US3454092A - Down hole self-adjusting tubing anchor - Google Patents

Description

July 8, 1969 J. 5. PAGE, JR

DOWN HOLE SELF-ADJUSTING TUBING ANCHOR Sheet Filed Dec. 16, 1968 5. v my w T) N6 5 m m mm 7 s M N w {M J J. 5. PAGE, JR

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ATTQEA/VS United States Patent 3,454,092 DOWN HOLE SELF-ADJUSTING TUBING ANCHOR John S. Page, Jr., Long Beach, Calif., assignor to Cook Testing Co., Long Beach, Calif., a corporation of Nevada Continuation-impart of application Ser. No. 616,121,

Feb. 14, 1967. This application Dec. 16, 1968, Ser. No. 784,120

Int. Cl. E21b 23/04 US. Cl. 166212 3 Claims ABSTRACT OF THE DISCLOSURE An improved well tubing anchor functions in response to fluid pressure application to anchor tubing to the well bore, remaining anchored during fluid pressure increase accompanied by tubing stretching, and also remaining anchored during pressure fall-off. Tubing tens-ion urges a wedge member upwardly to hold slip means anchored to the well bore, and release of the anchor can be secured by relieving tubing tension, as by lowering. Cyclic movement between the wedge member and the slip means is isolated from the part receiving the fluid pressure application, to prevent deterioration of its sealing means under repeated small-amplitude movements.

This application is a continuation-in-part of my copending application Ser. No. 616,121 filed Feb. 14, 1967.

Background of the invention This invention relates generally to oil well tubing anchors and more particularly concerns a highly advantageous fluid pressure settable and tubing tension lockable tubing anchor.

When tubing in oil wells is not'anchored to the casing, certain problems result. For example, on the down stroke of the well pump, the entire fluid load is transferred from the pump rods to the tubing causing it to be stretched down the hole. Also on the down stroke, a dynamic impact is created, throwing a shock load onto the tubing. Instrument recordings measuring the stresses on the top joint of the unanchored string in producing wells shoW load reversals that are fifty percent greater than the calculated fluid load pickup of the pump. Such recordings show that this additional force is applied onto the tubing with a sudden impact, the severity of which depends upon the pump diameter, the speed at which the pump descends, the amount of gas in the fluid and the amount of filling of the pump on the up stroke. Such dynamic impact of the down stroke shortens the life of the tubing thread sealing capability and the over all life of the pumping complex.

On the pump up stroke, the rods pick up part of the fluid load causing the tubing to unstretch and engage the casing. This movement, typically occurring many thousands of times a day, causes substantial tubing and casing wear, as well as rod Wear. Further results of unanchored breathing tubing include lost pump efliciency and lost product-ion, increased pulling and repair costs, excessive pumping unit and gear wear due to fluid load reversal shock transmitted to the entire pumping system, and tubing buckling.

Efforts to alleviate the above problems have resulted in the provision of various types of tubing anchors that operate to transfer fluid load reversal shock forces to the casing, and which result in reduced tubing, casing and rod wear. However, in the case of mechanically operated anchors, disadvantageous tubing manipulation is required to set the anchor, foreclosing its further adjustment down 3,454,092 Patented July 8, 1969 ice the hole to allow for tubing stretching without further tubing manipulation. Fluid pressure operated anchors developed to avoid tubing manipulation setting have suffered from the problem of anchor release upon fluid pressure dropoff. For example, where a cone is hydraulically actu ated into engagement with slips to urge them into forcible enagement with a casing, the cone yields and releases the slips when the actuating fluid pressure drops off. Such a device also requires several slips spaced about the tubing axis.

Also, a difliculty has been encountered in the operation of hydraulic set tubing anchors in that the wedge block has been used to move a slip into engagement with the casing, and this wedge block has been direct-connected to a piston slidable in a vertical cylinder. A seal ring on the piston engages the cylinder Wall to prevent fluid leakage. However, the minute amount of movement during the pumping cycle between the slip and the wedge block causes corresponding movement of the piston within the cylinder. Since it is not unusual for a well to pump one thousand strokes per hour, the reciprocating movement between the piston and the cylinder wall, although of very small amplitude, is suflicient to cause premature failure of the seal ring.

Summary of the invention The present invention has as its major object the provision of an improved fluid pressure responsive tubing anchor that overcomes the above problems and that is further characterized by a number of additional advantages including capacity for fluid pressure setting and tubing tension locking of the anchor to the well bore. Basically, the anchor comprises a body adapted for carriage on a tubing string into a well having a bore wall, slip means carried by and bodily movable relative to the body at the side thereof toward and away from the bore wall, means including an actuator operable in response to fluid pressure application thereto to move the slip means generally longitudinally of the body, and a wedging member carried by the body to urge the slip means toward and into gripping engagement with the bore wall in response to actuator effected slip movement in a longitudinally downward direction and to transmit string tension acting in a longitudinally upward direction to maintain the slip means wedged into gripping engagement with the bore wall during dropoff of fluid pressure application to the actuator.

Typically, the wedging member has an upwardly tapering wedge surface located in the path of slip longitudinal movement effected by the actuator to urge the slip means generally away from the string axis in response to fluid pressure communication to the actuator. Since the slip means is displaced relative to the wedging member on the body, the slip tends to remain in engagement with the bore wall even though fluid pressure dropoff relieves actuator force transmission to the slip. Further, the slip typically has Wickers angled in such relation to the angularity of the wedge surface with res ect to the string axis that the slip means adjusts downwardly While engaged with Well bore as the tubing stretches downwardly during fluid pressure application to the actuator, the wedge surface blocking inward displacement of the slip means.

As a result, the apparatus functions hydraulically to anchor tubing to the bore wall and remains anchored during fluid pressure increase accompanied by stretching of the tubing, as well as during fall-off as accompanies pulling of the pump and fluid drainage down the hole; the tension of the tubing serves to urge the wedge member upwardly to hold the slip means anchored to the casing bore, and release of the anchor can be 3 simply and rapidly accomplished by relieving tubing tension, as by lowering the tubing at the surface.

Other objects and advantages of the invention include the provision of a connection between the body and the wedging member and characterized as shearable in response to predetermined longitudinal force transmission by the connection imposed as a result of forcible elevation of the body in a well, whereby the slip means may be disengaged from the bore wall during an emergency; the provision of a simple anchor construction comprising a body formed for attachment to standard string tubing as by welding, the slip means, wedging member and actuator located at one side of the body and the slip means located in a body recess at that side. In order to eliminate the cyclic movement between the piston and the cylinder wall, a heavy duty spring is positioned between the piston and the rod on the wedge block, and a shoulder is provided on the cylinder wall which limits the stroke of the piston. The small-amplitude cyclic movement of the wedge member and rod is absorbed by the spring, and the piston and its seal ring remain stationary. The provision of other highly advantageous constructional features will appear hereinafter.

These and other objects and advantages of the invention, as well as the details of illustrative embodiments, will be more fully understood from the following detailed description of the drawings, in which:

FIGURE 1 is a vertical elevation showing the anchor installed in a tubing string in a well with a pump operated from the surface;

FIGURE 2 is an enlarged vertical section showing the anchor as run into a well, before connection to the well bore;

FIGURE 3 is a view like FIGURE 2, but showing the anchor connected to the well bore;

FIGURE 4 is a view like FIGURE 2, but showing the anchor during emergency elevation in a well; and

FIGURES 5-7 are horizontal sections taken on lines 55, 66, and 77 of FIGURE 2.

Description of a preferred embodiment Referring first to FIGURE 1, a well casing 10 is shown receiving a tubing string 11 comprising tubing sections 11a interconnected at 11b. Installed in the string is a vertically reciprocable pump generally indicated at 12 and is operable in response to upward and downward movement of the pump rod string 13. The latter extends vertically within the tubing and is suspended from the walking beam 14 suitably driven at 15 for vertically reciprocating the pump rods. In operation, upon upward movement of the rod string, well fluid is drawn through the perforations 16 in the casing and upwardly into the tubing string via an inlet port 17, a valve ball 18 then being lifted. Upon downward movement of the rod string, the ball 18 seats to close the port 17, and a second ball 19 is lifted off its seat to admit fluid from the chamber 20 into the space 21 above the upper ball 19 and into the tubing extending thereabove. Such fluid so admitted stands in a column within the tubing as the rod string is reciprocated, and the fluid is removed from the string at the surface to appropriate connections.

Also shown in FIGURE 1 is the tubing anchor of the present invention, which is generally indicated at 22. Extending the description of FIGURES 2 and5-7, the anchor is shown to include a body 23, which may advantageously be yoke-shaped as seen in FIGURES 5 and 6 and attached to a standard tubing section 11a as by welding thereto, indicated at 24. For this purpose, the body 23 may comprise a metal casting having a bore 25 receiving the tubing section 11a. Attached to the upper terminal of the tubing secion 11a is a tubular part 26 to form an upper extension of the tubing and having external threading .at 27 to attach to a collar 11b connecting to the next upper section of tubing 11a as is clear from FIGURE 1. The body 23 includes arms 28 which 4 are circularly spaced at 29 and which have terminals 30 formed to grip engage the bore 31 of the casing when the anchor is attached to the casing as seen in FIGURE 3. Two pairs of such arms are provided at upper and lower elevations as indicated.

Another element of the anchor comprises slip means carried by and bodily movable relative to the body 23 at the side thereof toward and away from the bore wall. In this regard, the slip means may typically comprise the single slip member 32 received within a side recess 33 formed in the body 23, and extending generally longitudinally therein. Also received within the recess 33 is a wedging member 34 carried by the body to urge the slip toward and into gripping engagement with the bore wall in response to slip movement in a longitudinally downward direction. In this regard the wedging member has T-slot or tongue and groove connection with the slip at the location 35, and the slip and wedging member have slidable interengagement along their upwardly tapering interengaged surfaces at 36.

Such movement of the slip member relative to the wedging member is effected by means including an actuator operable in response to fluid pressure application thereto to move the slip generally longitudinally of the body. One such actuator of unusually advantageous construction includes a piston 37 having a seal ring 38 forming a sliding seal within the bore 39 of the cylinder 40'. The cylinder 40 extends longitudinally vertically at the side of the tubing 11a in vertical alignment with the slip 32. The cylinder 40 is releasably connected at 41 with the part 26, the latter having porting 42 to communicate fluid pressure from the interior of the tubing to the piston 37. In this regard, the body 23, tubing 11a carrying the body 23, and the part 26 may be considered as one integral body.

The cylinder 40 has an internal shoulder 51 which limits downward travel of the piston 37. A coil spring 52 within the cylinder 40 engages the piston 37 at its upper end, and at its lower end engages the flange 55 formed at the upper end of the piston rod 44. Another spring 56 within the cylinder 40 encircles the piston rod 44 and extends between the flange 55 and the shoulder 57 at the lower end of the cylinder 40. The rod has a lower projection 44a connected to a second member 45, which may be considered as part of the actuator, and which also projects within the recess 33. Member 45 has a wedge surface 46 tapering downwardly and inwardly to slight extent, and engaging the correspondingly tapered 'upper surface 47 of the slip 32 for urging the slip generally longitudinally and away from the axis 48 in response to downward displacement of the member 45. Member 45 also serves to retain the slip, i.e. suspends it by virtue of a suitable T-slot connection therewith, as indicated by the broken line 49. Thus, in the absence of sufl'icient fluid pressure downward exertion on the actuator, the actuator piston is urged upwardly by the spring 43, and the retainer 45 holds the slip 32 in raised position, the slip moving to inwardmost position as seen in FIGURE 2 due to the downward and inward angularity of the T-slot connection between the retainer member 45 and the slip.

Fluid pressure transmitted from the interior of the tub ing to the piston 37 occurs when the level of production fluid within the tubing string builds up during the op eration of the pump, as previously described. Thus, when the head of the production fluid within the tubing string which is applied via the porting 42 to the piston 37 is sufliciently great to overcome the upward force exerted by the compression spring 52 on the piston 37, the piston 37 is urged downward within the cylinder 40, and this downward movement is arrested by the shoulder 51. The force of the spring 52 then acts on the rod flange 44 in opposition to the force of the spring 56 to displace the piston rod 44 downwardly.

As the level of the production liquid pumped into the tubing string rises, the weight of that liquid transferred to the string during downward stroking of the rods 13 acts to downwardly stretch the string within the well. Such stretching tends to progressively lower the anchor 22 within the well, and it is a feature of the anchor that it accommodates itself to such movement by progressive movement of the slip 32 downwardly relative to the bore 31 with which the slip is in engagement. This occurs even though the slip is urged outwardly with great force due to the angularity of the slip wickers 50 as related to the angularity of the inner engaged surfaces of the slip and the wedging member at 36, the wedging member blocking inward displacement of the slip. On the other hand, it sometimes happens that the fluid pressure within the string 11a drops ofi, as for example during removal of the rod string and the pump part attached thereto including the upper ball 19, from the tubing, for repair or replacement of pump structure. Such removal of course displaces liquid from within the tubing, thereby relieving the downward pressure on the actuator which urges the slip into forceable gripping engagement with the bore wall 31.

The result of the piston 37 coming to a positive stop against the shoulder 51 is that the piston does not thereafter mo've relative to the cylinder 40 and hence the seal ring 38 does not move relative to the inner wall surface 51, even though there may be a minute amount of movement between the slip 32 and the actuating block 45. For example, if the cross sectional area of the bore 51 is 0.8 square inch, and if a fluid pressure of 2500 p.s.i. is applied against this area above the piston, a net force of 2000 pounds would be applied on the piston 37 to hold it against the stop shoulder 51. The spring 52 would then have a compression loading of perhaps 250 pounds force acting downward against the rod 44. Therefore any movement between the slip 32 and the actuator block 45 that would be transmitted up through the rod 44 would be absorbed by the spring 52, and without causing any movement of the piston 37 or its seal ring 38.

It is a further and important feature of the invention that the wedging member not only performs the functions described above, but it also performs the additional function of transmitting string tension acting in a longitudinally upward direction to maintain the slip means wedged into gripping engagement with the bore wall during drop-ofl of fluid pressure application to the actuator. Note in this regard the steep angularity at the interengagement locus 36 between the wedging member 34 and the slip 32. Upward tension exerted by the stretched tubing from which production fluid has been displaced is exerted via the wedging member to the slip 32 for transfer to the casing 10, whereby the anchor connects the stretched tubing to the casing even though production fluid is removed from the tubing. In this regard, the anchor has the characteristics of being fluid pressure settable, as well as tubing tension lockable to the casing, thereby partaking of the most advantageous features of fluid pressure and mechanically responsive connection to the casing while eliminating otherwise undesirable features of fluid responsive and mechanically responsive anchor conections. To relieve the connection, with the tubing under tension as described, it is only necessary to lower the tubing in the well suificiently to induce disconection of the anchor from the well bore. Such lowering may be effected by dropping the tubing at the well head, as for example by removing the slips 53 to allow lowering of the tubing uppermost section sufiiciently, and then reinserting the slips 53 to again support the tubing in the structure 54. This action serves to back the wedging member 34 away from the slip 32, allowing the slip to be raised by the actuator spring 56 to the position seen in FIGURE 2.

A further feature of the invention permits emergency withdrawal of the anchor from the well despite the fact that the anchor is connected to the well bore as described above. This feature makes use of a particular type of connection between the wedging member 34 and the body 23, the connection being characterized as shearable in response to predetermined longitudinal force transmission by the connection imposed as a result of forceable elevation of the body 23 in the well. In other words, a sufficiently sharp upward pull on the tubing string will serve to shear the connection referred to, allowing backing way of the wedging member 34 relative to the slip 32 to release the connection of the slip to the well bore.

In this regard, a particularly advantageous shear connection is illustrated as including a rod 60 connected to and extending downwardly from the wedging member 34, the rod passing through a bore 61 in a lower portion 23a of the body 23. The rod 60 is normally suspended in position to hold the wedging member fixed in the position seen in FIGURE 2 by means of a shear ring 63 supported at 64 by the body lower section 23a. The shear ring is received within an annular groove 65 formed in the rod as illustrated, whereby the shear ring shoulder supports the rod at the location 66. Under these conditions, the wedging member 34 functions in the manner described above. When the tubing and the body 23 are pulled sharply upwardly in an emergency, the ring 63 is sheared by the rod shoulder 67, and the wedging member drops relative to the body as seen in FIGURE 4, thereby allowing disconnection of the anchor from the casing.

Finally, an abutment 70' suitably attached to the tubing 11a as seen in FIGURE 4 projects beneath the rod cap 71 to capture the anchor and prevent its dropping in the hole should the body 23 loosen from the tubing.

I claim:

1. In a tubing anchor adapted to be installed in a well casing, the combination of: a tubular member adapted for connection at its ends to a string of well tubing, a body fixed to and circling a portion of said tubular member, the body having a slip-receiving recess at one side, a wedge member mounted on one side of the body member in axial alignment with said recess, a movable slip in said recess having a case-engaging face provided with wickers permitting downward movement of the slip relative to the casing, a block movable in the recess and contacting the slip, a hydraulic actuator at one side of said tubular member in axial alignment with said recess, said actuator having piston and cylinder parts, one being mounted to move relative to said tubular member, a spring operatively interposed between the moving part and the block, a stop acting to limit movement of said moving part in a direction to compress the spring, and passage means for transmitting fluid under pressure from the interior of said tubular member to said actuator whereby downward force may be transmitted through said moving part and spring to said block for moving the slip radially outward with respect to the body.

2. In a tubing anchor adapted to be installed in a well casing, the combination of: a tubular member adapted for connection at its ends to a string of well tubing, a body fixed to and circling a portion of said tubular member, the body having a slip-receiving recess at one side, a wedge member mounted on one side of the body member in axial alignment with said recess, a movable slip in said recess having a casing-engaging face provided with wickers permitting downward movement of the slip relative to the casing, a hydraulic actuator at one side of said tubular member in axial alignment with said recess, said actuator having a cylinder fixed relative to said tubular member, a piston slidably mounted within said cylinder, seal means on the piston in fluid tight relation with the cylinder, a rod extending from the cylinder and having a block thereon movable in the recess and contacting the slip, a spring within the cylinder interposed between the piston and the rod, a stop within the cylinder acting to limit movement of the piston in a direction to compress the spring, and passage means for transmitting fluid under pressure from the interior of said tubular member to said piston whereby downward force may be transmitted through the spring and rod to said block for moving the slip radially outward with respect to the body.

3. In a tubing anchor adapted to be installed in a well casing, the combination of: a tubular member adapted for connection at its ends to a string of well tubing, a body fixed to and circling a portion of said tubular member, the body having a slip-receiving recess at one side, a wedge member mounted on one side of the body member in axial alignment with said recess, a movable slip in said recess having a casing-engaging face provided with Wickers permitting downward movement of the slip relative to the casing, a hydraulic actuator at one side of said tubular member in axial alignment with said recess, said actuator having a cylinder fixed relative to said tubular member, a piston slidably mounted within said cylinder, seal means on the piston in fluid tight relation with the cylinder, a rod extending from the cylinder and having a block thereon movable in the recess and contacting the slip, a first spring within the cylinder interposed between the piston and the rod, a second spring positioned within the cylinder and acting on the rod in opposition to the first spring, a stop within the cylinder acting to limit movement of the piston in a direction to compress the first spring, and passage means for transmitting fluid under pressure from the interior of said tubular member to said piston whereby downward force may be transmitted through the first spring and rod to said block for moving the slip radially outward with respect to the body.

References Cited UNITED STATES PATENTS 1,619,268 3/1927 Rasmussen 166-217 2,328,840 9/1943 OLeary 166-212 X 2,332,749 10/1943 Page 16 6-212 2,350,973 6/1944 Brumleu et a1 166-2112 X 2,435,899 2/1948 Page 166-212 2,624,409 1/ 1953 ONeill 166-212 X 2,765,855 10/1956 Reed 166-217 3,045,758 7/1962 Muse 166-217 X 3,136,364 6/1964 Myers 166-212 X CHARLES E. OCONNELL, Primary Examiner.

IAN A. CALVERT, Assistant Examiner.

US. Cl. X.R. 166-217

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