SHREVEPORT, La.—A mounting backlash against a technique used in natural-gas drilling is threatening to slow development of the huge gas fields that some hope will reduce U.S. dependence on foreign oil and polluting coal.
The U.S. energy industry says there is enough untapped domestic natural gas to last a century—but getting to that gas requires injecting millions of gallons of water into the ground to crack open the dense rocks holding the deposits. The process, known as hydraulic fracturing, has turned gas deposits in shale formations into an energy bonanza.
The industry’s success has triggered increasing debate over whether the drilling process could pollute freshwater supplies. Federal and state authorities are considering action that could regulate hydraulic fracturing, potentially making drilling less profitable and giving companies less reason to tap into this ample supply of natural gas.
Exxon Mobil Corp. placed itself squarely in the middle of the wrangling when it agreed last month to acquire gas producer XTO Energy Inc., a fracturing pioneer, in a deal now valued at $29 billion. Wary of the rising outcry, Exxon negotiated the right to back out of its deal if Congress passes a law to make hydraulic fracturing illegal or “commercially impracticable.”
On Wednesday, Exxon Chairman and Chief Executive Rex Tillerson faced questions about the environmental impact of hydraulic fracturing at a Capitol Hill hearing on the merger.
“We can now find and produce unconventional natural-gas supplies miles below the surface in a safe, efficient and environmentally responsible manner,” Mr. Tillerson told members of the House Energy and Commerce Committee.
Criticism of hydraulic fracturing was muted at the hearing, with most representatives focusing on the potential benefits of increased gas use. But the merger has given drilling opponents a new target.
“It puts Exxon at front and center of this whole issue,” said Michael Passoff, associate director of As You Sow, an environmental-minded investment group.
Even before the Exxon-XTO deal, the controversy over hydraulic fracturing, also known as “fracking” or “fracing,” was growing.
Oilmen were injecting water into wells to free up valuable oil and gas as far back as the 1940s. But in the past decade the technique has really taken off. First in East Texas and in the outskirts of Fort Worth, companies began pumping water under enormous pressure to see if they could break open dense shale-rock formations to release gas.
These initial efforts were largely welcomed by communities, with homeowners and landlords often receiving lucrative checks for the mineral rights that allowed companies to drill on their land.
When early efforts succeeded, the companies began running bigger fracturing jobs, using more water and higher pressure—and in turn searching for even more gas-bearing shale deposits.
This took the gas industry into places where drilling was less common in modern times, including downtown Fort Worth, northeastern Pennsylvania and within the city limits of Shreveport, La.
Hydraulic fracturing and some other technology improvements have created a way to tap a domestic fuel source that has proved abundant. U.S. natural-gas production has risen about 20% since 2005 in large part because of these developments, making gas a much bigger player in energy-policy planning.
Natural gas heats more than half of U.S. homes and generates a fifth of America’s electricity, far less than coal, which provides the U.S. with nearly half its power. The industry and its allies are promoting natural gas a bridge fuel to help wean the U.S. off coal, which emits more global-warming gases, and imported oil until renewable fuels are able to meet the demand.