CHAPTER VII

DRILLING THE OIL WELL

Methods of well drilling differ in various regions in accordance with the special problems to be encountered and perhaps no other industry furnishes more examples of mechanical ingenuity in the solution of physical difficulties. Drake went about the business of drilling the first well by using the traditional methods of boring for salt. Improvement was inevitable, however, and the Canadian wells of Western Ontario, which came into existence almost contemporaneously with those of Pennsylvania, were fruitful of inventions which have influenced drilling practices in many parts of the world. If we go back to the origins of oil and salt drilling mechanisms we find ourselves in China centuries before the Christian era. The Chinese used an auger attached to a pole that was held in a vertical position from a cross pole supported on a post. The end of the cross pole was fastened to a lever while a driller guided the cable to which an auger or boring tool was attached. Several coolies jumped from a platform on to the reverse side of the board, so that the tool would be jerked up and would plunge down and thus deepen the hole with each stroke. The deeper the hole became, the more coolies required for the task of “kicking down.” Jumpers were not a part of the staff of an oil-drilling organization in America in the early days but foot power was sometimes employed for the same purpose of driving the drilling tools into the ground. To-day labour-saving machinery plays as great a part in well drilling as in other branches of industry.

Let us suppose then that an oil company, or an individual with the requisite capital at his back, has advanced through the preliminaries which must precede drilling operations; the geologists have made a favourable declaration as to the prospective site; the leases and royalties have been arranged and the title is secure. When it is decided to start drilling, roads are built, water lines laid, and the lumber, casing machinery and other equipment are hauled to the location (often under very primitive and difficult conditions). The apparatus most commonly installed under these circumstances is the Pennsylvania cable system, which consists of a standard derrick or rig, built of wood or steel, about eighty feet in height, having a twenty-foot base and a four-foot top. The strength of the derrick is conditioned entirely by the size and depth of the well the operator wishes to drill, for nowadays nothing is left to chance. The size of the hole necessary in starting a well depends upon the physical formation. If it is soft, it is necessary to start with a hole of large diameter, to overcome the disabilities produced by caving. It sometimes happens that soft formations cave so much that it is necessary to insert several columns of casing before the required depth is reached. A hole with a large diameter is also used in deep drilling.

[Illustration: The Drader Well in the Moreni field, Roumania. This well was producing 20,000 barrels daily when it caught fire]

[Illustration: Burkburnett in northern Texas, showing development since August, 1918]

The drilling equipment is called by the oil workers a “string of tools.” It consists of a rope socket, a stem or sinker about thirty feet long and five inches or more in diameter, depending on the size of the hole to be drilled, with a bit at the bottom. Attached to a string of tools is a set of what are known as “jars,” which take their name from their function of enabling the driller to jar the sinker loose. Manila or wire cable is wound upon a large reel known as the “bull wheel” which is placed in the base of the derrick and a section of this cable passes over a crown pulley at the top of the derrick and is fastened to the rope socket and “string of tools.” The drilling movement is created by a power-driven walking beam which is a heavy timber working on an axis. This walking beam rocks up and down, with a stroke of three or four feet; thus the tools are raised and dropped at regular intervals, their great weight giving them a stroke equal in force to a steam hammer. The power used is ordinarily steam and the cable is connected with the walking beam by a temper screw, which enables the driller to lower the tools and handle them with ease and accuracy.

Another method of growing importance is the rotary system, perfected within the present century in the Gulf Coast field of Texas and Louisiana and which in many sections is coming into common use. Its special advantage is speed in soft or caving formations. It consists of a perforated fish-tail bit screwed to a string of drill pipe, which projects up through the derrick platform and is rotated at the rate of about two hundred revolutions per minute by a turn-table. The top or “grip” joint of the pipe is usually made square, or hexagonal, to supply a good bearing surface for the turn-table. The tools are suspended by means of a swivel at the top of the grip joint. This swivel also has a hose connection through which thin mud is pumped down to the bottom of the hole. The circulation of this mud carries out the cuttings made by the fish-tail bit, and also serves to plaster up the side of the hole and thus prevent caving. The column of mud in the hole exerts a hydrostatic pressure which absolutely prevents quicksand from running in and causing the hole to collapse. A rotary appliance has been known to drill two hundred feet or more in twelve hours, but usually so high a rate of speed is impossible, since the pipe stem has to be pulled out at frequent intervals and the bit replaced. The fact that the delicate fish-tail bit grows smaller with wear creates this necessity.

Another periodical process that must be carried on in the intervals of drilling is that of lining the hole with casing, in order that water and caving strata may be cased off before the oil sands are reached. After a well is operating, the lower part of the casing may rust through, causing leakage. To meet this difficulty an inner casing is put in place with a casing shoe, on the outside of which is lead or other soft material which expands under pressure from above to make a snug fit. Not infrequently, it is necessary to decrease the size of the hole with packers in this way four or five times, though it is kept as large as is practicable all the way down.

When oil is struck it is sometimes suddenly driven to the surface by imprisoned gas, and another gusher, a comparatively common phenomenon in Mexico, is recorded. But if this condition does not arise, tubing and pump are inserted and the oil is drawn to the surface. Not infrequently, however, the oil sands at the outset do not yield an adequate flow and in a great number of cases what is known as “shooting” with nitro-glycerine, an interesting and once dangerous process, is resorted to. In the early days before oil production had been reduced to scientific formulas the obtaining of crude was often attended with serious hazards to life. Ignorance of the properties of petroleum also created imaginary dangers for the pioneers. In 1860 the people of Western Pennsylvania were thrown into a panic by the proposal of a stranger, claiming to be a European scientist, to shoot a white-hot bolt into the bowels of the earth through an iron pipe driven to a great depth for the purpose. By the ignition of inflammable gases thought to exist in the great cavities beneath the earth’s crust the promoter expected to produce a sufficient explosion to lay bare the subterranean reservoirs of oil. The Pennsylvania populace, instead of viewing this proposal with the apathy usually accorded to the first essays of inventive minds, possessed sufficient imagination to picture the possible results, and were so convinced that the alleged scientist minimized the possibilities of his project that they selected a small but determined committee to lynch him. Because he threatened to undermine not merely the foundations of society but the ground on which society subsisted, he was taken into custody by the authorities and solemnly warned to desist.

Less than a year afterward nitro-glycerine was being exploded in large quantities down deep in the earth to shatter the oil-bearing rock and make wells flow, without noticeable public or physical disturbance. Any one who has watched farmers blow up tree stumps with dynamite may imagine what effect eighty quarts of nitro-glycerine would produce at the bottom of a deep eight-inch well. The “oil-shooters” are necessarily men of steady nerve and extreme caution. A shot will vary from ten quarts to as much as three hundred quarts, as the well to be treated may seem to require. For this purpose the nitro-glycerine is contained in tin tubes or shells five feet long and two inches or more in diameter, pointed at the lower end and having bail handles at the top. From five to fifteen shells, as the case may be, are lowered into the hole with extreme delicacy, and then the “go-devil”--a five-pound pointed shell--is released point downward. Nowadays, it is customary to use a nitro-glycerine squib wound with a long fuse more often than a “go-devil,” since the lowering of the cans of explosives may loosen earth which forms a cushion above the shells. An example of the presence of mind of a well shooter was provided a few years ago. Just after the first shell had been lowered, the rope suddenly slackened. This could only mean that the well had unexpectedly begun to flow and that in the space of a few seconds the shell containing six quarts of deadly explosive would be hurled from the well mouth. There was no time to run and the only thing that could be done this “well shooter” did. Bracing himself directly over the well he grasped the shell as it came to the surface, and although the impetus with which it had ascended threw him across the derrick and dislocated his shoulder, he held it free from contact and saved the lives of the entire crew.

Under the careful arrangements now made, a well is controlled with no more loss of oil than the driller thinks necessary to flush out the dirt and debris caused by the explosion.

The early or flush production of a well is usually of considerably greater volume than its normal or settled flow after it has been in operation for a few weeks. This decline in production is often as much as 50% in the first 30 days. Where wells do not flow naturally, various devices can be used to stimulate the output. Gas pressure has much to do with the problem. As a general rule the well of low gas pressure must be pumped from the beginning. The “gusher” which is the result of high gas pressure usually recedes rapidly in the matter of flow and becomes what is known as a “pumper,” the name given to wells when pumping is resorted to.

The minimum of flow at which a well ceases to be profitable varies according to location, and is fixed by many conditions of which transportation and quality are the most important. Thus, in Mexico, a well yielding only fifty or one hundred barrels per day is usually abandoned as uncommercial, whereas in Pennsylvania and West Virginia, where the facilities for handling are better, there are thousands of old “pumpers” in operation producing a superior grade of oil, many of which supply only one-fourth of a barrel per day.

The production of the first well drilled on a new location fixes the policy to be pursued with regard to the rest of the acreage under lease. After it has been tested and proven to be satisfactory the remainder of the property is drilled as quickly as possible. If the field is shallow and the wells are all “pumpers,” a central power station operated by gas or gasoline is sometimes installed which may provide the energy for pumping as many as a dozen wells. The shackle-rods spread out over the field like a spider’s web, and the rhythmical “chug-chug” is music to the ears of the oil man and also to the farmer who has leased the oil rights to him--for the song of the pumping plant symbolizes fat royalties.

It will be clear to the reader that even in the initial process the production of crude petroleum under modern standardized processes which eliminate, so far as possible, waste of labour or of product, involves a considerable capital expenditure. The cost of a well in a new district, where the depth is likely to be in the neighbourhood of three thousand feet, may amount to considerably more than $50,000 and a year may pass in the process of drilling. In the case of deep wells a permanent derrick is built, but in earlier days, for shallower holes a portable drilling machine was used, and with good fortune oil was often reached within a short time and the cost kept well within a margin of $5,000. It will be remembered that in the original Drake well at Titusville, oil was struck at sixty-nine and a half feet and that it took seven months to drill the well; a concrete illustration of the improvement in methods which has transpired in sixty years. But the days of cheap drilling have passed into the limbo of half-forgotten things and there is practically no oil production at the present time which does not represent a very considerable initial outlay.