Sets in minutes, seals for millennia

Reducing the corporate liability and potential environmental impact of abandoning decommissioned wells demands that fluids are sealed securely and reliably for generations to come.

BiSN has developed more effective solutions for P&A programs with our patented BiSN Wel-lok™ technology. Our eutectic alloys offer higher expansion ratios than conventional bridge plugs and higher differential pressure ratings than inflatable packers, forming a V0-rated, gas-tight seal that cement cannot provide.

Available in a number of unique toolstring configurations to suit your requirements, the proven BiSN technology behind them is the same.

Make rigless well decommissioning and abandonment a reality – speak to BiSN today.

Due to their material construction, elastomer and cement plugs can deteriorate over time, particularly in corrosive environments. Conventional bridge plugs also have very small expansion ratios that limit their application. And while inflatable packers have high expansion ratios, they lack the differential pressure capabilities required for many oil well abandonments, and cannot provide a gas-tight seal.
Set a Gas-Tight Plug or Isolate Zones with Wel-lok™ TS and MXD

Set plugs and seal off zones permanently from production

Casing damage can severely affect the already-limited space available downhole to carry out operations such as setting bridge plugs and cementing – escalating the rig time and costs involved for both well interventions and P&A.

BiSN has developed an alternative system, our patented BiSN Wel-lok™ technology, that overcomes the shortcomings of traditional methods of setting bridge plugs using cement, by delivering savings in both speed and cost.

Developed to be run on wireline, slickline or coiled tubing, the BiSN tool passes through small restrictions such as damaged or crushed casing before setting a gas-tight plug that can be used for isolation, thanks to the larger drift than conventional bridge plugs.

BiSN engineers were challenged to further increase the expansion ratio beyond that of the original system without compromising its pressure differential and gas-tight sealing capabilities.

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By incorporating a bailer in its configuration, the eutectic alloy could be deployed downhole in the form of shot balls instead of as a solid piece. This allows for a smaller diameter tool to be run in hole while increasing the expansion ratio of the tool up to three times the OD of the tool.

The result is a higher expansion ratio than conventional plugs, higher pressure ratings than inflatable packers and gas blocking abilities that cement cannot match.


  • Reduce intervention costs
  • Reduce environmental impact
  • Reduce corporate liability
  • Available in a range of sizes to suit API & non-API tubings
  • Deploy even in damaged or corroded casing
  • Larger expansion than traditional plugs
  • Non-corrosive and not affected by H2S or CO2
  • Retrievable without milling

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Permanently Seal Multiple Annuli with Wel-lok™ STC

Seal multiple annuli through casing in a single trip

Cement pumping and placement of conventional balanced plugs is especially challenging in wells with multiple casing strings. And due to cement’s physical limitations as a barrier material, it cannot deliver the long-term gas-tight seal required by today’s operators, or for permanent well abandonment.

Now Performance Barrier Technologies from BiSN change all of this. As with every tool in the portfolio, the through-casing system is run on electric line, and is a truly rigless solution without the need for surface pumping equipment to circulate the eutectic alloy into place. Instead, due to its viscosity and density, once melted the liquid alloy simply flows through perforations under gravity and into the annulus, displacing well fluids.

When it cools below its melting point it solidifies but, in contrast to cement, the alloy expands on setting to create a V0 gas-tight seal across the entire wellbore. The whole process, from melting to solidification, takes place in minutes and the seal is ready to test within an hour.


  • Reduce intervention costs
  • Reduce corporate liability
  • Seal in cased or open hole
  • Deploy even in damaged and corroded tubings and casings
  • Electronically activated with no mechanical parts
  • Differential pressure ratings up to 4,000 psi
  • Available in a range of sizes to suit API & non-API tubing and casings
  • Temperature ranges up to 150 °C
  • Non-corrosive and unaffected by H2S or CO2

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Seal Perforations in Cased Hole Completions with Wel-lok™ Perf-lok

Permanently isolate perforations in cased hole completions for zonal isolation, or as part of your P&A programs.

Cement squeeze jobs have typically been used to seal perforations in well casing. However, one consequence of applying enough pressure to squeeze viscous cement slurry into these small spaces is that it can often cause perforations to collapse, making it impossible to fill the entire void effectively.

BiSN Wel-lok™ technology is a smart alternative to a squeeze. Unlike typical cement squeezes, the Perf-lok system does not require high pressure pumping for placement, as the eutectic alloy flows into perforation tunnels under gravity due to its viscosity and density. Perforations are plugged with a V0 gas-tight, metal-to-metal seal, free from the leak paths that result from poor cement jobs.

For production wells where fullbore access is required inside the casing, Perf-lok can also be milled out, leaving behind a long-term seal within the perforations, thanks to its unique expansion properties.


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Eliminate Gas Migration in Cemented Annuli with Wel-lok™ CRT

A simpler way to fix cement failures

In cemented annuli, leak paths can develop that allow gas migration. The result can be wells that develop sustained casing pressure, or casing vent flow. Traditional methods of repair such as perf-and-squeeze or perf-and-wash require surface pumping pressure to squeeze or circulate the sealing material into place.

Performance Barrier Technologies from BISN represent a faster, simpler and longer lasting alternative. The tool is run rigless on electric line, sealing through casing perforations so that section milling is not required. The eutectic alloy flows under gravity like water, solidifying to create a non-porous seal in just minutes compared to the hours taken to set by traditional cement and resins.

If fullbore access is required, the solid alloy can be milled out while still retaining a gas-tight seal in the annulus.

Importantly, BiSN Wel-lok™ technologies eliminate the possibility of additional micro-annuli being formed over time, putting a stop to future gas migration once and for all. For well abandonment applications in particular, any other cement repair seems like a temporary fix.


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Unique Alloys In Action

More than just a great idea, our Performance Barrier Technologies have been proven in the field time and time again.