THE ORIGIN OF PETROLEUM.1
Reading edition
THE ORIGIN OF PETROLEUM.1
By O.C.D. Ross, M.Inst.C.E.
Petroleum is one of the most widely distributed substances in nature, but the question how it was originally produced has never yet been satisfactorily determined, and continues a problem for philosophers. In 1889 the total production exceeded 2,600,000,000 gallons, or about 10,000,000 tons, and, at fourpence per gallon, was worth about £44,000,000, while the recognition of its superior utility as an economical source of light, heat, and power steadily increases; but, notwithstanding its importance in industry, the increasing abundance of the foreign supply, and the ever-widening area of production, practical men in England continue to distrust its permanence, and owing to the mystery surrounding its origin, and the paucity of indications where and how to undertake the boring of wells, they hesitate to seek for it in this country, or even to extend the use of it whenever that would involve alterations of existing machinery. The object of this paper is to suggest an explanation of the mystery which seems calculated to dissipate that distrust, since it points to very abundant stores, both native and foreign, yet undiscovered, and even in some localities to daily renovated provisions of this remarkable oil.
The theories of its origin suggested by Reichenbach, Berthelot, Mendeleeff, Peckham, and others, made no attempt to account for the exceeding variety in its chemical composition, in its specific gravity, its boiling points, etc., and are all founded on some hypothetical process which differs from any with which we are acquainted; but modern geologists are agreed that, as a rule, the records of the earth's history should be read in accordance with those laws of nature which continue in force at the present day, e.g., the decomposition of fish and cetaceous animals could not now produce oil containing paraffin. Hence we can hardly believe it was possible thousands or millions of years ago, if it can be proved that any of the processes of nature with which we are familiar is calculated to produce it.
The chief characteristics of petroleum strata are enumerated as:
I. The existence of adjoining beds of limestone, gypsum, etc.
II. The evidence of volcanic action in close proximity to them.
III. The presence of salt water in the wells.
I. All writers have noticed the presence of limestone close to petroleum fields in the United States and Canada, in the Caucasus, in Burma, etc., but they have been most impressed by its being "fossiliferous," or shell limestone, and have drawn the erroneous inference that the animal matter once contained in those shells originated petroleum; but no fish oil ever contained paraffin. On the other hand, the fossil shells are carbonate of lime, and, as such, capable of producing petroleum under conditions such as many limestone beds have been subjected to in all ages of the earth's history. All limestone rocks were formed under water, and are mainly composed of calcareous shells, corals, encrinites, and foraminfera—the latter similar to the foraminfera of "Atlantic ooze" and of English chalk beds. Everywhere, under the microscope, the original connection of limestone with organic matter—its organic parentage, so to speak, and cousinship with the animal and vegetable kingdoms—is conspicuous. When pure it contains 12 per cent. of carbon.
Now petroleum consists largely of carbon, its average composition being 85 per cent. of carbon and 15 per cent. of hydrogen, and in the limestone rocks of the United Kingdom alone there is a far larger accumulation of carbon than in all the coal measures the world contains. A range of limestone rock 100 miles in length by 10 miles in width, and 1,000 yards in depth, would contain 743,000 million tons of carbon, or sufficient to provide carbon for 875,000 million tons of petroleum. Deposits of oil-bearing shale have also limestone close at hand; e.g., coral rag underlies Kimmeridge clay, as it also underlies the famous black shale in Kentucky, which is extraordinarily rich in oil.
II. As evidence of volcanic action in close proximity to petroleum strata, the mud volcanoes at Baku and in Burma are described, and a sulphur mine in Spain is mentioned (with which the writer is well acquainted), situated near an extinct volcano, where a perpetual gas flame in a neighboring chapel and other symptoms indicate that petroleum is not far off. While engaged in studying the geological conditions of this mine, the author observed that Dr. Christoff Bischoff records in his writings that he had produced sulphur in his own laboratory by passing hot volcanic gases through chalk, which, when expressed in a chemical formula, leads at once to the postulate that, in addition to sulphur, ethylene, and all its homologues (CnH2n), which are the oils predominating at Baku, would be produced by treating:
2, 3, 4,5equivs. ofcarbonate of lime (limestone) with
2, 3, 4, 5"sulphurous acid (SO2) and
4, 6, 8,10"sulphureted hydrogen (H2S);
and that marsh gas and its homologues, which are the oils predominating in Pennsylvania, would be produced by treating:
1, 2, 3, 4,5equivs. ofcarbonate of lime with
1, 2, 3, 4,5"sulphurous acid and
3, 5, 7, 9,11"sulphureted hydrogen.
Thus we find that:
Carbonate of lime, 2CaCO3, Sulphurous acid, 2SO2, and Sulphureted hydrogen, 4H2S, }yield { 2(CaSO.H2O) (gypsum), 4S (sulphur), and C2H4, which is ethylene.
And that:
Carbonate of lime, CaCO3 Sulphurous acid, SO2, and Sulphureted hydrogen, 3H2S }yield { (CaSO4.H2O) (gypsum), 3S (sulphur) and CH4, which is marsh gas.
So that these and all their homologues, in fact petroleum in all its varieties, would be produced in nature by the action of volcanic gases on limestone.
But much the most abundant of the volcanic gases appear at the surface as steam, and petroleum seems to have been more usually produced without sulphurous acid, and with part of the sulphureted hydrogen (H2S) replaced by H2O (steam) or H2O2 (peroxide of hydrogen), which is the product that results from the combination of sulphureted hydrogen and sulphurous acid:
(H2S + SO2 == H2O2 + 2S).
It is a powerful oxidizing agent, and it converts sulphurous into sulphuric acid. Thus:
CaCO3 H2S, 2H2O, }yield { (CaSO4.H2O) (gypsum) and CH4, which is marsh gas.
And
2CaCO3 2H2S, 2H2O2, }yield { 2CaSO4.H2O and C2H4, which is ethylene.
Tables are given showing the formulæ for the homologues of ethylene and marsh gas resulting from the increase in regular gradation of the same constituents.
Formulæ Showing how Ethylene and its Homologues (CnH2n) are Produced by the Action of the Volcanic Gases H2S and H2O2 on Limestone.
Carbonate of lime.Sulphureted hydrogen.Peroxide of hydrogen.Gypsum.Ethylene and its homologues.
2CaCO3+2H2S+2H2O2yield2(CaSO4.H2O)+C2H4ethylene (gaseous).
3CaCO3+3H2S+3H2O2"3(CaSO4.H2O)+C3H6
4CaCO3+4H2S+4H2O2"4(CaSO4.H2O)+C4H8
5CaCO3+5H2S+5H2O2"5(CaSO4.H2O)+C5H10Boiling
6CaCO3+6H2S+6H2O2"6(CaSO4.H2O)+C6H12point.
7CaCO3+7H2S+7H2O2"7(CaSO4.H2O)+C7H14—
8CaCO3+8H2S+8H2O2"8(CaSO4.H2O)+C8H16189°C.
9CaCO3+9H2S+9H2O2"9(CaSO4.H2O)+C9H18136°C.
10CaCO3+10H2S+10H2O2"10(CaSO4.H2O)+C10H20160°C.
11CaCO3+11H2S+11H2O2"11(CaSO4.H2O)+C11H22180°C.
12CaCO3+12H2S+12H2O2"12(CaSO4.H2O)+C12H24196°C.
13CaCO3+13H2S+13H2O2"13(CaSO4.H2O)+C13H26240°C.
14CaCO3+14H2S+14H2O2"14(CaSO4.H2O)+C14H28247°C.
15CaCO3+15H2S+15H2O2"15(CaSO4.H2O)+C15H30—
It is explained that these effects must have occurred, not at periods of acute volcanic eruptions, but in conditions which maybe, and have been, observed at the present time, wherever there are active solfataras or mud volcanoes at work. Descriptions of the action of solfataras by the late Sir Richard Burton and by a British consul in Iceland are quoted, and also a paragraph from Lyall's "Principles of Geology," in which he remarks of the mud volcanoes at Girgenti (Sicily) that carbureted hydrogen is discharged from them, sometimes with great violence, and that they are known to have been casting out water, mixed with mud and bitumen, with the same activity as now for the last fifteen centuries. Probably at all these solfataras, if the gases traverse limestone, fresh deposits of oil-bearing strata are accumulating, and the same volcanic action has been occurring during many successive geological periods and millions of years; so that it is difficult to conceive limits to the magnitude of the stores of petroleum which may be awaiting discovery in the subterranean depths.2
Gypsum may also be an indication of oil-bearing strata, for the substitution in limestone of sulphuric for carbonic acid can only be accounted for by the action of these hot sulphurous gases. Gypsum is found extensively in the petroleum districts of the United States, and it underlies the rock salt beds at Middlesboro, where, on being pierced, it has given passage to oil gas, which issues abundantly, mixed with brine, from a great depth.
III. Besides the space occupied by "natural gas," which is very extensive, 17,000 million gallons of petroleum have been raised in America since 1860, and that quantity must have occupied more than 100,000,000 cubic yards, a space equal to a subterranean cavern 100 yards wide by 20 feet deep, and 82 miles in length, and it is suggested that beds of "porous sandstone" could hardly have contained so much; while vast receptacles may exist, carved by volcanic water out of former beds of rock salt adjoining the limestone, which would account for the brine that usually accompanies petroleum. It is further suggested that when no such vacant spaces were available, the hydrocarbon vapors would be absorbed into, and condensed in, contiguous clays and shales, and perhaps also in beds of coal, only partially consolidated at the time.
There is an extensive bituminous limestone formation in Persia, containing 20 per cent. of bitumen, and the theory elaborated in the paper would account for bitumen and oil having been found in Canada and Tennessee embedded in limestone, which fact is cited by Mr. Peckham as favoring his belief that some petroleums are a "product of the decomposition of animal remains."
Above all, this theory accounts for the many varieties in the chemical composition of paraffin oils in accordance with ordinary operations of nature during successive geological periods.—Chem. News.
[1]
Abstract of a paper read before the British Association, Cardiff meeting, 1891, Section G.
[2]
Professor J. Le Conte, when presiding recently at the International Geological Congress at Washington, mentioned that in the United States extensive lava floods have been observed, covering areas from 10,000 to 100,000 square miles in extent and from 2,000 to 4,000 feet deep. We have similar lava flows and ashes in the North of England, in Scotland, and in Ireland, varying from 3,000 to 6,000 feet in depth. In the Lake District they are nearly 12,000 feet deep. Solfataras are active during the intermediate, or so-called "dormant," periods which occur between acute volcanic eruptions.