Comprehensive Investigation for CO2 Flooding Methodology in a Reservoir with High Water Content

本文针对中国某高含水、低孔低渗、强非均质性致密砂岩C油藏，系统开展了CO₂驱油适应性评价与开发优化研究。通过模糊综合评价、岩心驱替实验与CMG数值模拟相结合的方法，评估了CO₂驱、表面活性剂驱与水驱的开发效果。

实验结果表明，在束缚水饱和度约30%条件下，CO₂驱采收率高达68.38%，明显优于其他驱替方式。但高含水会显著抑制CO₂驱效果。数值模拟进一步表明，在保持注入压力高于最小混相压力（16.44 MPa）的前提下，注入速度受地层破裂压力限制，区块A和B的10年采收率分别为27.39%和0.48%，换油率较低，开发经济性差。研究为类似高含水致密油藏的开发提供了重要参考。

CMG软件应用情况

  • 软件平台：CMG GEM模块
  • 模拟内容：
    • 建立三维地质模型（由Petrel导入），模拟CO₂驱油过程；
    • 采用五点井网（1口生产井+4口注入井）进行开发模拟；
    • 优化注入速度（1000~15000 m³/d），分析其对采收率与注入压力的影响；
    • 模拟不同压差下的换油率（t/t）与开发效果；
    • 模拟层合并前后产量一致性，验证模型简化合理性；
    • 模拟时间跨度为10年，考虑混相驱与地层破裂压力限制。

结论

  1. 适应性评价：采用模糊层次综合评价法，C油藏CO₂驱适应性指数为0.8711，表明其适合CO₂驱开发。
  2. 实验结果：CO₂驱采收率最高达68.38%，远高于水驱（51.61%）和表面活性剂驱（62.55%），但高含水（>50%）会显著降低驱油效果。
  3. 吞吐实验：CO₂吞吐采收率为35.29%，低于连续驱替；添加表面活性剂可略微提高至36.14%，但经济性不佳。
  4. 数值模拟优化：
    • 区块A：注入速度≤7500 m³/d，10年采收率为27.39%，换油率为0.2 t/t；
    • 区块B：注入速度≤3000 m³/d，10年采收率仅0.48%，换油率为0.07 t/t；
    • 提高注入速率有利于提高采收率，但受限于地层破裂压力。
  5. 经济性评价：尽管CO₂驱技术可行，但由于油藏含水高、油换率低、需新增注采井，整体开发经济性较差，需谨慎推进。

作者单位

中国石油冀东油田分公司

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Abstract

In response to the development challenges caused by the high initial water saturation, low porosity, low permeability, and strong heterogeneity in C tight sandstone reservoirs, a comprehensive study was conducted on the optimization of development methods using a AcademicEditor: QingbangMeng Received: 29September2025 Revised: 4November2025 Accepted: 7November2025 Published: 11 November2025 Citation: Chen,S.;Wang,B.;Wu,Q.; Miao,J.; Kang, H.; Wang,X. ComprehensiveInvestigationfor CO2 Flooding MethodologyinaReservoir withHighWaterContent. Processes 2025, 13, 3657. https://doi.org/ 10.3390/pr13113657 Copyright: ©2025bytheauthors. Licensee MDPI,Basel,Switzerland. This article is an open access article distributed under the termsand conditions of the Creative Commons Attribution (CC BY)license (https://creativecommons.org/ licenses/by/4.0/). fuzzy model, core flooding experiments, and reservoir numerical simulations. The initial evaluation indicates the good adaptability of CO2 flooding for improving oil recovery in a Creservoir; the experimental result of the CO2 displacement method also performs the best, with a recovery rate of 68.38% at a connate water saturation of about 30%, compared with surfactant flooding and water flooding. However, higher water saturation inhibits the CO2 development effect. The oil recovery factor of pure CO2 huff-n-puff is 32.24% lower than the CO2 displacement method, while surfactant-assisted CO2 huff-n-puff can increase the recovery rate by 0.85% compared to pure CO2. Based on actual geological models, numerical simulations were conducted on Well Block A and B. The results showed that the optimized production pressure is above the Minimum Miscibility Pressure (16.44 MPa); with consideration of the fracture pressure limitation, the CO2 injection rate in Block A should be less than 3000 m3/d, andtherecovery rate after 10 years is only 0.48% (oil change ratio is 0.07 t/t), while the CO2 displacement rate of Block B should not exceed 7500 m3/d, and the recovery rate after 10 years can reach 27.39% (oil change ratio is 0.2 t/t). CO2 displacement is an effective development method for a C reservoir, but due to a high water content the oil change ratio is very low, indicating a low potential for further development. The research provides important references for the development of similar oil reservoirs.

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