Geology Reference
In-Depth Information
11,000 feet deep. For years it was considered uneconomical to drill there, but
with the advent of modern fracking this resource trove set off the legendary
“Bakken boom,” which enriched North Dakotans and brought people from
across the country to one of the biggest oil discoveries of recent years.
Barnett
: Situated directly beneath the Dallas-Fort Worth metroplex, the Barnett
holds some 360 trillion cubic feet of natural gas, and represents one of the
biggest shale gas plays in the country. The Barnett is known as a “tight” gas
deposit, where the rock is very hard, permeability is low, and the extraction
of natural gas is difficult. The combination of horizontal drilling and hydro-
fracking opened up the Barnett in the late 1990s. Today, with 13,000 well-
bores reaching maturity there, companies like Halliburton—which has drilled
over 10 million feet of horizontal wells, and fractured and refractured wells in
the Barnett—are exploring the region's nooks, crannies, and edges for gas re-
serves and untapped oil deposits.
Eagle Ford
: stretching some 400 miles long, this play underlies southwest and
central Texas. The shale here dates to the Upper Cretaceous period, and is
brittle (which is good for fracturing). The shale formations occur as a wide
sheet some 40 to 400 feet thick, at depths of 4,000 feet to 14,500 feet, and con-
tain oil and some 150 trillion cubic feet of dry and wet natural gas.
Fayetteville
: Located in the Arkoma Basin in Arkansas, this is the nation's second-
most-productive shale play (after Haynesville, below), is among the United
States' 10 largest energy fields, and holds some 20 trillion cubic feet of gas.
The Fayetteville covers some 4,000 square miles, ranges in thickness from 60
to 575 feet, and runs from 1,450 feet to 6,700 feet deep.
Granite Wash
: A group of plays in the tight sand beneath north Texas and south
Oklahoma, where layers of minerals were deposited by ancient streams and
washouts. Here a number of oil and gas formations are 1,500 to 3,000 feet
thick, and are stacked at 11,000 to 15,000 feet deep.
Haynesville
: With 5.5 billion cubic feet of natural gas recovered from the play
every day, Haynesville contains an estimated 250 trillion cubic feet of gas, and
could surpass the Barnett Shale to become the most productive shale play in
the United States. Rich in organic fissile black shale of the Upper Jurassic age,
it is located on what is called the Sabine Uplift, which separates the salt basins
of east Texas and north Louisiana. The play covers 9,000 square miles, and,
running at depths of 10,000 to 14,500 feet, it is far deeper than most plays.
