| 川东南丁山地区石牛栏组成脉流体来源与油气成藏 |
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| 引用本文： | 罗涛,何治亮,郭小文,黄亚浩,陶泽,陈家旭. 川东南丁山地区石牛栏组成脉流体来源与油气成藏[J]. 地质科技通报, 2021, 40(5): 231-241. DOI: 10.19509/j.cnki.dzkq.2021.0024 |
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| 作者姓名： | 罗涛 何治亮 郭小文 黄亚浩 陶泽 陈家旭 |
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| 基金项目： | 国家自然科学基金项目41872139中石化科技部项目p19022-3 |
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| 摘 要： | 四川盆地东南部志留系油气成藏过程研究缺少成藏和破坏阶段的直接证据，丁山地区志留系石牛栏组储层内沥青和方解石脉体记录了储层内流体演化的信息，对研究油气藏油气成藏演化过程有重要的指示作用。运用显微岩相学、阴极发光、微区原位元素和流体包裹体分析方法，确定了古流体来源和活动时间，并恢复了甲烷包裹体古压力，结合烃源岩生烃演化史和地质特征揭示了石牛栏组油气成藏演化过程和主控因素。研究结果表明丁山地区石牛栏组储层内发育两期方解石脉体，原油充注发生在两期方解石脉形成之前。第一期方解石脉形成于距今约127 Ma，阴极发光颜色为褐红色，方解石脉形成于偏还原环境，成脉流体来源于同层位成岩流体。第二期方解石脉形成于距今约83 Ma，阴极发光颜色为褐黄色，方解石脉形成于偏氧化环境。龙马溪组烃源岩大量生油阶段在距今190~150 Ma之间，生成的石油充注到石牛栏组储层中并在距今约135 Ma裂解成气藏。甲烷包裹体捕获压力为51.77~57.46 MPa，储层压力系数为1.26~1.40。石牛栏组古气藏在燕山期以来，由于构造运动导致地层抬升剥蚀和断裂发育，促使天然气泄漏。
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| 关 键 词： | 方解石脉 成脉流体来源 脉体形成时间 古压力恢复 油气成藏过程 丁山地区 |
| 收稿时间： | 2021-01-31 |
Origins of vein-forming fluid and hydrocarbon accumulation in Shiniulan Formation in Dingshan,southeast Sichuan Basin |
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| Abstract: | The Silurian hydrocarbon accumulation research in the southeastern Sichuan Basin lacks evidence of the hydrocarbon accumulation and destruction stages in reservoirs. Bitumen and calcite veins that were developed in the Shiniulan Formation had recorded the information of the fluid evolution in reservoirs and have important implications for fluid activities and hydrocarbon accumulation processes in the Dingshan area, southeast Sichuan Basin. Based on analysis of petrographic, trace element, fluid inclusion and laser Raman spectroscopy of the calcite veins, this research determines the timing and origin of the paleo-fluids formed the calcite veins; recovers the paleo-pressure of the methane inclusions, and reveals the petroleum system evolution and controlling factors of the Shiniulan Formation. The results indicate that two phases of calcite veins were developed in the Shiniulan Formation, and oil charging happened before the formation of the two phases of the calcite veins. The first phase of calcite veins were formed at ~127 Ma under relative reduction conditions, with the forming fluid sourcing from the diagenetic fluid of the same strata, which show brown-red cathode luminescence colors. The second phase calcite veins were formed at ~83 Ma under relative oxidation conditions, showing brown-yellow cathode luminescence colors. Oil generation peak of the Longmaxi source rocks, which were the main source of the Shiniulan reservoirs, was from ~190 Ma to ~150 Ma. Oil to gas cracking happened at ~135 Ma. The trapping pressure of methane inclusions is 51.77-57.46 MPa, and the pore fluid pressure coefficient is 1.26-1.40. Since the Yanshanian period, a series of tectonic movements have taken place in the Dingshan area, which uplifts and lead to erosion and fracturing of the Dingshan area is accounts for the destruction of the Shiniulan gas reservoirs. |
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