Artificial lava used to plug oil and gas wells

The novel technique involves the creation of a metal plug, including a bismuth alloy, that is produced at depth in the well casing. An artificial lava, or magma, is effectively created in the subsurface which melts all the manufactured components and materials. These then solidify to form a permanent barrier that seals the well.

Developed by Norwegian oilfield services company Interwell, the core component of the technology is called ‘RockSolid’, which consists of a solid barrier made up of several phases that are formed during a thermite reaction. This involves the ignition of a metal in the presence of the oxide of another metal that is less reactive than the first, and is the same chemical reaction used for welding rail tracks together.

During the thermite reaction, the oxygen in the reaction changes places, or ‘jumps’ from the oxide to the unoxidised metal, releasing intense heat of more than 3,500°C. This causes both the well casing and the cement surrounding it to melt. The intense reaction creates an elongated plug that completely fills the available space, adapting itself to the irregular shape of the borehole.