Nov 18 (Reuters) - U.S. energy company Summit Midstream Partners LP said on Thursday its Double E natural gas pipeline in New Mexico and Texas had entered service.

Summit owns a 70% equity interest in the joint venture that built Double E and will operate the pipeline. The project cost an estimated $450 million, according to federal energy data.

Double E is a 135-mile (217-km) pipeline that will transport about 1.35 billion cubic feet per day (bcfd) of gas from southeast New Mexico and west Texas to downstream pipeline interconnections in the Waha Hub region in Texas.

One billion cubic feet of gas is enough to supply about 5 million U.S. homes for a day.

Double E is one of several gas pipelines to enter service this year in the Permian basin, the biggest shale oil region in the United States, and should help operators in the region continue to reduce gas flaring.

Drillers in the Permian mostly seek oil but also pull a lot of gas out of the ground. In the past, many drillers burned or flared off the waste gas because the region did not have enough pipelines and other infrastructure to move or process the gas.

Flaring has declined in recent years as more pipes have entered service.

Other pipes that have entered service in Texas so far this year include the 2.0 bcfd Whistler, the first phase of the 1.5 bcfd Gemini Gulf Coast, the 1.0 bcfd CJ Express and the 2.1 bcfd Permian Highway.

(Reporting by Scott DiSavino; Editing by Edmund Blair)