As the CSG fields mature, the wells become more active and harder to suspend using conventional intervention fluids. This unit provides the capability to work on live wells under pressure improving cost efficiencies for clients through reduced downtime.

The rig assist snubbing unit is single trailer mounted, making it highly mobile. Transfield said the unit featured the "best available" electronic interlock safety system which reduces the risk of human error.

The unit, which is available from July for clients to contract on an as needed or fixed term basis, started work early this month and is currently snubbing for Santos in the Surat Basin.

Snubbing is a method for inserting tools and tubulars into wells under pressure that ensures that wells can be safely serviced without having to use conventional intervention with fluids.

The process, which involves the tripping of pipe into and out of a well with surface pressure, eliminates the need to use conventional intervention with fluids. There is no need to suspend production by using fluids thereby saving time and money associated with buying, transporting and disposal of fluids.

There is also no need to use rig time to suspend wells or recover the fluids to bring the wells back to production. Snubbing greatly reduces the need to handle fluids, thus reduces the chance of spills and disposal of contaminated fluids in environmentally sensitive areas is not a concern.

Snubbing also reduces formation damage, as there is no need to introduce non-native fluids into the producing formation.

Under this process, reservoirs are not subjected to overbalanced hydrostatic pressure and fluid losses into the formations are not encountered.

It also saves well formations from being damaged due to suspension fluids swelling clays or other sensitive formation materials, which in turn reduce production capability. The same completion and workover tasks can be performed while maintaining a situation beneficial to the formation, usually resulting in increased production.

The well can be tested to quickly determine the production capability of a zone being drilled into or worked on during a completion or workover. In some situations the well may be produced during the snubbing workover.

The unit is compact and relatively light, so the rig up and down time is minimised substantially. It also only requires a small crew size and efficient tripping time.

Two separate blow-out preventer accumulator systems are available for the well control equipment; and the well operator can use the rig assist only for the portions of the well program that require snubbing.

It also ensures lower day rates compared to other snubbing platforms.

It also has a green footprint, as it produces a safer environment on wells with low formation pressure that will not support a column of fluid like in CSG wells.

The unit's compact and portable equipment also has minimal impact on roads in environmentally sensitive areas.

Transfield says the rig assist snubbing unit is the latest snubbing technology in Australia.