渤海海域南堡35-2油田油源研究

Study of Oil Sources in NB 35-2 Oilfield in Bohai Sea Area

在分析和归纳2个凹陷3套可能烃源岩的有机地球化学特征并对原油样品进行分析测试的基础上,主要运用饱和烃色谱、生物标志物、稳定碳同位素、含氮化合物、原油黏度等指标,首次对渤海海域南堡35-2油田的原油来源进行了系统的研究。研究表明:研究区原油均遭受了严重的生物降解,其中北区原油二次充注特征明显;原油的全油碳同位素组成较为集中,δ13 C在-26.3‰^-26.9‰;原油中伽马蜡烷、4-甲基甾烷含量较高,三环萜烷、四环萜烷含量较低;原油的生物标志物特征基本一致,供烃源岩为同一有机相;原油充注方向为由南向北。结合烃源岩成熟特征综合认为,渤中凹陷沙河街组三段烃源岩是为区内提供油源的主要烃源岩,其次为沙河街组一段。

Based on the analysis and testing of three sets of effective hydrocarbon source rocks and organic geochemical characteristics of oil samples in 2 depressions,the parameters such as saturated gas chromatograph,biomarkers,stable carbon isotope,nitrogen compounds and crude oil viscosity etc.were mainly used for the first time to systematically study the oil sources of NB35-2 Oilfield in Bohai Sea.The study showed that crude oil had serious biodegradation,in its north secondary charge of oil was obvious,the whole oil carbon isotopic compound was concentrated,the δ13 C values was from-26.3‰ to-26.9‰,high Gammacerane,lower Tricyclic Terpane,lower Tetracyclic Terpane and high 4-Methyl Steranes existed in crude oil,all biomarkers were basically the same,source rocks for hydrocarbon supply was from the same organic facies,the oil charging direction was from the south to the north.Combined with the maturities of source rocks,analysis shows that the source rocks of in Bozhong Depression are the main source rocks for oil exploration in the area,followed by the 1st member of Shahejie Formation.