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tion. It is, by way of excelience, a household fuel, and but little beyond this should be expected or asked of it. As a source of light, it is somewhat less satisfactory, as the percentage of illuminating agents in it is small, but for heating purposes it is in every way admirably adapted. It is equally valuable for stoves, ranges, grates, and steam production on a small scale. In many houses supplied with gas the kitchen fire never goes out. The convenience resulting from its introduction into household use is inexpressible, and a surprising reduction in the labors of housekeeping is effected by it. There is no greater luxury in the modern house than gaseous fuel.

The light arising from the burning of the gas is blue and feeble, but the heat is intense. A simple method of enriching the flame in grate fires, supplied with the gas, was accidentally discovered by Mr. George H. Ely, of Elyria, a short time since. By sprinkling, from time to time, a small quantity of common salt over the fire-brick or fire logs, the bright yellow flame of sodium is communicated to the gas. The salt makes a glaze upon the brick and the effect lasts for some time. The gas fire is made much more enjoyable when a bright and cheerful light is added to its other advantages.

The use of this low-pressure gas is accompanied with little of the danger that has been encountered in bringing high-pressure gas into cities and towns. Experience is teaching us how to reduce this danger to a minimum, it is true, but in the case of shale gas-wells the danger never existed.

For manufacturing purposes on any considerable scale the shale gas is scarcely applicable. There is too little of it. There are comparatively few wells of this group that produce 50,000 cubic feet per day, but without at least this amount, a well can scarcely be expected to supply steam for a fifty horse-power engine. Such an amount of gas is doubtless enough for several such engines, if it could be applied at the well's mouth, and with the assurance that proper economy in its use would be secured, but in all such cases it is always desirable to leave an untaxed supply of production, and upon this ground the statement above given is justified.

A like inadequacy is usually found in the shale gas-wells for the supply of gas for villages or towns. It has not the force requisite to carry it through long lines of pipe and maintain a vigorous supply at their termination. It is quantity again that is at fault. The details given in the subsequent portions of this chapter will fully illustrate these statements.

It is not only domestic supply that the shale gas is specially fitted to furnish, but it is individual household supply for which it is likely to

be most valued in time to come. Those who own farms or even village or city lots within the productive areas of the shale gas-field-and so far as is now known a very large percentage of the shale territory is productive on the scale already noted-will come to value their lands for the gaseous fuel which they hold in store as much, or perhaps more, than they would value the same lands if supplied with wood lots or coal mines. Farm houses within these limits will be arranged, in coming time, for the use of natural gas, and a hundred-acre farm will be found to have great possibilities in this respect. If a single well will last a score of years, such a farm will contain an available supply for many centuries. The initial expense of piping a house and drilling a well seems burdensome, but these items can be reduced by good management to low figures, and there is no doubt that a wise economy will justify the expenditures. Wells can be drilled in the shales at the rate of 150 to 200 feet per day. The interest on the investment will be much less than the ordinary fuel account of a year, let alone all the other great advantages to be derived from the use of gas. It must be borne in mind that a well yielding but 1,000 cubic feet per day, or even less, if attached to but a single residence, can make itself very serviceable. There would be at almost all times a "head" of pressure upon the well arising from accumulation during the intervals in which the gas is left unused. An ordinary stove does not actually consume more than twenty-five to fifty feet of gas per hour, so that several stoves could be supplied by a well of very moderate capacity. The most of the chances for measurement in the case of the shale gas-wells have been obtained when the wells were recently drilled and while at their best. Wherever measurement has been applied to wells that have been in use for several years, the production has been found to be small, not exceeding one or two thousand feet per day. The largest production of any shale well measured has not exceeded 100,000 cubic feet per day.

There is a mode of estimating the capacity of these shale gas-wells in northeastern Ohio that may be mentioned in this connection. Every pound of pressure when the well is shut in is counted equal to a production of 1,500 feet of gas per day. The method is supposed to be established on practical tests, but it is certainly unsound. The facts from a single well have, no doubt, given such results, but there is nothing to warrant the conclusion that the same relations will be found in other wells. In fact, direct measurements show that the claim is entirely untenable. Still, it is true that the shale gas-wells of a district are. more nearly alike than high-pressure wells, and it may be that calculations on this basis will not be very far from the truth for a single district so long, at least, as the entire closed pressure is confined to a few

pounds. Even this reduced ciaim has no authority whatever. The proper instrument for measuring the flow of these low-pressure wells is the anemometer. Its use for this purpose was first suggested by E. McMillin, Esq., of Columbus.

STRUCTURE AS RELATED TO SHALE GAS WELLS.

In the production of oil and gas, and especially of the latter, from both the Trenton limestone and the Berea grit, the elements of structure, that is, of the arrangement of the strata, including the folds, fractures, and dips by which they are affected, have been found to be of paramount importance. Is this factor equally influential in determining the gas production of wells sunk into the shales? There are some reasons why it might not seem to be equally important in this latter field. For example, no reservoirs on a large scale are found in the shales, and inasmuch as the principal effects of structure seem to be exerted on this element of oil and gas production in differentiating gas, oil, and saltwater in the rocks, it appears probable that wells in the shales are not so entirely dependent on and conditioned by this factor. A well drilled into a mass of rock throughout which gas is everywhere distributed, and from which water is excluded, would yield, at least, a small supply under any circumstances and without special regard to the facts of structure. But it is probable that such supplies would be very limited, and wells drilled under these conditions would be practically failures. On the other hand, it is obvious that in rocks as compact and closegrained as the shales of the Ohio system, the passage of gas would be very much facilitated by any crevices that are open in the shales, and along every minor axis of elevation we should have the right to look. for the largest supply of gas. It seems probable that slight disturbances which would be inadequate to secure concentration in the great gasbearing rocks, are much more effective here, or in other words, that crazed or broken structure is all that is required. This latter view was clearly brought out by Newberry many years ago in his discussions on this subject. Structure is, therefore, in all probability, even more effective in the shales than in the sandstones and limestones, because so much lighter phases of it can be turned to account in the way of furnishing wells with gas, but the special phases of it on which high pressure gas is dependent are not required in this field.

The difficulty or impossibility of marking and following horizons. in the shales has already been pointed out. We can scarcely go beyond the portions of the rock that are uncovered in the beds of streams and other such situations in our recognition of lines of uplift. When the beds are covered by drift, or even by soil, we have thus far found no

clues whatever. It is quite possible that persistent beds will come to be recognized when study enough has been given to the formation, from which the facts of structure may be made out independent of exposures, but up to the present time few such horizons have been found.

The leakage of the shales, which has already been spoken of under the head of "surface indications, " generally escapes through the joints of the rocks, at least where the exposures are such that the facts can be made out. In some cases there are faint but distinct axes of elevation that can be traced for several hundred feet, occasionally, and these are outlets for gas along their whole extent. In the bed of Rocky River, four miles below Berea, near the residence of H. A. Mastick, Esq., such an axis was found, bearing N. 40° E. A rise of but eight feet is visible in the beds that are uncovered here, but gas, accompanied with salt-water, has been found escaping since the country was first occupied. A well recently drilled on this line of uplift, obtained a fairly vigorous supply.

The moderate success of so large a number of wells covering so considerable a scope of country, through town after town and county after county along the shore of Lake Erie, is sufficient proof that these wells are dependent on no large structural features. The only explanation of such production that would be possible, if such features were counted essential, would be the presence of a broad and low anticlinal, parallel to the shore of the lake. Of the existence of such a fold it is scarcely necessary to say we have no proof. There is, in fact, no room for these large structural features in the country traversed, that is, the frequent natural exposures of the rocks are seen to be destitute of all important arches and folds. The minor rolls and light disturbances, such as the shales everywhere show in exposed sections, are probably sufficient to account for the facts of production. The great differences of production, and the occasional failures that occur, must also be borne in mind as we consider these facts. The points last-named can be rationally connected with the minor points of structure already described, or with the absence of such facts. We conclude, therefore, that structure, in its less pronounced phases, is probably essential to the gas production of the shales, but that the great features upon which the accumulation of the reservoir wells depends are not needed here.

AREAS OF SHALE GAS TERRITORY.

The territory in which gas of the character described above is to he found in Ohio can readily be pointed out. The northern and western outcrops of the great shale formation, in the eastern and central parts of the state, constitute its outer boundary. Passing southward and westward from this boundary, the shale gas territory is, without question, co-extensive with the shale formation. It does not, however, stop at this limit, but it takes in also nearly as great a breadth of the Waverly formation, in addition, as has been already assigned to it. No highpressure gas is found in the Waverly until the Berea grit has taken at least 400 to 500 feet of cover. We must add, therefore, to the shale formation as much of the adjoining Waverly border as is necessary to carry the Berea grit to an average depth of about 300 feet below the surface, and we thus obtain a belt fifteen to thirty miles wide that can be followed continuously from the Pennsylvania border to the Ohio Valley and beyond. This is by way of excellence the area of low pressure gas in Ohio. It is shown on the map that accompanies this chapter.

A second area, but of less importance, is found in a few of the northwestern counties of Ohio. The Ohio shale, as will be remembered, constitutes the surface rock in the whole, or in parts of Lucas, Fulton, Henry, Williams and Defiance counties. It is, however, deeply covered with drift deposits through most of this area, so that it has but few outcrops, and moreover, it was so reduced by glacial agencies before the drift was deposited upon it that there are, at most, but a few hundred feet of the shales to be found in any section. It has not exceeded 200 feet in the wells that have thus far been drilled within this general area.

Within the areas thus indicated, a large amount of exploration has been and is still being carried on. A part of this exploration and its results have been described in Chapter IV, in which various records are given of wells that have been drilled in districts where the Berea grit makes the surface rock, or where it is struck at moderate depths. But there remains a great body of facts drawn from unmistakable shale territory, that is, from regions in which the shales are the surface rocks. The explorations have been so extended that nothing like a full account can be undertaken here. The experience of various towns and localities will be briefly indicated, and from them it will be possible to deduce the general laws that seem to govern the gas production of the formation.

RECORDS OF SHALE GAS WELLS.

A brief review of the results of drilling in the shale belts of the state will here be given. The experience of towns beyond the state line, along the shores of Lake Erie, in seeking supplies of natural gas, is quite widely known. Fredonia, New York, began as far back as 1821, to utilize natural gas derived from springs in the valley that passes through the town. Barcelona, the harbor of Westfield, N. Y., used gas

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