The two greatest wastes connected with oil-well drilling are caused by the harmful infiltration of water from water-bearing strata and the uncontrolled escape of natural gas encountered in the course of drilling. Water is a formidable enemy to oil extraction; as the position of the oil depends, in part, upon a nice equilibrium between oil and water, the undue influx of water into the drill hole means a reduced recovery of oil, if not a total loss of the well; and not only may a single well be completely ruined by inadequate protection against water, but what is more grave a whole field of operations may thereby be spoiled. The damage done in the past by water is immeasurable and largely irretrievable, but the danger from water may be controlled by means of a method of cementation already employed with success in California and Texas, whereby a water-tight band of cement is forced into the space between the well casing and the water-bearing stratum.

Many wells in sinking penetrate gas-bearing formations, and in such instances it has usually been customary to suspend operations while the gas escaped into the air, so that the pressure might be relieved against which continued drilling was difficult or impossible. The actual waste of gas due to this circumstance has been first and last enormous, amounting to billions, if not trillions, of cubic feet, with a fuel equivalent of millions of tons of coal; indeed, it would be safe to say that over half of the natural gas developed to date has been made no use of whatever. But this physical waste, great as it has been, is of small consequence as compared with the waste of the energy represented by the gas-pressure, the dissipation of which leads to a reduced and more difficult recovery of the oil. The gas, therefore, is not only substance but energy, and represents a force which must be conserved for the sake of later gaining a proper petroleum yield. It is rather interesting that the waste of oil and gas involved in the premature production of gas may be prevented by comparatively simple means; namely, by drilling in a medium of mud-laden fluid which serves to encrust the critical parts of the drill-hole, sealing off the formations so that there is no improper escape of gas and preserving the conduit intact down to the productive stratum.2

After the oil is struck, there are many methods for controlling the output so as to avoid the waste incidental to much of the current practice. The flow may be controlled by rather elaborate mechanical

1 See R. S. Blatchley, Waste of Oil and Gas in the Mid-Continent Fields: Technical Paper 45, Bureau of Mines, 1913.

J. O. Lewis and W. F. McMurray, The Use of Mud-Laden Fluid in Oil and Gas Wells: Bulletin 134, Bureau of Mines, 1916.

2 This process is described in detail in Bulletin 134, Bureau of Mines, 1916. There are numerous details of drilling practice which are subject to improvement, but these need not be gone into here.

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devices, preventing an overproduction;1 gushers "gone wild" may be capped and brought under subjugation; "blow-outs" may be guarded against and prevented; and losses due to fire, seepage, and evaporation largely nullified through adequate development of storage facilities. All these gains will accrue more fully through widespread application of well-known engineering technique already successfully practiced in many instances.

The gas that almost invariably comes forth along with the oil customarily carries some of the lighter components of the oil itself. These components are recoverable by means of appropriate methods in the form of a very volatile gasoline, which can be blended with a heavier petroleum distillate to form commercial gasoline. Until a few years ago, the recovery of the gasoline suspended in natural gas was neglected, but now a very significant yield of this so-called "casing-head" gasoline is obtained. The natural gas is made to yield up its gasoline either through compression, which squeezes out the liquid content, or by absorption, which entices it out by means of a certain type of oil which later is heated and thus forced to yield up in turn the gasoline absorbed. Even with full gasoline extraction, however, there remains in many fields much more gas than can be consumed by legitimate demand, which necessitates a waste of the surplus, unless it can be cheaply transported to points where demand exists.* In this connection possibilities open up in connection with processes of liquefaction, by means of which the gas may be compressed into reasonable bounds for transportation."

3

Due chiefly to the decline of pressure upon the escape of natural gas, wells quickly mature and then produce at a declining rate; but recent investigations go to show that even when a well is apparently exhausted, its full quota of oil has by no means been exacted. On the contrary, as demonstrated by established practice in Ohio and elsewhere, an additional yield may be forced by means of compressed air or its antithesis, a vacuum. The more promising of the two methods consists in forcing compressed air down to the porous oil-bearing formation, thus driving the oil to positions reached by pumping wells. The full possibilities of these methods may not be safely forecast, but they are certainly capable, if widely applied, of increasing by a large

1 Thus, for example, the flow from Mexican oil wells is at present held down to the transportation capacities available for export, avoiding a tremendous local overproduc

tion.

2 Production of gasoline from natural gas has grown from 7,000,000 gallons in 1911 to 104,000,000 gallons in 1916.

The absorption method is especially adapted to "dry" gas lean in gasoline vapor. When the natural pressure is insufficient or distances too great, the normal transportation through pipes is unprofitable.

See I. C. Allen and G. A. Burrell, Liquefied products from natural gas: Technical Paper 10, Bureau of Mines, 1912.

59319-18-Bull. 102, pt. 6- -4

percentage the future yield of the country over the estimates made in respect to current practice.1

It would seem, then, that the wastes in connection with oil production, which are exceedingly heavy, are more due to inadequate utilization of technical knowledge, than to lack of means for effecting the economy. To gain a greater return from the resource, then, is more a matter of shaping a proper economic situation in respect to its exploitation than it is a matter of technological research.

Greater extraction of values.-We have seen that the oil in sight in the United States can not be reasonably expected to undergo significant enlargement through new discoveries of oil-bearing territory. The main hope of prolonging the life of the resource, therefore, lies in the two-fold direction of applying improved production technique, as already noted, which will, let us say, double the resource, and of gaining a fuller measure of value from the oil extracted, which is capable of multiplying the resource again by another factor no less great. Improvements in value extraction from the petroleum output will come through the extension and further improvement of "cracking" methods of distillation; through improvements in the design and efficiency of the internal-combustion engine; through the widening use of the Diesel type of engine, thus gradually deflecting fuel oil from its illegitimate rôle of a steam-raising understudy to coal; and through a carefully planned program for building up a great oil by-products industry to give multiplications of value to the portion of oil left after the energy, light, and lubricating values are extracted.

The "cracking" method of petroleum distillation has already been adverted to as representing the most promising means in sight whereby the growing demand for gasoline can be met from a slowing production of crude petroleum. The principle, therefore, is of the utmost importance, since it can be made to shove into the future the most threatening limitation to the growth of the automotive activity. Many "cracking" processes have been developed, all giving the same result, namely, a larger yield of gasoline at the expense of heavier components; but two of them stand out with especial prominence. These are the Burton process, for many years in successful practice in the refineries of the Standard group; and the Rittman process, recently developed by the Bureau of Mines and now also established on a commercial basis.2 There is no need here

to go into the technical differences between these processes; the prin

1 For example, the petroleum reserve is 7,000,000,000 barrels, with a valuation on the basis of 1915 prices of $4,500,000,000. For each per cent gain in extraction there will accrue to the reserve 70,000,000 barrels, worth $45,000,000. Expressed in another way, a 60 per cent gain in extraction efficiency will yield the equivalent of the total oil production to date in this country.

2 See Rittman, Dutton, and Dean, Manufacture of gasoline and benzine-toluene from petroleum and other hydrocarbons: Bulletin 114, Bureau of Mines, 1916. See also Yearbook of the Bureau of Mines, 1916, Washington, 1917, pp. 131-133.

45 ciple is the matter to which emphasis is called. "Cracking" is the leading potentiality in petroleum refining, no less so because it permits the production of the other main products according to demand, without sacrifice of by-product possibilities.1 The importance of the whole matter may be evalued by having regard to the fact that at present, even with "cracking" well launched into practice, less than one-half of the petroleum produced is manufactured into products representing an ideal apportionment of the raw material into its components. The production of gasoline may be doubled eventually or even more greatly multiplied without increasing the production of crude petroleum.*

3

2

The internal-combustion engine of the type currently in use in the United States has been the subject of greater refinements in special qualities-luxury qualities-than in respect to efficiency. That is evidenced in the widely varying gasoline consumption on the part of the familiar brands of automobile motors, which show a range from 20 miles and more to the gallon down to a yield of only 6 or 8 miles in the case of high-price cars. While the sacrifice of efficiency in favor of special qualities is, perhaps, legitimate to a certain degree, it would appear that the desire for invidious distinction has led to an undue focus of attention away from utility. With the rigors born of resource limitation-a certain eventuality-and upon the passing of the automobile more fully from the realm of a luxury into that of a necessity, a greater and more universal reach toward motor efficiency may confidently be counted on. But improvements in motor design will not lie along the single line of gaining more energy from gasoline; the effective use of heavier petroleum distillates, such as kerosene and fuel oil, and of other liquid fuels, such as alcohol, benzol, and tar oil, will be planned for and the broad trend of motor development will shape toward the character of the resource in its

5

1 It should be clearly held in mind that "cracking," with its attendant by-product possibilities, is a matter in constant course of development. actively engaged in furthering research and experimentation along those lines, though The Bureau of Mines is progress is hampered by inadequate financial resources.

2 An ideal apportionment can not be attained so long as there is an overproduction of crude petroleum in respect to the demand for gasoline and other motor fuel, kerosene, and lubricating oil, and there remains an economic demand for such an overproduction. Hence the extent to which "cracking' factors. may be applied is, of course, limited by economic

"We are to-day efficiently-that is, for gasoline and lubricating purposes-not more than 30 per cent of our oils. The other 70 per cent is used in competition with coal or exported for foreign countries and is generally sold for less than cost of production." Yearbook of the Bureau of Mines, 1916, Washington, 1917, p. 133.

4" Cracking brings in the asphaltic oils as effective producers of gasoline, a fact of no small economic significance.

"Perhaps no phase of the fuel situation has so interested automotive engineers as the use of kerosene in place of gasoline. Present market conditions are such that kerosene is one of the cheaper petroleum products, and as it has already been demonstrated to work satisfactorily in internal-combustion engines under certain conditions, there has been a great desire to render it available for general use in automobiles. of Mines has had called to its attention many devices for the utilization of kerosene, but believes that mechanical development in this particular line is a mistake. The Bureau logical and reasonable way to utilize kerosene is not as such, but as a mixture with The

entirety—a bent as yet only dawningly perceptible. Whether radical changes in motor principle are in prospect is a question that need not affect the present argument.

3

1

In point of bulk nearly three-fourths of the petroleum consumed in the United States goes into the production of power. Of this amount, one-quarter1 is employed in the form of gasoline as a motor fuel, while three-quarters,1 in the form of crude petroleum and fuel oil, is used as a convenient substitute for coal chiefly in firing steam boilers. While the efficiency of the internal-combustion engine is much greater than the steam engine, now commonly referred to as wasteful" in comparison with more modern types of power generation, the use of the superior principle has thus far been confined in this country almost exclusively to an explosion motor using gasoline the ordinary automobile engine familiar to all. The fact has generally been ignored in this country that a type of engine, comparable in efficiency to the gasoline motor, but making use of heavy oils (as fuel oil and even crude petroleum) and suitable for power generation on a large as well as a small scale, has for many years been in successful use abroad. This is the so-called Diesel type of engine, which has its conception as far back as 1893 and "has proved to be, from a thermal standpoint, the most economical heat engine so far devised, and the one that most nearly approaches theoretical maximum efficiency."

994

This high-compression oil engine, as it may be termed, gains its energy from the expansion that results when oil is sprayed into a cylinder filled with compressed air and ignites under the influence of the heat of compression. The relative efficiency of this type of engine may be shown in the accompanying tabular comparison:

the gasoline produced with it in the refining of crude oil. In other words, attention should not be given to the utilization of kerosene, but to the utilization of petroleum distillates containing both the gasoline and kerosene fractions of crude oil."-E. W. Dean, Fuel for automotive apparatus, Journal of the Society of Automotive Engineers, January, 1918, p. 53.

1 Rough approximation.

2 It has been estimated for the United States that the horsepower of gasoline internalcombustion engines is over twice that of all engines driven by steam. While the latter are more continuously used, the importance of the gasoline engine in power generating is strikingly great.

The relatively small quantity of kerosene used in power generation need not enter the present consideration. A small portion of fuel oil is used for gas making and for other purposes than steam raising, but for most of this work coal is likewise effective. 4 O. P. Hood in Technical Paper 37, Bureau of Mines, 1913, p. 8.

5 Figures generalized from data presented in Technical Paper 37, Bureau of Mines, 1913, pp. 12-15.

For marine use the advantages of the Diesel engine over the coal-fired steam engine includes the factors of speedier bunkering, greater fuel storage, etc.