CO₂-storage capacity-combining geology, engineering and economics

Abstract

This paper argues that any carbon dioxide (CO2) capacity-estimation method requires a combination of geological, engineering, and economic analyses to provide rigorous capacity estimates. It also argues that the classification of capacity estimates should follow concepts in the existing SPE Petroleum Resource Management System (PRMS) (SPE 2007) as closely as possible. The paper takes the discussion of CO2-storage capacity significantly further. It also aligns storage-capacity definitions more closely to the widely accepted PRMS. Numerous authors and organizations have proposed CO2-capacity classification and calculation systems. In most of them, there is a definition of CO2-storage capacity that is intended to parallel the definition of petroleum reserves—namely, the volume of hydrocarbons that can be commercially recovered from known accumulations from a given date. However, each of the proposed systems applies economics only at the highest classifications of their systems. This is attributed to the infancy of the carbon-capture-and-storage (CCS) industry and/or the lack of a carbon price. However, in this paper, we demonstrate how economics combined with analytical and numerical injectivity modeling on the basis of geological models of the subsurface can help determine practical storage capacity. In doing this, the paper makes observations about methods for estimating storage capacity, shows results of reservoir simulations and economic analyses, draws on SPE and internationally accepted methodologies and definitions of petroleum resources, and discusses how equivalent definitions can be applied to storage capacity. Finally, the paper provides recommendations for an improved CO2-storage-capacity classification system.