Aberdeen-based Helix Well Ops (UK) Ltd. completed the industry’s first riser-based coiled tubing intervention project from a mobile offshore drilling unit (MODU) class light well intervention vessel (LWIV).
The Well Enhancer, from Helix.
The pioneering project was conducted from the company’s MODU class mono-hull vessel Well Enhancer.
Launched in 2009, the 132m long vessel was designed specifically to perform complex operations such as wireline and coiled tubing interventions and has undertaken over 130 well interventions in the North Sea, the Atlantic Ocean in Irish waters and offshore West Africa.
Delivering coiled tubing well intervention from this type of vessel has been anticipated by the oil and gas industry for some time. In the quest to enhance oil recovery and reduce the costs associated with subsea well abandonment, it may be seen as a potential industry game changer due to its cost effectiveness over traditional rig-based methods.
Helix Well Ops is a global provider of subsea well intervention and operates a fleet of three mono-hull well intervention vessels – Seawell, Well Enhancer and the chartered Skandi Constructor. The company works with the oil and gas industry to deliver a range of well maintenance, production enhancement and well abandonment solutions to boost efficiencies.
Earlier this summer, the firm conducted the first live riser-based coiled tubing intervention project from a LWIV, which took place in the central North Sea in water depths of 83m (275ft). The project involved drifting and milling to 4400m (14,500ft) and performing a reservoir saturation tool (RST) log before perforating 267m (877ft) of reservoir section in four runs, followed by a venturi clean-up.
The coiled tubing unit was provided by Altus Intervention and features its bespoke fatigue management system. When combined and interfaced with Well Ops’ patented technology and equipment the unit virtually eliminates the effect of vessel motion and reduces the coil fatigue towards that of a fixed installation or platform.
Initial results of the intervention indicate an increase in daily oil output of over 1500 boe/d. Helix Well Ops’ coiled tubing intervention system is designed to operate in water depths of between 80m and 200m and can deploy a variety of coil sizes up to 2⅜in and 20,000ft in length.
“This recent riser-based coiled tubing project represents an important step in the development of the intervention industry. It clearly demonstrates the production potential and cost-effectiveness that coiled tubing intervention can deliver,” Steve Nairn, Helix Well Ops UK vice president said. “Mobilizing a rig to undertake coiled tubing interventions is a complex process and the time and costs involved could outweigh any potential benefit. Unsurprisingly, coiled tubing intervention on subsea wells has been an underutilized practice in the North Sea as a result. However, it is hoped that our proven technology will enable operators to open up opportunities that were previously thought uneconomical or unviable.”
“Every business operating in the North Sea has a responsibility to contribute to maximizing the recovery of hydrocarbons. Through our fleet of well intervention vessels and innovative technologies we are playing our part in this,” he said.