REDUCED-ORDER MODELING FOR ESTIMATING CO2 STORAGE AND ENHANCED COALBED METHANE OF UNCONVENTIONAL COAL SEAM RESERVOIRS

Carbon capture, utilization, and storage (CCUS) is a promising technology for mitigating climate change while providing opportunities for the continued use of traditional fuel sources. While difficulties remain for employing carbon capture technologies at a competitive cost, the process of injecting CO₂ into underground storage reservoirs is well understood. Still, the development of resource storage estimates for CH₄ production and CO₂ storage in hydrocarbon reservoirs at a regional scale is important for incentivizing industrial-scale implementation of CCUS technologies.

There are multiple methods for developing resource storage estimates with varying degrees of uncertainty. While static volumetric models can provide quick reservoir estimates, they necessarily include high uncertainty. Alternatively, dynamic reservoir simulations can reduce uncertainty, but require large amounts of time and data that may not be available. The reduced-order model developed in this study, SCO2T-ECBM, utilizes sensitivity and uncertainty analyses of dynamic reservoir simulations to generate proxy models for enhanced coalbed methane (ECBM) resource storage estimates. The parameters used in SCO2T-ECBM have been limited to those most likely available at a regional scale: depth, thickness, fracture porosity, fracture permeability, fracture water saturation, and injection rate.

Storage and utilization resource estimates from SCO2T-ECBM indicate that static volumetric models may be overly optimistic, particularly in mid- and high-estimates provided by static models. This result is consistent with other studies that have compared static estimates with dynamic simulations and may suggest a reevaluation of regional CO₂ storage and utilization resource estimates, particularly when considering ECBM opportunities. Moving forward, SCO2T-ECBM can be a useful tool in generating CO₂ storage and utilization resource estimates in unconventional reservoirs to aid in the deployment of CCUS technology.