Low oil recovery which is very predominant in shale oil reservoirs has stimulated petroleum engineers to investigate the applications of enhanced oil recovery methods in these formations. One such application is the injection of gases into the formation to stimulate increased oil recovery. In many gas flooding projects performed in the field, the miscibility of the gas injected is usually the most desired displacement mechanism, and carbon dioxide (CO₂) gas has been recognized to be the best performing gas for injection due to its ability to be miscible with oil in the reservoir at low pressures compared to other gases such as nitrogen. This minimum miscibility pressure (MMP) is of very crucial importance because it is the primary limiting factor in the feasibility of a miscible gas flooding project. However, there are other limiting factors such as cost and availability and, in these instances, nitrogen (N₂) and lean gas are the more preferred candidate as opposed to carbon dioxide gas. Mixing carbon dioxide gas with lean gas or with nitrogen in a required ratio can allow us to design an injection gas that will be suitable enough to satisfy both the availability and cost constraints and at the same time allow us to achieve a reachable and reasonable miscibility pressure. The objective of this paper is to investigate the effect of mixing nitrogen gas and carbon dioxide gas in a 50:50 ratio on oil recovery in tight oil formations. The experiment was performed with controlled constraints such as the same core sample, same crude oil and same core cleaning and saturation process which was repeated for each trial. The oil used was live oil from Eagle ford formation, and the gases used were nitrogen (99.9% purity), carbon dioxide and a mixture of nitrogen and carbon dioxide in a 50:50 ratio. The injection pressure ranged from 1000 to 5000 psi with pressure increments of 1000 psi, and the same flooding time was 6 h. The potential of the N₂, CO₂ and N₂–CO₂ mixture for improving oil recovery was assessed along with the breakthrough time. The results showed that CO₂ gas had the highest recovery followed by the N₂–CO₂ mixture and N₂ gas had the lowest recovery. The gas breakthrough time results showed that the N₂–CO₂ mixture had the longest breakthrough time, N₂ had the shortest breakthrough time, and CO₂ had a significantly longer breakthrough time than pure N₂ gas. The RF increased with increasing pressure, but the gas breakthrough time decreased with increasing pressure. However, the incremental RF decreased in all three cases when the injection pressure was above 3000 psi.

页岩油储层中非常重要的低采收率刺激了石油工程师研究增强采油方法在这些地层中的应用。一种这样的应用是将气体注入到地层中以刺激增加的石油采收率。在现场进行的许多天然气驱工程中，注入的气体的混溶性通常是最理想的驱替机理，而二氧化碳（CO ₂）天然气被认为是最佳注入气体，因为与低压氮气等其他气体相比，该气体在低压下可与储层中的油混溶。最小可混溶压力（MMP）具有至关重要的意义，因为它是可混溶天然气驱项目可行性的主要限制因素。但是，还有其他限制因素，例如成本和可用性，以及在这些情况下的氮（N ₂）和稀薄气体是比二氧化碳气体更优选的候选气体。将二氧化碳气体与稀薄气体或氮气按所需比例混合可以使我们设计出一种注入气体，该注入气体将足以满足可用性和成本方面的限制，同时使我们获得可达到的合理混溶压力。本文的目的是研究以50:50的比例混合氮气和二氧化碳对致密油地层中油的采收率的影响。实验是在受控的约束条件下进行的，例如相同的岩心样品，相同的原油以及相同的岩心清洁和饱和过程，每次试验都要重复进行。所用的油是来自Eagle Ford地层的活油，所用的气体是氮气（纯度为99.9％），二氧化碳和氮气与二氧化碳的比例为50:50的混合物。注射压力范围为1000至5000 psi，压力增量为1000 psi，相同的驱油时间为6 h。N的潜力₂，CO ₂和N ₂ -CO ₂用于提高油采收混合物与穿透时间一起评估。结果表明，CO ₂气体的回收率最高，其次是N ₂ -CO ₂混合物，N ₂气体的回收率最低。气体穿透时间结果表明，N ₂ -CO ₂混合物的穿透时间最长，N ₂的穿透时间最短，CO _2的穿透时间比纯N ₂明显长。气体。RF随压力增加而增加，但气体穿透时间随压力增加而减少。但是，当注射压力高于3000 psi时，这三种情况下的增量RF都会降低。