Drilling companies operating in Pennsylvania appear to be doing more with less.
Even as the amount of natural gas produced in the Keystone State quadrupled between 2009 and 2011, the number of actual wells fell as drillers used new technology to extract more gas from a single rig, according to a new study by the U.S. Energy Information Administration.
The development of more efficient horizontal drilling technology severely slowed the number of vertical wells drilled between 2009 and 2011, a period that represents a time when the drilling boom became visible above the Marcellus Shale natural gas formation. At the same time, falling commodity prices have forced companies to slow activity so far this year.
For decades, vertical wells were drilled straight through the ground across Pennsylvania to extract oil and natural gas. The more recent use of horizontal drilling technology, which allows a drill to turn and run parallel to the shale rock, has allowed companies to more effectively drill in regions that once weren't economically viable.
Vertical wells produced little output compared to horizontal wells because the latter can pull gas from a larger part of the shale rock, said John Staub, an exploration and production analyst at EIA.
Prior to 2009, thousands of vertical -- or "conventional" -- wells across Pennsylvania produced about 400 million to 500 million cubic feet of gas per day, according to the study.
Two years later, with the boom in full swing and horizontal drilling the common technique, the state produced about 3.5 billion cubic feet per day.
The preference for horizontal drills was starkly seen in 2011: almost 2,000 new horizontal wells were drilled, whereas only about 500 vertical wells were started.
The study also offered some insight into drilling trends for 2012. Low natural gas prices -- and the lure of more lucrative gas in Ohio -- have already prompted a year-over-year slowdown in the number of Pennsylvania rigs.
In the first quarter of 2012, drilling started on 618 new gas wells, down from the 700 seen during the same period last year.
But the focus of that new development also reflects a shifting commodity market that prefers oil and natural gas liquids: 263 wells were drilled seeking a combination of oil and natural, up from the 164 that sought the oil-gas combo last year.
Researchers at the EIA said the trend toward liquids-rich parts of the shale is also seen in more developed formations such as the Barnett and Eagle Ford shales in Texas.state - marcellusshale
Erich Schwartzel: email@example.com or 412-263-1455. First Published May 31, 2012 12:00 AM