石油与天然气地质 ›› 2024, Vol. 45 ›› Issue (5): 1417-1430.doi: 10.11743/ogg20240515

• 方法技术 • 上一篇    下一篇

渤海湾盆地济阳坳陷陆相断陷湖盆中-低成熟度页岩“富烃-成储-富集-高产”的理论认识与开发实践

倪良田1,2(), 杜玉山1,2, 蒋龙1,2, 孙红霞1,2, 程紫燕1,2, 刘祖鹏1,2, 钟建华3,4, 曹增辉1,2, 马存飞4   

  1. 1.中国石化 胜利油田分公司 勘探开发研究院,山东 东营 257015
    2.页岩油气富集机理与高效开发全国重点实验室,北京 102206
    3.东北大学秦皇岛分校 资源与材料学院,河北 秦皇岛 066004
    4.中国石油大学(华东) 地球科学与技术学院,山东 青岛 266580
  • 收稿日期:2024-05-23 修回日期:2024-09-06 出版日期:2024-10-30 发布日期:2024-11-06
  • 第一作者简介:倪良田(1985—),男,博士、副研究员,沉积学及非常规油气研究。E‑mail: 382938098@qq.com
  • 基金项目:
    中国石油化工集团公司重点科技项目(P21060);国家自然科学基金项目(42072138)

Medium-to-low maturity shales in the faulted lacustrine basin in Jiyang Depression,Bohai Bay Basin: Theoretical understanding of their hydrocarbon generation, reservoir formation, and shale oil enrichment and high-yield nature and exploitation practices

Liangtian NI1,2(), Yushan DU1,2, Long JIANG1,2, Hongxia SUN1,2, Ziyan CHENG1,2, Zupeng LIU1,2, Jianhua ZHONG3,4, Zenghui CAO1,2, Cunfei MA4   

  1. 1.Exploration and Development Research Institute,Shengli Oilfield Branch Company,SINOPEC,Dongying,Shandong 257015,China
    2.State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development,Beijing 102206,China
    3.School of Resources and Materials,Northeastern University at Qinhuangdao,Qinhuangdao,Hebei 066004,China
    4.School of Geosciences,China University of Petroleum (East China),Qingdao,Shandong 266580,China
  • Received:2024-05-23 Revised:2024-09-06 Online:2024-10-30 Published:2024-11-06

摘要:

渤海湾盆地济阳坳陷页岩油资源丰富,初步估算资源量超100×108 t,分析、研究、总结页岩油形成、富集和高产理论认识对指导页岩油勘探开发都具有重要意义。通过系统研究济阳坳陷古近系沙河街组四段(沙四)上亚段和沙河街组三段(沙三)下亚段2套主力页岩油层系有机质形成与演化特征以及页岩油富集与可动规律,提出了济阳陆相断陷湖盆中-低成熟度页岩“富烃-成储-富集-高产”的理论认识。研究表明:济阳陆相断陷湖盆页岩具有高有机质丰度和中-低成熟度特征,页岩为高生烃潜力和低成烃活化能的优质烃源岩。济阳坳陷沙河街组页岩沉积期,咸化水体中嗜盐菌藻等类脂类化合物发育,有机质古生产力高、富硫有机相成烃活化能低且生烃转化率高。生、排烃早,镜质体反射率(Ro)值约0.65 %时游离油量达到峰值。富有机质层与多孔纹层高频互层、有序分布,源-储配置好。洼陷带低级序断层未打破厚层页岩层系自封闭性,页岩层系普遍高压。页岩油层系多为纹层状富碳酸盐页岩和纹层状混积页岩2大类岩相。这2类岩相具有“纹层控油富集、缝网控油流动”的优质页岩油甜点特征,纹层组合控制了储集空间的发育和分布。多尺度、多类型基质微缝与压裂缝网的空间耦合,构成了页岩天然-人工多级缝网叠加的高效渗流系统,纹层框架下页岩具有“满层皆油”的富集特征。

关键词: 生烃-成储-流动特征, 纹层类岩相组合, 页岩油开发, 中-低成熟度页岩, 沙河街组, 济阳坳陷, 渤海湾盆地

Abstract:

The Jiyang Depression in the Bohai Bay Basin boasts abundant shale oil resources, with a preliminary estimate of over 10 billion t. Analyzing, investigating, and summarizing theories on the formation, enrichment, and high-yield nature of shale oil are significant for guiding shale oil exploration and production efforts in this region. We systematically examine the formation and evolutionary characteristics of organic matter, as well as the enrichment and mobility of shale oil, in two major shale oil-bearing sequences in the Jiyang Depression: the upper submember of the 4th member of the Paleogene Shahejie Formation (also referred to as the Sha 4 Member) and the lower submember of the 3rd member of the Formation (also referred to as the Sha 3 Member). Accordingly, the theoretical understanding of the hydrocarbon generation, reservoir formation, and shale oil enrichment and high-yield nature of middle- to-low maturity shales is proposed for the faulted lacustrine basin in the depression. The results indicate that shales in this basin exhibit a high abundance of organic matter and medium-to-low maturity during deposition. These characteristics establish the shales as high-quality source rocks with high hydrocarbon-generating potential and low activation energy for hydrocarbon generation. During the deposition of shales in the Shahejie Formation within the Jiyang Depression, lipoid compounds such as halophilic bacteria and algae were present in saline water bodies, resulting in the high paleoproductivity of organic matter, low activation energy for hydrocarbon generation in sulfur-rich organic facies, and high hydrocarbon conversion rate. Additionally, the depositional period of the shales was marked by early hydrocarbon generation and expulsion, with the free oil content peaking at a vitrinite reflectance (Ro) value of approximately 0.65 %. The organic-rich layers and porous laminae, frequently interbedded, display regular distributions and a favorable source-reservoir configuration. The thick shale sequences generally exhibit high pressure as their self-sealing performance remains undestroyed by low-order faults in the sub-sag zone. The shale oil-bearing sequences largely consist of laminated carbonate-rich shales and laminated mixed shales. Both types of lithofacies exhibit the characteristics of high-quality shale oil sweet spots, as evidenced by shale oil enrichment governed by laminae and shale oil flow influenced by fracture networks, with the lamina assemblages determining the distribution of reservoir spaces. The spatial coupling of multi-scale and multi-type matrix microfractures with induced fracture networks forms an efficient seepage system with superimposed natural and artificial multi-scale fracture networks in shales. Consequently, the shales demonstrate oil enrichment throughout all shale sequences of the laminated framework.

Key words: hydrocarbon generation-accumulation-flow characteristics, laminated lithofacies assemblage, shale oil development, medium-to-low maturity shale, Shahejie Formation, Jiyang Depression, Bohai Bay Basin

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