As world leaders in reservoir- to basin-scale evaluation, Canadian Discovery Ltd. (CDL) specializes in assessing subsurface properties, pressure, fluid flow, fluid chemistry and geomechanics. Using our extensive subsurface knowledge and GIS capabilities, CDL has established workflows to evaluate carbon sequestration targets and answer the key questions: Is there a storage opportunity? Is the storage capacity of the CCUS opportunity large enough to sequester the CO₂ in the given time frame? Is the storage opportunity suitable? (i.e. Does it meet certain critical screen criteria? Can the site be effectively monitored? Is groundwater safe?). CDL has used these workflows in northeastern BC, central and southern Alberta, southern Saskatchewan and in the southern US onshore Gulf Coast Basin.
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Carbon Storage Introduction

Carbon capture and storage (CCS) and carbon capture, utilization and storage (CCUS) are important tools to help Canada and the rest of the world meet net zero greenhouse gas emissions by 2050 as set out by the 2015 Paris Agreement. Western Canada is well placed to play a leading role in storing CO₂ as it has an abundance of pore space suitable for both sequestration and EOR projects. CO₂ can be stored underground in saline aquifers or depleted oil and gas pools (figure, left) as a supercritical fluid (density of a liquid, but viscosity of a gas) provided specific temperature and pressure conditions are met. The main advantage of storing CO₂ in a supercritical condition is that the required storage volume is substantially less than if the CO₂ were at “standard” (surface) conditions (figure, right).
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CO₂ storage in saline aquifers (Type 1) has the highest capacity potential for long-term sequestration
Storage in depleted oil and gas pools (Type 2) is suitable to sequester CO₂ for geological (long) time frames
In enhanced oil recovery (EOR) schemes (Type 3), CO₂ is injected into a depleted oil reservoir. The CO₂ dissolves in the previously unrecoverable oil, reducing the oil’s viscosity, which allows it to flow to a production well. EOR schemes maximize oil recovery while eventually sequestering CO₂, which minimizes environmental impacts.

Underground Storage Types

Modified by CDL from IPCC (2018)

Pressure Effects on CO₂

Modified by CDL from NETL (2021) for Donaldson (2021)

There are a number of criteria that are either critical, essential or desirable to ensure that a depleted pool or saline aquifer is suitable to safely and economically store CO₂ in the subsurface. These include:

Reservoir-seal pairs (i.e. the reservoir is effectively sealed from leakage)
Being in a suitable pressure regime
The ability to monitor CO₂ injection and flow
Protecting groundwater quality.

The table (right) summarizes screening criteria for subsurface CO₂ storage.

Criterion Level	Preferable Criterion
Critical	Reservoir-seal pairs that provide extensive and competent barrier to vertical flow
	Pressure gradients <12 kPa/m
Essential	Low to moderate seismicity
	Limited to moderate faulting and fracturing intensity
	Intermediate to regional scale hydrogeological flow
Desirable	Depth > 800m
	Temperature ≥ 35°C
	Pressure ≥ 7.5 Mpa
	Thickness ≥ 20m
	Porosity ≥ 10%
	Permeability ≥ 20 mD
	Caprock thickness ≥ 10m
	Low to moderate well density

Data from IEAGHG, 2009, Table 2

CDL's CCUS Workflows

CDL’s CCUS workflows (figure, left) combine geological and hydrodynamics evaluations at the regional scale (figure, middle), and when data are available, at the reservoir and local level (figure, right), and focus on minimizing CCUS risk:

Categorizing the subsurface
Identifying saline aquifers and depleted pools
Identifying reservoirs and seals
Protecting groundwater

Regional Reservoirs, Seals

Local Reservoir Characterization

Ensures target zones meet critical parameters including reservoir-seal pairs, porosity and permeability requirements
Provides rock volume data (area and thickness) and porosity and permeability data to determine the pore volume available for CO₂ storage capacity calculations
Structure, isopach (thickness), net to gross ratio, porosity and facies mapping

TVD Structure Map

Phi-h Map

Estimated Pore Volume Map

Basal Cambrian Sandstone (BCS) maps created by CDL using publicly available data from Shell Quest applications

Ensures target zones meet regional scale flow and containment requirements
Provides CO₂ density estimates for storage capacity calculations, estimate of density difference between aquifer and CO₂, and confirmation of permeability estimates through analysis of DSTs
Pressure gradient, absolute pressure, temperature gradient, temperature and salinity mapping
Pressure vs Elevation plots

Estimated Pressure Map

Estimated Temperature Map

Estimated CO₂ Density Map

Basal Cambrian Sandstone (BCS) maps created by CDL using publicly available data from Shell Quest applications

Regional Pressure vs Elevation Plot

Local Pressure vs Elevation Plot

Theoretical CO₂ storage capacity: the mass of CO₂ that can be stored in the hydrocarbon reservoir assuming that the volume occupied previously by the produced fluids will be occupied in its entirety by the injected CO₂
Effective CO₂ storage capacity: the mass of CO₂ that can be stored in hydrocarbon reservoirs after taking into account reservoir characteristics and flow processes, such as heterogeneity (Ch), aquifer support (Cw), gravity override (Cb), and CO₂ mobility (Cm)
Hydrocarbon reservoirs considered for CO₂ storage are often near the end of productive life so the theoretical storage capacity is relatively well understood
Current pressure needs to be well understood to properly estimate storage capacity
Wellbore liability (density and vintage) needs to be considered

Storage Calculation Methodology from Bachu (2006)

Limited data make saline aquifer storage capacity more difficult to evaluate
Storage efficiency factor (AKA Esaline) Es accounts for the presence of both water and CO₂, and is a function of reservoir properties and fluid dynamics:
Geometry (structural vs dynamic traps)
Heterogeneity
Gravity segregation
Permeability distribution
Pressure limitations
Initial estimates of storage coefficients (Es) are based on data distribution and quality, expected continuity of reservoir from analogues, and the scale of the storage estimate (local or regional)
Es values change with scale: increased potential for these factors to negatively impact storage with increasing areal extent and heterogeneity (i. e. small Es < 10% regional evaluations, larger Es 10-30% local evaluations)

Storage Calculation Methodology from DOE-NETL (2015)

CCUS Project Phases

CDL’s technical workflows address the Subsurface Evaluation Phase of a CCUS project. CDL, with its partners, can address the entire life cycle of a CCUS project from initially assessing project needs to application submission to implementation and monitoring. The benefits to clients are many:

A team that can answer the key questions
A single point of contact for the process
Extensive experience in the scope of the challenges in these applications
A team that stays up-to-date on the regulatory frameworks of individual jurisdictions

CDL CCS/CCUS Projects

Alberta CO₂ Emitters Map

CDL is developing a fully integrated subsurface study to help clients characterize the suitability of selected Lower Paleozoic deep saline aquifers for carbon storage in Alberta
The study will be delivered via an interactive, web-based Spotfire platform
Deliverables will include a stratigraphic framework, reservoir parameters, aquifer volumetric estimates and CO₂ storage capacity estimates
Initial delivery of Cambrian units (the deepest/oldest Lower Paleozoic unit) is scheduled for mid-April 2022 to coincide with the formulation of individual Full Project Proposals as requested by the Government of Alberta
Additional stratigraphic intervals will be evaluated and delivered as completed

Learn more Press Release Back to projects

Carbon AXIOM is an online tool to screen and assess depleted oil and gas pools for suitability to sequester CO₂ and as EOR candidates across southeastern Texas, southern Louisiana and southern Mississippi
CDL designed a database that integrates proprietary and public datasets comprising formation tops, production forecasts, temperature models, pressure profiles, and reservoir and fluid characteristics. These standardized attributes provide a basis to compare and rank CO₂ storage opportunities over large areas based on estimates of CO₂ storage capacity, uncertainties and risk elements

Project Area

Inputs for Storage Capacity Estimation

Modified from TGS

Hydrocarbon pools were generated in a GIS by combining wells within a field producing from the same geologic formations; pools were aggregated to storage units by combining laterally contiguous pore spaces within equivalent reservoir units. About 7,000 potential storage units over 87,000 square miles were assessed.
Users can visualize and filter the opportunities using TGS' user-friendly Carbon AXIOM web application, and emitters can identify potential storage sites near their facilities.

Online Screening Tool

Storage Unit Card Example

From TGS' Carbon AXIOM web application

Emitter Card Example

From TGS' Carbon AXIOM web application

View on CDL Technical Studies Purchase through TGS Back to projects

Geological and hydrogeological assessment of Paleozoic saline aquifers east of Calgary in support of submissions and applications to develop and operate a CCUS hub
Four zones were identified as having sufficient rock characteristics at depths below 1,000m to meet the criteria to sequester CO₂
The hydrodynamics systems were analyzed regionally, and locally where sufficient data were present, to classify hydrodynamic systems using pressure, total dissolved solids and salinity to understand aquifer isolation and water chemistry. These separate systems assist in mapping future containment of the sequestered CO₂

CDL Workflow