(Reuters) - The FBI said on Thursday it will open a field office in Williston, North Dakota, capital of the state's oil patch and an area grappling with a rise in drug use and sex trafficking.

At least two agents from the FBI, the national law enforcement agency, will have jurisdiction over western North Dakota's oil counties, where the population has spiked due to the development of the Bakken shale formation, one of the world's largest reserves of crude.

Williston alone has seen its population more than double since 2010 to roughly 30,000. State demographers forecast that, even with the recent dip in crude oil prices, the population will double yet again to 60,000 by the end of the decade.

Alongside the population growth has been a rise in types of crime not common for this part of the United States. Last year, for instance, a Williston man was charged with human trafficking, the first time such charges had been filed in the city. Cocaine, methamphetamine and other drug use has also spiked.

"The FBI will be in a better position to effectively address these issues in this region of North Dakota through this new office," Special Agent in Charge Richard Thornton said in a press release.

The announcement confirms what had been an open secret in Williston for months, as the FBI hinted last year it wanted to expand into the city but struggled to find affordable housing for staff.

The new field office marks a victory of sorts for state and federal officials, who for years said the area was woefully underrepresented by law enforcement.

"When you have something like the Bakken, where there is an additional amount of money flowing in that wasn't there before, organized crime and criminal activity are going to follow," said North Dakota Senator Heidi Heitkamp, a Democrat.