| 东海陆架盆地第三系煤系烃源岩油气生成与聚集研究 | |
| 姜亮 | |
| 2001 | |
| Degree Grantor | 中国科学院地球化学研究所 |
| Place of Conferral | 中国科学院地球化学研究所 |
| Degree Name | 博士 |
| Degree Discipline | 地球化学 |
| Keyword | 东海陆架盆地 第三系 煤系烃源岩 飞行时间二次离子质谱 自生伊利石定年 油气生成 聚集 |
| Abstract | 东海陆架盆地广泛分布着第三系煤系烃源岩，根据勘探和研究结果，它们对该区油气资源的形成具有重要意义。论文选择西湖凹陷和台北坳陷作为重点研究地区，应用有机岩石学、煤岩学、石油地质学、油气地球化学等学科的基础理论，采用显微傅立叶红外、核磁共振、飞行时间二次离子质谱、热解气相色谱、加水热模拟等先进技术和测试手段，对该区煤系烃源岩的物质组成、化学成分与结构、生烃潜力与特征进行了深入细致的研究。明确了东海盆地西湖凹陷第三系煤系烃源岩的物质组成以镜质组为主，且其中基质镜质体B(或称富氢基质镜质体)常见，含量可达25～55％。其次是壳质组，含量一般大于10％。而惰质组含量一般小于5％。煤中富氢组分以树脂体和基质镜质体B为主，尤其是树脂体含量丰富，在其边缘常见到与其具有渊源关系的渗出沥青体，这是煤系烃源岩形成烃类并发生运移的直接标志。暗色泥岩中主要是矿物沥青基质和壳屑体。根据不同有机显微组分生烃性质、生烃潜力及含量特征，可以认为，树脂体、基质镜质体B是该区煤系烃源岩中主要生烃组分。树脂体、角质体和孢子体的化学结构中富含甲基、亚甲基等富氢官能团，但树脂体相对更丰富，这是它具有较强生烃能力的根本原因。基质镜质体B也发现少量脂肪族结构官能团，说明它以生气为主，少量生油的特点。根据核磁共振和飞行时间二次离子质谱研究结果，确定了不同有机显微组分生烃贡献的系数，并结合煤系烃源岩中有机显微组分含量统计，对不同有机显微组分的生烃贡献大小进行了评价。结果表明，对生油贡献最火的是煤系烃源岩中的壳质组，而由于壳质组组成中主要是树脂体，因此，也可以说，对该区生油贡献最大的是树脂体。基质镜质体本身对生油的贡献较小，但由于它含量丰富，弥补了质量上的缺陷，对该区油的形成也有一定的贡献。根据煤系源岩中主要有机显微组分的热解气相色谱研究，结合加水热模拟实验，确定了不同有机显微组分生烃演化轨迹和相对生烃能力的大小。结果表明，树脂体在室温～300℃时已大量生烃，孢子体在300℃以后才开始大量生烃,而基质镜质体B的最大生烃期则在400～450℃，明显比树脂体和孢子体晚。在对主要有机显微组分生烃演化特点和生烃潜力研究的基础上，建立了东海盆地第三系煤系烃源岩生烃模式。与我国石炭一二叠纪和侏罗系煤及山东黄县第三纪褐煤模拟实验对比表明，东海盆地第三系煤系烃源岩的生油能力相对较低，但最大生油温度明显提前，这与其中树脂体具有早期生烃的性质有关。说明东海盆地第三系煤系烃源岩在该区油气资源形成中，以生气为主，生油为辅。从而决定了该区应该以天然气勘探开发为主的战略思路。通过对东海盆地所产油气的物理化学性质及化合物成分的研究，并与煤系烃源岩相关特征进行对比。结果表明，二者具有明显的渊源关系，说明煤系烃源岩是该区目前所采油气的主要源岩层，尤其是其中的树脂体成为主要生烃母质。对有机包裹体类型、相态、丰度、分布特征、均一温度及化学成分(拉曼光谱)进行了系统研究，结合储层自生伊利石K-Ar定年的测定，并以盆地沉积构造演化史及热史的综合分析为基础，对西湖凹陷地质历史中油气生成、运移与聚集的时间及期次进行了确定。结果表明，台北坳陷明月峰组煤系烃源岩仅在T°_2。构造层形成前发生过一次生烃作用，生烃规模和生烃量都有限。西湖凹陷中央隆起带的花港组煤系烃源岩分别在T°_2、T°_1构造层形成期发生过两次较大的生烃作用，其中以T°_2构造层形成前的一期最强。而平湖组则除了T°_2、T°_1。二次生烃作用外，在T°_3构造层形成前就已经发生过一次生烃作用，但主要的生烃期发生在T°_2构造层形成前。西湖凹陷西斜坡带的情况比较特殊，其花港组煤系烃源岩一直到现在仍然处于低成熟～成熟阶段，平湖组也仅处于成熟～高成熟阶段，这里的主要生烃作用分别发生在T°_1、T°_0构造层形成前，且以T°_0构造层形成前为主。根据不同地区生烃时间与构造演化史相关关系的分析，结合自生伊利石测年结果，可以确定：西湖凹陷隆起带油气运聚最早发生在23Ma前的渐新世，黄岩地区则发生在约18Ma左右的中新世早中期。 |
| Other Abstract | The Tertiary source rocks are widespread in the East China Sea and play an important role in the formation of oil and gas in this area according to the exploration and studies. The dissertation chooses the Xihu and Taibei depressions as a case study. The characteristics of organic petrology, coal petrology, petroleum geology, geochemistry of oil and gas have been invested with state-of-the-art instruments such as Micro-FT. IR, TOF-SIMS, Py-GC and the heat simulation by adding water. The constitute, chemical composition and structure, characteristics and the potential generating hydrocarbon of coal measures source rocks have been studied in detail. The compositions of the Tertiary source rocks in the Xihu depression of East China Sea have been analyzed and it is confirmed that the Tertiary source rocks in this area mainly consist of Vitrinite, especially Vitrinite B (desmocollinite with hydrogen-rich) with a content up to 25～55%; Exinite with a content is often over 10% and Inertinite with a content usually less than 5%. The hydrogen-rich compositions are mainly Resinite and Vitrinite B. Especially the Resinite is abundant and usually has seepage bituminites at its edge which have genetic relationship with it. This is the direct symbol of hydrocarbon generating and accumulating by coal measures source rocks. Dull mudstone is mainly composed of mineral bituminite matrix and liptodetrinite. According to the characteristics such as the quality of generating hydrocarbon and the potential and content of generating hydrocarbon, it can be figured out that resinite and desmocollinite B are the chief hydrocarbon generating components of this coal measures source rocks. The chemical structures of resinite, cutinite, sporinite have abundant hydrogen-rich functional groups such as methyl, methylene, but resinite is comparatively abundant and is responsible for good hydrocarbon generating potential of this kind of source rock. A small amount of aliphatic functional group can be found in Desmocollinite B which explains the characteristics of generating more gas and less oil. According to the result of NIMR and TOF-SIMS, the hydrocarbon generating parameters of different macerals can be ascertained and estimated the relative importance of different macerals in hydrocarbon generating. The result indicates that the exinites in coal measures source rocks citribute most in generating oil. Resinite, one of most commonly found maceral in exinite is believed to have played the most important role in generating oil. The importance of generating oil of democollinite is minor but it also has contributed to oil generating because of its rich content which makes up its limitation of quality. The studies of Py-GC of main macerals combined with the experiment of heat simulation by adding water have confirmed the hydrocarbon evolution track and the relative importance of different macerals in generating hydrocarbon. The result makes it clear that resinite generates lot of hydrocarbon before 300 ℃ while sporinite begins to generate hydrocarbon after 300 ℃ and the most peak period of generating hydrocarbon of the desmocollinite B is 400～500℃, which obviously lag behind the resinite and sporinite. We can establish hydrocarbon generating pattern of the Tertiary coal measures source rocks of the East China Sea Basin on the basis of the study of the evolution characteristics of hydrocarbon generating and the hychocarbon generating potential of main organic macerals. Compared with the coal of Perm-Carboniferous and Jurassic coals as well as Tertiary in Huangxian, Shandong province, the oil generating capacity of Tertiary coal measures source rocks of the East China Sea Basin is relatively lower, but the highest temperature of generating oil occurred earlier. This relates closely with the early stage of oil generates resinite. All of this indicates that the Tertiary coal measures source rocks of East China Sea Basin are more gas-prone than oil-prone, which determines the strategy exploration of natural gas. The study of the physic-chemistry and compound compositions of the oil and gas in the East China Sea Basin and the comparison with the relative characteristics of coal measures source rocks have indicated that both aspects have clear genetic relations, which explains why the coal measures source rocks are main source rocks of extracting oil and gas at present, especially why the resinite is main oil generating maceral. By studying the types, facies state, abundance, distribution, uniformity temperature and chemical composition(LAM) of organic inclusions, combined with the authigenic illite K-Ar dating in reservoir and synthetical study of the evolution of sedimentary structure and heat, we can ascertain the time and period of generation, migration and accumulation of the oil and gas in the Xihu depression. Tine result indicates that coal measures source rocks of Ming-Yuefeng formation in Taibei depression have only generated hydrocarbon one time before the formation of T°_2 structural layer with limited scale and amount. Coal measures source rocks of Huagang formation in the central Xihu depression have two times of bigger hydrocarbon generation with each being in T°_2, T°_1 structural layer, respectively, in which the period before the formation of T°_2 structural layer is the strongest. The Pinghu formation there had generated hydrocarbon one time before the formation of T°_3structural layer besides two times hydrocarbon generation actions in T°_2 and T°_1, but its peak hydrocarbon generating period was before the formation of T°_2 structural layer. The situation of western slope of Xihu depression is relatively unusual where the coal measures source rocks of Huagang formation is still in low mature and mature stages at present while the source rocks in Pinghu formation is in mature and high mature stages and the main hydrocarbon generation finished before the formation of T°_1, T°_0 structural layer especially before the formation of Too structural layer. According to the analysis of the relationship between the hydrocarbon generating time of different zones and analysis of structural evolution history, combined with the results of authigenic illite dating, we can ascertain that the earliest oil and gas accumulation of the uplift belt in Xihu depression happened in the Oligocene before 23Ma while in Huangyan zone it happened in the early and midle stage of Miocene. |
| Pages | 112 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://ir.gyig.ac.cn/handle/352002/3574 |
| Collection | 研究生_研究生_学位论文 |
| Recommended Citation GB/T 7714 | 姜亮. 东海陆架盆地第三系煤系烃源岩油气生成与聚集研究[D]. 中国科学院地球化学研究所. 中国科学院地球化学研究所,2001. |
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