US2171410A - Pump - Google Patents

Description

Aug. 29, 1939. F, E. STEELE l 2,171,410

PUMP

Filed oct. 18, 1937 A TT ORNE YS.

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Patented Aug. 29, 1939 UNITED STATES PATENT.'I OFFICE PUMP Francis E. Steele, Shreveport, La., assig'nor to Phillips Petroleum Company, a corporation of Delaware This invention relates to improvements in means to prevent the ineffective operation of the pumping equipment of oil wells so that a maximum flow of oil may be obtained incident to a pumping operation.

In certain types of oil wells a gas locking condition exists which permits the pump plunger of the usual type working barrels to travel through several strokes without opening the traveling valve. This greatly reduces the pumps efficiency and the heat generated by compressing and expanding the entrapped gas is transmitted to the polish rods and results in frequent shutdowns due to burning out of stuffing boxes and packing Thus the elimination of gas-locking is particularly essential in deep wells where the high compression ratio of the pump would cause a large portion of the Working stroke to be lost in compressing and expanding the entrapped gas.

Heretofore in all attempts to eliminate gas- ...locking in oil well pumping equipment and to increase the effective operation of the pump a gas vent valve or a gas anchor has been incorporated Within the structure but has been located below and supported below the standing valve. The thought behind this construction is that the gas would collect below the standing valve and be vented olf before the liquid associated with the gas could be drawn into the displacement chamber. As a result of this type of construction the area between the standing valve and the traveling valve remains sealed during the down stroke of the plunger with the result that any gas within that chamber must be compressed before the' traveling valve would open and allow the liquid to raise above the traveling valve preparatory to being discharged from the pump on the up stroke of the plunger.

'I'he present invention is based upon the results of discoveries that natural gas is soluble in crude oil and that the solubility is approximately proportional to the absolute pressure. This pressure may be appreciable if a pump has a submergence of several hundred feet and hold the gas in solution with the oil until the liquid has risen above the standing valve. During the up stroke of the plunger, the weight of the oil is transferred to the traveling valve which permits oil to enter the pumpthrough the standing valve. If the pump submergence and suction are appreciable oil will pass through the standing valve with much velocity and agitation. This action will release some of the gas that was held in solution in the oil while it was below the standing valve. The free and occluded gas will tend to rise in the pump and accumulate below the traveling valve and above the standing valve.

When oil of 38 A. P. I. gravity is pumped from a depth of 5,000 feet, for example, the hydrostatic pressure in pounds per square inch exerted upon 5 the traveling valve during the up stroke will be 1812 pounds. If no gas is present between the pump valves, the traveling valve would open immediately after the plunger reverses and starts downward, transferring this fluid column pres- 10v sure to the standing valve, closing it instantly.

But when gas is present below the traveling valve, it must be compressed to the static pressure in the tubing above the traveling valve before this valve can open or the standing valve close. Thus. a part of the downstroke is used to compress gas, and a portion of the work of the plunger in displacing oil is lost. i

Not all of the oil in a pump is displaced by the plunger during its downstroke; and the gas in the oil remaining between the two valves must expand during the following up stroke to the pressure existing below the standing valve because of pump submergence,v before the standing valve can open to permit the pump to refill. Therefore, at a pressure of 1812 pounds (123 atmospheres) one cubic inch of gas under compression should expand theoretically to 123 cubic inches during the up stroke. In a pump having an inside diameter of 1.75 inches, this expanded gas 30 should occupy about 50 linear inches of the pump. As a matter of fact, however, this distance would be less than 50 inches because the standing valve would open before the gas is completely expanded.

It will now be apparent that any means to vent gas which is operative in or below the standing valve will not prevent gas-locking of the'pumping equipment where the gas is held in solution until after it has risen above the standing valve and then separates from the liquid due to the decreased pressure. It was previously thought that any means for venting the gas which was locatedl above the. standing valve would be impractical since this would tend to break v the vacuum created by the up stroke of the plunger and thus prevent the pump from filling.

An object of the present invention is the 'provisionof a gas vent in pumping equipment.

A further object of the present invention relates to a means for preventing gas-locking in oil well pumping equipment. Y

A still further object of the present inventio relatesto a means for preventing gas-locking in oil well pumping equipment which does not depend on the setting depth of the pump or upon of this specification, and in which like numerals are employed to designate like parts throughout the same,

Fig. 1 is a cross-sectional view taken through certain well pumping equipment, and more par ticularly showing my improved and novel venting means,

Fig. 2 is an elevation view with a part broken away showing a modification of the structure disclosed in Fig. 1,

Fig. 3 is a cross-sectional view of a further modication, and

Fig. 4 is a diagrammatical view of mountedin an oil well.

In the course of the following description, similar characters of reference are used to indicate parts constituting the novel construction of the invention and their function wherein; I represents the working barrel of the pump which is lowered into the well within the casing 3 and well tubing 2 as can be readily seen by referring to Fig. 4. The numeral 4 represents a packing member which seals with the well tubing when the pump is inserted within the same to insure that the oil being pumped enters the well pipe or tubing and not the space between the casing and the tubing. The packing is secured to the upper end of the working barrel I by a cap or closure 5 which is screw threaded to the working barrel. The cap or closure 5 has an opening 1 therein which allows the polish rod 6 to reciprocate back and forth therethrough. The cap 5 also has openings 8 which, as can be seen from the drawing, are located above the packing 4 and serve as discharge ports for the accumulation chamber 9 and direct the oil into the tubing.

At the bottom of the working barrel I is a member I0 screw threaded into the working barrel. The member serves as an inlet to the accumulation chamber from the well and has a seat portion which supports the pump in the well. Mounted in the working barrel I directly above the member I0 is the standing valve comprising themember II having an oriiice I3 therein and a ball valve I2 closing the orifice. Located above the standing valve is the inlet member I4 leading to the accumulation chamber 9. The inlet member also serves as a cage for the ball valve I2.

Mounted in `the accumulation chambennnd slidable therein is the traveling valve meber or plunger I5 connected at the top thereof to the bottom of the polish rod 6 at I6. The traveling valve has a close sliding t with the accumulation chamber, orln other words, a ground joint seal to prevent leakage between the inner wall surface of the accumulation chamber and the outer surface of the traveling valve. It is further pointed` out that the traveling valve member is mounted to reciprocate with the polish rod.

On the bottom end ofthe traveling valve member is the member I1 screw threaded to the main body member I5 and having a channel 2|! terthe pump minating in a seat 2|. Mounted on the seat ZI is a ball valve I8 and screw threaded to the upper end of the member I1 is the cage I9; Openings 22 lead from the cage into the chamber of the member I5 and the oil in turn is discharged into the accumulation chamber through the openings 23.

Up to this point the operation of the pump structure is the same as any sucker rod pump. The polish rod 6 is pulled upward thus carrying along with it the travel valve member I5. As the travel valve member moves upward, it creates a vacuum back of it, the oil from the well coming in through the member I0, thus unseating the standing valve I2 and allowing the oil from the well to iiow into the accumulation chamber 9 back of the traveling valve member I5. When the traveling member I5 reaches the top of its stroke, the accumulation chamber will be full of liquid. When the traveling member starts downward, it will exert a force on the liquid which force will be transmitted through the liquid to close the standing valve I2 and in turn open the valve I8 in the traveling member. This will allow the liquid to passv through the channel 20, opening 2| and out openings 23 so as to be above the traveling member. When the traveling member reaches the bottom of its stroke the accumulation chamber will be full of liquid above the traveling member. Upon upward movement of the traveling member, the force of the liquid will close valve I8 and due to the close sliding lit of the traveling member in the accumulation chamber, the liquid will be lifted, passing out through openings 8 and thence to the well tubing. The, upward movement of the traveling member also unseats valve I2 again and allows liquid to ow in back of the traveling member. It can thus be seen that the filling and emptying of the accumulation chamber is a continuous operation.

It will be noticed that the wall 24 which forms the outer wall of the accumulation chamber 9, has an opening 25 therein which communicates with the interior of the accumulation chamber and is closed by the traveling member I5 except when the traveling member reaches the top of its stroke or for any predetermined position of the traveling member dependent upon the amount of free gas in the oil being pumped. The opening or port 25 communicates with the passageway 26 and through channel 21 opens up to the formation.

'I'he port 25 is drilled through the wall 24 of the plunger displacement chamber. 'Ihe port or portsbecause there can be more than one if desired, are so drilled and located in the wall of the accumulation chamber that they will be open and allow any gas that has collected above the standing valve and below the traveling valve to be discharged into the annular space 26 and then outithrough port 21. 'I'he ports 25 will be open, uncovered by the plunger, near the completion of the up stroke. As the plunger reverses and starts -on the down stroke any gas which has collected below the traveling valve will be .forced out through port or ports 25 which will remain uncovered on the down stroke until the plunger is almost ready to reverse. Thus the vacuum is not broken during the suction stroke until the plunger reaches the top of its stroke. This allows complete'iilllng of the chamber above the standing valve with liquid and the gas it is carrying in solution. As the gas escapes from solution it ls vented through port and is not compressed,

during the down stroke of the plunger.

As can be seen from this description and discussion, instead of pumping gas to the surface, a pump is here disclosed which lincreases the amount of liquid which can be raised, prevents shock on the polish rods from compressing the gas and insures against gas lock because the gas is discharged from the accumulation chamber and never has a chance to buildup in any large volume. The openings 25 are always placed in the wall of the accumulation chamber at the same place, hence they become more or less standard equipment. It is noted that all oils coming from the ground do not have the same percentage of gas in solution or the same percentage of free gas. Pumps in diierent wells meet with different gas conditions, hence for the venting to be adapted to all types of wells it must be adjustable.

Fig. 4 shows a diagrammatic view of the pump just described down in the'well with the polish rodV 6 running down to the same. The numeral 3| represents a pumping jack which is connected to the power means to actuate thevpolish rod. 'Ihe polish rod B and the pumping jack 3| are connected together at bymeans of a slip coupling. The polish rod 6 can be raised or lowered in the coupling 30 as conditions may demand.

If the liquid being pumped shows no free gas there is no need for the ports-25. Hence by lowering the polish rod 6, the stroke of the traveling member or plunger I5 can be so controlled that it will not uncover port 25. But if the liquid is found to contain gas, the stroke of the plunger I5 can be lengthened by raising the polish rod 6 in the coupling 30. In this manner the pump allows of adjustment and is adaptable for all gas conditions encountered. It is to be understood that the port 25 is placed near the top of the accumulation chamber so that the adjustments of the plunger stroke in no way cut down the volume of liquid being pumped.

Fig. 2 of the drawing shows a slight modification of the structure previously described. In

liti

has been found practical. The ports 25 are small andalso the vspace 2B is very small so that any back ilow through space 26 and port 25 into the accumulation chamber -when the same is under vacuum would be negligible, so it has been found that there is very little difference in operation whether the check valve is included or omitted.`

Fig. 3 shows a slight modification over what has previously been described. 'The well casing is shown at 3 having mounted therein a` seat member 'Ihe pump barrel I is connected directly to the well tubing 2' by means of the tubular member 36' which also has a seat portion 31' that rests on the seat 35 thus supporting the pump in the well. The pump has the standing valve l2' at the bottom thereof, traveling valve plunger I5' connected to polish rod 6' and adapted to reciprocate in the accumulation chamber 9. The operation of the pump is the same as the pumps previously described, being a reciprocal plunger type of pump. Ports 29' are mounted in the wall 24' of the accumulation chamber for the discharge of gas which collects between the standing valve and the traveling valve. However in this modification, the check valve 28 is mounted right in the port itself. The operation of this modification is the same as that disclosed for Fig. 2. Thegas is discharged through check valve 28', port 29 into annular space 26' which leads back to the formation.

It is to be understood that the forms of my invention herewith shown and described, are to be taken as preferred examples of the same and various changes in the shape, size and arrangement of parts may be resorted to, without departing from the spirit of my invention, or the scope of the subjoined claim.

Having thus described my invention, I claim: In a deep well pump mechanism for pumping a mixture of liquid and gas, an outer pump barrel, an accumulation chamber within the' accumulation chamber, saidvopenlngs being closed f by the plunger for the major portion of its stroke but being opened when the pluiiger approaches its extreme upward position;

'FRANCIS E. STEELE.

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