LNG operator INPEX Australia has emerged as a global leader in best-practice risk management for subsea well completion safety, following 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 an integrated back-up heave compensation system. It’s 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 equipped with a passive Crown Mounted Compensator (CMC).
Why Subsea Well Completion Safety Is Under Industry Scrutiny
In a post-Macondo industry, the safety and environmental consequences of a landing string or completion workover riser rupturing beneath a floating drill rig during live operations are drawing more attention from management and industry technicians alike. Professional discussion groups such as the WellTesting Network (WTN) are driving the technical conversation, while major operators including 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, and others — are also recognising the severity of this issue, and have incorporated clauses into international standards requiring the consequences of accidental loads, including rig compensator lock-up, to be fully assessed as part of global riser analysis, with mitigation measures put in place accordingly.
Interestingly, landing strings or workover risers on wells in shallower water (broadly, under 300m) have less elasticity and flex less due to their reduced length, and can therefore pose a greater risk than true deepwater drilling applications.
The ICON ARTP is designed to provide compensation redundancy and overload protection, working 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, helping operators comply with regulatory requirements around eliminating single points of failure, with the ARTP providing full system redundancy — part of ICON’s broader Heave Compensation Solutions capability.
Crew and Rig Safety
Beyond its safety benefits, the ICON ARTP has streamlined coiled tubing and wireline operations. It’s a modular, self-contained system which, compared to traditional compensated coiled tubing lift frames, significantly reduces rig-up time on the critical path, and provides a safe, functional work window for rigging up 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.
Caption: The ICON ARTP B-Series helps make locked-to-bottom completions and flowback operations safer and more efficient.
Technical Background
Locked-to-bottom operations on floating drill rigs are inherently riskier than initial drilling activities. Floating drill rigs — semi-submersibles or drillships — don’t have the stability of ground-supported platforms or jack-up drilling rigs, and heave with every ocean swell as a result.
When conducting completions, production testing, or well clean-up, 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’s heave compensator has the potential to trigger a Major Accident Event (MAE).
Rig heave compensation systems were originally developed for drilling operations, but lacked the failsafe mechanisms and redundancy needed 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 avoided a safety or environmental catastrophe. The ICON ARTP has been engineered specifically to mitigate this hazard, so operators now have a second safeguard against rig heave movements — this kind of subsea well completion safety work sits within ICON’s broader Drilling, Completions & Well Test Support capability.
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, undergoes preliminary processing offshore to remove water and raw liquids, including condensate, before being exported to onshore processing facilities in Darwin via an 889km pipeline. The project’s design output is 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.
