ENID — Harold Hamm is an Oklahoma oil man.

He was born and raised in the state, one of 13 children, the son of a sharecropper who grew up in a one-bedroom home with no indoor toilet.

Hamm cut his professional teeth in the oil fields of northwest Oklahoma, drilling his first well in 1971.

Today his company, Continental Resources, still is drilling for oil in Oklahoma, in the Anadarko Woodford, Anadarko Atoka and Anadarko Basin. But in the late 1980s the company began looking elsewhere for domestic oil.

“I felt like I knew too much about natural gas,” said Hamm, Continental’s chairman and chief executive officer. “We saw some things occurring within the regulatory environment that concerned me. It concerned me that all the nation’s reserves of natural gas were going to be dumped on the market at one time, and they were. I thought the intrinsic value to the market of natural gas in the U.S. was really going to be cheap for a long time, and it was.”

Continental bought a package of land from Exxon and drilled its first Bakken formation test well in 1989 in Montana near the Canadian border. It was a vertical well and was not a success.

“We had the Bakken in mind, even at that time,” Hamm said. “We went up there, No. 1 to look for oil, No. 2 to look for very large fields.”

They found one in the Cedar Hills field in southwestern North Dakota, the first field ever drilled in the U.S. strictly with horizontal wells. After drilling straight down several thousand feet, the bit then would turn and drill laterally some 5,000 feet.

“We found out horizontal drilling worked,” Hamm said. “It was low perm (permeability) rock and by exposing a lot of that low perm rock to the drill core, it would produce commercially. That made the whole play work.”

Hamm then began looking for the next large field in the Montana-North Dakota re      gion. In 1996 a Continental geologist mapped the Elm Coulee field, but because of the tight nature of the rock in the area it didn’t seem commercially viable for ever horizontal wells.

Another operator drilled in the field, and Continental took notice.

“We just said, ‘Let’s just see if he does any good,’” Hamm said. The first 18 wells didn’t show much promise, until the operator began using different techniques to fracture the oil-bearing rock.

“As soon as that happened, we jumped in and leased,” Hamm said, “and wound up with almost 150,000 acres. We saw how that worked, and we started getting some really nice wells. I decided that, if that worked, there’s a lot more Bakken. I asked my exploration group, ‘Where’s the rest of it?’”

The answer was the Nessen Anticline, which was discovered in 1951 and had seen production nearly ever since. Continental leased more than 300,000 acres along Nessen Anticline and in 2003 drilled the Robert Heuer well, the first horizontal well in the Bakken play in North Dakota.

“It wasn’t just a barnburner, but it showed us that it would produce,” Hamm said. “It gave us a lot of hope.”

That hope turned into reality. Today Continental is the biggest player in the biggest crude oil play in the lower 48 states — according to U.S. Geological Survey — with 674,000 acres under lease in the Bakken region of Mon-tana and North Dakota.

“It’s turned out to be the premiere oil play in America today, any way you look at it,” Hamm said.

Horizontal drilling is effective but expensive. A horizontal well can cost $6 million to drill, some three to four times the cost of a vertical well.

Hamm hopes to use a lesson learned in the Bakken to help increase profitability of drilling for oil in Oklahoma. In North Dakota, Continental employs 1,280-acre spacing for its drilling operations, with as many as four wells, while Oklahoma allows only 640-acre spacing.

Hamm is hoping to change the laws in Oklahoma, in part because it costs so much more to drill a horizontal well in the dense limestone of wes-tern Oklahoma than it does the more permeable rock in Montana and North Dakota.

“If you think we need it up there, we really need it here,” Hamm said. “They have had a state statute that you couldn’t have over 640-acre unit, and boy it just makes no sense for this type of development. It seems like you’re always having to change the world.”

Hamm said there is support in the Legislature for changing the limits for well spacing.

“We are working with landowners and royalty owners and everybody, because it’s in their best interest to do this,” said Hamm.