石油与天然气地质 ›› 2025, Vol. 46 ›› Issue (2): 575-585.doi: 10.11743/ogg20250216

• 方法技术 • 上一篇    下一篇

超临界二氧化碳混合压裂技术机理及应用——以渤海湾盆地济阳坳陷页岩油为例

周德华1(), 杨勇2, 王运海3, 孙川翔4, 郑永旺3(), 钟安海2, 鲁明晶2, 张珂5   

  1. 1.中国石油化工股份有限公司,北京 100728
    2.中国石化 胜利油田分公司,山东 东营 257001
    3.中国石化 华东油气分公司,江苏 南京 210000
    4.中国石化 石油勘探开发研究院,北京 102206
    5.中国地质大学(北京),北京 100083
  • 收稿日期:2024-07-04 修回日期:2024-11-13 出版日期:2025-04-30 发布日期:2025-04-27
  • 通讯作者: 郑永旺 E-mail:zhoudh@sinopec.com;zhengyw.hdsj@sinopec.com
  • 第一作者简介:周德华(1968—),男,博士、教授级高级工程师,非常规油气勘探开发。E‑mail: zhoudh@sinopec.com
  • 基金项目:
    中国石化科技部项目(P23190)

Mechanism and application of supercritical carbon dioxide hybrid fracturing: A case study of shale oil in the Jiyang Depression, Bohai Bay Basin

Dehua ZHOU1(), Yong YANG2, Yunhai WANG3, Chuanxiang SUN4, Yongwang ZHENG3(), Anhai ZHONG2, Mingjing LU2, Ke ZHANG5   

  1. 1.SINOPEC,Beijing 100728,China
    2.Shengli Oilfield Branch Company,SINOPEC,Dongying,Shandong 257001,China
    3.East China Oil & Gas Company,SINOPEC,Nanjing,Jiangsu 210000,China
    4.Petroleum Exploration and Production Research Institute,SINOPEC,Beijing 102206,China
    5.China University of Geosciences (Beijing),Beijing 100083,China
  • Received:2024-07-04 Revised:2024-11-13 Online:2025-04-30 Published:2025-04-27
  • Contact: Yongwang ZHENG E-mail:zhoudh@sinopec.com;zhengyw.hdsj@sinopec.com

摘要:

陆相页岩油是中国油气增储上产的战略接替领域,但烃类流体流动性差和储层可压性差是制约页岩油开发的两大关键问题。针对这两大关键问题,以渤海湾盆地济阳坳陷页岩油为研究对象,开展了超临界CO2-水-岩反应实验、扩散置换实验、真三轴压裂实验和三轴压缩实验,研究了超临界CO2混合压裂机理及其应用技术。研究结果表明:页岩经过超临界CO2溶蚀后,孔隙度可增大1 ~ 5倍,孔隙以中、大孔为主。裂缝随反应时间增加而变大,溶蚀2 h后裂缝宽度为399 nm,溶蚀12 h后裂缝宽度达到1 535 nm,宽度增大4倍,渗透率增大1 ~ 3个数量级。超临界CO2对原油单次萃取效率高达24 %,超过30 h后,萃取作用不再明显。与干燥页岩相比,经过超临界CO2-水作用后的页岩抗拉强度降低31 %。与干法压裂相比,超临界CO2混合压裂既能充分沟通层理,形成层理缝,还能与后续水力压裂裂缝形成复杂的裂缝网络。在室内实验理论研究的基础上,开展超临界CO2混合压裂矿场试验。试验结果对比表明:Y-1井中未注入CO2的各段裂缝平均延伸压力为103.4 MPa,而注入了CO2的各段裂缝平均延伸压力为100.5 MPa。注入CO2后Y-1井的裂缝事件分布较为密集,各段平均事件数量为160.8个,各段平均有效改造体积为64.78 × 104 m3。同时,储层流体黏度和密度均有所降低,流动性能增强。

关键词: 超临界CO2混合压裂, 压裂机理, 陆相页岩油, 济阳坳陷, 渤海湾盆地

Abstract:

Continental shale oil represents a strategic replacement for improving reserves and well productivity in China. However, its development is facing two major challenges: the limited mobility of hydrocarbon fluids and poor reservoir fracability. To address these issues, we explore the mechanism and application of supercritical carbon dioxide (SC-CO2) hybrid fracturing for shale oil in the Jiyang Depression, Shengli oilfield, through an array of tests, including the SC-CO2-water-rock interactions, diffusion and displacement, true triaxial compression, and triaxial compression. The results indicate that dissolution with SC-CO2 can increase shale porosity by 1 ~ 5 times, resulting in the predominance of mesopores and macropores. In addition, the fractures get enlarged as the reaction goes on. Specifically, the fracture width increased from 399 nm after 2-hour dissolution to 1.535 μm after 12 h, representing a fourfold increase in width, and concurrent permeability increase by 1 ~ 3 orders of magnitude. The SC-CO2-invovled oil extraction achieved an efficiency of up to 24 %, with minimal effects observed beyond 30 h. Compared to dry shales, the tensile strength of shales subjected to SC-CO2-water treatment decreased by 31 %. Unlike dry fracturing, SC-CO2 hybrid fracturing can create bedding-parallel fractures by removing barriers to enhance bedding connectivity, which tend to form a complex fracture network in combination with subsequent hydraulic fractures. Grounded on theoretical research in lab, we conduct field tests of SC-CO2 fracturing. The test results indicate that, in well Y-1, the average fracture propagation pressure for all sections decreased from 103.4 MPa before CO2 injection to 100.5 MPa after CO2 injection. Additionally, microseismic events recorded during fracturing in well Y-1 became more concentrated, with an average event number of 160.8 and an average effective stimulated rock volume (SRV) of 647 800 m3 overall. Moreover, both the viscosity and density of reservoir fluids decreased, resulting in an improvement in their mobility.

Key words: SC-CO2 hybrid fracturing, fracturing mechanism, continental shale oil, Jiyang Depression, Bohai Bay Basin

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