| 歧口凹陷沙一下亚段页岩形成环境及页岩油潜力综合评价 |
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| 引用本文： | 周立宏,陈长伟,甘华军,张广旭,张亦康,刘海涛,陈思,李志胜.歧口凹陷沙一下亚段页岩形成环境及页岩油潜力综合评价[J].地质科技通报,2022,41(5):19-30. |
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| 作者姓名： | 周立宏 陈长伟 甘华军 张广旭 张亦康 刘海涛 陈思 李志胜 |
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| 作者单位： | 1.中国石油大港油田分公司，天津 300280 |
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| 基金项目： | 国家自然科学基金项目42072202国家自然科学基金项目41972117中国石油天然气股份有限公司重大科技专项2018E-11-01 |
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| 摘 要： | 渤海湾盆地是目前我国主要的陆相页岩油资源开采区，歧口凹陷位于盆地腹地，是渤海湾盆地内典型的富油气凹陷之一，但长期以来缺少对不同层位页岩形成环境及页岩油潜力的综合评价。选取歧口凹陷沙一下亚段富有机质页岩为研究对象，综合运用地化录井技术和生排烃模拟技术，进行歧口凹陷沙一下亚段页岩沉积特征的描述和页岩油潜力的综合评价。研究结果显示，①歧口凹陷沙一下亚段沉积于水体盐度较高的还原-强还原环境，营养物质丰富，气候炎热湿润，适宜生物大量繁殖，生产力水平高；②结合生排烃模拟实验结果，研究区沙一下亚段页岩生烃能力强、生烃效率高、排油率较低，生成的原油仍大部分残留在页岩中，具有良好的勘探潜力；③研究区沙一下亚段页岩中含有适量碳酸盐矿物，在成岩过程中改善了储集条件，为页岩油提供了良好的储集场所。歧口凹陷西南缘海侵的发生从沉积环境、古生产力及对成岩作用影响等方面促进了沙一下亚段有机质的富集，而有机质富集、生烃强度高以及良好的储集条件共同控制了沙一下亚段页岩油的大面积分布。研究区沙一下亚段页岩油储层可分为碳酸盐岩和混合沉积岩2种类型，综合2种储层的含油性特征后发现，碳酸盐岩矿物含量和脆性指数对页岩含油性有着极大影响。有利勘探区域为构造裂缝发育的宽缓斜坡区和白云岩化程度较高的地区; 有利勘探层段为孔隙和微裂缝发育的白云岩、白云质页岩和灰质页岩层段。该研究成果可为歧口凹陷页岩油的勘探开发提供指导。
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| 关 键 词： | 歧口凹陷 沙河街组一段下亚段 页岩 沉积环境 页岩油 潜力评价 |
| 收稿时间： | 2022-07-28 |
Shale formation environment and comprehensive evaluation of shale oil potential of the Lower First Member of Shahejie Formation in Qikou Sag |
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| Affiliation: | 1.Dagang Oilfield Branch Company, PetroChina, Tianjin 300280, China2.Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education, China University of Geosciences(Wuhan), Wuhan 430074, China3.Research Institute of Petroleum Exploration & Development, PetroChina, Beijing 100083, China |
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| Abstract: | Bohai Bay Basin is one of the main exploitation areas of continental shale oil resources in China.Qikou Sag, located in the hinterland of the basin, is one of the typical oil and gas rich depressions in Bohai Bay Basin.This paper selects the organic rich shale in the Lower First Member of Shahejie Formation in Qikou Sag as the research object, and comprehensively uses geochemical logging technology and hydrocarbon generation and expulsion simulation technology to describe the shale sedimentary characteristics and comprehensive evaluation of shale oil potential in the Lower First Member of Shahejie Formation in Qikou Sag.The results show that the Lower First Member of Shahejie Formation in Qikou Sag was deposited in the reduction strong reduction environment with high water salinity, rich nutrients, hot and humid climate, suitable for biological mass reproduction and high productivity.Combined with the hydrocarbon generation and expulsion simulation experiment results, the Lower First Member of Shahejie Formation shale in the study area has strong hydrocarbon generation capacity, high hydrocarbon generation efficiency and low oil discharge rate.Most of the generated crude oil is still left in the shale, which has good exploration potential.The Lower First Member of Shahejie Formation shale in the study area contains an appropriate amount of carbonate minerals, which improves the reservoir conditions during diagenesis and provides a good reservoir site for shale oil.The occurrence of transgression in the southwest margin of Qikou Sag affects the enrichment of organic matter in the Lower First Member of Shahejie Formation from the aspects of sedimentary environment, paleoproductivity and its impact on diagenesis.The enrichment of organic matter, high hydrocarbon generation intensity and good reservoir conditions control the large-area distribution of shale oil in the Lower First Member of Shahejie Formation.Shale oil reservoirs in the Lower First Member of Shahejie Formation in the study area can be divided into carbonate rocks and mixed sedimentary rocks.After synthesizing the oil-bearing characteristics of the two reservoirs, it is found that the mineral content and brittleness index of carbonate rocks have a great impact on shale oil-bearing properties.In the process of further exploration, oil reservoirs can be found in the wide and gentle slope area conducive to the formation of structural fractures and the area with high degree of dolomitization in the study area.The favorable exploration intervals are dolomite, dolomitic shale and calcareous shale with developed pores and micro fractures.The research results provide guidance for the exploration and development of shale oil in Qikou Sag. |
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