The former wife of Oklahoma oil billionaire Harold Hamm says that her divorce award of nearly $1 billion isn't enough, and that the judge is to blame.

Sue Ann Arnall appealed an Oklahoma court's divorce decree, arguing that the quarter-century she spent with Hamm as he built a shale-oil fortune entitled her to more than the $972 million she was awarded by a judge, who she claimed made unsupported rulings in the 10-week divorce trial.

Divorce attorneys expressed surprise after the ruling that a billionaire's spouse didn't get as much as 30 percent of the couple's assets when the marriage was dissolved last month. A stake that size could have been worth as much as $5.1 billion, said Seymour J. Reisman, a New York divorce specialist.

Instead, the ex-wife of the Continental Resources Inc. chairman got much less, and none of Hamm's 68 percent ownership of the company. Hamm, 68, is worth $10.7 billion, according to the Bloomberg Billionaires Index.

"As Sue Ann has stated previously, 6 percent is not a fair proportion of the wealth the couple accumulated during their marriage," Ron Barber, her lawyer, said Friday in an e-mail.

The court ruling was a victory for Hamm, who was allowed to retain control of the company in part because witnesses testified he was the driving force behind Continental, with one calling him the "captain of the ship."

Hamm, who helped develop the use of sideways drilling and hydraulic fracturing, was an early proponent of the Bakken oil-shale field. Continental is now the biggest Bakken operator, with a 1.2 million-acre leasehold that exceeds even that of ExxonMobil Corp., the world's largest energy producer by market value.

In her appeal, Arnall zeroed in on Judge Harold Haralson's decision to give Hamm all of their Continental stock, along with most of the increase in value the shares underwent while they were married. Hamm also got the bulk of their other investments.

Arnall also faulted the judge for not explaining how he calculated her "contribution to the marital estate in her roles as a wife, mother, and public supporter of her prominent husband."