US3037456A - Well pumping apparatus and packer assemblies therefor - Google Patents

Description

C. R. NElLON June 5, 1962 WELL PUMPING APPARATUS AND PACKER ASSEMBLIES THEREFOR Filed Feb. 5; 1959 INVENTOR.

CLAUDE R. NEILON United States Patent 3,037,456 WELL PUMPING APPARATUS AND PACKER ASSEMBLIES THEREFOR Claude R. Neilon, Houston, Tex., assignor to Armco Steel Corporation, Middletown, Ohio, a corporation of Ohio Filed Feb. 5, 1959, Ser. No. 791,366 Claims. (Cl. 103-46) This invention relates to well pumping apparatus, and more particularly to novel fluid-operated free-pump apparatus and improved packers and packer assemblies useful therewith.

In the oil fields, it is common practice to employ well pumping apparatus including two strings of tubing in the well, one being a pump tubing and the other a production tubing, a fluid-operated pumping unit being disposed in the bottom of the pump tubing and being powered by power fluid delivered under pressure down the pump tubing. Disposed beneath the fluid-operated pumping unit in such an apparatus is a distributor serving, in normal operation, to convey both the fluid output of the pump and the engine exhaust fluid to the production tubing. In order that the power fluid shall not pass to the production tubing, means must be provided above the distributor to seal between the wall of the pump tubing and the conduit means employed to introduce the power fluid into the pumping unit. With such apparatus, it is necessary that the pump unit be removable, via the pump tubing, so that the pump unit can be taken from the well. There are other arrangements of such free-pump apparatus, For example, often times a sealing means is provided between an extension on the lower end of the distributor and the Well casing so that the annulus formed by the pump tubing and the well casing is utilized as a fluid passage in lieu of a string of production tubing.

In employing such pumping apparatus, a particular difficulty is encountered in Providing a sealing means capable, on the one hand, of accomplishing the necessary seal during operation of the pumping unit to force fluid up the production tubing and, on the other hand, of being disengaged from the pump tubing in such fashion as to allow the pumping unit to be passed up the pump tubing. While various types of sealing means have been successfully employed to provide the desired sealing action during pumping operation, such arrangements have been characterized by two disadvantages. First, there has always been a tendency for the material of the sealing element to be abraded and torn away during removal of the pumping unit from its tubing, so that pieces of the material of the seal would fall in the pump tubing and clog valves and the like. Next, in order to obtain a satisfactory seal, it has frequently been necessary for prior art workers to employ, in the pump tubing at the particular location of the seal, a nipple or coupling having a spe cially machined internal surface to cooperate with the sealing means' A general object of the present invention is to provide an improved fluid-operated well pumping assembly of the so-called free-pump type embodying a novel packer assembly by which the above-mentioned diificulties are avoided.

Another object is to provide in such well pumping apparatus, a packer assembly which is actuated into sealing engagement with the pump tubing by the pressure of the power fluid during the pumping operation and which is collapsed, out of sealing engagement with the tubing, by fluid pressure during removal of the pumping unit from its tubing.

A further object is to provide a packer assembly, particularly for use in connection with free-ptunps embody- 3,037,456 Patented June 5, 1962 ing the combination of a fluid actuated packer to provide a positive seal above the pumping unit during pumping operation and at least one packing cup against which power fluid may be directed to elevate the pumping unit when the same is to be removed from its tubing, the construction being such that the packer is automatically deactivated when power fluid is delivered upwardly to the packing cup.

Yet another object of the invention is to devise an improved expansible packer embodying novel means for preventing the material of the packer from being extruded when the packer is expanded to sealing position,

In order that the manner in which these and other objects are accomplished in accordance with the invention can be understood in detail, reference is had to the accompanying drawings, which form a part of this specification, and wherein:

FIG. 1 is a vertical sectional view, with some parts shown in elevation, of a typical well pumping installation in accordance with one embodiment of the invention;

FIG. 2 is a vertical sectional view, on larger scale than FIG. 1, of a packer assembly constructed in accordance with the invention;

FIG. 3 is a detailed vertical sectional view of a portion of the device of FIG. 2, on enlarged scale, and

FIG. 4 is a sectional view taken on the line 4-4, FIG. 3.

Referring to the drawings, FIG. 1 shows a portion of a well pumping installation of the free-pump type to which the invention is particularly applicable, this installation being generally like that described in U.S. Patent 2,568,320, issued September 18, 1951, to Coberly. Such an installation usually includes well casing 1 in which a pump tubing string 2 and production tubing 3 are located in paralleled relation and depend from the usual well head equipment indicated at 4.

Connected to the upper end of the pump tubing 2 and the production tubing 3 is a valve means 5 having a discharge pipe 6 and a supply pipe 7 connected thereto, the supply pipe being connected to a pump (not shown) employed to pump power fluid under high pressure to the valve means. Valve means 5 is operable selectively to connect the supply pipe 7 either to the pump tubing 2 or the production tubing 3 and to correspondingly connect the discharge pipe 6 either to the production tubing or the pump tubing.

Connected to the lower end of the pump tubing 2 .and the production tubing 3 is a distribution member 8 provided with a conical seat 9 in which there is seated a standing valve assembly 10 which also has a conical seat into which the pumping unit 11 is inserted. The standing valve assembly 10 receives the production fluid from the well in which casing 1 is set through a conventional type of gas anchor 12. Distribution member 8 provides fluid communication between power tubing 2, the producing formation (via the standing valve assembly 10) and production tubing 3.

In accordance with the invention, a tubing packer assembly indicated generally at 13 is located within pump tubing 2 .to serve as a means for sealing off the upper portion of the pump tubing 2 from the pumping unit 1 1. The packer assembly 13 comprises a tubular mandrel 14 threadedly secured at its lower end to the inlet port of pump engine 15 at the upper end of the pumping unit 11. Thus, the packer assembly provides for the flow of power fluid under high pressure from the upper portion of the pump tubing 2 through the axial bore of the mandrel 14 to the power fluid inlet of the pump engine 15, such high pressure power fluid driving the pumping unit.

Pumping unit 11 can be any suitable conventional hydraulically driven deep well pumping unit. The production pump of such unit discharges the production fluid, via exhaust ports 16, into the annular space 17 between the pump and pump tubing 2. This production fluid mixes with exhaust power fluid discharged, via ports 13, from the engine 15. The mixed fluid passes to production tubing 3 via distributor 8 and then to discharge pipe 6 via valve means 5.

As best seen in FIG. 2, mandrel 14 is provided with an upwardly directed annular shoulder 19 serving as an assembly stop for the expansible packer unit, indicated generally at 20. The packer unit 20 includes a resilient packer sleeve 21 the end portions of which are bonded to ring members 22, 23. Lower member 22 has a central portion threaded onto the mandrel 14, a lower cylindrical portion abutting shoulder 1?, and an upper cylindrical portion, of larger diameter, embracing and bonded to the lower end portion of the packer sleeve 21. Beneath the threaded portion of member 22, the mandrel 14 is provided with an outwardly directed transverse annular groove 24 in which is disposed a resilient O-ring sealing element 25.

Upper ring member 23 comprises a dependent cylindrical skirt embracing and bonded to the upper end portion of sleeve 21. Member 23 also includes, at its upper end, a cylindrical main body portion slidably embracing the mandrel 14 and provided with an inwardly directed transverse annular groove 26 in which is disposed a resilient O-ring sealing element 27. Thus, while the lower end of the packer sleeve 21 is fixed to the mandrel, the upper end thereof is free to slide axially therealong.

Packer sleeve 21 is fabricated of rubber, synthetic rubber, or other suitable resilient material, with or Without fabric or like reinforcing. The internal bore of sleeve 21 is cylindrical and of such diameter as to snugly embrace mandrel 14- when the sleeve is unexpanded. At its midpoint, sleeve 21 has an outer diameter substantially larger than that of the sleeve end portions. From the midpoint of the sleeve, the outer surface thereof tapers inwardly toward the ends of the sleeve. Thus, the exposed outer surface of the packer sleeve is made up of two opposed frusto-conical portions indicated at 28, 29.

Adjacent the midpoint of packer sleeve 21, the mandrel 14 is provided with a transverse annular groove 30 of such width as to extend to points adjacent members 22, 23, so that an annular space of substantial size is provided at this point between the mandrel and the packer sleeve. The mandrel is also provided here with a plurality of radially directed ports 31 communicating between the interior of the tubular mandrel and the annular space afforded by groove 30.

Embedded in the packer sleeve 21 adjacent to ring 22 is an anti-extrusion ring 32 made of a relatively hard material having a modulus of elasticity substantially greater than the modulus of the material used for sleeve 21. The elastic material of which ring 32 is fabricated has a proportional limit such that the ring will contract to its original diameter after having been expanded to a diameter greater than the ID. of the power tubing 2. The anti-extrusion ring 32 is advantageously made of polytetrafluoroethylene or a polyamide resin such as ny- Ion and has a portion of smaller outer diameter underlying ring 22; it also has a portion of larger outer diameter of substantial length extending upward beyond ring 22. This enlarged portion of ring 32 lies flush with the outer surface of ring 22 and has a wall thickness such that the retained power fluid pressure when sufficiently great will cause the rings upper extremity to expand outwardly until restrained by the inner wall of the power tubing 2.

A short distance above the upper end of clamping ring member 23 the outer diameter of tubular mandrel 14 is reduced for the remaining upper portion thereof. The lower end of a spacing collar 33, which has an inner diameter substantially equal to the outer diameter of the adjacent mandrel portion, engages a shoulder 34 formed on the mandrel by reason of the difference in outer diameters just mentioned. A resilient downwardly and outwardly flared packing cup 35 is disposed with a central portion of its inner surface supported by collar 33. The lower portion of cup 35 flares away from collar 33 so that the outer diameter of the cup at its lower end is large enough to engage the inner surface of pump tubing 2. The upper portion of cup 35 directly embraces mandrel 14. A follower 36 is used to retain packing cup 35 in position on the mandrel. A second spacing collar 37, a second packing cup 38 and a second follower 39 are similarly positioned above follower 36.

That portion of the mandrel which extends above follower 39 is threaded to receive a nut 40 which acts to retain the element of the assembly.

A plug member 41 is threadedly connected to the upper end portion of mandrel 14 and has an axial bore 42 which communicates with axial bore of the mandrel. Bore 42 does not extend for the full length of plug, radial ports 43 being provided to communicate between the interior of pump tubing 2 and the bore 42 of plug 41.

At installation, the expansible tubing packer 20, the packer cups 35, 38 together with the associated elements thereof are assembled on the mandrel 14 which in turn is secured to the pumping unit 11, and this assembly hereinafter referred to as the fluid operated pump assembly is then lowered into position in the pump tubing 2 by any of the conventional methods. One method requires the pump tubing 2 to be first filled with fluid. 'Ihe fluid-operated pump assembly is then inserted into the upper end of the pump tubing 2. The upper end of the pump tubing 2 is suitably plugged and the supply pumping device (not shown) is operated to pump power fluid under pressure through the supplying pipe 7, the valve means 5 and downwardly through the pump tubing 2, forcing the fluid-operated pump assembly downwardly until the seat in the standing valve 10 located in the distributor 8 is engaged. Since only a small fluid pressure on the upper end of the fluid-operated pump assembly is required to force it downwardly into position, any pressure differential occurring at this time between the inner and outer surface of packer sleeve 21 is insuflicient to cause anti-extrusion ring 32 to be forced outwardly to engage the inner surface of the pump tubing.

After the fluid-operated pump assembly is seated, an increase in the pressure of the power fluid, which is being fed into the upper end of pump tubing 2, causes power fluid to flow through the ports 43 of plug member 41, and through the axial bore of the mandrel to the power fluid inlet at the top of the engine 15, actuating the pumping unit 11. The power fluid passing through the axial bore of the mandrel 14 is also transmitted via ports 31 to the annular space between the mandrel and the inner surface of packer sleeve 21. The pressure of the exhaust fluid which is discharged through radial ports 18 of engine 15 into the annular space 17 is less than the power fluid pressure. The O-ring 25 prevents the power fluid from passing from the inner portion of the packing sleeve 21 to the annular space between the tubing packer assembly 10 and pump tubing 2. Since the inner surface of packer sleeve 21 is subjected to the higher power fluid pressure while the outer surface of the sleeve is subject to the lower exhaust fluid pressure, the sleeve 21 is urged outwardly into contact with the inner surface of pump tubing 2. This creates a seal between the packer sleeve 21 and pump tubing 2, such seal being effective to cause the total fluid output of pumping unit 11 to be delivered, via distributor 8, to the production tubing 3.

The upper ring 23 moves along the outer surface of mandrel member 14 toward the lower ring 22 when the sleeve 21 is urged outwardly. This feature allows the packer sleeve to expand into sealing engagement with any of the various internal diameters permitted by the commercial manufacturing tolerances under which the power tubing is produced.

When the power fluid pressure retained by the packer sleeve 21 reaches a substantial value it causes the antiextrusion ring 32 to expand. The amount of this expansion increases as the retained power fluid pressure increases, until the ring 32 is restrained by the walls of the power tubing 2. The ring 32, being made of a relatively hard material, resists downward extrusion of the packer sleeve. If the ring 32 were not used, the pressure forcing packer sleeve 21 into engagement with the inner surface of pump tubing 2 would tend to force the packer sleeve material downwardly into the annular space between ring member 22 and the inner surface of pump tubing 2. Assuming a suflicient flow of packer sleeve material into the clearance in this manner, the packer would fail. Because there is no pressure differential to force the upper portion of sleeve 21 into the space between the outer surface of member 23 and the inner surface of pump tubing 2, a ring similar to ring 32 is not required at the upper end of sleeve 21.

When the fluid operated pump assembly is to be raised for cleaning or repairs, power fluid is directed via supply pipe 7, valve means 5, production tubing 3, and distribution member 8 to the space below the seal created by packer unit 20. Power fluid is now no longer applied to the area above the seal created by the packer unit. The pressure existing at the outer surface of the lower portion of packer sleeve 21 is now greater than the pressure inside the sleeve, so that packing sleeve 21 and its anti-extrusion ring 32 move radially inward. The O- rings 25, 27 prevent the passage of power fluid from the outer to the inner portions of the packing sleeve 21. The packer sleeve 21 and anti-extrusion ring 32 are thus held clear of the inner surface of the pump tubing and its couplings as the fluid operated pump assembly is forced out by the pressure of the power fluid acting upwardly on the under side of the lower resilient packing cup 35.

Further pumping of power fluid in this manner continues to raise the fluid operated pump assembly as a whole. The lower resilient packing cup 35 cooperates with the upper resilient packing cup 38 in order to allow the apparatus to pass discontinuities in the walls of pump tubing 2, such as occur at joints in the tubing, without losing the seal afforded by the packing cups. The use of two resilient packing cups, properly spaced, enables movement of the cups across a tubing joint without loss of pressure, since one of the cups will always be seated against a smooth surface of the tubing string when the other encounters a discontinuity presented by a joint or coupling.

I claim:

1. In a fluid-operated well pump apparatus of the type comprising a pump tubing string, a fluid-operated pump unit disposed in the tubing string and having a power fluid inlet and a pumped fluid exhaust, conduit means out-side of the tubing string and connected to communicate with the pumped fluid exhaust of the pump unit, and control means selectively operable to supply power fluid either to the tubing string, to operate the pump unit, or to the conduit means, to force the pump unit upwardly through the tubing string, the combination of a tubular mandrel connected to the power fluid inlet of the pump unit and extending upwardly within the tubing string, said mandrel being provided at its upper end portion with port means for admitting power fluid thereto from the tubing string for operating the pump unit, resilient sealing means mounted on said mandrel below said port means and biased outwardly for sealing engagement with said tubing string, and an expansible packer unit carried by said mandrel below said resilient sealing means, said packer unit comprising an expansible packer sleeve embracing said mandrel and means providing a seal between each end of said packer sleeve and said mandrel to prevent escape of fluid therebetween, said mandrel being provided with port means disposed to supply power fluid from the interior of said mandrel to the inner surface of said packer sleeve to expand the sleeve into sealing engagement with the tubing string when power fluid is supplied to the pump unit via said mandrel, said sleeve being collapsible against said mandrel when power fluid is applied down the conduit means rather than down the tubing string, such collapsing allow ing the fluid to flow upwardly about the mandrel against said resilient sealing means to force the mandrel and pump unit upwardly through the tubing string.

2. An apparatus in accordance with claim 1 and wherein said means providing a seal at each end of said sleeve comprises a first ring member secured to the lower end of said sleeve and fixed to said mandrel, a second ring member secured to the upper end of said sleeve and slidable axially on said mandrel, and sealing means cooperating between said clamping n'ng members and said mandrel.

3. An apparatus in accordance with claim 1 wherein said means providing a seal at each end of said sleeve includes a lower ring member embracing and bonded to the lower end portion of said sleeve, and said sleeve is provided with an inset, nonmetallic anti-extrusion ring adjacent said lower ring member.

4. In fluid operated well pump apparatus of the type comprising a pump tubing string, a production tubing string, a fluid operated pump unit disposed in the pump tubing string, and means selectively operable to supply power fluid to the pump tubing string for operating the pump unit and to the production tubing string for forcing the pump unit upwardly through the pump tubing string, the combination of a tubular mandrel connected to the pump unit and extending upwardly therefrom within the pump tubing string, said mandrel having a smaller transverse section than that of the pump tubing string, said mandrel being provided at its upper end portion with first port means for admitting power fluid from the pump tubing string into said mandrel for operating the pump unit, said mandrel further being provided at a medial portion with second port means extending between the interior and the exterior thereof; an elongated resilient sleeve disposed in contact with the outer surface of said mandrel and having a medial portion which overlies said second port means; means mounting each end of said sleeve in sealing engagement with said mandrel on each side of said second port means whereby the medial portion of said sleeve is expansible radially outwardly of said mandrel into sealing engagement with the inner wall of the pump tubing string when power fluid flows through the pump tubing string and operates the pump unit, and whereby the medial portion is collapsible against said mandrel when power fluid flows through the production tubing string; and expansible means mounted on said mandrel above said sleeve and engageable with the inner wall of the pump tubing string, said expansible means being operable to force the pump unit upwardly through the pump tubing string when power fluid flows through the production tubing string.

5. In a packer assembly for free pumps, the combination of a tubular mandrel, an expansible packer sleeve surrounding said mandrel at a point intermediate the ends thereof, means operatively associated with said sleeve and said mandrel to provide a fluid-tight seal at each end of said sleeve to prevent escape of fluid from within the sleeve, said mandrel being provided with port means communicating between the interior thereof and the inner surface of said sleeve, at least one resilient packing cup mounted on said mandrel, the end of said packing cup 7 8 adjacent said sleeve flaring outwardly away from said References Cited in the file of this patent gnandrel, the end ofdsaid sleeve opposite such packing cup UNITED STATES PATENTS eing secured to sai man re by an annular member and a portion threadably attached to the mandrel and a second g gi gg zf fi u portion embracing and bonded to said sleeve, and an anti- 5 2527929 Hebard 1950 extrusion ring inset in said sleeve, said anti-extrusion ring 2568320 12111211:fir; 1951 comprising a portion disposed Within said ann lar mem 2:625:109 coberly J 1 5 her and a portion extending beyond said annular member. 2,764,244 Page Sept, 25, 195

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