摘要
准噶尔盆地中部1区块和3区块原油地球化学特征相近,正构烷烃分布完整,呈单峰型,主峰碳为C17～C23,弱姥鲛烷优势(Pr/Ph为1.33～1.75).生标特征:三环萜烷含量丰富,伽马蜡烷含量高,孕甾烷、升孕甾烷含量较高,规则甾烷呈'上升型'分布,ααα20RC27相对含量高,β - 胡萝卜烷和γ - 胡萝卜烷含量高.碳同位素值偏轻(一般小于 - 29‰),生源构成可能以低等水生生物和菌藻类为主,母源形成环境为湖相还原环境.原油主要源自二叠系源岩.中部2区块和4区块原油地球化学特征相近,正构烷烃分布完整,呈单峰型,主峰碳为C13和C19,明显姥鲛烷优势(Pr/Ph为5.62～7.24).生标特征:三环萜烷含量很低,伽马蜡烷含量较低或缺乏,孕甾烷、升孕甾烷含量低,C29甾烷含量很高,规则甾烷呈'反L型'分布,不含β - 胡萝卜烷和γ - 胡萝卜烷.碳同位素偏重(一般大于 - 27‰),生源构成可能以高等植物为主,母源形成环境为氧化环境.原油主要源自侏罗系煤系烃源岩.
Crude oils in the block 1 and 3 in central Junggar basin have similar geochemical behaviors. The distribution of normal alkanes is complete and shows a single peak, with the main peak carbons ranging in C17～C23 and weak pristane prevalence （ the pristane/phytane ratios ranging from 1.33 to 1.75 ）. The characteristics of biomarkers are： （1） high contents of tricyclic terpane and gammacerane, （2） relatively high contents of pregnane, （3） “ascending” type homosterane distribution, （4） relatively high content of ααα20RC27 sterane, and （5） high contents of β-and γ-carrotanes. The carbon isotope value is generally below -29‰. It is suggested , therefore, that the biological sources of crude oils would mainly be composed of low-grade aquatic organism and thallophyta, and the source rocks would have been deposited in lacustrine and reducing depositional environment. The crude oils are mainly generated from the Permian source rocks. Crude oils in the block 2 and 4 in central Junggar basin have also similar geochemical behaviors. The distribution of normal paraffin hydrocarbons is complete and shows a single peak, with the main peak carbons being C13 and C19 and strong pristane prevalence （the pristane/phytane ratios ranging from 5.62 to 7.24）. The characteristics of biomarkers are （1） very low content of tricyclic terpane, （2） relatively low content or absence of gammacerane, （3） low content of pregnane, （4） very high content of C29 sterane, （5） a “reverse L”-shape homosteranes distribution, and （6） absence of β-and γ-carrotanes. The carbon isotope value is generally over -27‰. Therefore, the biological sources of the crude oils might be mainly composed of higher plants, and the source rocks would have been deposited in oxidizing environment. The crude oils are mainly generated from the Jurassic coal-measure source rocks.
出处
《石油与天然气地质》
EI
CAS
CSCD
北大核心
2005年第4期461-466,472,共7页
Oil & Gas Geology
基金
国家攻关专题"准噶尔盆地中部油气成藏条件与选区评价"(2003BA613A-03-05)
