Science & Technology: Plasma Could Power Faster Geothermal Drilling

Plasma power (OEdigital)

Slovakian company GA Drilling hopes to make short shrift of section milling using a plasma-based downhole tool technology.

Standard milling operations currently involve removing the wellhead and the Xmas tree, then pulling the production tubing, before deploying a section milling tool, often requiring a sizeable and costly rig. GA Drilling, based in Bratislava, says its solution, Plasmabit, will be able to mill out sections of tubing or casing, without having to remove wellheads, Xmas trees or production tubing.

The tool, which could be deployed using a light well intervention vessel, uses a non-mechanical rotating electrical arc, with up to 800 revolutions per second, to create a plasma which will fragment steel, cement, rock or other material, in the well.

The plasma arc is created by passing electricity through a plasma forming media, typically water, which is heated to 3000-6000°C. Hydrodynamic and magnetic forces are then used to either radially or axially direct the plasma arc, for either milling or drilling operations, respectively. The impact and speed of disintegration is computer controlled.

After selling their previous company, they looked for a new challenge, setting up GA Drilling in 2008, which initially focused on the geothermal energy sector.
Geothermal energy has had a big impact in places like Iceland and Slovakia. But, because you have to drill very deep to get the temperatures needed, it can be costly. GA assessed various technologies, including laser drilling and water jetting, but chose plasma, opting to build laboratories and testing facilities to develop and commercialize the technology.

Longer term, the firm anticipates the technology will be a solution for geothermal well drilling. But, it has also been looking at options for well stimulation and even temporary wellbore stability enhancement.

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