Techongy | Surface intervention technology achieves more than 60% cost and efficiency in North Sea oilfield decommissioning project

Unity, Europe's largest provider of well integrity solutions, is supporting a major international operator's North Sea well 

decommissioning project. This project uses a unique compact, versatile ground intervention system (SIS). The vaule of 

the project is very large.

SIS has completed workover operations on the first well, where the SIS was deployed off-line, running a shallow bridge 

plug in perparation for removal of the wellhead equipment. Unity's stand-alone technology replaces the need for 

traditional workover equipment, providing operators with significant cost, time and efficiency savings by operating 

below deck when conducting P&A drilling operations. The intervention was implemented approximately 60% faster and 

saved 66% in cost and personnel compared to traditional methods.

On this project, deck and bed space was limited due to drilling operations, but Unity's compact SIS technology required 

only two technicians to operate, providing an ideal shallow workover solution. The SIS has a small footprint and is easy 

to install in confined well areas below the rig. The SIS and pressure control package was installed below deck using a 

small A-frame crane provided by Unity. The plug was installed for the first time and the device was all installed within 

24 hours.

Gary Smart, CEO of Unity, said: “SIS has enormous utility and has been used by several operators in milling, inspection, 

fracturing and P&A operations, compared to traditional shallow well intervention techniques. Material savings. This 

technology will soon be combined with our latest release of the Tight Shear Seal Valve technology, further reducing the 

footprint and weight of the overall system.”

(Unity's ground intervention system, part of the company's range of compact technologies, offers efficiency savings 

of between 50-75%)

into a compact mobile package. It is simple to operate, quick to deploy, and can well assist in well completion, plugging, 

and abandonment operations through bridge plug setting, tree and wellhead equipment removal. Additionally, it can be 

used to carry out inspection and remedial work on internal surfaces prior to removal of equipment and piping. The SIS 

features powerful hydraulic motors that drive push, pull and rotate functions that rival the performance of cable or coiled 

tubing.

Unity has built an impressive track record of well decommissioning projects, now expanding to 150 wells, with 230 more 

in pipeline over the next 3 years, including plug setting, isolation verification, Christmas tree and surface wellheads Removal 

of equipment, installation of hanging flanges and manufacture of wellhead removal tools. The company has extensive 

experience in using various models of surface wellhead equipment.

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