Removal of Hard Wax From Unpiggable Subsea Tiebacks
Proceedings Publication Date
Steve Wheeler
Steve Wheeler
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AIC abrasive Ice cleaning is a technique, mature in the food, water / wastewater industries, which is being developed for subsea Oil and Gas applications. This paper will detail successful trials on removal of hard wax under conditions required for intervention into to a previously unpiggable subsea tieback system.

A, high-solids ice slurry is pumped under pressure to deliver shear stress at the pipe wall, cleaning takes place through physical abrasion. Made of just water and a small percentage of a freezing point depressant, ice slurries do their cleaning, unblocking, debris entraining and transport before melting back into their original components (commonly salt and water); offering a physical clean thousands of times more effective than flushing, without chemicals or risk(s) of getting stuck.

The trials completed for the line in question had no conventional pigging infrastructure and due to the appearance of wax severely restricting production output trails on the suitability of ice slurries for removing the wax by pumping ice from the subsea tree back to the platform took place. The intention being to connect to the system from a floating vessel and push the debris from the subsea tree back to the platform for collection and processing. The outcome of these trails gives high likelihood of increased cleanliness and production performance in these types of situation.

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