A large gas discovery in the Dutch North Sea could be even bigger after an exploration drill beat expectations, one of the companies involved said, a shot in the arm to the traditionally gas-rich Netherlands where output has seen declining.

The Ruby well, the first drilled in the area about 20 km (12 miles) off the northern Dutch coast since the early 1990s, produced gas at a higher rate than expected thanks to “excellent” geological quality, said John Martin, CEO of Hansa Hydrocarbons, the operator of the field.

The wider license, within which the Ruby well is located, is estimated to contain about 2 trillion cubic feet of gas, more than the Netherlands’ annual gas production.

Martin told Reuters he was “optimistic” this figure could be upgraded following expectation-beating results from Ruby.

“Not only have we proved up a substantial volume but it also confirms the extent of the hitherto poorly understood basal Rotliegend sands in the offshore basin,” he said.

Hansa Hydrocarbons, a London-based exploration company backed by U.S. private equity firm Avista Capital Partners, is partnering on the project with Dutch oil and gas explorer Oranje-Nassau Energie, which has a 40% stake, and state entity Energie Beheer Nederland, with a 20% stake.

Dutch gas production has been steadily declining, partly due to a lack of new developments and partly to a government-mandated cap on output from the country’s largest field at Groningen after it was established that it triggered earth tremors.

Offshore