US3454091A - Down hole self-adjusting tubing anchor - Google Patents

Description

July'8, 1969 5. PAGE. JR

DOWN HOLE SELF-ADJUSTING TUBING ANCHOR Fi ed Feb. 14, 1967 Sheet IA/vEA/rap. Jam 5. Pass ,Je.

United States Patent 3,454,091 DOWN HOLE SELF-ADJUSTING TUBING ANCHOR John S. Page, In, Long Beach, Calif., assignor, by mesne assignments, to Cook Testing Co., Long Beach, Calif., a corporation of California Filed Feb. 14, 1967, Ser. No. 616,121 Int. Cl. EZlb 23/04 U.S. Cl. 166-212 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 tension 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.

Background 0) 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 fitfy 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 easing wear, as Well as rod wear. Further results of unanchored breathing tubing include lost pump efliciency and lost production, 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 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 drop-01f. For example, where a cone is hydraulically actu- 3,454,091 Patented July 8, 1969 ated into engagement with slips to urge them into forcible engagement with a casing, the cone yields and releases the slips when the actuating fluid pressure drops otf. Such a device also requires several slips spaced about the tubing axis.

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 drop-off of fluid pressure application to the actuator.

Typically, therwedging 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 drop-ofl? 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 respect 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 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; and the provision of other highly advantageous constructional features as will appear.

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

Brief description the drawing FIG. 1 is a vertical elevation showing the anchor installed in a tubing string in a well with a pump operated from the surface;

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

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

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

FIGS. 5-7 are horizontal sections taken on lines 5-5, 66 and 7-7 of FIG. 2.

Description of a preferred embodiment Referring first to FIG. 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 thereabovc. Such fluid so admitted stands in a column within the tubing and is lifted and lowered as the rod string is reciprocated. Further, such fluid is removed from the string at the surface via appropriate connections.

Also shown in FIG. 1 is the tubing anchor of the present invention, which is generally indicated at 22. Extending the description of FIGS. 2 and 5-7, the anchor is shown to include a body 23, which may advantageously be yokeshaped as seen in FIGS. 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 section 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 FIG. 1. The body 23 includes arms 28 which are ircularly 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 FIG. 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 disc 38 providing a piston surface 39 for receiving fluid pressure introduced within the cylinder 40 which extends longitudinally vertically at the slip side of the tubing 11a. The cylinder 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 actuator piston surface 39. In this regard, the body 23, tubing 11a carrying the body 23, and the part 26 may be considered as one integral body.

Such fluid pressure may be considered to arise under various circumstances, one of which is the existence of the production fluid received within the tubing string during operation of the pump as previously described. Thus, when the head of the liquid within the string applied via the porting 42 to the piston surface 39 is suflicient to overcome the upward force exerted by a compression spring 43 acting on the piston, the latter is urged downwardly within the cylinder 40 to displace the piston rod 44 downwardly. 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., suspend it by virtue of a suitable T-slot connection therewith, as indicated by the broken line 49. Thus, in the absence of sufficient 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 FIG. 2 due to the downward and inward angularity of the T-slot connection between the retainer member 45 and the slip.

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 off, 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.

In this regard, 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-off 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 connections. To relieve the connection, with the tubing under tension as described, it is only necessary to lower the tubing in the Well sufficiently to induce disconnection 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 sufliciently, 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 43 to the position seen in FIG. 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 and 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 wildciently sharp upward pull on the tubing string will serve to shear the connection referred to, allowing backing away 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 FIG. 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 FIG. 4, thereby allowing disconnection of the anchor from the casing.

Finally, an abutment 70 suitably attached to the tubing 11a as seen in FIG. 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 encircling a portion of said tubular member, the body having a pair of circularly spaced casing-engaging arms at one side and a single slipreceiving recess at the other side,

a hydraulic actuator at one side of said tubular member in axial alignment with said recess, and having a part movable in said recess,

a wedge member mounted on one side of the body member in axial alignment with said recess,

a movable slip in said recess interposed between said actuator and said wedge member and slidably connected to both, said slip having a casing-engaging face provided with wickers permitting downward movement of the slip relative to the casing,

and passage means for transmitting fluid under pressure from the interior of said tubular member to said hydraulic actuator whereby the slip may be moved radially outward with respect to said body to bring said slip face and said arms into casing-engaging position.

2. The tubing anchor of claim 1 in which the hydraulic actuator comprises a piston and cylinder assembly and a coil spring, all mounted outside the tubular member and parallel thereto.

3. The tubing anchor of claim 1 in which the wedge member is fixed to a rod axially slidable on the body and axially aligned with said recess, and means including a shear ring encircling the rod for releasably holding the rod against movement relative to the body.

References Cited UNITED STATES PATENTS 1,619,268 3/1927 Rasmussen 166217 2,332,749 10/1943 Page 166212 2,350,973 6/1944 Brumleu et a1 166\212 X 2,435,899 2/1948 Page 166212 2,624,409 1/1953 ONeill 166212 X 2,765,855 10/1956 Reed 166217 3,045,758 7/1962 Muse 166-Q17 X 3,136,364 6/1964 Myers 1662l2 X CHARLES E. OCONNELL, Primary Examiner.

I. A. CALVERT, Assistant Examiner.

US. Cl. X.R. 1662 17

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