US3175512A - Deep well pump for viscous oil - Google Patents

Description

March 30, 1965 W- N. SUTLIFF DEEP WELL PUMP FOR VISCOUS OIL Filed March 25, 196.3

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INVENTOR. MAY/V5 M 5074/1;

BY 7 I 1 W ATTOEA/fy United States Patent 3,175,512 DEEP WELL PUMP FOR VISCOUS 01L Wayne N. Sutliif, 2931 Pierce Road, Bakersfield, Calif. Filed Mar. 25, 1963, Ser. No. 267,562 3 Claims. (Cl. 103-179) This invention relates to the art of oil well production and particularly to production from wells in which the oil has a relatively high viscosity.

Discovery of new and important compounds derivable from natural petroleum with a high viscosity has recently awakened interest in improving the techniques of removing this type of oil from the ground. Thinning viscous oil by the addition of a solvent or by heating it with steam have been extensively tried to expedite pumping this oil to the surface. These expedients have proved either too cumbersome and expensive or have introduced intolerable fire hazards.

It is accordingly an object of the present invention to provide an improved pump which is particularly adapted to pump relatively viscous oil from a deep well without resorting to the above expedients.

One of the chief problems met with in pumping viscous petroleum from a well is the retarding of the return movement of the plunger in the pump barrel by the viscous film of oil between the working parts of the pump. To solve this problem, heavy weights have been applied to the plunger to speed up the return stroke of the plunger in the barrel, but the effect of these weights greatly decreases where the bottom portion of a well slants as much as 45 from vertical, and such an angle of inclination is not at all uncommon.

Another expedient widely tried has been to apply a coiled spring to the plunger which is stretched or compressed on the upstroke of the plunger, the tensioned spring thus speeding up the downstroke of the plunger. This functions regardless of the angle at which the well is slanted, but the spring can be made effective for only a relatively short stroke and the power applied varies radically from one end of the stroke to the other.

Another object of the present invention, therefore, is to provide an improved deep well plunger pump incorporating means for increasing the speed of the downstroke of the plunger which means is operative regardless of the slant of the well bore where the pump is located, and which is equally efliective throughout the stroke, regardless of how long the stroke may be.

The manner of accomplishing the foregoing objects as well as further objects and advantages will be made man ifest in the following description taken in connection with the accompanying drawings in which FIG. 1 is a diagrammatic vertical sectional view of a preferred embodiment of the pump of the invention illustrating this pump in the midst of an upstroke of the plunger thereof, and showing the lower travelling valve closed and the upper travelling valve open.

FIG. 2 is a view similar to FIG. 1 illustrating the pump of the invention at a point in the operation thereof close to the end of \a downstroke of the plunger, and showing the lower travelling valve open and the upper travelling valve closed.

FIG. 3 is a detail horizontal sectional view taken on the line 33 of FIG. 2 and illustrates the cross sectional area of the sucker rod by which the pump of the invention is operated.

FIG. 4 is a horizontal sectional view taken on the line 4-4 of FIG. 2 and illustrates the cross sectional area of the hollow plunger-actuating piston of the invention.

Referring specifically to the drawings, the invention is there shown as embodied in a pump including a cylindrical tubular pump barrel 11 which is internally threaded at its upper end to screw onto the lower threaded end 12 of a sub 13 the upper threaded end 14 of which is threadedly received into the lower end of a production tubing string 15. The sub 13 has an axial bore 16 which is relatively large in diameter.

Extending downwardly from the top of the well through the tubing string 15 is a sucker rod string 17 which is made up of a series of sucker rods 18 connected end-to-end each of these sucker rods being approximately feet in length and having a cross sectional area for most of its length as shown in section in FIG. 3.

Secured to the lower end of rod string 1? is a rod connector 19 including an open cage 20 and an internally threaded lower collar 25 which screws downwardly on the externally threaded upper end of a hollow actuating piston 26 which slidably fits and reciprocates in the bore 16 of sub 13. Formed outwardly from a lower end portion of the piston 26 and integral therewith is an externally threaded head 27 onto which screws a cylindrical body 28 of an upper travelling valve 29. The valve body 28 has a lower wall 30 which is centrally apertured to form a valve seat 31, said body thus providing a closed valve chamber 32 in which a valve ball 33 is confined.

The valve body 28 has a substantially smaller external diameter than the internal diameter of pump barrel 11 and is integrally connected by a frusto-conical neck 34, having a series of laterally opening holes 35, with a heavy annular reinforcing band 40 provided integrally with the upper end of a tubular pump plunger 41. The band 40 and tubular plunger 41 have a common external diameter which causes these to slidably fit within the cylindrical tubular barrel 11.

The plunger 41 may be of any suitable length and is internally threaded at its lower end .to receive an externally threaded plug 42 of a lower travelling valve 43. The plug 42 is centrally apertured to provide a fluid passage 44, at the upper end of which a valve seat 45 is provided surrounded by a conical face 46 for causing a valve ball 47 to return by gravity to said seat.

Operation The pump 10 is of course provided with the usual sucker rod reciprocating mechanism (not shown) at the top of the well which is connected to the upper end of sucker rod string .17 and operated to reciprocate said rod vertically in the tubing string 15.

During the upstroke of the pump 10, illustrated in FIG. 1, the ball 47 of lower travelling valve 43 closes as shown in this view thus trapping the well fluid confined between the piston 26 and pump barrel 11 and the sub :13 and the upper end of pump plunger 41. The space within which production fluid is thus trapped may be referred to as the pumping chamber 48, because it is alternately a fluid compression chamber and a fluid suction chamber. This chamber functions as a compression chamber on the upstroke of pump 10 as shown in FIG. 1

vand as a suction chamber during the downstroke of said pump as shown in FIG. 2.

During the upward or compression stroke of the pump,

fluid trapped in chamber 48 is forced to flow through the the space between the sucker rod string 17 and the pump tubing string 15.

During the upstroke of the pump, when the fluid trapped between valve 43 and sub 13 in the pump chamber 48 equals the hydrostatic pressure of the production fluid 50 in tube 15, valve 29 will open and discharge the fluid in pump plunger 41.

operate this pump than is involved in the area of the plunger 41;

It also should be noted that there is a constant stretch held in the rod string 17 by the hydrostatic pressure downward on the area of the plunger actuating piston 26. This increases the efficiency of pump by decreasing the loss of stroke due to rod stretch. The rod stretchfrom full load to no load in common pumping practice results in as much as inches loss in pump stroke.

Conventional plunger pumps employed in deep oil wells depend upon the high specific gravity of the material of which the pump plunger is made and the weight of the sucker rod string directly thereabove to rapidly overcome any resistance set up by viscosity of the oil being pumped to the rapid return downwardly in the pump barrel of the pump plunger. As above pointed out, however, where the well fluid being pumped is a highly viscous petroleum, the viscosity factor becomes so excessive that the weight of the pump plunger and the sucker rod is inadequate to secure a rapid return downward of the pump plunger on the downstroke of the same. This deficiency is overcome in the pump 10 by the hydrostatic pressure aforesaid which is applied downwardly on the piston 26 and the plunger 41 by the column of production fluid 50 occupying the tubing string 15.

The manner in which this hydrostatic pressure becomes 7 effective to add a substantial downward force to the pump ing chamber 48 of the pump. This suctioncauses the lower travelling valve 43 to open as shown in FIG. 2

'so that production fluid in the pump barrel 11 below the pump plunger 41 rises through valve 43 and flows up-.

wardly through the plunger .41 and out through the holes and around the valve body 28 of the upper travelling valve 29 into the pumping chamber 48.

During this downstroke, the hydrostatic head of the production column 50 in the tubing string 15 is applied downwardly to the pump plunger 41 through the closed upper travelling valve 29 over an area equal to the cross sectional area of the hollow piston 26, which is clearly shown in FIG. 4, less the'minimum cross sectional area of individual sucker rods 18 of the rod string 17 which is clearly shown in FIG. 3. As can readily be seen, the design of the pump 10 may be varied to precisely determine the net area thus subject to the hydrostatic head of the production fluid column 48, but each square inch of this area in a well 5,000 feet'deep causes the downward application of a hydrostatic pressure of 1700 lbs. to the It is thus clear that the hydrostatic pressure available for assisting in the downward movement of the plunger of the pump on the downstroke of thelatter which .is available in pump 10 is far in exoess of any assistance which can be proivded by the use of metal springs. Furthermore the hydrostatic pressure made available in the pump 10 for expediting the down travel of the plunger 41 of the pump is constantly applied to the plunger on both the upstroke and downstroke so that this pressure does not vary throughout the downstroke of the pump whereby a pump may be designed with a relatively long stroke and it will successfully perform in pumping a highly viscous oil by virtue of the fact that the hydrostatic assist provided by this pump will be applied to the plunger thereof equally throughout the downstroke of the plunger regardless of how long this downstroke maybe.

It is also clear that the hydrostatic assist given by pump '10 'to the downstroke of the plunger is effective regardless of the extent to which the lower portion of the well bore is slanted away from'vertical. Indeed, this hydrostatic assist would function with equal effectiveness even if the lower portion of the well bore occupied by the pump were to be horizontal, which, in extremecases is actually the case.

It is to be understood that the invention is shown in the drawings diagrammatically and for illustrative purposes only and that various changes and modifications may be made in the invention as shown without departing from the spirit of the invention or the scope of the appended claims.

I claim: I

1. In a deep Well pump, the combination of: a tubular pump barrel; a sub closing the upper end of said barrel and connecting it to the lower end of a string of production tubing, there being a relatively large diameter axial bore provided in said sub; a plunger slidable in said barrel, and having an axial passage connecting the space in said barrel below said plunger and the space in said barrel between said plunger and said sub, the latter space being referred to hereinafter as the pump chamber; a bottom travelling valve checking downward fluid flow through said passage; a hollow piston slidably fitting said sub bore, the lower end of said piston being attached to the upper end of said plunger and having a fluid connection with said plunger passage; an upper travelling valve checking downward fiuid flow through said hollow piston and a rod connector connecting the upper end of said piston'to a sucker rod string for reciprocating said piston and plunger, said connector having opening means allowing free fluid communication between the upper end of said piston and the interior of said production tubing string.

.2. A combination as recited in claim 1 wherein said plunger is tubular, said lower travelling valve including a centrally apertured plug fixed in the lower end of said plunger, the aperture in said plug having a valve seat formed therein, and a ball resting on said seat, and wherein said upper travelling valve includes a cylindrical hollow body which has a substantially smaller outside diameter than the inside diameter of said pump barrel and provides a closed valve chamber having an upper opening which connects with the lower end of said hollow piston and a lower opening providing a valve seat which connects with the interior of said plunger, and a' valve ball confined in said chamber and normally resting on said valve seat, and wherein said body has means connecting the same to the upper end of said plunger, said connecting means providing fluid passage means connecting between the interior of said plunger and said pump chamber.

3.. In a deep well pump adapted to be located at the lower end of a string of production tubing and be actuated by a string of sucker rods provided in said tubing, the combination of: sub means secured to and closing off the lower end of said tubing string, said sub means having an axial bore of a relatively large diameter; a hollow pump actuating piston slidably fitting said bore; a connector connecting the upper end of said pistonwith the lower end of said rod string and providing communication between the upper end of said piston and the space within said production tubing string; ;a travelling valve provided on and travelling vertically with said piston for checking any downward travel of fluid through said piston, the cross sectional area of said bore being very substantially in excess of the minimum cross sectional area of said sucker rod string whereby said piston and travelling valve are subjected during the downstroke of said tube to a very substantial net amount of downward hydrostatic pressure from the hydrostatic head of the production fluid column occupying said tubing string; and reciprocating suction-compression pump meansdisposed below said sub means and actuated by the reciprocation of said piston to accomplish a suction stroke during the downward movement of said piston so as to take in a charge of well fluid fluid through said hollow piston and into said pump tubing string.

References Cited in the file of this patent UNITED STATES PATENTS Martin Sept. 21, 1954

Claims (1)

1. IN A DEEP WELL PUMP, THE COMBINATION OF: A TUBLAR PUMP BARREL; A SUB CLOSING THE UPPER END OF SAID BARREL AND CONNECTING IT TO THE LOWER END OF A STRING OF PRODUCTION TUBING, THERE BEING A RELATIVELY LARGE DIAMETER AXIAL BORE PROVIDED IN SAID SUB; A PLUNGER SLIDABLE IN SAID BARREL, AND HAVING AN AXIAL PASSAGE CONNECTING THE SPACE IN SAID BARREL BELOW SAID PLUNGER AND THE SPACE IN SAID BARREL BETWEEN SAID PLUNGER AND SAID SUB, THE LATTER SPACE BEING REFERRED TO HEREINAFTER AS THE PUMP CHAMBER; A BOTTOM TRAVELLING VALVE CHECKING DOWNWARD FLUID FLOW THROUGH SAID PASSAGE; A HOLLOW PISTON SLIDABLY FITTING SAID

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