Evaluating the CO₂ geological storage suitability of coal-bearing sedimentary basins in China

The geological storage of CO₂ is potentially one of the most effective methods to reduce the CO₂ concentration in the atmosphere. Coalbeds are possibly suitable storage reservoirs, meaning that evaluating the suitability of individual coalbeds and associated engineering and construction is an important step in developing geological CO₂ storage. This evaluation requires the development of a reasonable evaluation index system and associated weightings. This paper focuses on coal-bearing basins in China and outlines a technical process whereby the CO₂ storage suitability of these basins can be comprehensively evaluated. This study uses an earth system science approach to determine the uncertainties involved in identifying ideal CO₂ storage sites, develops an index that outlines the conditions related to the suitability of Chinese coal-bearing basins for geological CO₂ storage, and incorporates this index into a hierarchical index system model for geological CO₂ storage suitability that allows the comprehensive evaluation of coal-bearing basins and includes 5 aspects, 23 indexes, and 5 index levels. The weighting assigned to each evaluation index was determined using the analytic hierarchy process (AHP) and was subsequently incorporated into a fuzzy logic-based comprehensive evaluation approach. This approach was applied to assess the suitability of the Qinshui Basin for geological CO₂ storage, revealing that this basin is indeed a suitable coalbed reservoir. The comprehensive geological CO₂ storage evaluation model outlined here can also assess the CO₂ storage suitability and capacity of other coal-bearing basins elsewhere in China and globally.