The U.S. Department of Labor has ordered Halliburton to pay 27 employees in Wyoming $506,000 in back wages as part of an $18.3 million settlement with employees nationwide, an agency spokeswoman said.

During a years-long effort, the department's Wage and Hour Division found Halliburton incorrectly categorized employees in 28 positions as exempt from overtime, according to a news release.

Those salaried positions included field service representatives, pipe recovery specialists, drilling tech advisors, perforating specialists and reliability tech specialists. Halliburton did not pay them overtime when they worked more than 40 hours in a workweek in violation of the Fair Labor Standards Act, according to a news release Tuesday.

Salaried employees are not necessarily ineligible for overtime. The Fair Labor Standards Act outlines what kinds of employees are eligible for overtime.

The company also failed to keep accurate records of hours worked by these employees.

The settlement requires Halliburton to pay $18,293,577 to 1,016 employees.

Spokeswoman Tania Mejia said employees in Halliburton's home state of Texas will receive $6.5 million in the settlement, and employees Oklahoma will receive $1.3 million.

"The Department of Labor takes very seriously its responsibility to ensure workers receive the wages they have earned, U.S. Secretary of Labor Thomas E. Perez said in a prepared statement Tuesday.

"This settlement will put millions of dollars where they belong — in the pockets of hardworking people and their families," Perez said. "Employers who don't pay their employees the wages they have earned don't just hurt their workers, they undercut employers who play by the rules. That's why we work every day to help level the playing field."

According to its website, Halliburton is one of the world's largest providers of products and services to the energy industry. The company has more than 70,000 employees in 80 countries.