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June 2016
EPIC Abandonment & Decom 32
SUBSEA Deepwater Tech 42
DRILLING MPD in the GOM 48
oedigital.com FLNG Vol. 41 • No.6
Offshore Engineer • June 2016
• Abandonment & Decommissioning • Southeast Asia
The FLNG Issue page 24
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EPIC
Plasma power Elaine Maslin reports how Slovakian company GA Drilling hopes to make short shrift of section milling using a plasma-based downhole tool technology.
Assembly of a plasma testing prototype. Photos from GA Drilling.
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ection milling is a time-consuming operation often required as part of plugging and abandonment (P&A) operations. Section milling often has to be carried out when there is uncertainty over the annular cement in the well, which has the potential to cause flows, cross flows, or seepage of water, gas or oil. To avoid such risks, section milling is used to remove casing and cement to allow placement of new isolations, as part of the P&A process. A 50m section could take more than 10 days to mill, GA Drilling says. 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 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. “You can mill away the part of the production tubing you want milled,” says Tomas Krištoficˇ, CTO, GA Drilling. “The advantage is that you do not need a rig. Using a coiled tubing type approach is another advantage because you don’t need to pull the production tubing out of the well.” 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. During tests on simple and
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drilling and water jetting, but chose plasma, opting to build laboratories and testing facilities to develop and commercialize the technology. At the end of 2012, after four years’ testing, it presented its first working prototype. At that point, GA Drilling realized the technology Casing and cement string after plasma milling testing. could have other applications, Kocˇiš multi-string casing samples in brine ensays. In 2013, the firm launched a joint vironments, a 3½in tool was able to mill industry project with a number of operaa range of casing sizes including 4½in, tors and service companies. By 2014-15, 5½in and 7in. Rate of penetration was the first priority application for the techachieved at similar rates to traditional nology was identified – section milling section milling techniques, but because for P&A operations. Work is ongoing. GA Drilling is one tool can mill various casing dimenlooking at two different conduits to sions, tripping time is reduced. Testing take the tool to the work site – either also found the tool could mill carbon coiled tubing or a hybrid cable, which steel as well as steel alloys without sigcould perform in downhole condinificant difficulty. tions. The hybrid cable would contain The operation generates a finer a fluid line and electrical and fiber powder, compared to the swarf created optic elements for power and data in traditional milling, he says. Fluid transmission. management is integrated within the In March, GA Drilling opened an Plasmabit device, which also has a office in Aberdeen, as it looks to grow movement and anchoring sub-assembly, its P&A services. In 2015, the firm which can also enable milling of wider created an advisory board includdiameters. ing Nigel Jenkins, previously CEO of “We are also able to deliver and industry body Decom North Sea, as generate the energy needed continuits decommissioning, commercializaously, which is different to the thermite tion, strategy and growth adviser; reaction solutions currently offered Mikhail Gelfgat, a wells and drilling by others,” Krištoficˇ says. In the next expert previously with Weatherford, two years, GA Drilling intends to trial and former Shell senior well abandonthe technology onshore before runment and intervention engineer Iain ning offshore field tests in early 2018, Pittman. Longer term, the firm anticiwith offshore operational deployment pates the technology will be a solution planned for 2019. “We are structurally changing the for geothermal well drilling. But, it whole process,” says Igor Kocˇiš, CEO. has also been looking at options for GA Drilling was founded by Krištoficˇ well stimulation and even temporary and Kocˇiš, who worked together in wellbore stability enhancement. embedded systems and IT system security. After selling their previous company, they looked for a new chalWATCH lenge, setting up GA Drilling in 2008, which initially focused on the geotherGA Drilling presents this mal energy sector. video clip demonstrating Geothermal energy has had a big how the Plasmabit tool impact in places like Iceland and works, watch it on Slovakia. But, because you have to OEDigital.com: drill very deep to get the temperatures needed, it can be costly. GA assessed http://ow.ly/RKow300JzHP various technologies, including laser
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