东海盆地西湖凹陷B气田原油地球化学特征  

Geochemical Characteristics of Crude Oil from B Gas Field in Xihu Sag,East China Sea Basin

作　　者：胡碧瑶 石兴廷 林章鹏 吴雨 黄奕莹 洪婧 Hu Biyao;Shi Xingting;Lin Zhangpeng;Wu Yu;Huang Yiying;Hong Jing(Shanghai Experimental Center,Engineering Technology Branch of CNOOC Energy Technology&Services Limited,Shanghai 200941,China)

机构地区：[1]中海油能源发展股份有限公司工程技术分公司上海实验中心,上海200941

出　　处：《云南化工》2024年第5期159-163,共5页Yunnan Chemical Technology

摘　　要：基于B气田7口井的原油样品,利用气相色谱仪和同位素质谱仪开展了油气地球化学分析和研究。研究表明:B气田原油轻烃组成中正构烷烃含量低,富含异构烷烃和芳烃,指示B气田原油主要来源于陆源有机质;根据原油C_7化合物(甲基环己烷、正庚烷、二甲基环戊烷)组成三角图,原油主要来源于腐殖型母质,为湖湘油和煤成油的混源油;B气田碳同位素值在-27‰~-24‰,w(Pr)/w(Ph)为5.68~10.11,指示B气田原油形成于强氧化环境,是由煤系腐殖型有机质生成;利用庚烷值与异庚烷值对原油成熟度进行划分,属于低熟到成熟阶段。考虑西湖凹陷原油经历较为明显的蒸发分馏作用,原油的轻烃组分发生变化,结合Mango原油形成温度公式,计算出B气田原油的形成温度为129.6~132.0℃,进一步计算出原油成熟度在0.92%~0.95%,可以判断西湖凹陷原油处于成熟阶段。Based on crude oil samples from 7 wells in B gas field,oil and gas geochemical analysis and research were conducted using gas chromatography and isotope mass spectrometry.The research shows that the light hydrocarbon composition of the crude oil in B gas field is low in normal alkanes and rich in isoalkanes and aromatics,indicating that the crude oil in B gas field mainly comes from terrestrial organic matter;According to the composition triangle diagram of C 7 compounds(methylcyclohexane,n-heptane,dimethylcyclopentane)in crude oil,it is shown that crude oil mainly comes from humic parent material and is the mixed source oil of Huxiang oil and coal-formed oil;The carbon isotope value of gas field B is between-27‰and-24‰,and the w(Pr)/w(Ph)is between 5.68 and 10.11,indicating that the crude oil of gas field B is formed in a strong oxidation environment and is formed by humic organic matter of coal measures;The maturity of crude oil is divided by heptane number and isoheptane number,which belongs to the stage from low maturity to maturity.Considering that the crude oil in West Lake Sag undergoes relatively obvious evaporation and fractionation,and the light hydrocarbon composition of crude oil changes,combined with the Mango crude oil formation temperature formula,the formation temperature of crude oil in Field B is calculated to be 129.6℃~132.0℃,and the crude oil maturity is further calculated to be 0.92%~0.95%,which can be used to judge that the crude oil in West Lake Sag is in the mature stage.

关 键 词：西湖凹陷 地球化学 陆源有机质 腐殖型母质 蒸发分馏 成熟阶段 

分 类 号：TE122[石油与天然气工程—油气勘探]