尕斯库勒油田不同赋存状态烃类的地球化学特征  

Geochemical Characteristics of Hydrocarbons in Different States in Gasikula Oilfield,Qaidam Basin

作　　者：赵欣[1] 史基安[1] 王金鹏[1] 王琪[1] 王有孝[1] 

机构地区：[1]中国科学院地质与地球物理研究所

出　　处：《新疆石油地质》2007年第5期557-562,共6页Xinjiang Petroleum Geology

基　　金：国家自然科学基金"油气聚集历史及成藏年代精细分析"(40272065);中国科学院知识创新重要方向项目"中国西部典型沉积盆地优质油藏形成条件及动力学过程"(KZCX3-SW-128)资助

摘　　要：通过对柴达木盆地尕斯库勒油田古近、新近系六个油砂样品中游离烃、封闭烃、碳酸盐胶结物烃、束缚烃和石英颗粒包裹体烃的分步分离和GC-MS分析,研究了不同赋存状态饱和烃馏分生物标记化合物的地球化学特征。研究结果表明,①正构烷烃的峰形为单峰型;碳数范围为nC13—nC42,在不同赋存状态烃中略有差异;碳优势指数(ICP)小于1.2,具有较弱的奇碳优势;m(Pr)/m(Ph)值小于0.39,具有植烷优势,形成于强还原环境;高含量的伽马蜡烷指示了源岩的盐湖相沉积环境,不同赋存状态烃之间差异反映了盐湖的咸化演化过程。②油砂中不同赋存状态烃中含有丰富C27规则甾烷、藿烷和长链三环萜,4-甲基甾烷的含量相对较高,显示出低等水生生物的藻类和细菌对成烃的贡献。m(C29甾烷20S)/m[C29甾烷(20S+20R)]和m(C29甾烷ββ)/m[C29甾烷(ββ+αα)]的比值表明不同赋存状态烃为低熟-成熟生油岩生成的原油。油藏储集层(油砂)中这些不同赋存类型(期次)烃类,反映出油气从烃源岩进入储集层成藏的先后差异。Based on the stepwise separation and extraction on free oil, sealed oil, hydrocarbon in carbonate cement, bounded oil and inclusion hydrcarbon within quartz grain in six oil sand samples from Paleogene system and Neogene system in Gasikula oilfield of Qaidam basin, all these hydrocarbons are analyzed by GC-MS. The biomarkers of saturated hydrocarbon fractions in different states and their geochemical characteristics are studied. The result shows that the n-alkanes with single peak are dominant in the studied area with the range of carbon number from nC13 to nC42, ICP is lower than 1.2, being of weak odd-carbon preference. The ratio of m（Pr）/m（Ph） is lower than 0.39, being of phytane preference, assuming strong reducing environment. The high concentration of gammacerane indicates saline lacustrine depositional environment of source rocks. These differences of hydrocarbons in different states reflect the saline evolution process of lacustrine. Also, the relative high concentration of C27 regular steranes, hopanes and long-chain tricyclene from the oil sands suggest significant contributions of bacteria and algae to formation of hydrocarbons. The ratios of m （C29 sterane 20S）/m [C29 sterane （20S＋ 20R）] and m（C29sterane ββ）/m（C29 sterane ββ＋C29 sterane αα） suggest that the hydrocarbons in different states are crude oils generated from low mature and mature source rocks, and also reflect the different filling steps of sources into reservoirs.

关 键 词：柴达木盆地 尕斯库勒 古近系 新近系 烃 地球化学特征 

分 类 号：TE112.113[石油与天然气工程—油气勘探]