CDL Blog

A previous CDL blog presented a high-level view of the recently published Northeast BC Geological Carbon Capture and Storage Atlas. The atlas provides a high-level analysis of CO₂ geological storage potential in saline aquifers and depleted gas pools in NEBC; it found that there are multiple opportunities for geological carbon storage within both saline aquifers and depleted gas pools in a number of formations — on all scales from small to large.

Twelve formations are covered in the atlas; each has a chapter with statistics, maps and charts that summarize its CO₂ storage potential. CO₂ storage potential is calculated for saline aquifers and depleted gas pools in nine formations, and for depleted pools only in the remaining three formations. This article focuses on results from the Permian Belloy Formation, which is a prolific gas reservoir and water disposal target in the Peace River Block.

For aquifers, reservoir characterization is crucial to determine whether a unit is suitable for CO₂ storage; it is necessary to determine whether a unit has sufficient pore space to store the required mass of CO₂. CDL used existing Belloy net reservoir maps, and infilled with its own mapping where areal gaps existed, to make a high-level map (figure 1). The BC Energy Regulator (BC ER) provided net reservoir contours for the depleted pools (figure 2). Public core data were used to make porosity-permeability crossplots, which helped to delineate porosity trends (figure 3). CDL calculated reservoir pressure and temperature, which are the main reservoir conditions that determine whether CO₂ can be stored in the (preferred) supercritical phase or as a gas, and also to calculate its density, which is part of the storage calculation. A pressure-elevation plot helped to determine the hydrodynamic continuity of the various aquifers (figure 4).

The storage potential for depleted gas pools was calculated using the BC ER’s theoretical CO₂ storage potential estimates, which represents the total displacement of produced fluids by injected CO₂. These estimates were then used by CDL to calculate the high-level effective CO₂ storage potential, which represents the mass of CO₂ that can be stored in hydrocarbon reservoirs after taking into account intrinsic reservoir characteristics and flow processes, such as aquifer support. The Stoddart Belloy A Pool, which is the largest of the depleted Belloy gas pools, has an effective CO₂ storage potential of 27.6 Mt.

For aquifers, a theoretical CO₂ storage potential can be calculated using the mapped pore volume of the reservoir and CO₂ density, and assumes that the pore volume will be occupied entirely by injected CO₂. This is not the case because the pore space is already occupied by water, and that water is displaced as CO₂ is injected. As a result, a storage efficiency factor is introduced into storage calculations that is a function of reservoir and fluid properties and dynamics, including the geometry of the trap, gravity segregation, reservoir heterogeneity, permeability distribution and pressure. There are a wide range of static storage efficiency factors cited in literature; some are very small, which better reflect large-scale long term storage, and some are larger values that better represent local plume migration on a shorter timescale. The values used in this atlas reflect those in several editions of US DOE and NETL CCS Atlas publications of 0.5% for the 10^th percentile, 2.0% for the 50^th percentile, and 5.4% for the 90^th percentile. Table 1 summarizes the aquifer properties and the high-level P10, P50 and P90 effective storage potential numbers for the three Belloy aquifers, whereas figure 5 shows the CO₂ carbon storage potential of aquifers and pools.

The atlas was sponsored by Geoscience BC, the BC Centre for Innovation & Clean Energy (CICE), and the BC Hydrogen Office; the research (collating available public data/studies, filling in gaps in mapping and the CO₂ storage calculations) was undertaken by Canadian Discovery Ltd. The atlas can be downloaded from the Geoscience BC website; the link is in the references.

To learn more about the Northeast BC Geological Carbon Capture and Storage Atlas and explore CO₂ storage potential in 11 other formations, visit https://canadiandiscovery.com.  Contact us at info@canadiandiscovery.com to learn how we can provide similar cost-effective and sustainable solutions to fit your needs.