Shale production from Oklahoma basins increased 23 percent from the fourth quarter, rivaling North Dakota by nearly a quarter, Continental Resources said.

In terms of production, Continental's output from the Bakken shale in North Dakota was up 4 percent from the fourth quarter and 39 percent year-on-year to an average 135,538 barrels of oil equivalent per day. From the so-called SCOOP basin in Oklahoma, production increased 23 percent from fourth quarter and 70 percent year-on-year for an average 49,882 boe per day.

Continental said last year its acreage in the SCOOP basin was a "significant" part of its growth strategy.

Data from oil field services company Baker Hughes show 108 active rigs in Oklahoma and all of them are exploring for oil. Oklahoma is the No. 5 oil producer in the nation. Energy consultant Wood Mackenzie said investments in the region should top $4 billion for 2015.

The Oklahoma shale area is on par with the Eagle Ford basin in Texas and Bakken with production expected to pass 1 million barrels of oil equivalent per day by 2020.

Continental, the No. 2 oil producer in North Dakota, posted a net loss of $186 million for the fourth quarter compared with a net income year-on-year of $359.1 million. The company, which has headquarters in Oklahoma, is on par with its peers in the industry posting a loss in a weakened crude oil market.

The company said its costs, however, are on the decline. Costs for operating in the Bakken shale in North Dakota and in the SCOOP basin are down each by around 14 percent year-on-year.

Chairman and Chief Executive Officer Harold Hamm said he was optimistic about the company's momentum moving forward in 2015.

"Looking ahead, U.S. oil production is starting to roll over, as anticipated," he said in a Wednesday statement. "Given the depth and quality of our assets, Continental is well-positioned to resume growing cash flow and earnings when the oil price environment improves."