Regardless of how the global demand for petroleum products develops in the future, it is an inevitable fact that sooner or later, all current and future wells must be abandoned with eternity in mind. The traditional method for placing these barriers have been to pump a cement slurry into the well and wait for it to cure.
Responsible well integrity means combining several independent and co-dependent well barrier elements to make up a robust well barrier. Permeable zones penetrated by a wellbore should be protected by two of these barriers. Instead of creating the barrier from a single product aimed to provide both mechanical strength and seal with all the necessary compromises this involves, another approach is to place a combination of ideally suited materials optimised for its specific purpose. Flopetrol Well Barrier is the exclusive global provider ofa solution like this, namely QuartzPack™, a unique, non-curing, self-healing well barrier element that ensures zonal isolation for the lifetime of the well and beyond.
Plug and Abandonment applications
Whether a well is abandoned or still in production, sustained casing pressure or sustained annulus pressure (SCP/SAP) is a common challenge. A plug or an annulus barrier is often made of cement, a product ideally suited for providing mechanical strength rather than for sealing pressure. If the barrier should start to leak, it means the owner may have to shut in the well or implement a very costly intervention. Remediating degraded well barriers is a large cost to the industry, and sometimes even to the society, every year. As such, the financial exposure of having a portfolio of wells with sub-optimal integrity can seriously affect shareholder value for an operator.
The industry has come to realise that traditional P&A methods using cement may not be the ideal long-term solution. A curing material can shrink, break, degrade mechanically and/or chemically, and cause leaks into adjacent zones or the atmosphere even a long time after installation. Another common problem occurs during placement; as the slurry sets, the hydrostatic overbalance is lost before the material has become sufficiently solidified and allows migration of gas or liquid into the material, resulting in an open channel to flow.
Plug & Abandonment can be both temporary and permanent. Temporary P&A is typically done to defer cost to a later time or to prepare the well for intervention or permanent abandonment. Permanent P&A is typically performed when the well is no longer commercially interesting and it is designed to prevent leakage forever.
The ability to easily “undo” a temporary abandonment is therefore obviously of great benefit to the well owner. Examples of temporary P&A barriers are mechanical plugs, weighted liquid columns, settling solid particles, and sometimes using a curing material that must be removed by milling and circulating the broken pieces out of the well. Another option is using QuartzPack, which is easily removed by using an open-ended drill string or coiled tubing and circulating the non-consolidating particles out of the well.
Permanent P&A barriers have traditionally been done with cement, and in some regions of the world this is still the only material with regulatory approval for permanent P&A. During the last decades, alternatives such as non-setting grouts (i.e. QuartzPack), cured molten metal and resins have also been qualified for permanent P&A, in order to overcome some of the challenges described earlier. It is also worth mentioning that even in descriptive regions where a minimum amount of cement must be used, this compliance cement plug can always be combined with any other compatible barrier element to improve long term performance.
The solution to the above-mentioned challenges is QuartzPack, a self-healing, flexible zonal isolation material. Although the QuartzPack barrier is qualified as an independent stand-alone well barrier element, it typically does not provide sufficient mechanical strength and bonding to affix borehole tubulars to the formation. This is very much by design, as manufacturing a material strong enough to withstand downhole forces during the life of a well is literally impossible.
The industry is making tremendous efforts in providing sophisticated new additives to address the problems, but we at FloPetrol Well Barrier are convinced that a cured, solid material can never be an ideal pressure seal. Without the ability to self-heal and reshape, all curing products suffer from an inevitable reduction of its performance in a long-term perspective.
Whether forces increase or strength decreases, when shear stress becomes larger than shear strength, a solid material will fail or fracture, and leakage may occur. QuartzPack is a gas tight, solid material whenever at rest, but it will float and reshape whenever external forces exceed its inherent strength. This is a mechanical and reversible process that ensures a robust, self-healing well barrier element for eternity.
Real life example
Learn about the science behind the solution: Permanent Abandonment of a North Sea Well Using Unconsolidated Well-Plugging Material.
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Vidar Rygg Chief Technology Officer
Mr. Rygg holds an MSc degree in Petroleum Engineering from NTNU, Trondheim and has worked in the Oil Service industry since 1994. He started his career as a Wireline Field Engineer in with broad field experience from land, offshore and ultra-deep water districts in Africa, Europe and Latin America. After leaving the field he became the Operations Manager for Baker Atlas in Brazil, and later a Sr. Application Advisor at Baker Atlas main office in Houston TX, before returning to Norway in 2006.
He started with Sandaband Well Plugging as a Project Manager in 2008 and now holds the position of CTO at FloPetrol Well Barrier when the former company was acquired in 2016.
Phone: +47 452 08 100