BISMARCK, N.D. (AP) — North Dakota's top oil regulator says the state's booming oil patch has about 35,000 wells yet to be drilled and companies increasingly are making inroads with speedier but more costly technology.

State Department of Mineral Resources director Lynn Helms says drillers are finishing wells at a rate of eight daily. That's up from about one a day just five years ago

But Helms says the advanced technology has come at a cost. He says a well costs about $10 million to complete. That's about double the cost of a well drilled in 2007.

Helms says much of the increase comes from a shortage hydraulic fracturing crews and soaring cost of so-called proppants that provide a pathway for oil to flow to the well.