Exxon Mobil faces up to a $1 billion fine over allegations it sabotaged Texas oil wells it leased but no longer wanted by plugging them with cement, trash and dynamite to prevent others from tapping in.

The unusual case is under review by the Texas Railroad Commission, which oversees drilling and leases in the oil-patch state.

Deliberate plugging of leased wells, even if they’re anemic, is prohibited by numerous regulations in Texas. Even abandoned wells often have residual crude trapped in shale that can be recovered.

“Never in 30 years in the industry have I ever heard of anything like this,” said Peter Beutel, energy analyst at Cameron Hanover.

The allegations came from the O’Connor family, a Texas oil dynasty that owns the oil fields and ranch land near Corpus Christi, where the plugged wells were left behind after Exxon’s leases expired in the early 1990s.

The leases then were taken over by Emerald Oil & Gas, which said the effort to re-enter the wells ruined drill bits and other equipment. Litigation was tossed four months ago by the Texas Supreme Court, which said the O’Connor family waited too long to sue.

Regulators could make a decision in about two weeks against the world’s biggest energy company, which has legendary political pull in the Lone Star State. If the company is slapped with the fine, it would amount to about eight days’ worth of profits based on 2008’s record profit of $45.2 billion.

Exxon said the allegations were “groundless” and involved a “commercial dispute.” It said the wells were plugged to protect groundwater from contamination.

The dispute of the oil titans goes back a half-century, when the O’Connor family leased its lands to Exxon’s forerunner — Humble Oil — earning more than $40 million in royalties for the next four decades.

In 1990, Exxon demanded a 50 percent cut in the royalty payments, which the family refused. Exxon a year later began plugging the wells, saying they were no longer profitable.

paul.tharp@nypost.com