Setting the Standard: Kazakhstan’s First Deep-Set wel-lok™ Plug for P&A

November 14, 2024

An operator in Kazakhstan needed a deep-set Plug and Abandonment seal as part of their rock-to-rock barrier. The operator required a solution that could isolate the entire wellbore, creating a multi-annular barrier in a zone with well-bonded cement behind the outer casing. To ensure the barrier would fully prevent gas migration, a V0 impermeable seal was required. BiSN’s STC technology was chosen, representing the first deployment of a bismuth plug in Kazakhstan, and ensuring that a durable and dependable plug was the foundation of the P&A barrier.  

  • Challenge
  • Statistics
  • Solution
  • Results
  • Business Value
  • About the Application
  • How it Works
Challenge

Deep Set Multi-Annuli Plug and Abandonment

Deep Set Deployment: The barrier was to be set at nearly 10,000 ft which presented operational challenges during the deployment of the STC. The deployment required using bismuth beads that are deployed from surface through drill pipe. To form a good plug, operational procedures were designed to ensure the beads reached the setting depth at the right time.  

Well Preparation: To form a seal out to the surface of the 9-5/8” casing, a window was section milled and cleaned. Removing all of the cement that had been in the annulus between the 7” and 9-5/8” was crucial to ensure no leak paths compromised the bismuth seal. 

Statistics

Kazakhstan Downhole Parameters

Solution

wel-lok™ Seal Through Casing (STC)

The BiSN STC tool is the premier P&A tool to ensure a gas-tight seal in multi-annular wells. The operator needed to set an impermeable barrier that they could be confident would isolate any gas migration and form a permanent plug. They also needed the expertise and experience to ensure that the job would be executed smoothly, given the setting depth of nearly 10,000 ft.  

The well was prepared by section milling a 21m window in the 7” and flushing the zone to remove debris. An inflatable bridge plug was set at the bottom of the window to form a base upon which the bismuth beads that would be melted to form the plug would be deployed. 

A thermite heater was connected to drill pipe with a timer-activated running tool. Based on the expected duration of the operation and expertise gained from hundreds of tool deployments, an activation time was programmed, and the tool string was deployed to the setting zone.  

Once at depth, beads were deployed into the drill pipe and allowed to fall via gravity to the setting zone. The drill pipe was flushed to ensure that they had reached setting depth and that the drill pipe was clear. When the timer expired, the thermite heater was activated and began melting the bismuth alloy. After a short melting period, the thermite heater was removed from the plug, leaving a solid barrier across the entire wellbore. The alloy then cooled and solidified, expanding to form a gas tight plug.  

Results

Impermeable 1.4-meter plug

The deployment resulted in a verified 1.4-meter bismuth plug. The ability to set a short plug that was gas-tight as the foundation of the barrier allowed for a reduced section mill window, resulting in significant time and cost savings for the operator. The durable plug ensures that the well will stay sealed, protecting the environment and the operator continually. 

 

  • Installed permanent abandonment plug
  • Created a gas-tight V0 seal
  • Reduced section mill window length
  • Reduced deployment time, resulting in major cost savings
  • Lower environmental impact and carbon footprint compared to cement
  • Timer activation increased deployment flexibility
Business Value

Permanent Rock-to-Rock Gas-Tight Barrier

Seal Reliability and Durability 

  • Provides a permanent barrier that is more durable than cement, eliminating the risk of future leaks or required remediation 
  • The metal alloy plug is impermeable and robust, able to resist the harsh well environment while continuing to seal reliably 

Permanent Wellbore Isolation 

  • The gas-tight, V0 seal prevents migration of gases or liquids in perpetuity, ensuring continual compliance with regulatory requirements 
  • Prevents leakage and promotes sustainable abandonment that protects the environment and protects the operator from expensive remediation 

Operational Efficiency 

  • Minimizes operational complexity through a streamlined process using alloy beads and timer-activated tools 
  • Reduces requirements for lengthy well preparation by shortening section mill window preparation 

Cost Reduction 

  • Decreased operation time and section mill lengths results in significant cost savings and reduced budget risks 
  • Long-term reliability of the seal reduces probability of expensive future intervention or liability 

“I am pleased to extend my sincere congratulations to the entire team on the successful plug and abandonment operation.

Throughout the operation, the team demonstrated exceptional professionalism and the ability to navigate complex challenges. Implementation of new technologies and techniques are particularly admirable.

The team’s commitment to maintaining a safe working environment while achieving the desired outcomes is highly appreciated.” 

Wells Engineer – Operator Partner

About the Application

STC wel-lok™

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.

More wel-lok™ Case Studies

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