A collaboration between UK-based Rawwater Engineering Company Limited, Aarbakke Innovation AS and K2 Oilfield Services AS to establish Anglo-Norwegian consortium, Wellstrøm AS, has resulted in the creation of superior, highly controllable bismuth alloy-based plugging & abandonment techniques for the global oil and gas industries.
Rawwater invented the Bismuth Plug and created the world’s first 'anticipated' 3,000-year-life cast metal seal for oil & gas reservoir plugging & abandonment. Aarbakke Innovation’s expertise lies in heater and cable-deployed rig-less P&A technologies, and K2 Oilfield Services is a specialist oilfield consultancy providing innovative perforating and P&A solutions. By combining their individual strengths through Wellstrøm, the three organisations offer the reversible, gas-tight sealing capabilities of bismuth, supported by the advantage of fully controllable electrical heat for plug smelting, deployment and even removal, if required.
Wellstrøm’s use of controllable heat for deploying Rawwater’s bismuth alloys was put through its paces during extensive system integration trials in Aberdeen, Scotland in late 2020. The trials confirmed the consortium’s ability to deliver totally controllable melting of the bismuth alloy using electrical heat applied via cable, as well as complete control of the bismuth alloy during placement. Avoiding any need for milling operations, Wellstrøm, together with Core Laboratories, was also able to achieve totally controllable shattering of an existing cement annulus ready for the application of molten bismuth. Wellstrøm’s use of controllable electrical heat contrasts starkly with the approach adopted by other organisations that involves the pyrotechnic properties of thermite to deploy the bismuth alloy.
“Ever since Rawwater’s successful deployment of the world’s first bismuth alloy seals in two onshore wells in Alberta, Canada, I have been convinced of the superior capabilities of bismuth as a cost-effective alternative for sealing well abandonments and resealing failed abandonments that were previously plugged using cement,” comments Rawwater managing director, Professor Robert Eden PhD. “Thanks to the extensive system integration trials that have taken place through the Wellstrøm consortium, there is now also the means to deploy bismuth alloy seals in a totally controllable way, one that doesn’t require pyrotechnics.”
Recognising the need for a specialist alternative plugging medium to cement, Rawwater has been investigating the use of bismuth alloys for more than twenty years. The company has built up a large corrosion and creep database regarding the use of underwater cast bismuth alloys and also conducted research which underpins its belief that the development of bismuth alloys provides the opportunity for a significant reassessment of current approaches to well abandonment in particularly challenging applications, including resealing failed abandonments.
To ensure offshore capability and extreme reliability, Rawwater completed a two-year programme to deliver 7” alloy plugs for deployment in the North Sea, rated to 6000 psi differential pressure at 60 cm (2’) in length. Extensive development and testing took place in collaboration with an operator consortium and the UK Government to develop the formulation of the metal seals. To establish mechanical properties and creep behaviour under service pressure and temperature conditions, Rawwater worked with the University of Aberdeen, through an Oil & Gas Innovation Centre (OGIC)-funded partnership. The result of Rawwater’s research is a suite of alloys for onshore, offshore and subsea plugging & abandonment, with operating envelopes to cover downhole geothermal temperature conditions from 158 -194°F (70 – 90°C) and 284 – 320°F (140 – 160°C). Meeting the 3,000-year design life specified by Oil & Gas UK for plugs in the North Sea, Rawwater alloys have been subjected to a strict technical qualification programme overseen by Bureau Veritas, with stringent adherence to the qualification processes stipulated by DNV-RP-203 – Jul 2013, ISO 14310 (V0) and Oil & Gas UK.
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