US 852061 A
Description (OCR text may contain errors)
No. 852,061. PATENTED APR. 30, 1907.
R. J. HOFFMAN. DEEP OIL WELL PUMPING.
APPLICATION FILED JAN. 24, 1907.
(mm/ PM. fllgmw THE umams PETERS cu, WASHINGYON, n. c.
UNITED STATES PATENT orruon.
Specification of Letters Patent.
Patented April 30, 1907.
Application filed January 24,1907. Serial No! 363,818.
To all whom it may concern:
Be it known that I, Ross J. HOFFMAN, a citizen of the United States, residing at Bradford, Pennsylvania, have invented certain new and useful Improvements in Deep-Oil- VVell Pumping, of which the following is a specification.
My invention relates to the art of deep oil well pumping. In this art the capacity of the pump is known, the diameter of the b ore of the cylinder and the length of stroke of the walking beam, or piston of the engine. It has been observed that, in deep Wells, the delivery of oil at the discharge, does not correspond to the stroke or capacity of the pump with a given length of stroke but is less than the pump capacity, with such given stroke. I have further observed, especially in the use of pneumatic pumping engines, and the pneumatic system of pumping, (such as that de scribed in Letters Patent 773501, Oct. 25th 1904) that, at the beginning of the up stroke there is a failure of prompt action, in lifting the oil, and further that this temporary failure is followed by a sudden undesirable jerking movement of the pump red. I have further observed that when the pump of a deep well has been removed, the length of stroke of the pump piston, indicated by the wear, was less than the stroke of the engine, which operated the pump. This has indicated to me that the pump rod, for some reason, does not, in these deep wells, rigidly and positively communicate, in full measure, the stroke of the engine to the pump piston, but that there is some yielding of the pump rod (which is the medium of communication of motion between the engine and the pump piston) either on the down or up stroke or on both. It will be borne in mind that these pump rods are of wood in connected sections and of a diameter less than the interior diameter of the pipe of the well. Further, this rod, throu hout its length (often two or three thousand feet) is through a body of oil, which offers resistance to the movement of the rod. The downward movement of the engine piston which is on the upper end of the rod is against the resistance of a body of oil from five hundred to three thousand feet. This causes the red, when pushed down, to buckle in directions, at different points, of least resistance, at one point in one direction and at another in another or opposite direction. The rod therefore assumes a sinuous or buckled condition, and is no longer a straight line. The result of this is that the piston of the pump is not pushed as far on the down stroke as the movement of the engine piston, or walking beam, and does not move so far, unless time be given for the buckled rod to resume its normal straight position. But, if, as in the ordinary action of the engine, the up stroke immediately succeeds the down stroke, the first effect of the up stroke of the engine is spent in taking the crooks out of the rod, and does not move the piston of the pump at all, until the rod is so straightened. When that takes place the force of the engine falls upon the piston with a erking motion, as when one lifts a weight by a pull upon a loose cord attached thereto which is not only objectionable in itself but causes loss in the delivery of the oil.
To remedy this, I have devised a method in which I modify the movement of the pumping force and cause a delay, or dwell at or about the limit of the downward stroke of the engine. This gives time for the readjustment of the pump rod, and opportunity for it to straighten in the mass of oil in which it moves; and further, on the return of the stroke the piston having been further pushed down, by the straightening of the rod, is in position to lift upon the oil instantly, though with slower initial movement on the return stroke. The amount of shortening of the rod in a deep well is very considerable. I have found 1t to be about one inch in a hundred feet. This in a 2000 foot well, (the usual depth) would be one foot 8 inches. It will be seen further, that by my method where a pump is used driven by compressed air, I not only secure an increased output of oil but effect a saving in the power necessary to operate the pump. That is, under the present arrangement, where the movement of the piston in the pumping head is ineffective for a third or more of its stroke it requires a maximum amount of air to drive the piston back and forth, with a minimnmof effectiveness, while in my improved method the fact that the movement is effective throughout its length renders the reciprocation of the piston in the pump head slower and hence takes less air in spite of the fact that there is a greatly increased flow, so that I actually decrease the amount of power necessary to drive the piston in the pumping head and yet increase the amount of oil pumped.
In the accompanying drawing I show one means of carrying my invention into effect,
but do not limit myself to any particular means for this purpose.
In this drawing I have shown in diagrammatic form two sectional views of a pumping head actuated preferably by compressed air with the connection from the piston of the pumping head to the pump rods extending into the well.
In this drawing, A represents the tube of the well, B the puinp rod made in sections, and O is a pumping head, D being the piston within the head.
I have shown the bends in the pump rod B, in an exaggerated form, but correctly as to character. Though generally made of wood the weight of the rod in deep wells is very considerable, and this weight, as soon as the downward push of the rod is effected by the engine, aids the rod in assuming its normal straight position, so that it is ready, when the engine lifts, to act instantly upon the pump.
The piston D is, as described in Letters Patent 7 7 3501, actuated by admitting air to one side or the other according to the direction of its movement, and I make this device effective to carry out my present method in a very simple manner. The pipe for the exhaust is shown at a, the air discharging through this pipe as the piston descends, and in order to retard the piston in the cylinder as it approaches the limit of its downward movement I lengthen the piston D, and make it of slightly less diameter than the inner diameter of the cylinder 0, and it will thus be seen that as the piston descends, moving at a normal rate of speed this speed will be re tarded as soon as the lower edge of the ex tended piston crosses the opening to the exhaust a, by reason of the fact that the free outlet of air is checked and made more gradual, and this will give the necessary dwell in the downward action of the piston. Precisely the same action will occur on the initial upward movement of the piston, namely, the 45 the edge of the piston clears the openingthe upward movement will be accelerated. I do not limit myself, as I have said, to any particular means for effecting this result and neither do I limit myself to means for causing a retardation only of the movement of the pump piston, as it approaches the limit of its downward movement and in its initial ascent, though I prefer this action as it is possible to effect the same result though not in as satisfactory a manner by making the movement of the parts uniform throughout but causing an actual dwell or stop when the pump reaches its lowermost position before beginning the ascent.
In the drawing, Figure 1 shows ina diagrammatic and exaggerated form the bends in the pump rod in the descent of the piston under pressure, while Fig. 2 shows the piston in the pump descending slowly and permitting the pump rod to straighten out.
That I claim i s:
1. The method employed in pumping oil which consists in retarding the movement of the pump rod as it approaches and recedes from the limit of its downward movement.
2. In combination with a pumping engine, and with the pump and pump rod, means for retarding the movement of the piston as it approaches and recedes from at or near the limit of its downward movement.
In testimony whereof, I afIiX my signature in presence of two witnesses.
R. J. HOFFMAN.
Witnesses HENRY E. COOPER, EDWARD N. SARTON.