North Dakota's oil production slipped in March, but the state's minerals director says he's optimistic about the months ahead.

Oil prices have risen to heights not seen since November 2015. And petroleum production is expected to be strong this summer, Lynn Helms, director of the North Dakota Department of Mineral Resources, said in a conference call with reporters.

North Dakota, the nation's second-largest oil producing state, pumped out 1.16 million barrels per day in March, down 1.1 percent from the previous month, according to data released Tuesday. Severe weather contributed to the decline, Helms said.

"March wasn't bad, but it certainly wasn't good enough."

Oil prices have risen at a strong pace in recent months, with West Texas Intermediate — the benchmark U.S. crude — closing around $71 per barrel Tuesday. Last June, WTI was around $44 per barrel.

Helms noted that the downside risk for oil prices in 2018 has diminished. OPEC is on course to maintain production cuts through late in the year, while Venezuela's exports have collapsed. Also, U.S. sanctions on Iran are likely to keep a lid on supply, Helms wrote in a monthly report.

Oil companies are currently deploying 60 drilling rigs in North Dakota, unchanged from April but up three from February. A rising rig count indicates operators are drilling more oil wells.

With unemployment rates at low levels, the North Dakota oil fields are becoming desperately short of workers, Helms said. "There are just enough fracking crews to keep up with the 60 rigs we have today. There will not be enough to service 70 drilling rigs."

Helms noted that a recent job fair for oil workers in North Dakota attracted about 200 people for 2,000 jobs open in the petroleum industry.