RIGS AND EQUIPMENT.
The marvelous growth of the petroleum industry in a few years has brought out all the ingenuity of the men connected with it to meet the drilling conditions encountered in the different fields. This rapid development and the curious nature of the work, in which conditions are unlike almost any other branch of engineering, have resulted in wide divergences of opinion as to the best meth ods to follow, and it is not uncommon to see quite different outfits and methods in the same field and working under similar drilling conditions. Each will have its votaries and each will get the hole down, but the natural hazard of the work is such a factor, and so often the unforseen happens, that unless the merits of one method are sweepingly greater than the other it is often impossible to choose between them. The normal duty of materials used in drill ing is not unduly severe; the trouble arises with the occasional in cidents that are bound to occur and which suddenly throw a great strain on some one part of the equipment. An• example of this is seen when a bailer sticks in the hole, through the crumbling ma terial in the sides falling in about and over the bailer so that it is held tight. The wire line that sustains the bailer ordinarily may never have to hold up a weight greater than a ton, yet in the pull that comes with trying to free the bailer it may be required to with stand a strain of many tons before it is either loosened or the line broken.
The application of engineering data to the problems of drilling, except in a cut-and-slash way, is almost impossible as far as satis factory results are concerned. One man may build a certain type of derrick and find it well suited to his work ; his neighbor may build one exactly like it, and be drilling in the same kind of ground, but 'freezes' the casing through caving material falling in and bind ing the pipe. When he tries to pull the pipe up he pulls in the der rick instead. The same difficulty was just as liable to happen with the first operator, and illustrates the constant danger of mishaps in drilling wells. It also accounts, with the increasing depths and heavier tools used, for the increase in weight of almost everything in the way of equipment connected with drilling, and nowhere is this more apparent than in the rigs themselves. The term 'rig' is meant ordinarily to apply to the derrick, timbers and wheels, and does not include the boiler, engine, and other equipment.
Standard Drilling Rig. Except in rotary wells, which use the bare derrick only, the rig has two principal parts ; first, the derrick itself directly over the well; and second, the belt-house, which is the long, narrow building serving as a housing for the belt and band wheel and connecting the derrick with the engine house, covering the engine or motor. These rest on suitable foundations
of heavy timber which, with the heavier posts and walking beam, are known as the 'rig timbers.' With the exception of a comparatively small number of steel structures, 'derricks are built of timber. The former have not proved unsatisfactory, but their cost has been against them, as well as the Aifficulty in securing men understanding their erection. The itinerant rig-builder is found in all the fields and usually builds the rig by contract instead of day wages.
Where hard woods, such as oak or chestnut are found, they make excellent derricks, but more often some of the many forms of pine or other soft wood are the only available timber and the differ ence in their relative strengths 'govern somewhat the dimensions of the lumber in any particular rig.
The derrick is supported on posts which rest in turn on a suit able foundation of either timber or concrete, known as the 'derrick footing.' Light rigs need no concrete and often but little timber for the footing, while heavy ones may use a considerable quantity, as is seen by reference to the rig list on page 61, which provides for 1410 board feet of redwood for each of the four corners. This cor ner, in which the redwood boards are 3 in. thick, has a base of two layers 10 ft. square with succeeding pyramidal layers 9 ft. square, then 8, 7, 6 and 5 feet, the layers alternating in the direction of lay of the boards. Such a corner is very good for heavy work, as it is firm and yet has the slight 'give' to it that is desired. It is, how ever, very expensive and for this reason should be dispensed with where lighter and more simple timbers, or concrete, will serve as well. The latter is being used more and more and may be easily made of a 1 :3 :6 mix, 5 ft. high with a 5-ft. base and 3-ft. top. Loose surface material should be removed and the bottom of the forms placed below the surface so that the top of the concrete is a foot or two above it. Above the corners are placed the side sills (17), and the derrick sills (18), the latter supporting the floor of the derrick. .(These numbers and similar ones following refer to Fig. 34 on page 58.) The other principal foundation timbers are the mud sills (28), the main sill (27), the pony sill (36), the sub sill (45), the nose sill (46), engine sills (51), and engine block (41).