Wellhead Severance and Recovery

Using Remotely Operated Ultra High Pressure (UHP) Water Jet Cutting Tool

Overview

Four plugged and decommissioned wellheads were required to be removed off the North West Shelf, Western Australia.

The wellheads were located 85m below sea level which required specially developed precision cutting techniques to be developed. As a leading innovator in high and ultra-high pressure water jet cutting, iasgroup was approached to develop a system capable of cutting the wellheads safely and efficiently, without the use of explosives.

Scope

The project had the following specifications:

Structure	String wellheads
Application Type	Severence and recovery of wellheads
Operating Environment	Subsea, 85m below sea level
Quantity	4 wellheads
Cross Section	Steel circular hollow section containing 3 steel liners separated by concrete
Cut Dimensions	Diameter 762mm
Method	Remotely Operated UHP Water Jet Cutting Tool

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Solution

• In-house design developed specialised cutting tooling and abrasive delivery systems
• Sub-Sea Cutting (SSC) system using 40,000psi abrasive injection jet (AIJ) technology, capable of cutting through multi-liner wellheads
• SSC integration with offshore rated UHP water pumps and enclosures
• State-of-the-art quality control, testing and monitoring systems

Benefits

• Improvement in safety due to removal of divers from the cutting location
• Tool developed to operate at twice the pressure of other existing systems, improving cutting speed
• Reduced operating costs of up to 50% when compared to alternative cutting solutions at time of project
• Improvement in quality and efficiency through state-of-the-art automated precision cutting and monitoring systems
• Cutting and removal of wellheads completed safely, on time and on budget
• Reduction in disturbance to habitat through non-explosive method of wellhead removal