BiSN Seals Toughest Well First in £1Bn Carbon Storage Project

BiSN CCS Operations OffshoreBiSN CCS Operations Offshore

wel-lok™ Seal Through Casing and Tubing Seal Technology

Utilizing BiSN´s wel-lok™ Seal Through Casing (STC) and Tubing Seal (TS) technology with an aim to seal the 9-5/8″ casing, 20″ casing and 13″ open hole.

See Tool Specification
July 18, 2024

In the early 1990s, the operator drilled the subsea well in the Liverpool Bay Area (LBA) of the Irish Sea. The lateral leg of the well was drilled but never completed and was subsequently plugged and abandoned. Recent ROV surveys had detected bubbling from the debris cap on the seabed conductor, indicating a need for well barrier remediation. The remediation plan involved installing barriers in the lateral leg, utilizing a Bismuth alloy plug as an impermeable base for a longer cement plug. The Bismuth alloy would seal off gas flow, preventing it from compromising the cement.

  • Statistics
  • Challenges
  • Solution
  • Results
  • Business Value
Statistics

CCS Statistics Liverpool Bay - BiSNCCS Statistics Liverpool Bay - BiSN
Challenges

Meeting the Challenge of Carbon Storage

Focus on the Most Challenging Well: The most challenging well of the campaign was prioritized first due to its inherent challenges. Successfully sealing any leaks was crucial in order not to compromise any future plans for the abandoned field.

Adapting Exploration Wells for CCS: Exploration wells that had been previously abandoned likely have poor cement/casing and need to be upgraded to meet CCS standards.

Unknown Challenges and Flexibility: Unexpected issues often arise while working with older, previously abandoned wells. Any designed program needs to account for these issues and have the flexibility to adapt where needed.

BiSN CCS Liverpool BayBiSN CCS Liverpool Bay
Solution

wel-lok™ Seal Through Casing (STC) and Tubing Seal (TS)

BiSN technology offered a cutting-edge flexible solution for wellbore isolation, particularly in this scenario which required reliable sealing to prevent gas or fluid migration. The process started with the placement of alloy beads at predetermined depths within the wellbore. These beads were melted by a timer-controlled tool that was deployed in conjunction with a chemical reaction heater. It melted the alloy beads into a liquid form, which then flowed with a viscosity similar to water to fill the annular space and any irregularities within the wellbore. With the alloy fully melted and at its peak temperature, the heater was removed, allowing the molten alloy to cool and solidify, forming a robust, impermeable seal.

To validate the integrity of the seals, pressure tests were conducted. These tests were successful & were critical in confirming that the molten bismuth alloy had solidified and formed a plug that successfully sealed and effectively isolated the wellbore.

The bismuth plugs were installed using the following setting bases, highlighting the adaptability of the technology:

  • The largest plug, with a diameter of 20 inches, was set in place using an inflatable packer, a mechanical device designed to provide reliable support and isolation within the wellbore.
  • For the smaller 9-5/8-inch plugs, cement was used as a supporting medium.
  • The 13-inch plug was uniquely positioned directly on top of the lower 9-5/8-inch plug, showcasing a method of sequential placement to achieve multi-layered isolation.

This approach to wellbore sealing with bismuth plugs stopped all gas flow, ensuring that the well could be classified as fully abandoned under AB2 status. This classification implies a high standard of abandonment, where the well is sealed in a manner that guarantees no risk of future leakage or environmental contamination.

CCS - BiSN well schematic from CCS operationCCS - BiSN well schematic from CCS operation
Results

4 Bismuth Plugs Successfully Placed at 4 Depths for Permanent Abandonment

  • Installed permanent plugs in wells designated for abandonment.
  • Created a gas-tight (V0) seal.
  • Reduced the section milling window length.
  • Significantly reduced deployment time, resulting in major cost savings.
  • Lowered environmental impact and carbon footprint compared to using cement.
  • Employed timer activation for increased deployment flexibility.
Business Value

Permanent and Reliable Solution for P&A Applications

Enhanced Sealing Reliability:

  • Provides a more dependable seal compared to traditional cement, eliminating the risk of future leaks.
  • The solidified alloy forms a robust and impermeable barrier that remains stable under harsh subsurface conditions.

Effective Wellbore Isolation:

  • Prevents gas or fluid migration by creating a secure and long-lasting seal.
  • Ensures wells can be classified under high abandonment standards (e.g., AB2 status), guaranteeing no risk of leakage.

Tailored Solutions for Complex Wellbores:

  • Utilizes a variety of support mechanisms tailored to specific wellbore conditions, such as inflatable packers and cement for different plug sizes.
  • Sequential placement techniques enable multi-layered isolation, enhancing overall seal integrity.

Operational Efficiency:

  • The use of alloy beads and timer-activated tools streamlines the sealing process, reducing operational complexity and time.
  • Minimizes the need for lengthy and costly wellbore preparation, such as section milling.

Safety and Environmental Compliance:

  • Significantly reduces health, safety, and environmental (HSE) risks associated with well operations.
  • Ensures that abandoned wells are sealed in a manner that prevents environmental contamination and promotes sustainability.

Cost Reduction:

  • Shortening of section-milled windows and efficient sealing techniques lead to decreased rig time and lower operational costs.
  • Long-term reliability of the seal reduces the likelihood of expensive future interventions or repairs.

Lower Carbon Footprint:

  • Reduces the carbon footprint by streamlining operations and minimizing the need for prolonged rig activity.
  • Contributes to greener well abandonment practices through efficient use of resources and technology.

Scalability and Flexibility:

  • The technology can be adapted to various wellbore sizes and conditions, making it versatile for different applications.
  • Supports a wide range of abandonment strategies and requirements, enhancing its value across diverse projects.

Competitive Advantage:

  • Offers a unique and advanced solution that can differentiate operators in the marketplace.
  • Improves customer confidence by providing a proven and reliable method for wellbore isolation and abandonment.

About the application

The wel-lok™ STC (Seal Through Casing) has been developed to achieve a gas tight V0 seal well annuli that cannot be achieved by traditional cement balance plugs. Run on electric line, coil tubing or drill pipe, this tool does not need surface pumping equipment to circulate the alloy in place. Due to its viscosity and density, once melted the liquid alloy will flow with gravity into the annulus. When it cools below its melting point it solidifies, expands and creates a gas tight seal across the entire wellbore. The entire process, from melting to solidification, takes place in minutes and the seal is ready to test within an hour.

Seal Through Casing - BiSN
Seal Through Casing - BiSN
Seal Through Casing - BiSN
Seal Through Casing - BiSN

How it works…

The wel-lok™ STC (Seal Through Casing) has been developed to achieve a gas tight V0 seal well annuli that cannot be achieved by traditional cement balance plugs.

How it works…

More wel-lok™ Case Studies

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