crude oil/natural gas 

分 类 号：P61[天文地球—矿床学]