Different ways to approach shale reservoirs' CO2 storage potential in America

To achieve the Net Zero Carbon Emissions (NZCE) target by 2050, Carbon Capture, Utilization, and Storage (CCUS) is a major method. Gathering and injecting CO2 into shale reservoirs is an effective way to reduce the CO2 amount in the air and thus, release the greenhouse effect. CO2 injection into organic-rich shales could provide dual benefits of incremental oil or gas recovery and secure CO2 storage. When planning the CO2 injection project, the most important question is how much gas could be stored in the reservoir. Methods for calculating CO2 storage potential in shale reservoirs have been studied by many researchers. However, few researchers put those methods together and make comparisons to each other. This paper summarized five methods for evaluating CO2 storage potential in five shale reservoirs by using the literature published in recent years. This paper aims to discuss and evaluate the technical aspects related to gas storage. Those geomechanical properties, petrophysical properties, and construction parameters were discussed. Among those parameters, CO2 injection rate, skin factor, and Knudsen diffusion could significantly affect CO2 storage potential evaluation results. Also, if well integrity, especially cement quality, and permeability could be taken into consideration, CO2 storage simulation models' results will be more realistic. The significances of this study are: (1) served as guidance in calculating CO2 storage capacity in shale oil plays; (2) provides analyses in evaluating nowadays methods' limitations; (3) gives recommendations to researchers on how to improve those methods or create a new one.