well that it is to offset. Thus one well may be an offset to two or more contiguous wells. In other cases the shape of the tract will determine the position of the offset well. The primary feature to be borne in mind is that the offset well is drilled for purposes of protection, and that this is more important than hard and fast rules regarding exact location. The adventitious origin, migratory habits, and fugitive tendencies of natural gas, as well as the nature of the sand and the topography of the country, are also factors that must be considered. DRILLING OFFSET WELLS MAY MAKE EXISTING WELLS COMMERCIALLY WORTHLESS. In gas territory the lessee may sink many wells and find gas in them all, but he can utilize only such of them as have a volume and pressure sufficient to enable him to transport the gas through his line and deliver it to the purchaser. If no one of them has the requisite pressure, then no one of them can be utilized; the gas must be wasted, the cost of the wells will be lost, and the lessor entitled to no royalty. What is the proper way to operate a gas lease is therefore a question beset with some difficulty. Its settlement requires some general knowledge of the business and some knowledge of the local field. The lessee may have a good well, from which he can utilize the gas with profit. He may put down another on the same farm and thereby so reduce the pressure in the first as wholly to destroy its value, without getting a sufficient pressure at the second to enable him to utilize that. The gas, if coming from one well, would be of great value. Divided in such manner that the whole volume and pressure at each is below the necessary standard, the whole is lost.1 WHY OFFSET WELLS ARE FREQUENTLY DRY. It is a matter of common observation in natural gas mining that offset well locations are frequently dry holes. This is because most natural gas pools are not strictly continuous, but are made up of many small local pools, frequently surrounded in whole or in part by a gas rock of low porosity. For this reason, if a producing well has been drilled into one of these small local gas pools, there is a large chance that the offset well location may go beyond the limits of the pool and therefore be a dry hole. WHY OFFSET WELLS ARE FREQUENTLY OF LOW CAPACITY. The fact that offset natural gas wells are frequently of lower capacity than the wells that they offset may be accounted for as follows: If the offset well is drilled at the extreme edge of a small local pool its capacity would naturally be smaller than the original well drilled more nearly in the center of the pool. Furthermore, when the first well is drilled into the pool the rush of gas from the then high rock 1 Pennsylvania Supreme Court. McKnight versus Manufacturers Natural Gas Co. (146 Pa. St., p. 185). pressure has a marked tendency to open up numerous channels of low resistance in the rock formation, so that the gas in the gas sand can get to the well opening with a minimum of friction. The high initial rock pressure aids substantially in first creating such lines of least resistance and then in freeing them of loose particles of sand which are blown out through the well. Even though an offset well is afterwards drilled in the same pool, the initial rock pressure will probably be lower than for the first well, and the lower gas pressure will not be near as likely to produce favorable conditions for flowing to the bottom of the offset well as were produced in the first well. WHEN IS THE DRILLING OF OFFSET WELLS JUSTIFIABLE? The crux of the entire "offset well-drilling question" is whether the decision to make the additional investment in drilling offset wells for natural gas, providing the increased annual operating cost for their care and maintenance and cutting down the reserve acreage necessary for future continuity of service, shall be made by the farmer-with no risks involved and no obligation to the public-or the party who must provide the money, assume the financial risk and operating duty to the public. The following correctly expresses the equities of the situation: The development and protection of lines which is implied is such as is usually found in the business of an ordinary prudent man. The operator, who has assumed the obligations, has put his money and labor into the undertaking, and is now called upon to determine whether it will pay to spend some thousands of dollars more in sinking another well to increase the production of the tract, is entitled to follow his own judgment, if that is exercised in good faith, in accordance with the doctrines laid down on page 65. PUBLIC PAYS FOR WASTEFUL OPERATION. While the production of natural gas is strictly a mining venture, its distribution to the ultimate consumer is distinctly a public utility service. Even under State regulation of public utilities, any marked increase in the cost of natural gas mining operations will soon be reflected in the price the ultimate consumer must pay for the natural gas service. The acreage data given in figures 5, 6, and 7 show that not every landowner can have an offset well. The drilling and operation of unnecessary offset wells will represent a large increase in the capital investment and operation cost of natural gas companies. All of such increased burdens represent an unnecessary waste which will ultimately be paid for by the public. The following analysis gives the reasons for the drilling by one company of 429 wells in West Virginia during 1916, and emphasizes the offset well burden, as well as the large number that were drilled on the demands of the lessors. The difficulty in keeping gas joints tight is not ordinarily appreciated and results in an enormous waste from defective joints and minute openings in gas-carrying equipment. The laws controlling gas leakage may be stated as follows: 1. The relative leakage tendencies of any two fluids under the same conditions are practically inversely proportional to the square roots of their respective densities. Natural gas has a density of practically 0.64. With regard to air, the relative leakage of air and natural gas will vary as the square root of 1 and square root of 0.8 or as 1 is to 0.8. That is, the leakage tendency of natural gas will be 1-0.8-1.25 times that of air under similar conditions. Water has a density 819.5 times heavier than that of air; hence leakage tendency of natural gas in comparison to that of water at the same pressure is much greater than that of water. This accounts for the universal difficulty in keeping gas confined without leakage. 2. The quantity of leakage through a given opening will vary directly as the square root of the differential pressure. 3. Amount of leakage is independent of the quantity or velocity of gas passing through the main. In other words, the pressure remaining the same, the leakage will be just as much during the period of low gas consumption as during the period of high gas consumption. A typical gas main joint coupling, as shown on page 59, has four surfaces adjacent to the rubber and the metal where leakage may be possible. On a 16-inch main each coupler presents about 17 linear feet of such potential leakage surface. The magnitude of this in a large system is evident when we consider that about 270 couplers will be required to the mile, thus making 270×17=4,590 feet of possible leakage surface to the mile of a 16-inch gas main. Welded gas mains are coming into use, but the welded process can not be used except on new work or in such main line installations where the entire line can be shut down and drained of all gas before the welding operation is attempted. DEFINITION OF CARBON BLACK. In the American trade the term "lamp black" is usually understood to be a soot deposited by the smudge process and made from oil, rosin, or some other solid or liquid raw material, whereas "carbon black" is the term applied to a black deposited by actual contact of a flame upon a metallic surface.1 WASTE IN CARBON BLACK MANUFACTURE. Carbon black is now made by the wasteful process of incomplete combustion of natural gas. That is, the gas is simply burned in the open and the flame impinging against a metal plate makes the black deposit known as carbon black. From 13 to 11 pounds of carbon Rubber Bolt Joints where leakage is possible FIG. 19.-LONGITUDINAL SECTION OF GAS PIPE COUPLER SHOWING black are made to each M cubic feet of gas burned. The only product obtained is the carbon black, and this utilizes only a very small percentage of the total carbon content of the gas. The total annual quantity of natural gas used for carbon black manufacture is more than 26,000,000 M cubic feet. This wastes about 10 times as much gas as was used in the city of Louisville, or the equivalent of one-eighth of the domestic natural gas consumption in the United States. Dr. J. B. Garner, of the Mellon Institute of Industrial Research, Pittsburgh, Pa., has demonstrated that with correctly designed appliances the yield of carbon black can be made three times as high 1 U. S. Geological Survey Statistics. Natural Gas in 1916, p. 662. as that usually obtained by the wasteful process of incomplete combustion, and in addition thereto save a usable commercial gas.1 WHY CARBON BLACK MANUFACTURE MAY BE MORE ATTRACTIVE THAN PUBLIC UTILITY SERVICE. 1. No regulation.-Not carrying with it any public duties, it is not subject to the many phases of public regulation that control the marketing of natural gas as a public utility service. FIG. 20. MAP SHOWING COMPETITION FROM CARBON PLANT AT CHAPMANVILLE, W. Va. 2. Price. This is not controlled by rate fixing bodies, but is limited solely by the ordinary laws of trade, and is, therefore, more attractive from the investor's viewpoint than governmental price fixing. 3. No transmission lines necessary. The plants are located in the fields, as shown in figure 20, close to the leases, and sometimes on 1 J. B. Garner The Chemical Possibilities of Natural Gas. Paper, Natural Gas Association of America, Pittsburg meeting, May 23, 1918. |