Rethinking Geologic Carbon Storage Capacity: An Approach With Practical Considerations

Abstract

A realistic and practical understanding of storage capacity is essential during the scoping and planning phases of carbon capture, utilization, and storage (CCUS) projects. This study developed from the need to redefine carbon storage capacity in a way that it provides CCUS project developers with the information they need, not only on the size of the accessible pore volume they would require, but also –and as importantly- on the rate at which CO2 can be injected into it considering geological, technical, and economic constraints. In this paper, we think of geologic storage capacity as the rate at which CO2 can be technically and economically injected into an accessible pore volume for a period of time constrained by either a maximum injection pressure or a geologic boundary. We applied this concept to a region in the Offshore Northern Gulf of Mexico to understand the opportunities of its oil and gas fields. To estimate the accessible storage capacity we used EASiTool (Enhanced Analytical Simulation Tool) capacity calculator, a closed-form analytical solution in a public Windows application that provides fast, yet reliable estimates in any geologic setting. Results from EASiTool capacity assessments indicate that the total accessible CO2 storage capacity for pure carbon storage (no production) in oil and gas fields within the area of study is up to ~200 MTonnes. This paper illustrates how an average, representative reservoir in the area of study would have an open boundary storage capacity of 2.3 MTonnes, accessible over a period of 8 years at a rate of 0.28 MTonnes/year through one injection well. This carbon storage resource is an attractive complement to the vast storage capacity of the Offshore Northern Gulf of Mexico stratigraphy.