Natural gas is a non-renewable source of energy, which means that when it is used up it is gone forever. The process of using gas, typically pumping it up from the ground, is called gas depletion. As far as the average consumer is concerned, it means that there is less gas available for use in the home or on the job. The term gas depletion can refer either to the status of a single well or gas field, or to the amount of available gas when considered as a whole.
Gas depletion is a very serious problem. Less available gas means reduced resources for cooking, heating, and other uses. Prices go up, making it harder for consumers to afford this necessity. Since gas is seldom shipped overseas, areas that run out of gas are faced with the inescapable fact of gas depletion and the need to discover other methods of affordable energy production. The alternative is to find new gas deposits before the old ones are gone.
The production of natural gas in any given area tends to resemble a bell curve if plotted on a graph. Initial levels are small, gradually increasing until the field is outputting its maximum amount. As the gas is removed, production levels begin to drop off. The output of the well is affected by the gas depletion, and eventually there is no more gas available from that source and operations at that site are stopped.
Areas faced with the possibility of gas depletion, such as the United States, are sometimes able to make use of existing gas fields through the development of new technology. The Barnett shale formations in Texas are an example of this. The formation covers more than 5,000 square miles (about 8047 square km), and contains an estimated 2.5 trillion cubic feet (70.79 billion cubic meters) of natural gas. Until recently it seemed unlikely that this deposit would be able to be used, since it was not economically feasible to extract the gas from this type of rock.
New drilling techniques known as horizontal fracturing and horizontal drilling, however, have made such extraction viable. These methods have allowed drilling companies to tap into this huge resource, making natural gas readily available at an affordable price. Concerns about gas depletion in the United States in the immediate future have been eased as the additional gas deposits provide more time for other energy methods to be more fully developed. Other countries are also able to make use of these techniques and tap into previously unavailable reserves.