Blending gasoline with naphtha-Continued. Evaporation losses in blending-Continued. Discussion of results shown in Tables 8 to 11... Difference in evaporation rates of mixtures. Comparative evaporation losses of mixtures and condensates Page. 82 83 83 84 86 87 93 94 94 94 95 95 95 96 96 97 97 97 98 98 99 101 103 Page. PLATE I. A, Exterior view of gasoline plant at Sistersville, W. Va.; B, II. A, Cooling coils and accumulator tanks of gasoline plant; B, Gaso- 56 III. A, Gas engine and belt-driven compressor in gasoline plant; B, 58 IV. A, Results of an explosion in a gasoline plant; B, Part of stillhouse of a plant for condensing gasoline by refrigeration; C, General view of plant for condensing gasoline by refrigeration.... V. A, Oil well from which casing-head gas is drawn for near-by plant; 60 FIGURE 1. Apparatus for determining the gasoline content of natural gas. 5. Pitot tube with attachment for measuring static pressures. 35 36 37 40 6. Weights of 1 cubic foot of air at various temperatures, pressure being 43 Page. FIGURE 7. Weights of water at different temperatures.......... 44 8. Diagram illustrating physical changes that take place in the produc- 54 9. Compression type of plant for making gasoline from natural gas. 55 10. Compression type of plant for making gasoline from natural gas. 11. Evaporation losses of natural-gas condensation... 12. Evaporation losses when two natural-gas condensates were mixed 87 13. Evaporation losses from a condensate with a specific gravity of 93° 14. Evaporation losses from a condensate with a specific gravity of 95° 88 89 15. Vapor-pressure curves of natural-gas condensate under different 16. Vapor-pressure curves of two condensates..... 17. Vapor-pressure curves of a freshly drawn condensate and of a blend TABLE 1. Details of production of gasoline from natural gas in the Mid-Conti nent field in June, 1913...... 2. Results of analysis of samples of natural gas.. 3. Table to be used in testing gas wells with Pitot tube... 4. Results of laboratory and field tests of 16 different wells on the same 47 5. Results of laboratory tests of samples of gas from different gasoline 61 6. Evaporation losses of natural-gas condensate from plant A when al- 77 7. Evaporation losses of natural-gas condensate from plants B and C 77 8. Evaporation losses of natural-gas condensate from plant A mixed 9. Evaporation losses of different mixtures of natural-gas condensates 78 10. Evaporation losses of condensates from the same plant, but of differ- 81 11. Evaporation losses of mixtures of natural-gas condensates and refin- 81 12. Comparative evaporation losses of blends prepared by mixing differ- 84 THE CONDENSATION OF GASOLINE FROM NATURAL GAS. By GEORGE A. BURRELL, FRANK M. SEIBERT, and G. G. OBERFELL. INTRODUCTION. The Bureau of Mines is conducting a series of investigations with the common aim of minimizing the losses that occur in the mining and treatment of mineral substances. The results of the investigations are being published in reports of the bureau. This report treats of a method of preventing some of the waste of the natural gas incidental to oil mining. This method, the condensation of gasoline from natural gas, offers to the oil operator and others a profitable means of utilizing some of the oil-well gas now being wasted. The most desired constituent of crude oil is obtained, the production of oil is not hindered, and the gas, after the extraction of gasoline, can be returned to the leased area to drive pumps or into pipe lines for uses to which natural gas is ordinarily put, usually with its fuel value lessened only in slight degree. Publications already issued a briefly discuss the subject. In this report the work is treated in greater detail, and the results of many additional tests are shown. GENERAL STATEMENT REGARDING WASTES OF b NATURAL GAS. Arnold and Clapp classify as follows the various ways in which natural gas is wasted: (a) In drilling and casing wells. (b) From high-pressure wells. (c) In oil production. (d) Through lack of proper care of wells. (e) In transportation. (f) In utilization. (g) Through improper plugging of wells. This report concerns itself with method c, the waste incident to oil production. A. B. Macbeth, chairman of a committee on conservation appointed by the Natural-Gas Association of America, presented at the annual a Allen, I. C., and Burrell, G. A., Liquefied products from natural gas; their properties and uses: Technical Paper 10, Bureau of Mines, 1912, 23 pp.; Burrell, G. A., and Seibert, F. M., The sampling and examination of mine gases and natural gas: Bull. 42, Bureau of Mines, 1913, 116 pp. Arnold, Ralph, and Clapp, F. G., Wastes in the production and utilization of natural gas and means for their prevention: Technical Paper 38, Bureau of Mines, 1913, 29 pp. a meeting of the association in Cleveland, Ohio, in May, 1913, a report covering in brief different phases of the subject of the waste of natural gas. Following is an extract from that report, which defines the position of oil operators as regards waste in a new field: Where oil and gas are found in the same field, it is the general practice to blow off the gas. In some fields where the rock pressure is low and the production of both oil and gas is small, some operators are able to produce and market both oil and gas from the same sand. In large operations no practicable way is found of obtaining the oil without wasting the gas, and this is the principal cause of the depletion of many gas fields, and is responsible for a greater waste of gas than all other causes put together. It is natural for the owners of a well to want to produce and sell the well's full production, whether oil or gas, in the shortest possible time, but it is impossible to market gas in the way oil is marketed, for gas can not be stored like oil. The committee saw no way of saving the gas from these wells without seriously affecting the oil production. Arnold and Clapp, Arnold and Garfias, and Blatchley also discuss various means of preventing the waste of natural gas. They briefly mention the production of gasoline from gas. Arnold and Clapp state that at some wells the value of the recoverable gasoline in the gas is worth as much as 20 per cent of the oil produced, and that it is not extravagant to estimate the loss in gasoline, at 10 per cent of the oil produced, or, up to 1912, a clear loss of $4,000,000. OCCURRENCE OF GAS AND OIL. Gas may be found in a sand and separate from oil. It may be found in more than one sand separate from the oil, or the gas sand may be just above and in contact with the oil sand. A given sand may produce oil and gas in one place and in another part of a territory gas only. Gas may come from the same sand as the oil itself. It is this manner of occurrence of gas and oil that the authors desire to emphasize, for under these conditions the gas is frequently mixed with enough of the gasoline constitutents of the oil to warrant the erection of a plant for the purpose of condensing the gasoline. a Report of committee on the conservation of natural gas: Proc. eighth ann. meet. Natural-Gas Assn. Am., vol. 6, 1913, p. 240. Arnold, Ralph, and Clapp, F. G., Wastes in the production and utilization of natural gas, and means for their prevention: Technical Paper 38, Bureau of Mines, 1913, 29 pp. e Arnold, Ralph, and Garfias, V. R., The prevention of waste of oil and gas from flowing wells in California, with a discussion of special methods used by J. A. Pollard: Technical Paper 42, Bureau of Mines, 1913, 15 pp., 2 pls., 4 figs. d Blatchley, R. S., Waste of oil and gas in the Mid-Continent fields: Technical Paper 45, Bureau of Mines, 1914, 57 pp. e Arnold, Ralph, and Clapp, F. G., op. cit., p. 11. The gas usually finds its way to the atmosphere through the space between the casing of the well and the tubing inserted for the removal of the oil. This gas is the so-called "casing-head gas." At the beginning of an oil flow when the flow is natural, a large quantity of gas escapes to the air through the same tubing as the oil. Where the gas finds its exit to the atmosphere apart from the oil at the casing head it is a simple matter to make pipe connections between the casing head and any desired point where the gas is to be utilized. This is frequently done when the supply of casing-head gas is sufficient to warrant its utilization, but frequently, when the supply exceeds the small demands of the lease, the excess is wasted. When a well is first drilled, the quantity of gas escaping with the oil from the tubing is frequently enormous, being 10,000,000 to 15,000,000 feet or more at times. This gas is wasted. The flow in time diminishes. When gas comes with the oil in the flow pipe, the two are often separated by means of a gas trap. The oil, entering the top of a drum, settles to the bottom and is withdrawn, and the gas flows off at the top. Many of the plants in California utilize gas that flows with the oil for condensing gasoline. One gasoline plant in the Cushing field, Okla., also uses trap gas. A new type of trap for saving gas from gushers and separating the gasoline is described at the end of this report (p. 99). Oil wells that have passed the flowing stage and are being pumped may still continue to give off much gas at the casing head. The quantity may vary from little or nothing at some wells to 500,000 cubic feet or more at others. When enough of the gas is available, it is used for pumping on the lease, the excess being wasted. A steam pumping engine of 50 horsepower requires about 25,000 cubic feet of gas for 10 hours' operation. From 12 to 15 cubic feet of natural gas is needed per horsepower-hour for gas engines that are used on leases for pumping oil wells. If there is not enough of the gas available for working pumps, it is all allowed to go to waste, or perhaps some is used for heating and lighting a few scattered houses on the lease. The efficient utilization of the wasting casing-head gas ordinarily is a difficult problem. The many miles of pipe that would have to be laid to transport it from a field would usually be an unwarranted expense. However, some towns, among which may be mentioned Warren, Pa., and Sisterville, W. Va., are lighted and heated largely with casing-head gas. In general, however, the oil man considers casing-head gas as waste gas and its escape necessary in oil-well operations, to permit the maximum flow of oil into the well from the surrounding strata. |