Due to the costs of gathering natural gas from the ocean's depths and transporting it to processing centers on land, big oil companies are starting to develop facilities that will perform these actions out at sea. Royal Dutch Shell (RDS.A) was the first to announce that it had begun construction back in October 2012, but its larger rival ExxonMobil (XOM 0.42%) is not to be outdone.

Partnering with Exxon will be BHP Billiton (BHP -0.34%). Together, these two companies hope to begin processing millions of tons of liquids, LNG, and condensate by 2020 at the earliest. With that long time horizon, both companies are hoping that such a large investment will still be worth it.

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