There would likely be a lively debate about the start of the subsea processing era.

Some might date it back to the Troll Pilot project, the subsea separation and water reinjection system offshore Norway by Norsk Hydro in the late 1990s, or maybe even Lufeng 13-1, Statoil’s Chinese floater project from the mid-1990s that featured a seabed pumping module to assist in the recovery of the heavy-ish oil.

For me, it would probably be Statoil’s Tordis subsea separation, boosting and injection system, which was ordered in 2005 and came onstream three years later. Troll Pilot was a bit of a false dawn—it seemed to presage the arrival of more such systems, but it did not. While it was more than a glorified R&D project—Hydro had a genuine requirement for a solution to an apparent projected overabundance of produced water at Troll C—it would be five years before another application came along.

Tordis was, at least according to Statoil, the first commercial application of subsea separation, meaning the system would recover an additional 35 MMbbl of oil (at 2005’s $55/bbl oil price) with the revenue from that production far exceeding the $275 million price tag.

Like its predecessor at Troll, it had a teething problem that had nothing to do with the technology of the separation system. At Troll Pilot, it was the shrouding on the high-power connector that failed and set back full operation by more than six months, while at Tordis, it was a water disposal well drilled into the wrong (i.e., unsealed) strata, which percolated to the seabed and then to the surface.

So why rehash these old stories? Subsea processing is seen as an expensive add-on to facilitate the extra production that makes deepwater developments profitable, and it might just be shelved in the current climate. So is it still economically viable and accessible in a low-price era?

There might be a grain of truth in the “high-cost” perception, but it is not the whole story.

Two points: First, what followed Tordis was Total’s Pazflor, a development that aimed to produce from multiple reservoirs with two different types of oil. Without the subsea separation system, the heavier Miocene oil could not be produced. This also was the first development in which subsea separation was in the base case.

In addition, there have been a considerable number of boosting systems, such as on Ceiba and Topacio in Equatorial Guinea, Azurite in the Congo and Exeter-Mutineer in Australia, that made the projects fly.

Of more significance is the potential cost-saving element in another of the technologies under the subsea processing umbrella—subsea raw water injection (SSRWI).

This has been one of my pet favorites, which has so much going for it now and which will increase as time goes by, with ever-more long-distance tiebacks planned. There have been several SSRWI projects with different raisons d’être. The first was Columba in the U.K. sector, where a major brownfield engineering exercise was avoided by putting everything on the seabed with the only link to its host being a power umbilical.

The second was Tyrihans, where Statoil avoided the cost of a 43-km (27-mile) pipeline and the requisite topside water cleanup, pumping and power equipment to provide water for injection.

It is a no-brainer. SSRWI is the coming technology at any price.

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