ICON's safer subsea completions for Ichthys project

LNG operator INPEX Australia has emerged globally with best risk management practices while carrying out recent well completions and flowbacks for the Ichthys project, in the Browse Basin, offshore Western Australia.

LNG operator INPEX Australia has emerged globally with best risk management practices while carrying out recent well completions and flowbacks for the Ichthys project, in the Browse Basin, offshore Western Australia.

INPEX's engineers de-risked one of the more challenging operations in the offshore field development cycle following the successful deployment and operation of an ICON Advanced Riser Tension Protector (ARTP) on board the contracted semi-submersible drilling rig.

ICON Engineering successfully field tested the first ICON ARTP B Series, a coiled tubing lift frame with integrated back-up heave compensation system. It is specifically designed for use during well completions, production testing, clean-up and other "locked-to-bottom" operations on subsea wells from floating drilling facilities, especially those facilities equipped with a passive Crown Mounted Compensator (CMC).

Engagement by industry

In this post-Macondo world the safety and environmental consequences of a landing string or completion workover riser rupturing beneath a floating drill rig while conducting live operations are gaining more attention from management and industry technicians. Professional discussion groups such as the WellTesting Network (WTN) are driving the technical discussions while in the field, major operators such as ExxonMobil, ENI, Chevron and INPEX are leading by example in deploying back-up heave compensation and riser protection systems.

Classification societies, industry codes and regulatory authorities (DNV, ISO et al) are also recognising the severity of this issue and have incorporated clauses in international standards requiring the consequences of accidental loads, including rig compensator lock-up, to be fully assessed as part of the global riser analysis and mitigation measures to be put in place.

Interestingly, landing strings or workover risers on wells in shallow water i.e. >300m have less elasticity and flex less due to their reduced length, and hence can pose greater risk compared to true deepwater drilling applications.

The ICON ARTP is designed to provide compensation redundancy and overload protection, as it works as either a primary or back up system, in series with the rig's existing heave compensator. It can be retrofitted for temporary use on any floating rig and helps operators comply with recent regulatory requirement relating to eliminating single points of failure, with the ICON ARTP providing full system redundancy.

Crew and rig safety

In addition to its safety benefits, the ICON ARTP has streamlined coiled tubing and wireline operations. It is a modular and self-contained system which, when compared to traditional compensated coiled tubing lift frames, significantly reduces rig-up time on critical path, and provides a safe and functional work window for the rig-up of coiled tubing or wireline surface pressure control equipment.

ICON Engineering General Manager Equipment Steve Plain said the ICON ARTP was a direct result of designing safe and efficient solutions to the engineering problems raised in offshore field development.

"After several years of intensive development and testing, it is wonderful to have one of our units operational in the field, and pleasing to receive such positive feedback from our client and the rig crew regarding the practical equipment design, and the improvements in operational efficiency and safety over traditional methods," said Mr Plain.

"We're very pleased INPEX saw us as part of the solution to managing the completions risk on this field," he said.

Technical background

Locked-to-bottom operations on floating drill rigs are inherently more risky than initial drilling activities. Floating drill rigs, such as semi-submersible drilling rigs or drillships do not have the stability of ground supported platforms or jackup drilling rigs, and as such, heave with every ocean swell.

When conducting completions, production testing or cleaning up a well, heave compensation is essential to prevent enormous forces being exerted on the landing string or workover riser as the rig heaves. Compensator failure or inadvertent lock-up of the rig heave compensator may have potential to trigger a Major Accident Event (MAE).

Rig heave compensation systems were developed for drilling operations, but lacked the necessary failsafe mechanisms and redundancy to safely carry out locked-to-bottom operations. There have been numerous cases reported outside Australia where a rig's heave compensation system has inadvertently locked, and it has only been circumstance and good fortune that has avoided a safety or environmental catastrophe. The ICON ARTP has been engineered to mitigate this hazard, so operators now have a second safeguard against rig heave movements.

About the Ichthys LNG project

The Ichthys LNG Project is a joint venture between INPEX (operator), TOTAL, Tokyo Gas, Osaka Gas, Chubu Electric Power and Toho Gas. Gas from the Ichthys Field, in the Browse Basin offshore Western Australia, will undergo preliminary processing offshore to remove water and raw liquids, including condensate. The gas will then be exported to the onshore processing facilities in Darwin via an 889km pipeline. The Ichthys LNG project is expected to produce 8.4 million tonnes of LNG and 1.6 million tonnes of LPG per annum, along with approximately 100,000 barrels of condensate per day at peak. Detailed engineering, procurement and construction (EPC) of the Ichthys LNG Project is ongoing and production is scheduled to commence by the end of 2016.

For more information:
Contact Name: Steve Plain
Position: GM, Equipment
Email: [email protected]
Phone: +61 (08) 6313 5500

"The ICON ARTP being hoisted into position, with its bail arms visible beneath it."(as seen on the top left) and "The ICON ARTP B helps makes locked-to-bottom completions and flowback operations much safer and more efficient."(as seen on the bottom left)