Energy companies working in the North Sea need a sense of fiscal confidence no matter how the Scottish referendum turns out, Wood Mackenzie said Wednesday.

Scotland holds a one-sentence referendum Thursday for independence from the United Kingdom. The government in Edinburgh said it could support itself with oil and gas revenue while powering an independent Scotland with renewable resources.

Energy consultant group Wood Mackenzie said fiscal uncertainty is a primary concern for oil and gas companies working in the region.

"Regardless of which government is in charge of the industry, companies will seek stability and simplicity around existing fiscal terms as well as tax incentives for harder to produce reserves," it said. "Industry engagement will be paramount to maximizing value for both government and companies."

Wood Mackenzie, which has headquarters in the Scottish capital, said much of the oil and gas remaining in the region's waters would be in Scottish territory upon independence.

Mid-term production from regional waters should hold relatively steady with around 1.3 million barrels of oil equivalent expected per day in 2018. After that, production dips below 1 million by 2023, which is less than a quarter of the peak production reached in 1999.

The government of British Prime Minister David Cameron said the energy sector would be better off if Scotland stayed in the United Kingdom.