PETROLEUM.

New Zealand Herald, Volume LIX, Issue 18019, 18 February 1922, Page 1 (Supplement)

PETROLEUM.

THEORIES OF ORIGIN. BY M.I.M.E. Many theories have been advanced as to tho origin of rock-oil; for upward of a century brilliant chemists and geologists havo debated the problem from their different points of view. The most important are the chemical theory and the organic theory. Yet nothing is certain. We remain in doubt, although recently the tendency has beon toward tho conclusion that petroleum originates in some way or other, not well understood, from organic matter decomposing in shallow oiarino, lagunial, or estuarine conditions.

The organic school still hesitates between animal or vegetal origin, or both, under different conditions. American geologists and chemists agree- that petroleum has resulted from the decomposition of ancient organic matter in shales and limestones, chiefly the remains of animals, but in sonio cases also the remains of plants; that the petroleum and gas thus formed are stored in porous rocks and sands, and are prevented from escaping by a covering of impervious clay or shale. This hypothesis certainly serves best for many petroleum-bearing regions. The Chemical Theory. The chemical school has become more and raoro ingenious in its experiments, and in its theories. This theory supposes the existence of vast quantities of carbon in combination with metallic iron or manganese, forming carbides. Water descending from the surfaco and reaching these carbides would give rise to the oxidation of the metals, and the production of both gaseous and liquid hydrocarbons. It is conceivable that carbides may bo formed at great depths and that their contact with water will generate hydrocarbons ol all sorts. The association of mineral oil, marsh-gas, and other hydrocarbons and of carbonic acid in old volcanio districts may point to the continuous decomposition of such carbides by access of water. Dikes of massive cellular, igneous rock occur in New Mexico, and in Colorado, the cavities of which, thoroughly sealed in many cases, are filled with a fluid oil. This looks as though the oil were of volcanic origin, and argues in favour of the carbide origin of petroleum. It has also been suggested that water containing carbonic acid on being carried down to strata where metallic potassoum or sodium occur would generate petroleum. Others have suggested that bacteria play a part in the origin of petroleum. A& yet their mode of action is uncertain, but we do know the amazing chemical changes produced by these organisms in other cases. Dr. David Ellis, of Glasgow, has told us of odd little fellows called Spirephyllum ferrugineum and others, /whom we will call iron bacteria for short, who appear to perform the function of forming iron oxide crusts; certain deposits of iron ore may have been formed by the accumulation of the loosely agglomerated crusts. Whv should we not know sufficient one day to enable us to .prepare suitable culture of bacteria in proper surroundings to enable us to produce at wiU petroleum by this means? The question of the origin of petroleum is important, for if it has resulted from the decomposition of vegetal or animal remains, the supply must Oc limited, and sooner or later will bo exhausted. If chemical action is responsible, the supply may be practically inexhaustible. Prolific Fields. It is difficult to realise the enormous pressure which is exerted by the natural forces from beneath an oil deposit; this force is the same that produces tho flow in artesian wells. Water percolates downwards along a porous stratum from a high elevation to a lower one, and collects under the oil, and when the impervious cover is perforated by the drill, the water drives tho oil to the surface. In many oil-fields prolific rt spoulers," or "gushers" have rewarded the oil-men as soon as tho "oil-pool" v.as struck. The Carmen No. 1 well, in tho Elks Hills district, in California, spouted oil 120 feet, the flow varied from 10,000 barrels to more than 15.000 Barrels per day. Tho No. 30 Hogg well in Texas flowed at the rate of 30,000 barrels a dav from a depth of 3400 feet until a portion of the equipment failed. The Lake View spouted oil at The rate of 42,000 barrels per day for six montliß, in 1910 Many smaller producing wells had been sunk round the Lake View, but, as they were all shallow wells, it was not until a lower stratum of sand had been perforated by the Lake View that the enormous production from this field can be said to commence. Many large gushers resulted. Oil Well on Fire. In 1901, an American company drilled a woll on property they owned at Dos Boras, in Mexico. They failed to find any oil or gas. Six year* later, the English firm of Samuel Pearson and Son, Ltd., acquired tho property. The first well drilled on the estate by tho Pearsons produced 5000 bands of oil daily, from a depth of 2000 feet. On July 4, 1908, they had drilled their second well to a depth of 1824 feel, when all at onco the drill passed into soft shalo. This created no surprise, as it was expected. After drilling threo feet in the soft shalo, internal pressure began to exert itself, tho drill crow raised the drill rods a considerj able distance, and remained at the drill, thinking it was only a gas blowout, and would soon be over. It gradually became stronger, however, and fifteen minutes later the well was flowing at the rate of about 12,000 barrels daily, causing the ground to tremblo and open out in several places. One of these fissures wae beneath the boiler, the oil and gns caught fire, riio firo ignited, the gas coming from the well, and tho whole country surround-, ing the well was enveloped in ft mass of flame. Tho flow of the well increased until it was making between 75,000 and 100,000 barrels of oil daily. Tho wholo 1825 feet of 4in. drill rods, about eight tons, were blown entirely out of the well. Nino days aftor the firo started, the height of tho flames was estimated by the engineers to be 1500 feet. The Mexican Government sent a battalion of sappers to aid in extinguishing the fire and in saving the oil. The battalion remained for three months, building dikes and earthen reservoirs, when it was decided that engineering scienco was helpless when confronted with the extraordinary forces manifested. Tho well threw out an immense quantity of clav, sand, and gravel, forming a large crater. Soundings taken thirty feet from the sides showed a depth of 200 feet in places. Two acres of earth fell into the crater at one time. The well was finally abandoned when the volume of water and oil had risen to 14,000,000 barrels daily, nobody could say how much of it was oil, and the crater was almost one hundred acres in extent. Nino years later clouds of steam still rose from the ruins. The Pearsons owned another large gusher at Potrero. It required th c efforts of threo men to open th o gate-valve holding the well. Oil was thrown to a height of 491 feet, and the flow was estimated at 100,000 barrels daily. This well was brought under control after it had flooded the surrounding country. The oil was diverted into an earthen reservoir holding 3,000,000 barrels of oil. It was a mile round the reservoir, and in places the oil was 30 feet deep. In Mexico there are no oil sands, the oil is stored in ancient coral reefs, with sixty per cent.'porosity, samples of rock from ,these wells have the appearance of honeycomb, and as their thickness is generally spoken of as from one to three miles, we possess the explanation of the unusual qualities of the wells,