APPENDIX [Bureau of Mines Information Circular 7654, U. S. Department of the Interior, December 1952] UNDERGROUND STORAGE OF NATURAL GAS IN COAL-MINING AREAS By Henry P. Wheeler, Jr.' and William E. Eckard' INTRODUCTION GROWTH OF UNDERGROUND NATURAL-GAS STORAGE Natural gas was first stored underground in Welland County, Ontario Province, Canada, in 1915.' The following year natural gas in the United States was first stored underground successfully in the Zoar field near Buffalo, N. Y. Only three additional storage fields were in use in the United States in 1930, but by 1940 the number had increased to over 30, and since that time growth has been more rapid. At least 80 fields, with a combined storage capacity of 440,828 MM cubic feet, were being utilized by 1949. In May 1952, 142 storage projects having a capacity of 915,000 MM cubic feet were in operation." These fields are distributed from New York to California-from Michigan to Texas. In the Appalachian region alone, there are 101 storage fields with a combined capacity exceeding 526,000 MM cubic feet. WHY NATURAL GAS IS STORED Natural gas is stored in order to be readily available to meet the needs of consumers. The demand for natural gas is extremely irregular, particularly when a large percentage is distributed to residential customers. The daily average consumption of gas during the winter may be over twice the daily average in the summer; and on an exceedingly cold day, the peak demand is many times the average summer rate. The demand for natural gas for domestic use on a warm afternoon in the summertime is negligible. Peak demands occur on cold winter mornings when houses are being warmed and breakfasts are being cooked. It is not practical to operate the gas fields that are the primary source of the natural gas, or the pipelines that transport it, at such variable rates. Gas must be produced at rates low enough that the fields will not be damaged by rapid water encroachment, bypassing of less permeaable portions of the formation, excessive losses of reservoir energy, and other conditions. Consequently, natural gas is available from its source at a reasonably constant rate. Also, the capacity of pipelines that transport the gas to market is limited by their sizes, working pressures, and other factors. Efficient operation of these lines, which vary in length up to about 1,800 miles and cost many millions of dollars, requires that they be operated insofar as possible at constant rates at or near capacity. Storage of gas near the point of consumption is one way to equalize the supply and demand. Natural gas can be produced and transported to the point of storage at a constant rate. When the demand is less than that rate, the excess supply is put into storage, from whence it can be withdrawn later to meet 1 Petroleum engineer, Bureau of Mines, Washington, D. C. 2 Petroleum engineer, Bureau of Mines, Franklin, Pa. Interstate Oil Compact Commission. Projects in the United States: 1943. 19 pp. A Survey of Underground Natural Gas Storage * Ball, Max W., Underground Gas Storage: Natural Gas Department, American Gas Association, presented at spring meeting, May 1949, 30 pp. 5 Goodman, John V., Statistics for Storage Operations of Storage Fields: natural gas department, American Gas Association, presented at spring meeting, May 1952. 127 demands in excess of pipeline and gas-field capacity. As a result, natural gas can be made available to more customers than could otherwise be served. A typical seasonal cycle of injection and withdrawal is shown in figure 1. Storage of gas also provides a supplemental supply to meet emergencies caused by the mechanical failure of pipelines or other facilities; and better service is assured users of natural gas. WHY NATURAL GAS IS STORED UNDERGROUND Underground storage fields offer two major advantages over other types of natural-gas storage. They are bigger and less costly. They cannot replace other types of storage entirely, because there is a definite need for gas holders, steel-pipe storage, and other types with less capacity; but, if larger capacity is required, underground storage is the answer, provided of course that a suitable field can be found. A comparison by F. E. Vandaveer and J. J. Schmidt' of estimated capital costs for various types of storage is shown in table 1. The weighted average cost of storing gas in the 13 underground gas-storage fields referred to in the table is $0.27 per M cubic feet. The average capacity of the 13 fields is almost 5,000,000 M cubic feet, which is also about the average capacity of the 80 fields described by Max Ball in 1949. In recent years, however, the trend has been to larger fields, such as the Oakford storage field near Jeannette, Pa., of the New York State Natural Gas Corp. This field, the largest known to the authors, is reported to have a capacity exceeding 100,000,000 M cubic feet. It is difficult to visualize storage of a similar volume of gas above ground. TABLE 1.—Comparison of estimated capital costs for various types of storage 1 Assuming excavation of 1 M cubic feet cavity and disposal of salt brine in deep brine strata. Much less if salt is recovered and soid. Kornfeld. Joseph A., Gas Storage Growth: Oil and Gas Journal, August 2, 1951, vol 50. No. 13. pp. 41-42. Vandaveer, F. E., and Schmidt. J. J., Underground Storage-and Migration of Natural Gas: Gas, October 1950, pp. 121-128. WHY NATURAL GAS IS STORED UNDERGROUND IN THE APPALACHIAN REGION The natural-gas industry in the United States originated in the Appalachian region when, in 1820, a well was drilled near a gas seepage in Fredonia, N. Y., for the express purpose of obtaining a larger flow of natural gas. This well was completed at a depth of 27 feet, and the gas was marketed. Natural gas was utilized in West Virginia in 1841, in Ohio as early as 1860, and in several Pennsylvania towns by 1872. Natural gas was first piped to Pittsburgh in 1883 and has contributed substantially to the industrial growth of the region. As the industrial centers grew and the population increased, more and more people wanted to use natural gas in their homes. The Appalachian region was able to produce enough gas to meet the growing demand for a while, but eventually the local supply became inadequate. In 1951, the region consumed about 141⁄2 percent of all the natural gas consumed in the United States—more than twice as much as it produced—and it has only 2 or 3 percent of the Nation's gas reserves. Thus, it is necessary to bring gas into the region through long-distance pipelines from Louisiana, Texas, and other Southwestern States. Storage capacity is needed to permit efficient utilization of these pipelines, and many suitable exhausted fields are available close to centers of consumption. Through their use, the life of the industry is being prolonged in the Appalachian region, and the inhabitants enjoy an uninterrupted supply of natural gas. HAZARD OF STORING GAS UNDERGROUND IN COAL-MINING AREAS Concurrently with the growth of underground gas storage, the coal industry has become increasingly aware of the hazards of coal-mine explosions resulting from the ignition of combustible gas mixtures. No more insidious hazard to coal mining exists than emission into the mine workings of firedamp from the surrounding strata, including the coal itself. Firedamp cannot be smelled, tasted, or seen; usually it is liberated from coal at such low pressure that there is no sound. With rare exceptions, firedamp is methane with only traces of other gases that have no effect on its explosibility. Many hundreds of experiments have shown that the difference in explosibility between firedamp and natural gas is too small to have any significance. The deaths caused by firedamp explosions in coal mines over the hundreds of years of the industry's history are staggering and well nigh unbelievable to persons not associated with the industry. It is to be expected that coal-mining men should be alarmed by any possible increase in liberation of explosive gas in their mines. That they should want positive proof that gas stored in the ground cannot enter their mine workings is equally to be expected. PURPOSE OF THIS INFORMATION CIRCULAR The coal and natural-gas industries are two of the Nation's greatest. They compete directly in many fuel markets, and the resultant improvements in production, distribution, and utilization are of great benefit to the general public. The coal industry is justly concerned for the safety of its employees. The gas industry is equally concerned regarding the adequacy of the service that it offers to its customers. Underground storage is vital to the natural-gas industry and the many gas consumers in the Appalachian region. The gas industry does not wish the gas, which it has brought from distant sources and stored, to leak into coal mines or anywhere else. Such leakage would be cost), and the lost gas would not be available to meet the peak demands of the gas consumers. This report is issued to give information concerning underground gas storage ard to point out the authors' conviction that close cooperation between the coal and nature gas industries is necessary whenever gas is stored near active coal Tunes. Only through such cooperation can the maximum decree of safety protect or be afforded. Operating practices in both in lustries will undoubtedly chase over a period of years. Cogl will be mined in new areas: gas will be stored in additional felds Each industry must give some consideration to the possible effects of its expansion upon the other. By se doing, each can progress and contríóude more effectiveg to the overall strength of our Nation. NetLm (£s Gerings of Natural Gas-A Symposium: Am Assoc. Petra God. T OKA, 1953. pp 1078 1148 ACKNOWLEDGMENTS This report was prepared under the general supervision of R. A. Cattell, chief, Petroleum and Natural Gas Branch, Bureau of Mines, Washington, D. C.; H. P. Greenwald, regional director, Bureau of Mines Region VIII, Pittsburgh, Pa.; and S. S. Taylor, supervising engineer, Bureau of Mines Petroleum Field Office, Franklin, Pa. Dan Walker, Jr., chief, Pittsburgh Branch, Accident Prevention and Health Division, and George M. Smith, coal mine inspector, Bureau of Mines Central Experiment Station, Pittsburgh, Pa., were extremely helpful in criticizing the report as it relates to coal mining. Newell G. Alford of Alford, Morrow, & Associates, also offered many helpful suggestions. The assistance and cooperation of the gas companies in the Appalachian region, through the American Petroleum Institute eastern district study committee on natural gas operating practices (underground storage), J. G. Montgomery, Jr., chairman, and the American Gas Association, natural gas department, committee on underground storage, Fenton H. Finn, chairman, is acknowledged gratefully. John V. Goodman of Equitable Gas Co. was particularly helpful in supplying recent statistics on underground storage. CHOOSING A FIELD FOR UNDERGROUND NATURAL-GAS STORAGE KIND OF STORAGE NEEDED The size and type of gas storage required depend upon the purpose for which it is intended. If a storage field is desired to provide gas during an emergency, such as a pipeline break or other equipment failure, the field need not be large, but it must be capable of producing gas for a short period at a high rate of flow. According to Goodman," a field with a capacity of 200,000 to 300,000 M cubic feet of gas, with a delivery adequate to compensate the greatest probable interruption, would be the ideal storage unit for this purpose. If storage is required to smooth out the seasonal variations in supply and demand, a larger field may be required, depending upon the magnitude of the variations. This type of storage must be capable of producing gas for a sustained period of several months. Goodman has cited Equitable Gas Co. unit No. 3 as an example. It has a capacity of 2,800,000 M cubic feet and an initial delivery rate of 40,200 M cubic feet of gas per day. The larger storage fields are of this type. WHERE TO LOOK FOR A STORAGE FIELD Underground storage fields in the United States have been developed from depleted or partly depleted gas fields, oil fields, and abandone noncommercial gas fields, and also in formerly untested water sands. The old fields have demonstrated their capability of holding gas under pressure at one time; and, unless they have been irreparably damaged through indiscriminate drilling and completion of wells, they may be developed into storage fields. In many cases, the original wells in the field may be used again in the storage operations. Also, the fields may already be connected to existing pipeline facilities. The usual practice is to search for a suitable storage field as near the market as possible; however, if a major pipeline serves more than one market, storage may be desirable at a point that will enable the field to serve over one market. Thorough study of all depleted gas fields along the transmission lines and within a reasonable distance of the markets may disclose a field suitable for storage. Max Ball has suggested that a large transmission company might afford to go as far as 300 or 400 miles from its markets to obtain a suitable storage field, but most of the present fields are less than 200 miles from the markets they serve. In some cases, two or more small fields may be used if one large enough cannot be found. If a suitable depleted gas field cannot be found within the area selected for a storage project, it may be necessary to consider some other form of underground storage. In the Doe Run and Muldraugh storage fields in Kentucky, gas is being stored in sands that contained little or no natural gas originally. This idea of storing gas in a water sand has gained considerable popularity in recent months, Goodman, John V., Ten Years of Underground Gas Storage: Gas Age, May 3, 1945, pp. 33-37, 80-84. |