Validating compositional fluid flow simulations using 4D seismic interpretation and vice versa in the SECARB Early Test—A critical review
本文探讨了在美国密西西比州Cranfield油田商业驱油（EOR）项目中，利用4D地震技术监测大规模CO₂注入的优缺点。研究目标包括验证CO₂是否按设计和模型预测封存于储层，以及通过数据更新模型以评估是否需要补救措施。
研究采用CMG-GEM组分模拟器模拟储层中CO₂流动，并与注入超过200万吨CO₂后的地震属性变化进行对比。结果显示，数值模拟与地震解释部分吻合，差异可能源于储层物理复杂性（如残余气体、岩石刚度）及地震数据处理流程差异。研究强调了在监测中需综合考虑不确定性因素。
CMG软件解决方案
- 组分模拟优势
采用CMG-GEM组分模拟器（基于Peng-Robinson状态方程），替代传统黑油模型（CMG-IMEX），更精确模拟CO₂与油、水的混相过程，捕捉气体溶解/析出动态。 - 历史拟合与参数调整
- 通过调整高渗透通道的渗透率对比、相对渗透率曲线（基于Weaver & Anderson实验数据微调），拟合油田生产数据（油、气、水产量及CO₂突破时间）。
- 整合储层静态模型（孔隙度、渗透率分区）与动态响应，验证储层压力变化（最高达37 MPa）对CO₂迁移的影响。
- 地震数据对比验证
- 将模拟的CO₂饱和度分布与多组地震解释结果（时间偏移、振幅变化、概率反演）对比，揭示储层非均质性、残余气体对地震信号敏感性的影响。
结论
- 组分模拟有效性
组分模型能更准确反映CO₂与油/水的混相行为，历史匹配结果与生产数据高度吻合，验证了模型可靠性。 - 地震监测的局限性
- 储层残余气体（甲烷）会掩盖CO₂注入引起的地震属性变化，导致信号弱化（如构造圈闭区）。
- 薄层CO₂羽流（<1/4波长）及储层深度、岩石刚度等因素限制地震分辨率。
- 多数据一致性
大规模CO₂注入区域（如水驱带）的地震响应与模拟结果一致，但小尺度差异反映储层非均质性和解释方法差异。
Abstract
This paper discusses strengths and weaknesses of 4D seismic interpretation as a technique for monitoring carbon dioxide that was injected as part of a large scale test associated with commercial enhanced oil recovery (EOR) at Cranfield Field, Mississippi, USA. The goals of the monitoring effort are 1) to make measurements to verify that the CO2 is contained in the reservoir according to operational designs and model predictions, and 2) that if there are deviations, to provide data which can be used to update the earth models and determine if any mitigation is needed. The current work uses a compositional numerical simulation to model CO2 flow in the reservoir and compares the results with estimates of changes in seismic properties between a pre-injection and a survey after more than 2 million metric tons injected. The complicated physics of the problem in Cranfield field present challenges to seismic interpretations. Our results show partial agreement between the results of the numerical simulation and the seismic interpretations. Possible causes of discrepancies among the fluid flow model and multiple interpretations of the same seismic data sets performed with different work flows illuminates the types of uncertainties that should be considered to achieve the goals of monitoring.
作者单位
美国德州农工大学石油工程系
