Whiting Petroleum Corp.’s (NYSE: WLL) $3.8 billion purchase of Kodiak Oil & Gas Corp. (NYSE: KOG) will create the dominant crude oil producer in the richest U.S. shale region as energy explorers seek access to future drilling opportunities, Bloomberg said July 14.

Kodiak stockholders will receive 0.177 of a Whiting share for each Kodiak share they own, which is the equivalent of $13.90 based on the acquirer’s July 11 price, the Denver-based companies said in a statement July 13. Including $2.2 billion in debt, the total transaction is valued at about $6 billion.

The agreement will vault Whiting ahead of Oklahoma billionaire Harold Hamm’s Continental Resources Inc. (NYSE: CLR) as the premier oil supplier in the Bakken Shale in the northern Great Plains. Whiting is buying a company that more than doubled production last year, while Whiting’s own output growth slowed as costs to bring new wells online surged.

Competition for Bakken assets is fierce because the geologic formation beneath North Dakota and Montana is the most prolific U.S. shale region on a barrels-per-well basis, according to data compiled by Bloomberg. Because most drilling rights on privately owned land in the area have already been snapped up by corporations, explorers can only expand through acquisitions.

“This is the right deal, at the right time,” James Volker, Whiting’s chairman and CEO, said in a telephone interview July 13. “It massively enhances the scale of the two companies combined.”

Kodiak rose 4.7% to $14.90 at 9:34 a.m. in New York. Before July 14, the stock had advanced 27% for the year. Whiting climbed 5.2% to $82.66.

Kodiak’s decision to sell now is “curious,” Tim Rezvan, a New York-based analyst for Sterne Agee & Leache Inc., wrote July 14 in a note to clients. A second-quarter earnings miss might explain the move, he wrote. The company hasn’t announced a date to release second-quarter results.

The Bakken region of North Dakota and Montana has been a hotbed of U.S. oil exploration after innovations in sideways drilling and hydraulic fracturing, or fracking, enabled access to previously impenetrable rock layers.

New wells drilled in the Bakken pump an average of 510 barrels of oil a day (bbl/d), compared to 479 bbl/d for wells in the Eagle Ford Shale in South Texas, and almost four times as much as Permian Basin wells in West Texas and New Mexico, according to data compiled by Bloomberg.

The relatively high crude output means explorers may recoup their drilling costs and begin booking profits from Bakken wells faster than those in other formations.

The Kodiak purchase will give Whiting drilling rights across 855,000 net acres, surpassing Exxon Mobil Corp. (NYSE: XOM) as the second-biggest leaseholder in the area, according to data compiled by Bloomberg.

In North Dakota, home to some of the richest sections of the Bakken, daily crude output exceeded 1MMbbl in April for the first time in history, making the state a bigger oil supplier than Ecuador or Qatar, both members of OPEC. In the U.S., Texas is the only state that pumps more crude than North Dakota, according to the Energy Department.

The per-share price represents about a 5.1% premium to Kodiak’s volume-weighted average over the past 60 days, the companies said.

An enterprise value for Kodiak of $6 billion is about 8.8 times EBITDA last year. That compares with a median of 11.6 times EBITDA for U.S. oil and exploration deals since 2009 valued at more than $1 billion, according to data compiled by Bloomberg.

Whiting and Kodiak executives have known each other for years, but began to evaluate a deal in recent months, Kodiak chairman and CEO Lynn Peterson said in an interview July 13. “We both reside here in Denver; our offices are across the street.”