GRAND JUNCTION — The two leading natural gas producers in western Colorado’s Piceance Basin are squaring off in court over allegations of trespass involving horizontal drilling.

Encana Corp. has sued WPX Energy, saying WPX knowingly drilled a well that passed horizontally through Encana’s mineral estate in the Parachute Creek area without getting Encana’s permission.

WPX, Encana and other companies have been increasingly using horizontal drilling to explore for and develop gas from deep Mancos-Niobrara shale formations. They have drilled down into the shale and then out sometimes miles laterally through the formation, which is then hydraulically fractured to tap the gas.

Encana’s lawsuit says WPX drilled the well down through adjoining lands, then out laterally through Encana’s mineral estate in the Niobrara shale before reaching minerals beneath land on the other side of Encana’s minerals, the Grand Junction Daily Sentinel reported.

WPX hasn’t yet hydraulically fractured the well, and Encana is seeking an injunction barring it. The lawsuit says WPX has said it plans to complete the well and produce from it despite Encana’s demands that it not produce through, or from, Encana’s mineral estate.

The companies declined to comment, as is standard practice for both of them in the case of litigation.

The lawsuit says that nothing in the Colorado Oil and Gas Conservation Commission’s rules allows or authorizes mineral trespass, but the agency also doesn’t have jurisdiction to adjudicate mineral ownership or trespass claims.

The commission requires Niobrara wells to be located at least 300 feet from existing ones, which limits Encana’s ability to develop its minerals near the well in question, according to the lawsuit.