Carbon-neutral oil production is one way to improve the sustainability of petroleum resources. The emissions from produced hydrocarbons can be offset by injecting capture CO\(_{2}\) from a nearby point source into a saline aquifer for storage or a producing oil reservoir. The latter is referred to as enhanced oil recovery (EOR) and would enhance the economic viability of CO\(_{2}\) sequestration. The injected CO\(_{2}\) will interact with the oil and cause it to flow more freely within the reservoir. Consequently, the overall recovery of oil from the reservoir will increase. This enhanced oil recovery (EOR) technique is perceived as the most cost-effective method for disposing captured CO\(_{2}\) emissions and has been performed for many decades with the focus on oil recovery. The interaction between existing oil and injected CO\(_{2}\) needs to be fully understood to effectively manage CO\(_{2}\) migration and storage efficiency. When CO\(_{2}\) and oil mix in a fully miscible setting, the density can change non-linearly and cause density instabilities. These instabilities involve complex convective-diffusive processes, which are hard to model and simulate. The interactions occur at the sub-centimeter scale, and it is important to understand its implications for the field scale migration of CO\(_{2}\) and oil. In this work, we simulate gravity effects, namely gravity override and convective mixing, during miscible displacement of CO\(_{2}\) and oil. The flow behavior due to the competition between viscous and gravity effects is complex, and can only be accurately simulated with a very fine grid. We demonstrate that convection occurs rapidly, and has a strong effect on breakthrough of CO\(_{2}\) at the outlet. This work for the first time quantifies these effects for a simple system under realistic conditions.

碳中性石油生产是提高石油资源可持续性的一种方式。通过将捕获的 CO \(_{2}\)从附近的点源注入用于储存的咸水含水层或生产油藏，可以抵消生产碳氢化合物的排放。后者被称为提高石油采收率 (EOR)，将提高 CO \(_{2}\)封存的经济可行性。注入的 CO \(_{2}\)将与油相互作用并使其在储层内更自由地流动。因此，从储层中的石油总采收率将增加。这种提高石油采收率 (EOR) 技术被认为是处理捕获的 CO \(_{2}\)的最具成本效益的方法排放，并且已经执行了几十年，重点是石油回收。需要充分了解现有石油和注入的 CO \(_{2}\)之间的相互作用，以有效管理 CO \(_{2}\)迁移和存储效率。当 CO \(_{2}\)和油在完全混溶的环境中混合时，密度会非线性变化并导致密度不稳定。这些不稳定性涉及复杂的对流扩散过程，难以建模和模拟。相互作用发生在亚厘米尺度，了解其对 CO \(_{2}\)和油。在这项工作中，我们模拟了 CO \(_{2}\)和石油的混相置换过程中的重力效应，即重力覆盖和对流混合。由于粘性效应和重力效应之间的竞争，流动行为是复杂的，只能用非常精细的网格来精确模拟。我们证明对流发生迅速，并且对出口处CO \(_{2}\) 的突破有很强的影响。这项工作首次在现实条件下量化了一个简单系统的这些影响。