| 摘要: |
| 综合利用岩心薄片观察、流体包裹体和地球化学分析手段,研究歧口凹陷古近系沙河街组沉积时期热液活动对湖相碳酸盐储层物性的控制作用。结果表明:碳酸盐岩地层中广泛发育鞍状白云石,同时伴生黄铁矿和石英;多数碳酸盐岩样品富集轻稀土元素,Eu正异常明显,同时具有较低的87Sr/86Sr比值;流体包裹体均一温度普遍高于埋藏时的古地温;研究区热液活动对碳酸盐岩储层有着明显的改造作用。在深部富CO2热液的侵蚀下,碳酸盐岩形成大量溶蚀孔、扩大溶蚀缝和晶间孔,储层物性有着明显的改善;但随之产生的白云岩化作用在一定程度上堵塞已形成的孔隙,给物性带来负面影响;歧口凹陷热液碳酸盐岩储集相被深大走滑断裂所控制,在负花构造部位最为发育,热流体上涌的根源可能为新近系的广泛热事件。 |
| 关键词: 构造控制 古近系 湖相碳酸盐岩 储层物性 热液作用 歧口凹陷 |
| DOI：10.3969/j.issn.1673-5005.2020.02.003 |
| 分类号::P 585; P 597.1 |
| 文献标识码:A |
| 基金项目:国家自然科学基金项目(41502145)；吉林省科技发展计划优秀青年人才项目(20180520086JH)；吉林省教育厅“十三五”科学技术研究项目(JJKH20191247KJ) |
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| Hydrothermal activities of Paleogene Shahejie Formation in Qikou Sag and its effects on lacustrine carbonate reservoirs |
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YANG Yang1,2, GAO Fuhong3, PU Xiugang4
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(1.School of Prespecting ＆ Surveying Engineering, Changchun Institute of Technology, Changchun 130021, China;2.Jilin Laboratory for Oil Shale Drilling and Environmental Protection Engineering, Changchun 130021, China;3.College of Earth Sciences, Jilin University, Changchun 130061, China;4.Research Institute of Exploration and Development, Dagang Oilfield Company, CNPC, Tianjin 300280, China)
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| Abstract: |
| Based on observations of cores and thin sections, combined with the analysis of fluid inclusions and geochemical data, the control of hydrothermal activities on lacustrine carbonate reservoir porosity distributions of Paleogene Shahejie Formation in Qikou Sag was studied. The microscope analyses of carbonates show widely distributed saddle dolomites, which are associated with pyrites and quartzs. The geochemical data reveal light REE enrichment and positive Eu anomalies in most samples, coupled with low87Sr/86Sr ratios and high homogenization temperatures of fluid inclusions, indicating that Shahejie carbonates were deposited in hydrothermal environments. Numerous dissolution pores, corrosion fissures, and intergranular pores formed with CO2-enriched hydrothermal fluids, and the quality of reservoir property has been significantly improved. The subsequent dolomitization plays an important role, as they make the porosity slightly reduced. All available evidences show a strong structural control by extensional strike-slip faults. Negative flower structures on wrench faults are favored drilling sites for hydrothermal reservoir facies, probably resulting from Neogene thermal events. |
| Key words: structural control Paleogene lacustrine carbonate reservoir property hydrothermal activities Qikou Sag |
