COST of DRILLING AN OIL WELL. As might be anticipated from what has already been said, it is quite impracticable to estimate with entire accuracy what a well will cost, although in a certain district where previous drilling had pretty well defined the horizon of the oil-bearing sand, and the character and hardness of the different strata of that particular locality, contracts for the job will be readily undertaken by the professional driller. The following figures in detail were furnished as showing the cost of drilling a well in Bradford district, McKean County, in 1878. Belt, bull-rope, engine-telegraph, water-pipe, steam- Casing, say 300 feet at 80 cents per foot $350 00 100 00 750 00 "Tees" and "elbows" to make tank connections. One twenty-five barrel tank. One two hundred and fifty barrel tank Expense of tubing and packing well Expense of hauling tubing and material, etc. Total cost of well, flowing 975 00 240 00 320 00 100 00 25.00 8 00 3.00 5.00 25 00 110 00 25 00 20 00 50 00 $3106 00 In the above well no "drive pipe" was used, a short wooden conductor set up by the rig-builder being all that was required. In localities where from 100 to 280 feet of drive-pipe casing costing $1.80 per foot are required, the cost of the well is increased accordingly. The above estimate is for a flowing well. If it has to be pumped, the appliances necessary for that operation will cost about $175.00 additional. Both the cost and the time of drilling have been materially reduced since the early operations on Oil Creek, so much so, it is said, that the average cost to-day of a well 1500 feet deep is less than one of 500 feet in 1861. The time required to effect it has been reduced in like proportion. Very careful records have been kept of a number of wells, each day's progress accurately noted, and specimens preserved of the material through which the drill was passing. Previous to the year 1875 no authentic records of the number of wells bored are available. Since that time great care has been taken to secure and regularly publish full details of every well, its depth, and its outflow of oil. We take from the 'Derrick's Hand-Book' the following facts which we have tabulated: The above table represents the number of wells completed in the years enumerated, and also the proportion of "dry holes" to the producing wells. Many of the "dry holes" are "wild-cat" wells, and were drilled purely for the purpose of exploration. Upon examination of the maps of the oil region there will be observed clearly defined outlines of the oil-producing sands, which may lie buried 1500 or 2000 feet below the surface. The outlines of these producing spots are only determined by industriously drilling, with an accurate record of the exact location of each well and the results obtained. This is expensive mapping, but it has been by such a process that we are furnished with this valuable information. It has been estimated that if the distance bored in search for oil within the limits of the territory above mentioned were measured in one direction, the earth would have been bored through its longest diameter twice over. TORPEDOES. The device of adding to the productiveness of oil wells by the use of explosives is wholly American. The idea was suggested and put into successful operation in the year 1862 by Colonel E. A. L. Roberts, then of the United States volunteer service. This theory at first met with but little favor. It was supposed that it would not only be unsuccessful as to practical results, but would damage and choke up any well in which it should be tried. Permission was given him in 1866 to experiment in the Woodin Well, a dry hole which had never produced a barrel of oil. The result of the operation was to secure a production of twenty barrels a day, and in the following month a second torpedo was tried, which brought up the production to eighty barrels. These results established beyond a doubt the usefulness of the invention, and immediately a demand for it sprang up throughout the oil region. The mode of operation in adding to the yield of oil is probably to be explained by the complete disintegration of the oil-bearing strata in the vicinity reached by the terribly explosive force of the nitroglycerine employed, by which the petroleum is set free from the thousand small cavities in which it has been confined. The method of employing the torpedoes is thus described: "When the well is ready to be 'shot,' word is sent to the Torpedo Company, and the canisters are prepared in sections of about ten feet in length and five inches in diameter. These sections are made conical at the bottom, so that they will rest securely on top of each other. The nitro-glyce rine is carried in cans, that are placed in padded compartments, in a light spring wagon, which is often driven over the roughest mountain roads with great recklessness. Arrived at the well, one of the sections is suspended by a cord that passes over a pulley and is wound upon a reel. The nitro-glycerine is poured into the canister until it is filled, and then it is lowered by the cord to the bottom of the well. Another section is filled and lowered in like manner, until the proper amount is put in place; then the cord is drawn up, and a piece of cast iron weighing about 20 pounds, and made of such a form that it will easily slide down the bore, is allowed to drop down upon the cap, which is adjusted to the last section that was lowered. At a depth of 2000 feet no sound reaches the surface, although 80 quarts of nitro-glycerine, equal to 2160 pounds of gunpowder, may have been exploded by the hammer. After from three to ten minutes have elapsed a gurgling sound gradually approaches the surface, and the oil welling up in a solid column, filling the bore hole, and mounting higher and higher, falls first like a fountain and then like a geyser, and forms a torrent of yellow fluid, accompanied by the rattle of small pieces of stone and fragments of the canister in a shower of oil spray 100 feet in height; in five or ten minutes it is all over; 25 or 30 barrels of oil have been thrown to the winds." Fig. 23 represent the torpedo in position. A flow of oil does not always follow the use of explosives. It has been found that in the productive sands of fine close texture they have little or no effect. |