Wel-lok M2M STCTM

Provide a Permanent Seal in Multiple Annuli

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.

Summary of Wel-lok M2M STC™ Features

No mechanical parts

Electronically activated

One trip operation

Differential pressure ratings up to 10,000 psi

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

Temperature ranges up to 160 °C

Benefits of Wel-lok M2M STC™ for Annular Sealing

Can be used even in damaged and corroded tubings and casings

Creates a gas tight barrier without the need to pump from surface

Non-corrosive and not affected by H2S or CO2

Can seal in cased or open hole

Can seal in multiple annuli in a single run

Reduced intervention costs

Reduced corporate liability


The Wel-lok M2M STC™ (Seal Through Casing) has been developed to achieve a gas tight V0 seal in the well annuli that cannot be achieved by traditional cement balance plugs. Run on electric line, this tool is truly a rigless solution without the need for surface pumping equipment to circulate the alloy in place. Due to its viscosity and density, once melted the liquid alloy will flow through the perforated holes 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.

Flow prior to tool setting

Flow prior to tool setting

Flow after tool setting

Flow after tool setting

BiSN WEL-LOK M2M STCTM Current Qualified Tools 
(in) (A)
(ft) (B)
4 1/2" x 7"3.521
7 5/8" x 9 5/8"421
*5 1/2" x 9 5/8"4.2533
9 5/8" x 14"
open hole
9 5/8" x 13 3/8" x 20"821
13 3/8" x 20"1221
*20" x 30"18.521
* currently in development
** 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.