Underwater flooding = more oil

A technique to improve oil recovery used in many older onshore oil fields is being put to work by Shell to squeeze more out of a pair fields more than 100 miles offshore in the Gulf of Mexico and in waters more than 3,600-feet deep.

Water filtration, injection and sulphate removal modules on the deck of the Ursa platform. Photo courtesy of Shell.

Shell started its first water injection of the Ursa/Princess fields on July 3, which it plans to continue for years to come. According to the company the project will yield an additional 30,000 barrels of oil per day from the fields, extending their life by 10 years. About 400 million barrels have been recovered from the fields to-date.
The company clams the Ursa/Princess Waterflood is “one of the largest construction projects on an existing platform in the Gulf of Mexico.” If you’ve ever visited a platform you know that logistics of just getting people onboard is complicated and expensive, so juggling ongoing production with a new kind of project not typically done 100 miles offshore must have been, um, interesting.
Here’s Shell’s press release description of waterflooding:

“Waterflood is a method of secondary recovery in which water is injected into the reservoir formation to displace additional oil. The water from injection wells re-pressurizes the formation and physically sweeps the displaced oil to adjacent production wells”

The Ursa/Princess Waterflood injection system injects filtered and treated sea water through two flowlines to three subsea sites, one to an existing well site northwest of the Ursa platform, one to an existing well southeast of Ursa and one to a new well site northeast of Ursa. Producing wells will include three Princess subsea wells and as many as six Ursa wells.