geologyMcAfee SECURE sites help keep you safe from identity theft, credit card fraud, spyware, spam, viruses and online scams

Home » Oil and Gas » North Carolina Natural Gas

Unconventional Natural Gas from Organic Shales in North Carolina?

New drilling methods may open previously unproductive rock units.




Is North Carolina the Next Natural Gas Play?



Although North Carolina has no current oil or natural gas production, drilling methods developed in other states might be used to tap natural gas reservoirs beneath several North Carolina counties.


The U.S. Unconventional Shales Gas Rush



New methods of natural gas production are turning previously unproductive rock units across the United States into some of the largest natural gas reservoirs in North America. The Barnett Shale of Texas, the Marcellus Shale of the northeast, and the Haynesville Shale of Louisiana all went from relatively unproductive rock units to reservoirs hosting wells capable of yielding several million cubic feet of gas per day.

Natural gas companies are paying landowners above these reservoirs thousands of dollars per acre for temporary drilling rights. If gas is produced from their property they will also receive royalty payments - which could be thousands of dollars per year per acre for as long as the well is productive.

These successful gas plays have a few things in common: they are developed in deeply-buried, organic, low-permeability shales that were once marginal producers or unproductive. Today these shales are producing abundant quantities of natural gas through horizontal drilling and hydraulic fracturing.


Horizontal Wells and Fractured Reservoirs



Normal wells are drilled vertically down through the reservoir rock unit. If the reservoir is 100 feet thick then the well has a "pay zone" of 100 feet. However, if the well is drilled straight down, turned horizontal within the rock unit and drilled several thousand feet horizontally then the well has a pay zone of several thousand feet (see diagram at right). In other parts of the United States this drilling method is turning low-yield rock units into attractive reservoirs.

marcellus shale How Horizontal Drilling Made The Marcellus Shale A Major Gas Play
A well enhancement technique known as hydraulic fracturing is also being used in other states. It increases the permeability of the reservoir rock. After a horizontal well is drilled, water is pumped down the well to produce a very high pressure within the reservoir rock unit. This high pressure can fracture the rock, producing a fracture network drain natural gas from a large volume of rock and allow it to seep into the well.


Organic Shale In North Carolina



Rock units in the Dan River Basin and Deep River Basin of central North Carolina are potential candidates for the drilling methods used in other states (see location map at right). Each of these basins contains a sequence of sedimentary rock several thousand feet thick. The potential natural gas reservoirs in these basins are gray and black organic shales that are thought represent ancient lake sediments, deposited over 200 million years ago. The Cumnock Formation of the Deep River Basin and the Cow Branch Formation of the Dan River Basin both contain organic-rich shales that might yield commercial quantities of natural gas.


The Gas is Just One Piece of the Puzzle



If these rock units are able to yield abundant quantities of gas two more things will be needed to make them commercial: 1) nearby customers who are ready to buy a steady flow of gas; and, 2) a gas pipeline system that will collect the gas from the wells and transport it to consumers.

Although natural gas companies are normally the ones who drill wells, Universities, local governments and gas-consuming companies sometimes drill wells on their own property, consume the gas on-site or use it to generate electricity. They spend a few million dollars on the well and have a steady flow of gas that will last for years.


Will It Happen in North Carolina?



The new drilling methods could make North Carolina the newest gas-producing area in the United States. The United States Geological Survey and the North Carolina Geological Survey have done preliminary research that makes these shales look promising (see "Information Sources" box at right). Now it's up to the gas companies and North Carolina entrepreneurs to investigate.

Last update of this article: May 15, 2009.

Contributor:



Find it on Geology.com




More from Geology.com


Gems from Space
Gems from Space A number of materials from space have been used as attractive gems.
Sliding Rocks
Sliding Rocks Mystery: What causes these rocks to slide across a Death Valley playa?
Minerals
Minerals: Information about ore minerals, gem materials and rock-forming minerals.
Diamonds
Diamonds: Learn about the properties of diamond, its many uses and diamond discoveries.
Diamonds from Coal
Biggest Misconception: Lots of people think that diamonds form from coal. Not True!
Download Google Earth Free
Free Google Earth software allows you to browse seamless world satellite images. Free.
Cave of the Hands
Cave of the Hands: A cave in Argentina with wall paintings that date back to about 7000 BC.
Organic Gems
Organic Gems are gems formed from or by plants or animals. They might also be fossils.


Map of North Carolina's Natural Gas Basins
Map showing generalized locations of the Triassic basins of North Carolina. These hold sedimentary rocks sequences with organic shales that may be suitable for unconventional natural gas production (after Reid & Milici, 2008) Basemap by Geology.com and MapResources..


horizontal gas well
Generalized diagram illustrating a horizontal well with a hydrofracture zone.

Information Sources
"Natural Gas and Oil in North Carolina," 2009, North Carolina Geological Survey Information Circular 36 - A general interest publication that explains the origin of oil and gas and where they are known to be present in North Carolina. Drilling regulations and permitting details are also covered.

"Hydrocarbon Source Rocks in the Deep River and Dan River Triassic Basins, North Carolina," 2008, United States Geological Survey Open File Report 2008-1108 by Jeffrey Reid and Robert Milici- A technical publication that summarizes oil and gas source rock potential of rocks in North Carolina.

"Tools to evaluate the hydrocarbon potential of the Mesozoic Basins, North Carolina, USA," 2008, Reid, J.C. and Taylor, K.B., American Association of Petroleum Geologists Eastern Section Abstracts with Program.

© 2005-2014 Geology.com. All Rights Reserved.
Images, code and content of this website are property of Geology.com. Use without permission is prohibited. Pages on this site are protected by Copyscape.