By Lewis Delavan
Stephens Media
LITTLE ROCK — Engineers for natural gas industry giant Southwestern Energy became curious in 2002 when they noticed Arkoma Basin wells near Fayetteville were producing far more gas than anticipated.
They soon concluded that Arkoma’s Fayetteville Shale deposit was the source.
“We’ve known there was natural gas in these shales for decades,” said Ed Ratchford, senior petroleum geologist and fossil-fuel supervisor for the Arkansas Geological Survey.
But tapping the reserves was not economically feasible until service companies like Halliburton and Schlumberger developed hydraulic fracturing technology to pull gas from “unconventional” wells, such as Fayetteville Shale, Ratchford said.
Southwestern invested $28 million for leases and drilling 21 test wells in 2004, acquiring an additional 575,000 acres. A well near Jerusalem produced the first gas for an energy boom that a 2008 University of Arkansas study estimated will generate $19.9 billion and more than 11,000 jobs for the Arkansas economy through 2012.
Gov. Mike Beebe, industry officials and other dignitaries are scheduled to commemorate the fifth anniversary of the successful well during a ceremony today at the University of Arkansas Community College at Morrilton.
Later Monday, Southwestern will dedicate a new sand mining company in North Little Rock. SWN Sand Co. is expected to produce more than 2 billion pounds of sand per year for Southwestern Energy’s drilling operations.
SWN Sand plans to hire about 30 workers initially and up to 45 at full capacity.
Southwestern Energy is one of two oil-and-gas companies in the country to own its own sand plant.
Despite its name, the Fayetteville Shale play encompasses a vast region of northern Arkansas covering Cleburne, Conway, Faulkner, Van Buren and White counties.
It’s far cheaper to extract gas from “conventional” wells, such as those found in south Arkansas. Such gas flows to the well-head when tapped. Gas is unretrievable from shale without being fractured.
“The permeability of the Fayetteville Shale sandstone is similar to a slab of concrete,” Ratchford said. “Oil-and-gas companies hire those service companies to do the work.”
The companies work in concert on the site.
Deposits of the tight, finely grained sandstone — 300-million years old — are 50- to 550-feet thick.
First, a vertical hole is drilled to a depth of 1,500 to 6,500 feet.
The drill bit then turns horizontal and continues to penetrate.
A solution of sand suspended in water is injected into the targeted pressure zone, fracturing the sandstone, Ratchford said.
Engineers initially fractured from 500 to 700 horizontal feet of sandstone at a time, but learned much more gas could be reduced if 100 feet were fractured at a time.
The vertical hole is a means of access, while gas is retrieved from the horizontal hole, Ratchford said. Each well is carefully plotted, to ensure landowners are properly compensated, he said.
Sand remains in the ground, while water is pumped out.
Transmission lines were built to carry gas where it’s needed.
“It’s one thing going out and punching a hole in the ground, saying ‘I’ve got gas,’” Ratchford said. “It’s another thing, more difficult, to get a delivery system in place to where you have a gathering system from the well head to a gas transmission line and bringing that resource all the way into a person’s home or business.”
