The strata which are oil bearing have existed in their present condition for untold thousands, prob ably millions, of years. Hence the process of de composition must have been completed ages ago, or, if not yet completed, it must be so infinitely slow that the quantity accumulated in a thousand, or ten thousand, years would be entirely insig nificant. Whichever way the question is consid ered, indisputable evidence leads to the one conclu sion that the entire supply procurable is now already stored underground waiting for the drill.
This does not mean at all that man can win from nature her whole bountiful supply of the precious liquid. It means merely that certain great accumu lations have been gathered under favorable condi tions, and these man may have. Other far greater quantities exist in the rocks of the earth, but in such a way as to be entirely inaccessible and un available through any method now known.
A single formation, to take a specific example, underlies many hundred square miles of the dis trict south of Lake Erie. The formation is esti mated conservatively to be 500 feet thick, and to have a very uniform content of petroleum amount ing to about a tenth of one per cent. of its bulk. This quantity is, of course, far below the limit of possible productivity—Baku sands frequently con taining as high as twenty per cent. of their bulk— but, small as it is, it means an actual quantity of 2,500,000 barrels of petroleum for every square mile covered by the formation. To duplicate the entire production of the United States up to the present time would require the whole petroleum content from only 720 square miles of that one rock layer. Yet, disseminated as it is throughout the rock, it is entirely unavailable. It is dissem inated not because it is of more recent formation than the available supplies, but because the condi tions underground have not favored its concentra tion in a rich pool. Its actual age, in fact, is very much greater than that of some of the most pro ductive supplies now developed. There is, there fore, no cause to suppose that old pools may be replenished, or new pools be forming, from such sources. Every evidence says plainly : Here is so much oil accumulated by chance ; take it as fast as you wish, but remember that when it is gone the reservoir can never be refilled.
The history of whole districts and of individual wells tells the same story. The life of pools and wells, of course, varies greatly in different cases.
Thus, the Pithole district lasted only a few years and then failed entirely, while the Franklin area near by is still producing high-grade oil after forty years of activity. One well may fail after a few months or a year; others have been known to yield continuously for a quarter of a century. With very few exceptions, however, the original produc tion of a well is greater than at any subsequent time in its life, and the downward career begins almost from the very moment oil is struck. It may take years for the end to come, but its coming is as sure as the light of day.
The average duration of profitable production from a well is about five years, though a multitude of circumstances cause wide variations from the average. The important point, however, is that profitable production does cease sooner or later, and that as the older wells give out, new wells must be drilled to keep up the supply. This alternative, in turn, ceases to be effective, and the whole re gion gradually falls into decay. Every locality must eventually reach the limit beyond which the production begins to decline. Such has been the case in all the older pools; such must be the case with every pool discovered until the end of time.
The Texas field affords the most startling con firmation of these facts. Spindle Top began in 1901 with a giant gusher and a burst of glory un rivaled in this country before that date. Wells starting out with 75,000 to 100,000 barrels a day were encountered and gave the pool a production of over 34,000,000 barrels in the first four years of its life. But in 1905 the daily production had fallen to 4,000 barrels a day. All the Texas pools have had the same meteoric career, and, unless new ones are discovered soon, that state will cease to be an important factor in the in dustry. Even the highly productive Baku dis trict bears in effect the same sort of testimony. Over two hundred wells were opened there in 1888; less than two-score of them were producing at all fifteen years later. Out of 400 completed in 1900, more than a fourth had failed inside of three years—wells which may have taken several years for completion and cost as high as $20,000 each when done. The very life of the petroleum industry depends on unceasing activity in drill ing. As far as production is concerned, it is an industry here to-day and gone to-morrow.