Storage of large amounts of carbon dioxide (CO₂) within deep underground aquifers has great potential for long-term mitigation of climate change. The U.S. Gulf Coast is an attractive target for CO₂ storage because of the favorable formation properties for injection and containment of CO₂. Deltaic formations are one of the primary targeted depositional environments in the Gulf Coast. In this paper, we investigate CO₂ storage in deltaic saline aquifers through a combination of geological modeling and flow simulation. The approach presented in this paper based on a combination of invasion percolation and compositional reservoir simulation focuses on buoyancy-dominant flow of CO₂ in the long term and its pressure-driven flow in the short term. The results provide insights into how to screen and identify prospective locations for CO₂ storage and determine the underlying geological features controlling CO₂ migration for a basin-scale study.

The geological model in our study is developed based on a laboratory-scale three-dimensional (3D) flume experiment replicating the formation of a delta structure and populated with geologic properties according to Miocene Gulf of Mexico natural analogues. We used invasion percolation simulations to understand the buoyancy-driven flow and the relationship between architecture, stratigraphy, and fluid migration pathways. The results were used to develop an upscaled model for compositional simulation with the key features of the original geological model and to determine injection schemes that maximize the injection capacity and minimize the amount of mobile CO₂ in the formation. To achieve this, we used compositional reservoir simulations to study the pressure-driven flow and phase behavior.

The results of invasion percolation simulations were used to identify the key stratigraphic units affecting CO₂ migration. The realistic geometries and high resolution of the model facilitate the transfer of results from synthetic to subsurface data. The results allow for the analysis of deltaic depositional environments, important stratigraphic surfaces, and their impact on CO₂ storage. The reservoir simulation model and phase behavior were validated against available field and laboratory data. The results of reservoir simulations were used to investigate the effects of main mechanisms, such as gas trapping and solubilization, on storage capacity. We compared our simulation results based on invasion percolation (buoyancy driven) and reservoir simulation (pressure driven). The comparison is helpful to understand the strengths and weaknesses of each approach and determine best practices to evaluate CO₂ migration within similar formations.

The unique and extremely well-characterized deltaic model allows for unprecedented representation of the depositional aquifer architecture. This research combines geologic modeling, flow simulation, and application for CO₂ storage. The integrated conclusions will constrain predictions of actual subsurface flow performance and CO₂ storage capacity in deltaic systems while identifying potential risks and primary stratigraphic migration pathways. This research provides insights on prediction of CO₂ storage performance and characterization of prospective saline aquifers.

在地下深层含水层中储存大量二氧化碳（CO ₂）具有长期缓解气候变化的巨大潜力。美国墨西哥湾沿岸地区是CO ₂储存的一个有吸引力的目标，因为它具有注入和封闭CO ₂的有利地层特性。三角洲地层是墨西哥湾沿岸主要的目标沉积环境之一。在本文中，我们通过结合地质建模和流动模拟研究了三角洲盐水层中的CO ₂储存。本文提出的基于侵入渗流和成分储层模拟相结合的方法侧重于CO _2的浮力主导流从长期来看，其压力驱动的流量在短期内。结果提供了有关如何筛选和识别CO ₂储存的潜在位置以及确定用于盆地规模研究的控制CO ₂迁移的潜在地质特征的见解。

我们的研究中的地质模型是根据实验室规模的三维（3D）水槽实验开发的，该实验复制了三角洲结构的形成并根据中新世墨西哥湾天然类似物填充了地质特性。我们使用入侵渗流模拟来了解浮力驱动的流动以及建筑，地层学和流体运移路径之间的关系。结果用于开发具有原始地质模型关键特征的组成模拟的高档模型，并确定可最大程度提高注入能力并最小化地层中可移动CO ₂量的注入方案。为了达到这个目的，我们使用了组成油藏模拟来研究压力驱动的流动和相态。

入侵渗流模拟的结果被用于识别影响CO ₂运移的关键地层单元。模型的实际几何形状和高分辨率有助于将结果从合成数据传输到地下数据。结果可用于分析三角洲沉积环境，重要的地层表面及其对CO ₂的影响存储。针对现有油田和实验室数据验证了储层模拟模型和相行为。储层模拟的结果被用来研究气体捕集和溶解等主要机理对储量的影响。我们比较了基于侵入渗流（浮力驱动）和油藏模拟（压力驱动）的模拟结果。进行比较有助于了解每种方法的优缺点，并确定最佳实践以评估CO ₂在相似地层中的运移。

独特且特征鲜明的三角洲模型可以前所未有地描述沉积含水层的结构。这项研究结合了地质建模，流量模拟和用于CO ₂储存的应用。综合结论将限制三角洲系统中实际地下流动性能和CO ₂储存能力的预测，同时确定潜在风险和主要地层迁移路径。这项研究提供了对预测CO ₂储存性能和预测盐水层特征的见解。