Wel-lok M2M MXDTM

Provide a Seal in Through Tubing Applications, Wells with Restrictions & Large Diameter Casings

Wel-lok M2M™ – An Overview of the Technology

The Wel-lok M2M™ technology consists of utilising 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 MXD™ technology for Abandonment

In an effort to increase the expansion ratio beyond even that of the original TS without compromising pressure differential and gas tight sealing capabilities, BiSN developed the Wel-lok M2M MXD™ tool. The use of a bailer to carry the bismuth based alloy downhole in shot form allows for a smaller diameter tool to be run in hole while increasing the expansion ratio of the tool up to 3 times the tool OD.

Wel-lok M2M MXD™ Features

Slim tool profile design to negotiate restrictions

High expansion ratio capability for sealing in large diameters

Utilises modified thermite chemical reaction heater to quickly melt bismuth based alloys

Gas tight seal in large diameter casings without the use of elastomers

Easy and quick to deploy in a single trip intervention

Wireline set

Benefits of Wel-lok M2M MXD™ for Rigless Intervention & Abandonment

Reduced intervention costs

Long lasting reliable sealing solution despite restricted access

Extends the production life of the well

Non-corrosive and not affected by H2S or CO2

Reduced environmental impact

Temperature ranges up to 160 °C

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


The Wel-lok M2M MXD™ (Maximum Drift) has been specifically developed for rigless through tubing applications. This tool has a smaller OD and higher expansion ratio than some of the other Wel-lok M2M™ tools but uses the same technology to create metal to metal (M2M™) seals. Unlike conventional through tubing tools utilising a petal basket and cement or inflatable packers, the MXD™ offers a gas tight seal with up to a 10,000 psi differential pressure rating and can be deployed in a single trip. Utilising bismuth alloy pellets, deployed inside a bailer, eliminating any restrictions on the volume of alloy that can used to create a seal.

Flow prior to tool setting

Flow prior to tool setting

Flow after tool setting

Flow after tool setting

(in) (A)
(ft) (C)
(ft) (B)
*3 1/2" - 7"2.12512.528600
4 1/2" - 7 5/8"2.87512.528750
*5" - 9 5/8"3.512.528950
* currently in development

BiSN tool range

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