TROUT RUN - When David Dewberry landed in Pennsylvania in 2010, the veteran of the migratory worldwide oil-and-gas workforce said he required more than a month to drill a typical Marcellus Shale natural gas well.

On Dec. 4, a crew under Mr. Dewberry's direction dug into the mountaintop of a state forest near here with a diamond-studded drill bit. Mr. Dewberry reckons it will require only 16 days to finish drilling the well's full length, more than 2 miles.

"Since I came up here three years ago, it's 200 percent better," said Mr. Dewberry, who manages this Lycoming County site in Loyalsock State Forest for Seneca Resources Corp.

The well not only will require half the time to drill, the bore will extend farther horizontally than older wells. And, if it performs like other wells in the area, it will produce a staggering amount of gas.

When it's done, the towering rig will crawl 20 feet and begin drilling another well. Seneca plans to complete nine wells in an assembly-line fashion on this site, which is the size of five football fields.

"We've become so much more efficient," Mr. Dewberry said.

Marcellus Shale exploration companies are drilling bigger wells in less time at less cost, and they are producing more natural gas than ever.

Despite a reduction in the number of drill rigs operating in Pennsylvania in the past two years because of the low price of natural gas, each rig is accomplishing much more. The Marcellus now produces nearly a fifth of the nation's natural gas.

In the industry, productivity has become the watchword. Gas producers vying for investor money tout their skills to more efficiently deploy capital than the competition.

Many of the improvements in recent years are attributed to the experience producers have acquired in the Marcellus formation.

"You experiment until you hit the jackpot," said Terry Engelder, a Penn State University geoscientist and leading expert in Appalachian black shales.

The new fossil-fuel boom relies upon advances in horizontal drilling and hydraulic fracturing, the technique that involves pumping a mixture of water, sand, and chemicals under high pressure into source rock to crack it open to release oil and gas.

Seneca Resources, based in Pittsburgh, has been drilling gas wells in Pennsylvania for a century.

Seneca has mineral rights for 780,000 acres in the Marcellus, but its most productive wells are in 8,891 acres of Loyalsock State Forest that it leased for $28.5 million in 2008 from the state.

It has drilled 40 of 70 wells planned on the land.

The advent of "pad-drilling" - multiple wells from a single location - accounts for a lot of the saving. It means the 142-foot-high rigs do not have to be broken down and moved so often.

Seneca expects rigs to drill 1,200 feet per day in 2013, nearly twice as fast as in 2012.