By Edward McAllister
NEW YORK (Reuters) - Chesapeake Energy said it replaced a damaged wellhead and gained control of a Pennsylvania natural gas well which last week suffered a blow out that sent drilling fluids spewing into the surrounding area.
The U.S. company, one of Pennsylvania's biggest shale gas producers, said late on Monday the new wellhead "completed efforts to achieve permanent well control" at 6:05 p.m. (Eastern).
Chesapeake last week suspended hydraulic fracturing, or "fracking," in Pennsylvania after thousands of gallons of drilling fluid used in the process spewed from the well in Bradford County after the blowout.
Earlier, Chesapeake said it will not resume the controversial natural gas production process in the state until a well was permanently sealed and inspected.
Fracking involves releasing natural gas trapped in shale formations by blasting a mix of water, sand and chemicals into the rock. Environmentalists say that fracking can contaminate water supplies.
"Tests thus far indicate only minimal environmental impact as a result of this incident," Brian Grove, a senior director at Chesapeake, said in an e-mailed statement.
Chesapeake used a mix of plastic, ground-up tires and heavy mud to temporarily plug the well on Thursday. The halt on fracking affects seven Chesapeake well sites, the company said last week.
The blowout has fueled a fierce debate about whether fracking should be allowed to continue unabated in the United States.
Advances in drilling technology such as fracking have revolutionized U.S. energy markets, opening up the potential of vast reserves of natural gas in shale deposits.
Proponents say extracting shale gas through fracking will slash U.S. reliance on foreign oil and cut carbon emissions. President Barack Obama has made natural gas the cornerstone of his energy policy, in part thanks to the huge reserves unlocked by the use of fracking.
Shale gas now accounts for 23 percent of U.S. natural gas production, rising from a negligible amount in 2004.
But environmentalists and residents, concerned that fracking can pollute water supplies, have called for increased regulation on natural gas production.
(Additional writing by Jonathan Spicer; editing by Marguerita Choy, Himani Sarkar)