US3011557A - Hydraulic compensating tubing anchor - Google Patents

Description

Dec. 5, 1961 Filed July 26, 1957 M. B. CONRAD HYDRAULIC COMPENSATI NG TUBING ANCHOR 3 Sheets-Sheet 1 INVENTOR. Men/v B COMP/w MM7W ' Afro/9x496 Dec. 5, 1961 M. B. CONRAD I 3,011,557

HYDRAULIC COMPENSATING TUBING ANCHOR Filed July 26, 1957 3 Sheets-Sheet 2 INVENTOR.

Mew/v A5. f 04/9/10 BY I MM7W

United States Patent Ofiice 3,011,557 Patented Dec. 5,1961

3,011,557 HYDRAULIC CQMPENSATING TUBING ANCHGR Martin B. Conrad, Downey, Calih, assignor to Baker Oil Tools, Inc, Los Angeies, Calif., a corporation of California Filed July 26, 1957, Ser. No. 674,413 24 Claims. (Cl. 166-212) The present invention relates to subsurface well here equipment, and more particularly to anchors for securing tubular strings in well bores.

It is desirable to anchor at tubing string in a pumping well to secure a more positive displacement of the pump on each of its strokes. Without an anchor, the tubing string is subject to several factors that adversely affect the operation of the pump and of the tubing string itself. These include the ability of the tubing string to stretch or elongate caused by the weight of the tubing string itself, the weight of the column of oil or other fluid inside the tubing string, the rise in temperature of the tubing string resulting from pumping of hot oil there through, and increase in effective weight of the tubing string caused by its loss of buoyancy resulting from lowering of the fluid level in the annulus which surrounds it.

Another adverse factor is the upward and downward movement of the lower end of the tubing string during each upstroke and downstroke of the pump. On the upstroke of the pump, the fluid load is supported by the traveling valve and sucker rods, relieving the tubing string of such fluid load and resulting in its contraction. On the downstroke of the pump, the fluid load is reimposed on the standing valve and tubing string, causing the latter to elongate or stretch. This alternate contraction and stretching of the tubing string as the pump reciprocates is called tubing breathing, and causes a reduction in the eflective pump stroke and consequent loss of production. In addition, intermittent increase in the load on the tubing string as a result of its breathing is conducive to its ultimate fatigue failure.

Tubing strings also are subject to a phenomenon known as tube buckling. The lower end of the tubing string tends to buckle when they fluid load is supported by the sucker rods on the upstroke of the pump. Not only is this buckling action detrimental in and of itself, but the sucker rods, which are held straight by the fluid load being lifted, rub against the buckled tubing, the resulting friction causing excessive wear on the tubing and rods and decrease in pump plunger travel. Moreover, since the sucker rods are then misaligned with the pump, excess pump wear also results.

An object of the present invention is to provide an improved anchor capable of maintaining a tubing string secured to a well casing, or similar well conduit, in a tensioned condition.

Another object of the invention is to provide an anchor embodying slips to secure to a well casing and hold a tubing String in tension therein, the slips automatically moving down the casing, as the tubing string elongates, to successively lower holding positions, so that a companion slip expander, or the like, is prevented from hammering upon the slip as the tubing string tends to breathe.

Still another object of the invention is to provide an anchor for a tubular string capable of being set against the well casing, and which automatically releases and resets itself at a lower point in the well casing as the tubular string elongates, so as to compensate automatically for elongation of the tubular string and retain the lower portion on the tubular string in the lowermost position it reaches, thereby preventing buckling of the tubular string, its breathing under the action of the pump, and

insuring maximum effectiveness of each pump stroke.

A further object of the invention is to provide an anchor for a tubing string which sets automatically in the well casing by a hydraulic force. In a more limited sense, the anchor is set automatically by the fluid column in the tubing string as its level rises under the action in the pump. The anchor will also unset automatically in the well casing upon lowering of the fluid column in the tubing string.

An additional object otthe invention is to provide an anchor capable of securing a tubular string to a well casing in tension, which will automatically release from the well casing in the event the tubing string is subjected to a predetermined strain, thereby preventing the latter from being stressed unduly, which might result in its disruption or failure.

Yet another object of the invention is to provide an anchor for holding a tubing string in tension in the well casing, which can be placed in a released condition after having been set in the casing, with any fluid in the tubing string allowed to unload or drain through the anchor.

This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of a form in which it may be embodied. This form is shown in the drawings accompanying and forming part of the present specification. It will now be described in detail, for the purpose of illustrating the general principles of the invention; but it is to be understood thatsuch detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined by the appended claims.

Referring to the drawings:

FIGURE 1 is a combined longitudinal section and side,

elevation of a tubing anchor disposed in the well casing with its parts in their initial retracted position;

FIG. 2 is a view similar to FIG. 1 on an enlarged. scale illustrating the tubing anchor set against the well casing; I

FIG. 3 is a View similar to FIG. 1 on an enlarged scale illustrating the anchor with its parts in a subsequent under special conditions;

FIG. 5 is a quarter longitudinal section of the hydraulically operated portion of the apparatus disclosed in FIG. 1, drawn on an enlarged scale;

FIG. 6 is a quarter longitudinal section of the hydraulically operated portion of the apparatus disclosed in I FIG. 2, drawn on an enlarged scale.

As disclosed in the drawings, a tubing anchor A is provided in a tubing string B disposed in a well bore for the purpose of securing the tubing string to a well casing C, or similar well bore conduit, against upward movement to maintain the tubing string in a tension condition. Preferably, the tubing anchor A is mounted on the tubing string above its lowermost portion and above the pump (not shown) which is reciprocated by the usual string of sucker rods (not shown) extending to the top of the well bore.

The tubing anchor includes a tubular body or mandrel 10, the upper end of which is threadedly secured within a coupling 11, which is, in turn, threadedly attached to an upper tubing section B. The lower end of the body is threadedly attached to a lower body portion or guide 12 having a lower threaded pin 13 for'attachment to a lower coupling or lower tubing section 14.

V The tubular body 10 of the anchor is adapted to be secured to the wall of the well casing against upward movement therein. For this purpose, a plurality of ClIClllD' ferentially spaced segmental slips is disposed around the body, these slips being capable of moving laterally inwardly and outwardly with respect to the body, but being coupled together for joint longitudinal movement. Each slip 15 has an upper portion 16 receivable in a generally radial slot 17 in a slip retaining ring 18 slidably mounted on the upper portion of the body. The upper ends of each slip have oppositely directed tongues 19 adapted to slidably fit within companion side grooves 29 opening into each slot 17. The tongue and groove interconnection 19, 20 between the slip retaining ring 18 and each slip 15 causes the slip ring and all of the slips to move longitudinally in unison with respect to the body 10, but each slip 15 may move in a generally radial direction within its slot 17. Preferably, the tongues and grooves 19, 20 are inclined in an upward and outward direction so that the slips 15 move upwardly to a small extent when being expanded outwardly against the well casing C. Since the slips are to secure the tool to the casing against upward movement, they are provided with external casing engaging wickers or teeth 21 facing in an upward direction.

The slips 15 are expanded by a lower cone or expander 22, which is longitudinally slidable with respect to the body 10 of the tool and the slips. The expander is provided with a plurality of tapered surfaces 23 inclined in an upward and inward direction, these surfaces engaging a companion inner surface 24 on each slip for the purposes of shifting the slips outwardly upon upward movement of the expander 22 along the body 143 and the slips 15. Conversely, relative downward movement of the expander 22 with respect to the slips will effect retraction of the latter from the well casing. Such retraction is secured by providing a dove-tailed slidable joint between the expander and each slip. As disclosed, such joint includes a tongue 25 extending longitudinally along the tapered surface 23 of the expander, this tongue being received within its companion dove-tail groove 26 extending longitudinally along and inwardly of the rear face of each slip 15. The dove-tailed tongue and groove interconnection 25, 26 between the expander 22 and each slip 15 insures a positive shifting of each slip inwardly toward the body 10 of the well tools as the expander is shifted longitudinally downwardly relative to the slip; whereas, relative upward movement of the expander 22 with respect to the slips 15 will cause the expander surfaces 23 to engage the companion surfaces 24 on the slips and shift the latter outwardly into engagement with the well casing C.

Downward movement of the slips 15 with respect to the body 10 is limited by engagement of the lower end of the slip retaining ring 18 with an upwardly facing body shoulder 27. The slip ring 18 and the slips 15 are movable upwardly to some extent against the resistance offered by a helical compression spring 28 encompassing the body, with its lower end bearing or seating against the upper surface of the retaining ring 18 and its upper end seating or bearing upon the lower end of the upper body coupling 11. The spring 28 yieldably urges the slips 15 toward the expander 22 and downwardly of the body 10. However, the spring will permit the slip retaining ring 18 and the slips 15 to shift upwardly along the body 10.

When the slips 15 are to be expanded against the well casing, such action occurs in response to hydraulic pressure within the tubular string B and body 10 acting on the expander 22 and tending to shift it in an upward direction. Thus, the lower portion 30 of the expander actually constitutes the head of a cylinder 31. This cylinder includes a skirt portion 32 integral with and depending from the head 30, which is threadedly secured within the upper portion of a cylinder sleeve extension or housing 33 terminating at its lower end in an inwardly directed flange 34 above the upper end of the body guide 12. The cylinder shift 32 is spaced outwardly from the periphery of the body It) to define an annular cylinder space 35 therebetween in which an annular piston 36 is received. This piston can occupy an uppermost position along the body 10 determined by engagement of its upper end with a stop or shoulder ring 37 mounted on the body. This ring may be split and disposed in a peripheral groove 38 in the body, projecting outwardly therefrom to an extent suflicient to engage the upper end of the piston 36, and also to engage the cylinder head 30 to limit downward position of the expander 22 and cylinder 31 along the body 10.

The piston 36, body 10 and cylinder 31 have the annular cylinder space 35 therebetween into which fluids from the interior of the tubular body pass. Such fluid can enter through one or more side ports 39 in the body, flowing into a small annular space 40 between the piston 36 and the body 16 pro-vided by increasing the internal diameter of the upper portion 36a of the piston opposite the ports 39. Such fluid can then pass through vent openings or ports 41 at the upper end of the piston into the cylinder space 35, for action upon the cylinder head 30 in an upward direction and upon the piston 36 in a downward direction.

Leakage of fluid from the cylinder space 35 in an upward direction is prevented by a suitable seal 42, in the form of a rubber or rubber-like O ring, disposed in an internal groove 43 in the cylinder head 39 and sealingly and slidably engaging the periphery of the tubular body 10. Leakage of fluid in a downward direction is prevented by an external seal ring 44, in the form of a rubber or rubber-like O ring, disposed in a peripheral groove 45 in the piston and slidably and sealingly engaging the wall of the cylinder skirt 32. An inner seal ring 46, in the form of a rubber or rubber-like O ring, is mounted in an internal groove $7 in the piston 36 below its enlarged internal diameter upper portion 36a, this ring being adapted to slidably seal upon the periphery of the body. It is to be noted that the lower portion 10a of the body 10 is reduced in external diameter to permit by-passing of fluid into the cylinder 31 and around the piston 36 under certain conditions, as explained hereinbelow.

The piston as is prevented from shifting downwardly along the body 10 by a split lock ring 50 which inherently tends to contract. This lock ring has an upper inner tapered surface 51 inclined in a downward and inward direction, engageable with a companion tapered surface 52 on the lower outer end of the piston skirt. The inward position of the ring 50 is determined by engagement of its inner cylindrical surface 53 with a stop ring 54 surrounding the body 10 and having a counterbore or recess 55 receiving the outer portion 56 of a shear ring 57. The stop ring 54 at the upper end of the counterbore 55, engages the upper end of the shear ring 57, the inner portion 58 of the shear ring being disposed within a peripheral groove 59 in the body 10 of the tool. This inner portion 58 is of a much shorter length than the outer portion 56 and is adapted to shear from the outer portion when subjected to a predetermined longitudinal upward force imposed upon the body It? of the tool. The shear ring 57 itself is a split member, being held in the peripheral groove 59 by the lock ring 54 which surroundsv It.

The lock ring 54 has a lower flange 60 provided with a plurality of circumferentially spaced slots 61 therethrough. This flange 60 has a tapered surface 62 inclined in an upward and inward direction and engaging a companion tapered surface 63 at the lower and inner corner of the lock ring 59. It is evident that any downward force on the piston 36 will cause its tapered surface 52 and the tapered surface 62 on the lock ring 54 to tend to expand the lock ring 5% outwardly. When the force is sufficient to overcome the inherent contractibility of the lock ring 50, the latter is shifted outwardly to an extent limited by engagement of its periphery with the inner wall 65 ofthe housing 33. When such engagement occurs, the tapered surfaces 52, 62 at the lower end of the piston 36 and on the lock ring flange 6d are still engaging the lock ring 50.

Relative longitudinal movement between the cylinder 31 and expander 22, on the one hand, and the piston 36, on the other hand, is prevented initially by a holding ring 70, which is a split member that inherently tends to expand. This ring has an inner portion 71 mounted within a peripheral groove 72 in the piston skirt and an outer portion 73 which initially extends into a companion internal groove 74 in the cylinder skirt 32, 33, which may be defined between the lower end of the skirt 32 and an inwardly directed cam or flange 75 on the housing 33. This cam or flange has an upwardly facing tapered cam surface 76 inclined in a downward and inward direction engaging a companion tapered surface 77 on the outer portion of the releasable holding ring 70. When the downward force acting on the piston 36 becomes suflicient, it will cause the companion tapered cam surfaces 76, '77 to shift the ring 70 inwardly within the piston skirt groove 72 to the extent at which the outer portion 73 of the ring is forced out of the skirt and housing groove 74, whereupon, the cylinder 31 and expander 22 can shift upwardly along the piston 36 and the body 10 of the tool.

In one use of the anchor, it may be set hydraulically by the pressure of the fluid column inside the tubing string B. The tubing anchor A is secured in the tubing string B at a point immediately above the pump (not shown). The anchor, pump and the tubing string are then lowered in the well casing C to the location at which the anchor A is to be set in the well casing. The anchor A should be disposed above the pump so that the pressure of the fluid column inside the tubing string will be available to set the anchor, and maintain it in its set condition.

After the tubing string has been run to the desired depth in the well casing, the pump cycle will commence as the pumping action proceeds, the level of the fluid column inside the tubing B increasing. Such hydrostatic head of fluid enters the cylinder space 35 through the ports 39, acting in a downward direction on the piston 36 and in an upward direction on the cylinder head 30, tending to urge the expander 22 in an upward direction along the body 10 and with respect to the slips 15. However, the holding or latch ring '70 will first prevent any relative movement from taking place, and since the cylinder head 36) is resting upon the shoulder ring 37 at this time, the pressure is incapable of-moving the piston 36 downwardly within the cylinder 31 and of forcing the lock ring 50 outwardly against the inner wall 65 of the housing 33 (FIG. 1).

When the fluid level in the tubing string rises to a desired elevation above the fluid level in the tubing-casing annulus D, which will occur as the pumping action continues and as the fluid level in the annulus drops, a suflicient pressure differential inside the tubing string B and the body 1th of the tool will eventually be reached to overcome the holding force of the latch ring 7h. The cam surfaces 76, 77 then force the ring 79 inwardly, the fluid pressure shifting the expander 22 upwardly along the body 10 of the tool and within the slips 15. Such upward movement of the expander will shift the slips and 'slip retaining ring 18 upwardly along the body to a small extent against the compressive force of the spring 2 8, the expander then shifting the slips 15 radially in an outward direction along the slip retaining ring 18 and into engagement with the wall of the well casing. As the'expander 22 and the cylinder 31 move upwardly along the body, the housing cam or flange 75 move into a position above the latch ring 7%, a lower inwardly directed abutment flange 80 in the housing 33 moving'past the lock ring Shto a position thereabove. The fluid pressure can now shift the piston 36 downwardly, forcing the lock ring outwardly into the housing groove 65 between the lower flange 3d and the abutment flange 80 The upper, outer corner 81 of the lock ring 50 is tapered in an upward and inward direction, engaging a companion tapered surface 82 on the lower end of the abutment flange 80. The lock ring 50 is then held be tween the tapered surfaces 52, 62, 82 on the lower end of the piston skirt 36, the stop ring 54 and the abutment flange 80, so that any upward force on the tubular body 10 is transmitted through the shear ring 57 and the stop ring 54 to the lock ring 50 and directly to the housing flange 80. The piston 36 has moved downwardly along the body It) to a slight extent and away from the shoulder ring 37 as a result of the outward expansion of the lock ring 50. Inasmuch as the lock ring 50 is engaging the inner wall 65 of the housing 33, the piston 36 cannot move downwardly to any greater extent relative to the body 10 of the tool (FIG. 2).

The anchor A is now set in the well casing C against upward movement with respect thereto. However, the anchor can still shift downwardly in the well casing. As the pumping action continues, after the slips 15 have been shifted by the expander 22 against the well casing, the fluid level in the tubing string will rise, causing the tubing string B to elongate or stretch in a downward direction. The tubing string may elongate as the result of other factors previously described, such as an increase in its temperature and the loss or reduction of its buoyancy by the fluid in the tubing-casing annulus D as the fluid level in such annulus drops. Regardless of the reason for elongation of the tubing string B, as it moves downwardly the body it) of the tool will move down with it, the lock ring 54 engaging the housing flange 34 and pulling the expander 22 downwardly, such downward movement tending to lower the expander with respect to the slips 15. However, it is to be noted that the spring 28 is acting on the slip retaining ring 18 and the slips 15, tending to force them downwardly. As a result, as the expander 22 moves downwardly, the slips 15 will follow the expander, the wickers or teeth 21 merely sliding along the well casing C. The wickers 21 always remain engaged with the well casing C, so that when the tubing B tends to move upwardly, as on the upstroke of the pump, such upward movement is immediately prevented since it is transferred from the body 14 through the stop ring 54 and lock ring 50 to the housing flange 8d and directly to the expander 22, which need only shift to an exceedingly small extent upwardly within the slips 15 to cause the wickers 21 of the latter to grip or embed themselves in the wall of the well casing C. The expander 22 will also be urged upwardly into firm wedging engagement behind the slips 15 during the upstroke of the pump, since the hydrostatic head of fluid inside the tubing string is again acting through the ports 39 on the fluid-in the cylinder 31.

As the pump reciprocates and as the fluid level in the tubing B continues to rise, with the tubing stretching in a downward direction, the expander 22 will be released from anchoring the slips 15 against the casing, but the slips will be caused by the spring 28 to follow the expander 22; and then take a new gripping position as the tubing string B tends to contract or return to its original position. Thus, the slips 15 are intermittently anchored against the well casing C and released therefrom, progressively being anchored against the well casing in a lower position until no further downward elongation of the tubing string can occur. This condition will exist, for example, after the well has been discharging fluid at the top of the well bore for a period sufficient to lower the fluid level in the tubing-casing annulus D to a substantially constant level and after the temperature of the tubing string has risen to substantially its maximum degree. The tubing anchor A will hold the tubing string B in tension, automatically adjusting itself to the maximum adverse condition prevailing in the well bore tending to elongate the tubing string in a downward direction. The

anchor will not permit the tubing to contract from such maximum condition of elongation. As a result, the tubing string 13 is maintained in proper tension within the well casing C, insuring a maximum effective stroke of the pump in the tubing by preventing the tubing from breathing under the reciprocating action of the pump.

When it is desired to release the anchor A from the well casing C, as when it is to be removed therefrom, such release can occur by decreasing the fluid pressure differential in the tubing string 5, as by equalizing the hydrostatic head of fluid internally and externally of the tubing string. As the fluid pressure diiferential in the tubular body ill and the cylinder '31 decreases to a sufil cient value, the lock ring 56, which inherently tends to contract, will eventually exert a suflicient force as to overcome the pressure acting in a downward direction on the piston 36, the ring it shifting the piston upwardly along thebody to a slight extent and moving inwardly out oi engagement with the abutment flange 8d. After this occurs, and the pressures in the tubing B and in the tubingcasing annulus D have been equalized, as by reaching the same fluid level, there is no hydraulic or other force tending to hold the expander 22 in its upward position. It is then free to move downwardly along the body 19 with respect to the slips 15. The expander 22 drops downwardly and in doing so retracts the slips 15 from the well casing, because of the slidable dove-tailed interconnection 25, 26 between the slips and the expander (FIG. 3). The tubing string B and the anchor A can now be elevated in the well casing and withdrawn from the well bore, if desired.

It the expander 22; and the cylinder 31 do not move downwardly with respect to the body lit after the retraction of the lock ring then the tubing string B may be moved upwardly a short distance, causing the body shoulder 27 to engage the slip retaining ring 18 and then pull the slip retaining ring 13 and the slips l5 upwardly relative to the expander 22, which will shift the slips to their retracted positions along the expander. The up ward movement of the body relative to the expander 22; will normally be limited by engagement of the latch ring 70 with the lower portion of the cam or flange '75, as illustrated in FlG. 3.

It is to be noted that after the anchor A has been set (FIG. 2), the upward force between the tubular body 19 and expander 22 is transmitted through the shear ring 57 and the stop ring 54 to the lock ring 5%, such force then being transmitted through the abutment flange 8% to the expander 22. Thus, all of the upward strain on the tubing string B is being transmitted through the shear ring 57. If the upward strain exceeds the strength of the shear ring, the inner portion 58 of the latter will be sheared from its outer portion 55, freeing the body 1 of the tool from the expander 22 and permitting the body to move upwardly. The body shoulder 27 will engage the slip retaining ring 13 and ur e it and the slips in an upward direction away from the expander 22, shifting the slips 15 to the retracted position, in which the anchor A has been released from the well casing, (FIG. 4).

The shear riug 5? can be so designed and proportioned as to shear at forces that preferably do not exceed the yield point of the tubing string B. Accordingly, a safety device is incorporated in the tool which will prevent excessive strain from being opposed upon the tubing string insuring against its being stretched beyond the elastic limit or its possible disruption.

"in the present instance, the shearing of the ring 57, in the manner described, and upward movement of the body in of the tool along the piston 36 will result in automatic bleeding or dumping of the fluid in the tubing string B. As illustrated in FIG. 4, such upward movement of the body 10 relative to the piston 36 places the reduced diameter portion ltia of the body opposite the inner seal ring 46 of the piston. A by-pass passage is thus provided for the fluid to flow from the interior of the body it? through the ports 39 into the cylinder 31 and then through the vent ports 41 in the upper portionof the piston 36 into the by-pass passage 4t, between the reduced diameter portion of the body and the inner surface of the piston. Fluid will pass downwardly through such passage and through the slots or grooves 61 in the stop ring 54', discharging through the lower end of the housing 33 into the tubingcasing annulus D.

Because of the ability of the anchor to open the by pass passage just referred to, an effective emergency bleeder has been provided, in the event the tubing fluid cannot be bled off and equalized with the fluid level in the tubing-casing annulus D. As an example, if the anchor cannot be released in the normal manner, such as illustrated in FIG. 3, because of the inability to bleed" off the pressure within the tubing string B, a pull can be taken on the latter of sufficient force to shear the ring 57, after which the body 10 will move upwardly relative to the piston 36 and housing 33 to the position in which the by-pass passage 4% between the piston and the body of the tool is open. This will allow the fluid inside the tubing B to dump into the tubing-casing annulus D, until the pressure internally and externally of the tubing string has been substantially equalized, which will then reduce the hydraulic holding force securing the expander 22 anchored against the slips 15 to substantially zero, allowing the expander 22 to drop down along the body ll} and the slips to the position illustrated in FIG. 4. If need be, the body shoulder 27 will engage the slip ring 18 and shift the slips 15 to a retracted position with respect to the expander 22. The lock ring 50, however, will remain expanded outwardly until the downward pressure acting on the piston 36 has been relieved sufliciently to allow' the lock ring to retract inherently to its initial position.

In the event the shear ring 57 accidentally becomes sheared, the body it? of the tool and the piston 36 will be placed in the relative position illustrated in FIG. 4. The fluid internally of the tubing B will unload, providing a positive indication at the top of the well bore that the shear ring has been disrupted, whereupon appropriate remedial action can be taken.

It is, accordingly, apparent that a tubing anchor has been provided which will automatically hold the tubing string in the maximum downward position to which it has elongated, the anchor and its slips l5 progressively shifting downwardly along the casing C. Downward movement of the anchor A and tubing B is permitted, but their upward movement is prevented. Since the slips 15 are constantly in-eugagement with the casing, the tendency of the lower portion of the tubing string to contract or shift upwardly does not impose any hammering action of the expander 22 upon the slips, which might tend to cause them to bulge or pierce the well casing. An exceedingly slight upward movement of the expander 22 is suflicient to re-anchor the slips 15 to the casing. Since the tubing B is maintained in its elongated condition, and upward movement of its lower portion is prevented, tubing breathing does not occur, resulting in a maximum eflective pump stroke and a maximum delivery of production at the top of the well bore. Since the breathing of the tubing is eliminated, the probability of the tubing failing as a result of fatigue is minimized substantially. ln addition, the prevention of the lower portion of tubing from moving upwardly eliminates the tendency of such lower portion to buckle, minimizing wear on the tubing and the sucker rods, as Well as in the pump itself.

The inventor claims:

1. In apparatus to be disposed within and anchored to a well conduit: a body; slip means carried by and movable longitudinally of said body and adapted to engage the well conduit to anchor the body therewithin; expander means slidable along said body and adapted to coact with said slipmeans to expand and hold such slip means against the well conduit; hydraulically operable means responsive to the pressure of the fluid within said body for shifting said expander means in one longitudinal direction along said body and slip means to expand said slip means against the well conduit; means for transmitting movement of said body in the opposite longitudinal direction to said expander means with said slip means expanded against the well conduit; and means engaging said slip means to yieldably urge said slip means toward said expander means to maintain said slip means engaged with the well conduit.

2. In apparatus to be disposed within and anchored to a well conduit: a body; slip means carried by and movable longitudinally of said body and adapted to engage the well conduit to anchor the body therewithin; expander means slidable on said body and slidably coupled to said slip means to expand and retract said slip means with respect to said body as said expander means moves toward and away from said slip means, respectively; hydraulically operable means responsive to the pressure of the fluid within said body for shifting said expander means in one longitudinal direction along said body and slip means to expand said slip means against the well conduit; means for transmitting movement of said body in the opposite longitudinal direction to said expander means with said slip means expanded against the well conduit; and means engaging said slip means to yieldably urge said slip means toward said expander means to maintain said slip means engaged with the Well conduit.

3. In apparatus to be disposed within and anchored to a well conduit: a body; initially retracted slip means carried by said body and adapted to engage the well conduit to anchor the body therewithin; expander means slidable on said body and slidably coupled to said slip means to expand and retract said slip means with respect to said body as said expander means moves toward and away from said slip means, respectively; hydraulically operable means responsive to the pressure of the fluid within said body for shifting said expander means in one longitudinal direction along said body and slip means to expand said slip means from its initially retracted position laterally outwardly toward and against the well conduit; and means for transmitting movement of said body in the opposite longitudinal direction to said expander means with said slip means expanded against the well conduit.

4. In apparatus to be disposed within and anchored to a well conduit: 21 body; slip means carried by and movable longitudinally of said body and adapted to engage the well conduit to anchor the body against upward movement in the conduit; expander means slidable on said body below said slip means and adapted to move upwardly along said body to expand and hold said slip means against the well conduit; hydraulically operable means responsive to the pressure of the fluid within said body for shifting said expander means upwardly along said body and slip means to expand said slip means against the Well conduit; means for transmitting downward movement of said body to said expander means with said slip means expanded against the well conduit; and means engaging said slip means to yieldably urge said slip means downwardly towards said expander means to maintain said slip means engaged with the Well conduit.

5. In apparatus to be disposed within and anchored to a well conduit: a body; slip means carried by and movable longitudinally of said body and adapted to engage the well conduit to anchor the body therewithin; ex pander means below said slip means slidable on said body and slidably coupled to said slip means to expand and retract said slip means with respect to said body. as said expander means move upwardly toward and downwardly away from said slip means, respectively; hydraulically operable means responsive to the pressure of the fluid within said body for shifting said expander means upwardly along said body and slip means to expand said slip means against the well conduit; means for transmitting downward movement of said body to said expander means with said slip means expanded against the well conduit; and means engaging said slip means to yieldably urge said slip means downwardly towardssaid expander means to maintain said slip means engaged with the well conduit.

6. In apparatus to be disposed within and anchored to a well conduit: a body; initially retracted slip means carried by said body and adapted to engage the well conduit to anchor the body therewithin; expander means below said slip means slidable on said body and slidably coupled to said slip means to expand and retract said slip means with respect to said body as said expander means move upwardly toward and downwardly away from said slip means, respectively; hydraulically operable means responsive to the pressure of the fluid within said body for shifting said expander means upwardly along said body and slip means to expand said slip means from its initially retracted position laterally outwardly toward and against the well conduit; and means for transmitting downward movement of said body to said expander means with said slip means expanded against the well conduit.

7. In apparatus to be disposed within and anchored to a well conduit: a body; slip means carried by and movable longitudinally of said body and adapted to engage the well conduit to anchor the body therewithin; expander means slidable along said body and adapted to coact with said slip means to expand and hold said slip means against the well conduit; hydraulically operable means responsive to the pressure of the fluid within said body for shifting said expander means along said body and slip means to expand said slip means against the well conduit; means engaging said slip means to yieldably urge said slip means toward said expander means to maintain said slip means engaged with the well conduit; and means for transmitting longitudinal force directly and rigidly from said body to said expander means after said slip means has engaged the well conduit.

8. In apparatus to be disposed within and anchored to a well conduit: a body; slip means carried by and movable longitudinally of said body and adapted to engage the Well conduit to anchor the body against upwardmovement in the conduit; expander means slidable on said body below said slip means and adapted to move upwardly along said body to expand and hold said slip means against the well conduit; hydraulically operable means responsive to the pressure of the fluid within said body for shifting said expander means upwardly along said body and slip means to expand said slip means against the well conduit; means engaging said slip means to yieldably urge said slip means downwardly towards said ex pander means to maintain said slip means engaged with the well conduit; and means for transmitting upwardly directed forces directly and rigidly from said body to said expander means after said slip means has engaged the well conduit.

9. In apparatus to be disposed within and anchored to a well conduit: a body; initially retracted slip means carried by said body and adapted to engage the well conduit to anchor the body against upward movement in the conduit; expander means slidable on said body below said slip means and adapted to move upwardly along said body to expand and hold said slip means against the well conduit; hydraulically operable means responsive to the pressure of the fluid within said body for shifting said expander means upwardly along said body and slip means to expand said slip means from its initially retracted positron laterally outwardly toward and against the well conduit; and means for transmitting upwardly directed forces directly and rigidly from said body to said expander means after said slip means has engaged the well conduit.

10. In apparatusto be disposed within and anchored to a well conduit: a body; slip means carried by and movable longitudinally of said body and adapted to engage the Well conduit to anchor the body therewithin; expander means slidable along said body and adapted to coact.

with said slip means to expand and hold said slip means against the well conduit; hydraulically operable means responsive tothe P I pressure of the fluid within said body for shifting said expander means in one longitudinal.

1 direction along said body and slip means to expand said slip means against the well conduit; means for transmitting movement of said body in the opposite longitudinal direction to said expander means with said slip means expanded against the well conduit; means engaging said slip means to yieldably urge said slip means toward said expander means to maintain said slip means engaged with the well conduit; and means releasable by said bydraulically operable means upon a predetermined fluid pressure acting thereon for initially preventing movement of said expander means to expand said slip means against the well conduit.

ll. In apparatus to be disposed within and anchored to a well conduit; a body; slip means carried by and movable longitudinally of said body and adapted to engage the well conduit to anchor the body against upward movement in the conduit; expander means slidable on said body below said slip means and adapted to move upwardly along said body to expand and hold said slip means against the well conduit; hydraulically operable means responsive to the pressure of the fluid within said body for shifting said expander means upwardly along said body vand slip means to expand said slip means against the well conduit; means for transmitting downward movement of said body to said expander means with said slip means expanded against the well conduit; means engaging said :slip means to yieldably urge said slip means downwardly towards said expander means to maintain said slip means engaged with the well conduit; means for transmitting upwardly directed forces directly from said body to said expander means after said slip means has engaged the well conduit; and means releasable by said hydraulically operable means upon a predetermined fluid pressure acting thereon for initially preventing upward movement of said expander means to expand said slip means against the well conduit.

l2.-In apparatus to be disposed within and anchored to a Well conduit: a body; slip means carried by and movrable longitudinally of said body and adapted to engage the well conduit to anchor the body against upward movement in the conduit; expander means slidable on said body below said slip means and adapted to move upwardly along said body to expand and hold said slip means against the well conduit; hydraulically operable means responsive to the pressure of the fluid within said body for shifting said expander means upwardly along said body and slip means to expand said slip means against the well conduit; means engaging said slip means to yieldably urge said slip means downwardly towards said expander means to maintain said slip means engaged with the well conduit; and means for transmitting upwardly directed forces directly from said body to said expander means after said slip means has engaged the well conduit, said transmitting means including a releasable connection adapted to be released, after engagement of said slip means with the well conduit, in response to a predetermined upward pull on said body to permit upward movement of said body with respect to said expander means.

13. In apparatus to be disposed with and anchored to a well conduit: a body; slip means carried by and movable longitudinally of said body and adapted to engage the well conduit to anchor the body therewithin; expander means slidable along said body and adapted to coact with said slip means to expand and hold said slip means against the well conduit; piston means carried by said body; cylinder means slidabler along said piston means and connected to said expander means; means for conducting fluid under pressure from within said body to said cylindermeans to one side of said piston means to shift said cylinder means and said expander means in one longitudinal direction along said piston means, body and slip means to expand said slip means against the well conduit; means for transmitting movement of said body in the opposite longitudinal direction to said expander means with said slip means expanded 1) against the well conduit; and means engaging said slip means to yieldably urge said slip means towards said expander means to maintain said slip means engaged With the well conduit.

14. In apparatus to be disposed within and anchored to a well conduit: a body; slip means carried by and movable longitudinally of said body and adapted to engage the well conduit to anchor the body therewithin; expander means slidable on said body and slidably coupled to said slip means to expand and retract said slip means with respect to said body as the expander moves toward and away from said slip means, respectively; piston means carried by said body; cylinder means slid= able along said piston means and connected to said expander means; means for conducting fluid under pres sure from within said body to said cylinder means to one side of said piston means to shift said cylinder means and said expander means in one longitudinal direction along said piston means, body and slip means to expand said slip means against the well conduit; means for transmitting movement of said body in the opposite longitudi nal direction to said expander means with said slip means expanded against the well conduit; and means engaging said slip means to yieldably urge said slip means towards said expander means to maintain said slip means engaged with the well conduit.

15. In apparatus to be disposed within and anchored to a well conduit: a body; slip means carried by and movable longitudinally of said body and adapted to engage the well conduit to anchor the body therewitllin against upward movement; expander means slidable on said body and slidably coupled to said slip means to expand and retract said slip means with respect to said body as said expander means moves upwardly towards and downwardly away from said slip means, respectively; piston means carried by said body; cylinder means slida'ble along said piston means and connected to said expander means; means for conducting fluid under pres sure from within said body into said cylinder means above said piston means to shift said cylinder means and expander means upwardly along said piston means, body and slip means to expand said slip means against the well conduits; means for transmitting downward movement of said body to said expander means with said slip means expanded against the well conduit; and means engaging said slip means to yieldably urge, said slip means downwardly toward said expander means to maintain said slip means engaged with the well conduit.

16'. In apparatus to be disposed within and anchored to a well conduit: a body; slip means carried by and movable longitudinally of said body and adapted to engage the Well conduit to anchor the body therewithin; expander means slidableon said body and adapted to coact with said slip means to expand and hold said slip means against the well conduit; piston means carried by said body; cylinder means slidable along said piston means and connected to said expander means; means for conducting fluid under pressure from within said body to said cylinder means to one side of said piston means to shift said cylinder means and said expander means in one longitudinal direction along said piston means, body and slip means to expand said slip means against the well conduit; means engaging said slip means for transmitting movement of said body in the opposite longitudinal direction to said expander means with said slip means'expanded against the Well conduit; means to yieldably urge said slip means towards said expander means to maintain-said slip means engaged with the well conduit; and means releasably securing said cylinder means to said piston means.

17. In apparatus to be disposed within and anchored to a Well'conduit: a body; slip means carried by and movable longitudinally of said body and adapted to engage the Well conduit to anchor the body therewithin against upward movement; expander means slidable on said body and slidably coupled to said slip means to expand and retract said slip means with respect to said body as said expander means moves upwardly towards and downwardly away from said slip means, respectively; piston means carried by said body; cylinder means slidable along said piston means and connected to said expander means; means for conducting fluid under pressure from within said body into said cylinder means above said piston means to shift said cylinder means and expander means upwardly along said piston means, body and slip means to expand said slip means against the well conduit; means for transmitting downward movement of said body to said expander means with said slip means expanded against the well conduit; means engaging said slip means to yieldably urge said slip means downwardly toward said expander means to maintain said slip means engaged with the well conduit; and means for transmitting upwardly directed forces directly from said body to said cylinder means after said slip means has engaged the well conduit.

18. In apparatus to be disposed within and anchored to a well conduit: a body; slip means carried by and movable longitudinally of said body and adapted to engage the well conduit to anchor the body therewithin against upward movement; expander means slidable on said body and slidably coupled to said slip means to expand and retract said slip means with respect to said body as said expander means moves upwardly towards and downwardly away from said slip means, respectively; piston means carried by said body; cylinder means slidable along said piston means and connected to said expander means; means for conducting fluid under pressure from within said body to said cylinder means above said piston means to shift said cylinder means and expander means upwardly along said piston means, body and slip means to expand said slip means against the well conduit; means engaging said slip means to yieldably urge said slip means downwardly toward said expander means to maintain said slip means engaged with the well conduit; means for transmitting upwardly directed forces directly from said body to said cylinder means after said slip means has engaged the well conduit; and means releasably securing said cylinder means to said piston means.

19. In apparatus to be disposed within and anchored to a well conduit: a body; slip means carried by and movable longitudinally of said body and adapted to engage the well conduit to anchor the body therewithin against upward movement; expander means slidable on said body and slidably coupled to said slip means to expand and retract said slip means with respect to said body as said expander means moves upward-1y towards and downwardly away from said slip means, respectively; piston means carried by said body; cylinder means slidable along said piston means and connected to said expander means; means for conducting fluid under pressure from within said body to said cylinder means above said piston means to shift said cylinder means and expander means upwardly along said piston means, body and slip means to expand said slip means against the well conduit; means engaging said slip means to yieldably urge said slip means downwardly toward said expander means to maintain said slip means engaged with the well conduit; means for transmitting upwardly directed forces directly from said body to said cylinder means after said slip means has engaged the well conduit; and means releasably securing said cylinder means to said piston means; said transmitting means including a releasable connection adapted to be released in response to a predetermined upward pull on said body to permit upward movement of said body with respect to said expander means.

20. In apparatus to be disposed within and anchored to a well conduit: a body; slip means carried by and movable longitudinally of said body andadapted to engage the well conduit to anchor the body therewithin against upward movement; expander means slidable on 1'4 said body and slidably coupled to said slip means to expand and retract said slip means with respect to said body as said expander means moves upwardly towards and downwardly away from said slip means, respectively; piston means carried by said body; cylinder means slidable along said piston means and connected to said .expander means; means for conducting fluid under pressure from within said body to said cylinder means above said piston means to shift said cylinder means and expander means upwardly along said piston means, body and slip means to expand said slip means against the well conduit; means engaging said slip means to yieldably urge said slip means downwardly toward said expander means to maintain said slip means engaged with the well conduit; means for transmitting upwardly directed forces directly from said body to said cylinder means after said slip means has engaged the well conduit; means releasably securing said cylinder means to said piston means; said transmitting means including a releasable connection adapted to be released in response to a predetermined upward pull on said body to permit upward movement of said body with respect to said piston means and expander means; said body and piston means providing a by-pass therebetween, after said body has moved upwardly with respect to said piston means, through which fluid from the interior of said body and cylinder means can flow to the exterior of said cylinder means.

21. In apparatus to be disposed within and anchored to a well conduit: a body; slip means carried by and movable longitudinally of said body and adapted to engage the well conduit to anchor the body therewithin; expander means slidable along said body and adapted to coact with said slip means to expand and hold said slip means against the well conduit; hydraulically operable means responsive to the pressure of the fluid within said body for shifting said expander means along said body and slip means to expand said slip means against the well conduit; means engaging said slip means to yieldably urge said slip means toward said expander means to maintain said slip means engaged with the well conduit; and means on said body engageable with said slip means to move said slip means from expanded toward retracted position.

22. In apparatus to be disposed within and anchored to a well conduit: a body; initially retracted slip means carried by said body and adapted to engage the well conduit to anchor the body therewithin; expander means slidable on said body and slidably coupled to said slip means to expand and retract said slip means with respect to said body as said expander means moves toward and away from said slip means, respectively; hydraulically operable means responsive to the pressure of the fluid within said body for shifting said expander means along said body and slip means to expand said slip means from its initially retracted position laterally outwardly toward and against the well conduit; and means on said body engageable with said slip means to move said slip means from expanded toward retracted position.

23. In apparatus to be disposed within and anchored to a well conduit: a body; initially retracted slip means carried by said body and adapted to engage the well conduit to anchor the body therewithin; expander means slidable on said body and slidably coupled to said slip means to expand and retract said slip means with respect to said body as said expander means moves toward and away from said slip means, respectively; hydraulically operable means responsive to the pressure of the fluid within said body for shifting said expander means along said body and slip means to expand said slip means from its initially retracted position laterally outwardly toward and against the well conduit; said body having a shoulder thereon engageable with said slip means to move said slip means from expanded toward retracted position.

24. In apparatus to be disposed within and anchored to a well conduit: a body; slip means carried by and 15 movable longitudinally of said body and adapted to gage the Well conduit to anchor the body against upward movement in the conduit; expander means slidable on said body below said slip means and adapted to move upwardly along said body to expand and hold said slip means against the well conduit; hydraulically operable means respon sive to the pressure of the fluid within said body for shifting said expander means upwardly along said body and slip means to expand said slip means against the well conduit; means engaging said slip means to yieldably urge said slip means downwardly toward said expander means to maintain said slip means engaged with the Well conduit; and means on said body engageable with said slip means upon upward movement of said body to shift said slip means from expanded toward retracted position.

References Cited in the file of this patent UNITED STATES PATENTS Baker June 21, Brumleu etal. June 6, Roe June 19, Cypher May 27, Brumleu et al Feb. 21, Baker et al Feb, 24, Fredd Apr. 28, Webber Aug. 25,

FOREIGN PATENTS Great Britain May 19,

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