Wel-lok M2M CRTTM

Eliminate Gas Migration in Cemented 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 CRT™ 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 CRT™ for Eliminating Casing Vent Flow

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

Millable to achieve a full bore

Non-porous and solidifies in minutes as opposed to cement and resins

Eliminates the need for expensive interventions and unreliable cement squeezes

Reduced corporate liability


The Wel-lok M2M CRT™ (Cement Repair Tool) was developed to eliminate sustained casing pressure, or casing vent flow, in cemented annuli. Unlike traditional methods of perf and squeeze or perf and wash, this tool does not require any surface pumping pressure to squeeze or circulate the sealing material into place. The tool is also run rigless on electric line, sealing through casing perforations, so section milling is not required. The bismuth-based alloy has no porosity and solidifies to create a seal in minutes as opposed to hours with traditional cement and resins, eliminating the possibility of a micro-annulus being formed to allow future gas migration. If full bore access is required, it can be milled out and still maintain a gas tight seal in the annulus.

Flow prior to tool setting

Flow prior to tool setting

Flow after tool setting

Flow after tool setting

BiSN WEL-LOK M2M CRTTM Current Qualified Tools  
(in) (A)
(ft) (B)
4 1/2"3.58400
5 1/2"4.58550
9 5/8"8.25121,800
* 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.