The 4 Types of CO2 Injection Wells

Carbon capture and storage (CCS) is key to a clean, resilient energy future, and CO₂ injection wells are a critical component of CCS. Intended to inject CO₂ deep underground for safe storage, the success of CCS projects depends on the proper design, drilling, and management of these wells.

In this blog, we will explore the 4 different types of CO₂ injection wells, their purposes, and the data they collect. We will also discuss the importance of high-quality carbon sequestration data, and how to choose the right CCS well drilling partner.

Keep reading for what you need to know about CO₂ injection wells and be sure to download our white paper for the full picture on carbon sequestration well drilling.

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About CO₂ Injection Wells

A CO₂ injection well is a specialized well designed to inject carbon dioxide into deep underground formations for long-term geological storage. These wells are a critical component of carbon storage projects, which aim to reduce emissions by capturing and storing carbon dioxide.

CO₂ Injection vs. Oil and Gas Wells

While both CO₂ injection wells and oil and gas wells involve drilling into the earth, they have different purposes and requirements.

CO₂ injection wells are optimized for injecting and containing fluids, whereas oil and gas wells are designed for extracting fluids. Furthermore, CO₂ sequestration wells must remain stable and functional for decades after injection is complete, whereas oil and gas wells are typically not expected to last beyond the extraction activities they enable.

For more details, read our blog on the difference between oil and gas vs. sequestration drilling.

Comparison of oil and gas production wells and sequestration wells.

CCS Wells and Class VI Permits

CO₂ injection wells fall under the Underground Injection Control (UIC) Class VI category, established by the U.S. Environmental Protection Agency (EPA) in 2010. These wells require approved Class VI permit applications before construction, and must meet specific design specifications, regulatory standards, and data collection requirements.

A rigorous process is involved to meet Class VI requirements, including:

• Site characterization
• Construction
• Data collection
• Long-term testing and monitoring

The 4 Types of CO₂ Injection Wells

Different types of CO₂ injection wells serve different purposes in a carbon dioxide storage project, each designed to collect specific data and perform unique functions, ensuring the overall success and safety of the project.

#1: Preliminary Sequestration Stratigraphic Test Well (STW)

A preliminary sequestration stratigraphic test well (STW) is drilled to evaluate the suitability of a site for CO₂ sequestration. Used during the initial stages of a carbon sequestration project, a STW allows experts to thoroughly assess the geological characteristics of the site, from rock properties to hydrogeologic conditions.

Data collected from a STW includes:

• Coring
• Hydrogeologic characterization
• Rock properties (porosity, resistivity, permeability)
• Rock mechanics
• Fluid sampling
• Pressure
• Acoustics

#2: Shallow Monitoring Well

A shallow monitoring well is drilled to monitor conditions above the confining layer and detect potential CO₂ migration. Used throughout the life of a CCS project, experts use shallow monitoring wells to continuously watch the integrity of the storage site and ensure that CO₂ does not move out of the storage formation and contaminate groundwater.

Data collected from shallow monitoring wells includes:

• Pressure
• Temperature
• Groundwater quality
• Gas detection
• Moisture content
  
  

#3: Deep Monitoring Well

A deep monitoring well is drilled to monitor for CO₂ movement and confirm or refine plume and Area of Review (AOR) modeling. Used during and after CO₂ injection, deep monitoring wells allow experts to track the movement of CO₂ within a storage formation and ensure containment - verifying the effectiveness of the storage site.

Data collected from deep monitoring wells includes:

• Seismic activity
• Pressure
• Temperature
• Fluid sampling
• CO₂ presence and concentration

#4: Injector Well

An injector well is the primary well through which CO₂ is injected into the storage formation at the desired rate and volume. Used throughout the injection phase of a CCS project, properly drilled injector wells ensure efficient and safe CO₂ storage.

Data collected from injector wells includes:

• Injection rate
• Injection volume
• Well integrity
• Formation response
• CO₂ plume monitoring

Sequestration Wells: The Data Makes the Difference

High-quality data is essential for ensuring the stability, effectiveness and compliance of CO₂ injection wells. Beyond regulatory compliance and permitting, accurate data also helps experts:

• Confirm injection rates
• Assess storage potential
• Prevent CO₂ leakage
• Ensure long-term containment of CO₂

Collecting CO₂ Injection Well Data

Key data collection methods provide site operators with critical information about the well, injection zone and surrounding formation to ensure the well meets all required specifications for long-term CO₂ sequestration.

Data collection methods for CO₂ injection wells include:

• Coring
• Pressure testing
• Fluid sampling
• Seismic monitoring
  
  

Choosing A Sequestration Drilling Partner

When selecting a carbon capture, utilization and storage (CCUS) partner, the name is the game (as well as the reputation, history and expertise) - and CO₂ well drilling partners are no exception.

Look for a service partner with specific experience in drilling Class VI wells, a thorough understanding of the CCS lifecycle, expertise in geophysics and subsurface geology, and excellent project and vendor management skills.

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Choosing A CO₂ Sequestration Drilling Partner

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Choosing A CO₂ Sequestration Drilling Partner

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At Battelle, We Know the Drill

With extensive experience in drilling and managing sequestration wells, Battelle has been involved in drilling more than a dozen sequestration wells - more than any other single provider. In addition, our team has managed thousands of wells for oil and gas operations.

With over 25 years of CO₂ storage experience and 75+ CCS projects completed worldwide, Battelle is a recognized expert in CCS. Our team includes more than 100 subsurface and geotechnical experts, making us the most knowledgeable and reliable partner for your CCS needs.

Contact our experts for a free consultation, and let's discuss how we can help you achieve your CCS goals.