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