Total U.S. natural gas production in 2003 was 19.1 trillion cubic feet, below the peak levels produced from 1969 to 1975. (See Figure 3.3.) According to the Energy Information Administration (EIA) in its Annual Energy Review 2003, Texas, Louisiana, and Oklahoma accounted for 36% of the natural gas produced in the United States in 2003. Although production levels of natural gas are being driven up by increasing demand and rising prices, production continues to be outpaced by consumption. Imported gas makes up the difference between supply and demand.
Natural Gas Wells
In 2003, 366,000 gas wells were in operation in the United States. (See Figure 3.4.) Although the number of producing wells increased steadily after 1960 and more sharply after the mid-1970s, there are slight fluctuations in the number of gas wells in operation year-to-year due to the opening of new wells and the closing of old wells, as well as the effects of weather and economics on well operations.
The average productivity of natural gas wells dropped throughout most of the 1970s and the mid-1980s after hitting peak productivity in 1971; it has remained at a relatively steady low level since then. (See Figure 3.5.)
Offshore Production
Offshore drilling for natural gas accounted for about one-fifth of the total U.S. production in 2003. (See Figure 3.6.) Almost all natural gas produced offshore comes from the Gulf of Mexico and offshore California. U.S. offshore production is expected to increase to meet the nation's growing need for energy, although this type of production could be slowed by environmental restrictions.
Offshore drilling generally occurs on the outer continental shelf, the submerged area offshore with a depth of up to 200 meters (656 feet). Figure 3.7 is a diagram of a continental margin. The continental shelf varies from one coastal area to another. The shelf is relatively narrow along the Pacific coast, wide along much of the Atlantic coast and the Gulf of Alaska, and widest in the Gulf of Mexico. The U.S.
FIGURE 3.1
Department of the Interior has leased more than 1.5 billion acres of offshore areas to oil companies for offshore drilling.
The development of offshore oil and gas resources began with the drilling of the Summerland oil field in California in 1896, where about 400 wells were drilled. In the search for oil and gas in offshore areas, the industry has continually improved drilling technology. Today, deepwater petroleum and natural gas exploration occurs from platforms and drill ships, while shallow-water explorations occur from gravel islands and mobile units.
Even though natural gas is transported mostly by pipelines instead of tankers, accidents such as the 1989 Exxon Valdez oil spill in Prince William Sound, Alaska, and the Prestige oil spill off the coast of Spain in 2002 have focused attention on all types of offshore drilling and tanker transport. Even before the Exxon Valdez oil spill, environmentalists were calling for the curtailment of offshore drilling for both oil and gas.
Natural Gas Reserves
Reserves are estimated volumes of gas in known deposits that are believed to be recoverable in the future. Proved reserves are those gas volumes that geological and engineering data show with reasonable certainty to be recoverable. Proved reserves of natural gas amounted to 195.6 trillion cubic feet in 2002. (See Table 3.1.)
Natural gas reserves in North America are generally more abundant than crude oil reserves, although historically they have been difficult to estimate accurately. At one time the U.S. Department of Energy (DOE) estimated that proven supplies of recoverable gas in the United States would last fewer than eight years. But new discoveries and technological improvements have increased the estimated recoverable supply of natural gas to fifty years or more.
The North Slope fields of Alaska are estimated to contain reserves amounting to 35 trillion cubic feet, but at the moment there is no easy way to transport those reserves to the lower forty-eight states. By late 2004 the idea of building a gas pipeline was still being debated. If built, the pipeline could deliver 4.5 billion cubic feet of natural gas per day to the lower forty-eight states—about 10% of the nation's daily gas consumption.
Underground Storage
Because of seasonal, daily, and even hourly changes in gas demand, substantial natural gas storage facilities have
FIGURE 3.2
FIGURE 3.3
FIGURE 3.4
been created to meet supply needs. Many of these storage centers are depleted gas reservoirs located near transmission lines and marketing areas. Gas is injected into storage when market needs are lower than the available gas flow,
FIGURE 3.5
FIGURE 3.6
and gas is withdrawn from storage when supplies from producing fields and/or the capacity of transmission lines are not adequate to meet peak demands. At the end of 2003, gas in underground storage totaled approximately 6.9 trillion cubic feet. (See Figure 3.8.)
User Comments Add a comment…