How does the Wel-lok M2M™ employ the bismuth plug to create downhole seals?

Bismith Plug

The innovative new technology – Wel-lok M2M™ – developed by BiSN is still not completely understood by everyone in the well management market, not because it is complicated but because it is ground breaking and therefore breaks the mould of industry norms metaphorically and physically. So we thought we would endeavour to explain how it works in a bit more detail. M2M means metal to metal technology which may not seem to make sense initially but once you realise that the metal is applied in a molten form you will begin to realise how it can then form a tight seal. Bismuth alloys are deployed to ultimately create a bismuth plug.


How do you melt the bismuth alloys to create a bismuth plug?

Melting Bismuth Plug

For the bismuth alloys to become molten, it is necessary to heat them so causing them to melt and take on a viscosity similar to water. This is done once it has reached the desired well depth where the seal is required, either to form a permanent bismuth plug, a seal to shut off water or an annular casing packer. Using a modified thermite heater to create a chemical reaction with the bismuth alloy, the bismuth melts and allows it to flow into the desired area requiring sealing. It is simply deployed using a standard wireline. It is so straight forward and it requires no special licences or handling permits.

Why is this so revolutionary for the oil and gas industry?


Downhole TechnologyTraditionally sealing options in downhole technology have relied on elastomer and cement solutions which are not always easy to apply, reliable or completely safe to the environment. The award winning Wel-lok M2M™ technology which uses the bismuth alloys to create a bismuth plug is not only safer but more reliable and easier to deploy. Although the alloy, once heated by the thermite heater becomes a liquid, enabling it to flow around the inside of the hole and sit tightly so forming a tight metal to metal seal as it cools, having a density ten times higher than water it can also displace any welbore fluids.

How has BiSN developed a bismuth plug which doesn’t take a long time to heat?

Historically a number of organisations have tried a similar method of heating and melting alloys to create a seal in downhole technology. However the heating method used was electrical which proved impractical in the field as it takes hours for the alloy to heat and melt. In contrast, the BiSN technique using the modified thermite heaters takes just minutes and then cools and is ready for pressure testing all within one hour. To see more clearly how this works take a look at some of our mini videos

Alternatively for more information and to discuss your potential requirements for using a bismuth plug in a downhole sealing situation contact us on +1 832 919 7500 or email