莺—琼盆地原油地球化学特征及来源

发布时间：2018-03-04 08:00

本文选题：莺-琼盆地　切入点：原油　出处：《浙江大学》2017年硕士论文　论文类型：学位论文

【摘要】：莺-琼盆地是我国南海大陆架上重要的新生代含油气盆地,目前已发现了崖13-1、DF1-1等大型油气田及多个含油气构造,但其勘探程度还比较低,仍具有巨大的油气资源,勘探前景十分乐观。本文在细致地研究了原油轻烃、生物标志物和碳同位素组成特征的基础上,对莺-琼盆地东方、乐东和崖城气田的原油在成烃母质及其沉积环境上进行了区分,并对各个气田的原油进行了成因分类;同时,利用渐新世、中新世和上新世不同层位烃源岩饱和烃组分的GC/MS和碳同位素分析资料,进行了精细的油源对比,确定了这三个气田原油的主要烃源岩。研究表明,乐东和东方气田原油的轻烃、生物标志物和碳同位素组成特征基本一致,但与崖城气田的原油明显不同。乐东和东方气田的大部分原油全油碳同位素较重(-23.6‰～-21.8‰);其K1值较小,在1.08左右,C7轻烃组分中,二甲基环戊烷和正庚烷含量高,甲基环己烷和甲苯含量低;呈姥鲛烷优势(Pr/Ph3),C19三环萜烷含量低(C19/C233),陆源高等植物的生物标志物奥利烷及其降解产物、双杜松烷和蒲公英烷的含量均很低,而伽马蜡烷和4-甲基甾烷含量较高,指示有机质生源以水生生物为主,且来源于弱氧化的浅海相烃源岩。其中,DF13-2-1井、DF1-1-14井和LD20-1-2井的原油样品与乐东和东方气田的大部分原油有明显的区别。其Pr/Ph在3.1～3.4之间,C19/C23比值小于1.0,有含量较高的奥利烷、降A-奥利烷和双杜松烷等陆源标志物,且4-甲基甾烷很少,表明这类原油来源于氧化性的近岸滨浅海相烃源岩,有机质生源以陆源输入为主,水生生物占有一定比例。崖城气田的原油全油碳同位素轻得多(-26.9‰～-24.9‰);其K1值较大,达到了1.24,与乐东和东方气田的原油有明显的区分,C7轻烃组分中,富含甲基环己烷和甲苯,二甲基环戊烷和正庚烷含量低;姥鲛烷优势显著(Pr/Ph5),C19三环萜烷含量高(C19/C236),陆源高等植物的生物标志物奥利烷及其降解产物、双杜松烷和蒲公英烷的含量很高,几乎不含伽马蜡烷和4-甲基甾烷,指示以陆源高等植物为主的生物源,且来源于氧化的海岸沼泽相烃源岩。根据原油生物标志物的组合特征,可进一步将东方气田和乐东气田的原油分成三类,将崖城气田的原油分成两类。莺歌海盆地中新统烃源岩碳同位素较重,在-27.7‰～-20.9‰之间,与乐东和东方气田的原油接近。其中,黄流组和梅山组泥岩的双杜松烷和奥利烷含量很低,含有一定的4-甲基甾烷,与乐东和东方大部分原油有较好的对比性,说明其油源主要来自这两套地层。琼东南盆地渐新统烃源岩干酪根碳同位素较轻,在-27.3‰～-23.4‰之间,与崖城气田的原油相近。其中,只有煤和碳质泥岩C19/C23比值高(3.5～7.6),与崖城气田的原油相当,但其奥利烷和双杜松烷含量很低,与原油不相符合;而泥岩中奥利烷和双杜松烷都很丰富,与主体原油相近。这表明崖城气田主体原油是混源岩,源自渐新统各类岩性的源岩。
[Abstract]:Ying Qiong basin is an important continental shelf of the new generation of the South China Sea petroliferous basin in China, has found a cliff 13-1, large oil and gas fields DF1-1 and a number of oil and gas structures, but the exploration degree is relatively low, still have huge oil and gas resources, exploration prospects are very optimistic. This paper studies the light hydrocarbon the crude oil in the detailed, biomarker and carbon isotope composition characteristics based on the Oriental Yingqiong basin, Ledong and Yacheng crude oil were distinguished in the hydrocarbon precursor and its sedimentary environment, and the various fields of crude oil origin classification; at the same time, the use of the Oligocene, Miocene and Pliocene different hydrocarbon source rock saturated hydrocarbon GC/MS and carbon isotope analysis data, compares the fine oil source, the main source of the three crude oil field rock. The results show that light hydrocarbon Ledong and Dongfang gas field of crude oil, biomarker and Carbon isotopic composition is basically the same, but significantly different from Yacheng crude oil. Most of the crude oil Ledong and Dongfang gas field carbon isotope is heavy (-23.6% to -21.8%); the K1 value is small, at around 1.08, C7 light hydrocarbons, two methyl cyclopentane and heptane in high. Methyl cyclohexane and toluene content was low; pristane advantage (Pr/Ph3), C19 tricyclic terpane low content (C19/C233), terrestrial higher plant biomarkers of oleanane and degradation products, the content of double Du Songwan and dandelion alkanes were very low, while the gammacerane and 4- methyl steranes were higher, indicating organic the source matter dominated by aquatic organisms, and from weak oxidation of neritic facies source rocks. Among them, DF13-2-1 well, most of the crude oil DF1-1-14 and LD20-1-2 wells of crude oil samples and Ledong and Dongfang gas field has obvious difference. The Pr/Ph in 3.1 ~ 3.4, the ratio of C19/C23 small In 1, a high content of oleanane, down A- oleanane and double cadinane terrestrial markers, and 4- methyl steranes rarely, showed that coastal shallow marine hydrocarbon source rocks in the oxidation of this kind of source of crude oil, organic matter source by terrestrial input, aquatic organisms occupy a certain proportion of Yacheng. The crude oil and gas carbon isotope much lighter (-26.9% to -24.9%); the K1 value is larger, reaching 1.24, and Ledong and Dongfang gas field of crude oil has obvious distinction, C7 light hydrocarbon, rich in methyl cyclohexane and toluene, two methyl cyclopentane and heptane in low pristane; an advantage (Pr/Ph5), C19 tricyclic terpane high content (C19/C236), terrestrial higher plant biomarkers of oleanane and degradation products, the content of two Du Songwan and dandelion were very high, almost free of gammacerane and 4- methyl steranes, indicated by Lu Yuangao plant biological source, and Due to the oxidation of coastal marsh facies hydrocarbon source rocks. According to the characteristics of crude oil biomarker, may be further east gas and crude oil in Ledong gas field is divided into three categories, the Yacheng crude oil is divided into two categories. The Yinggehai Basin in Miocene hydrocarbon source rocks of carbon isotope is heavy, between -27.7% ~ -20.9%, close to Ledong and Dongfang gas field oil. Among them, Huangliu formation and Meishan formation mudstone double Du Songwan and oleanane content is very low, with certain 4- methyl steranes, compared well with the Ledong and Dongfang most of crude oil, the main oil source from the two sets of Qiongdongnan basin formation. Oligocene source rocks kerogen carbon isotope lighter, between -27.3 ~ -23.4%%, similar to Yacheng. Only the crude oil, coal and carbonaceous mudstone in the high ratio of C19/C23 (3.5 ~ 7.6), and Yacheng crude oil, but the oleanane and double Du Songwan The content is very low, which is not consistent with crude oil. However, in the mudstone, olane and dupentipines are very rich, similar to the main crude oil. This indicates that the main oil in the gas field of Ya Cheng gas field is mixed source rock, which is derived from Oligocene source rocks of all kinds of lithology.

【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.13

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