Wel-lok M2M CLSTM

Repairing Damaged Tubing or Casing

Wel-lok M2M™ – An Overview of the Technology

The Wel-lok M2M™ technology consists of utilizing a modified thermite chemical reaction heater to melt bismuth-based alloys downhole. The melted alloys have a viscosity similar to water, and a specific gravity 10 times that of water, allowing them to flow into the smallest areas of a wellbore without the need of any surface pumping equipment. As the alloys cool and solidify, they expand to provide a seamless gas tight seal that is non-corrosive and not affected by H2S or C02.

Application of the Wel-lok M2M™ technology for Intervention

For wells with integrity issues, such as holes or leaking connections, BiSN has developed the Wel-lok M2M CLS (Casing Leak Seal). This tool can be run as a single seal to isolate a small leak or as a straddle assembly to isolate larger intervals. The through bore allows for continued production and wireline runs or it can be milled out to achieve a full drift without compromising the integrity of the gas tight seal.

Summary of Wel-lok M2M CLS™ Features

Creates a metal to metal seal without using elastomers

Ready for pressure testing in one hour

V0 ISO 14310 tested

No mechanical parts

Electronically activated

One trip operation

Differential pressure ratings up to 10,000 psi

Benefits of Wel-lok M2M CLS™ for Tubing and Casing Leaks

Can be used even in damaged and corroded tubings and casings

Larger through bore than standard packoffs

Higher pressure ratings than standard expandable patches

Non-corrosive and not affected by H2S or CO2

Millable to achieve a full bore

Available in a range of sizes to suit API & non API tubing and casings

Temperature ranges up to 160 °C


The Wel-lok M2M CLS™ (Casing Leak Seal) was developed to address the shortcomings of traditional methods in sealing leaks in tubings and casings. This tool provides a V0 rated seal with higher pressure ratings than conventional casing patches with a larger through bore than traditional packoffs. If full bore access is required, it can be milled out leaving a seal only across the leaking area of the well.

Downhole Sealing

Flow prior to tool setting

Downhole Sealing Solutions

Flow after tool setting

(in) (A)
(ft) (B)
3 1/2"2.581.5
4 1/2" - 5”3.582.5
5 1/2"4.583
7” - 7 5/8"5.759.54.5
9 5/8”89.56.5
* custom sizes available

BiSN tool range

You can view or download a PDF data sheet of all our other tools by clicking the links below.