Repairing Damaged Cement for an Operator in Canada

Plug and Abandonment with Wel-lok™ Cement Repair Tool (CRT)

Canada P&A - BiSNCanada P&A - BiSN


An operator had a six well plug and abandonment campaign of onshore wells that had experience damaged cement. These wells had a range of configurations and characteristics, but all had cement that no longer could reliably hold gas pressure. BiSN was contacted to provide a gas-tight solution to allow the wells to be permanently abandoned.


1,793' - 1,969'
Downhole Pressure:
700 - 3900 PSI
30 - 125ºC
Setting ID:
Sealing OD:


Deployment across a variety of parameters:
This campaign featured well conditions that ranged from 30-125°C, 700-3900 PSI, and geometries that included running through a 4.653” restriction to seal inside 8.921”. This range of parameters required the deployment of three different tools using two different Bismuth alloys to address the individual needs of each well.


To prepare the well, the customer sectioned milled a zone of damaged cement to clear an area for a BiSN seal. BiSN then deployed Cement Repair Tools with Bismuth alloy cast on the outside of a thermite heater for five of the six wells, with Bismuth alloy beads deployed from surface around a thermite heater for the sixth well. In the section milled zone, the alloy was melted and the thermite heater removed from the liquid alloy, forming a single, full cross-section plug across the entire well diameter.


  • Damaged cement replaced by bismuth alloy
  • Permanent plugs set in wells for abandonment
  • Eliminate need for unreliable cement squeezes
  • Deployed on e-line
  • Significant cost savings for the operator

Business Value

BiSN provided the customer with a reliable solution for permanent abandonment. This eliminated the risk of an ineffective cement squeeze while providing the long-term reliability of bismuth alloy. Because Bismuth alloy can form an effective seal with a shorter plug length, the need to section mill a long window for a replacement cement plug represented significant cost savings for the operator. BiSN was able to help the operator reduce HSE risks, operation time, and cost.

How it works…

The Wel-lok™ CRT (Cement Repair Tool) was developed to eliminate sustained casing pressure, or casing vent flow, in cemented annuli.

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permanent solution for your well

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