The Riser Insertion Tube Tool involves inserting a four-inch diameter tube into the Horizon’s riser (21-inch diameter pipe) between the well and the broken end of the riser on the seafloor in 5,000 feet of water.
The insertion tube would be connected to a new riser to allow hydrocarbons to flow up to the Transocean Discoverer Enterprise drillship located on the surface. The oil will be separated and then safely shipped ashore.
The insertion tube device is now on location and is in the process of being prepared for installation.
This system was designed to minimize the formation of gas hydrates at 5,000 feet below the surface. Gas hydrates – similar to ice crystals – thwarted an earlier attempt to divert the flow of oil through a larger subsea containment dome.
The riser insertion tube will also have methanol injection to prevent the formation of gas hydrates in the ultra-deepwaters. The MMS and the Unified Area Command have approved use of methanol injections in this system.
In addition, the new riser will be heated with sea water to promote the flow of oil from the ocean floor to the drillship above. This is a commonly used practice in ultra-deepwater production because the temperatures at these water depths tend to stymie the flow of oil.
The operation is complex and has not been done before at such depths.
How it works
- The insertion tube is a five foot long steel pipe about four inches in diameter with specially designed rubber baffles. The tube will be inserted into the Horizon’s riser to provide a direct connection.
- The direct connection, combined with the injection of methanol, will minimize the formation of hydrates that could block the flow of hydrocarbons.
- The riser insertion tube will be installed about 600 feet from the wellhead.
- The insertion tube will be connected to a 5,000 foot riser that will convey the hydrocarbons to the Transocean Discoverer Enterprise drillship on the surface.
- Once in place, oil will flow up into the Enterprise’s riser to the surface.
- Once at the surface, the hydrocarbons will be processed and oil will be separated from water and gas. The oil will then be temporarily stored before being offloaded and shipped to a designated oil terminal onshore.
- The Enterprise is capable of processing 15,000 barrels of oil per day and storing 139,000 barrels.
- A support barge will also be deployed with a capacity to store 137,000 barrels of oil.
What’s happening now?
This riser insertion tube is on site and is being prepared for installation in the next few days. ROVs will assist in the installation and connections to the riser (tubing) back to the surface.
