US2590502A - Slip expander asembly for well tools - Google Patents

Description

.March 25, 1952 Filed Nw. 22, 194e ciwl ' im III 25 i I 1 /ZP I i 1 I l 26 i i C. C. BROWN SLIP EXPANDER ASSEMBLY FOR WELL TOOLS 3 Sheets-Sheet 1 lil INVENTOR.

Cprown @aha ATTORNEY March 25,' 1952 C. c. BRQWN 2,590,502

SLIP EXPANDER ASSEMBLY FOR WELL TOOLS Filed Nov, 22, 1948 A s sheets-sheet 2 INVENTOR. YC. C. Brown B v I ATTORNEY March 25, 1952 c. c. BROWN i SLIP EXPANDER ASSEMBLY FOR WELL TOOLS ATTORNEY Patented Var. 25, 1952 OFFICE sLI'P EXPANDER ASSEMBLY FOR WELL rrooLs Cicero C. Brown, Houston, Tex.

Application November 22, 1948, Serial No. 61,450

(Cl. 16S-12) 2 Claims.

l This invention relates to improvements in well tools of the hook-Wall type, and particularly to an improved form of slip and slip expander assembly for well packers.

Conventional types of hook-wall packers employ a plurality of toothed slip segments circularly arranged about a conical mandrel or expander which is adapted, in cooperation with wedge shaped inner surfaces of the slips, to radially expand or retract the slips relative to a well pipe in response to appropriate longitudinal movement of the expander relative to the slips. In such conventional packers, the primary engaging surfaces of the expander and slips are made in the form of segments of regular cones. That is, the expander is a regular cone or a frustum thereof, while the inner surfaces of the slip segments are likewise segments of a regular conical surface. However the exterior faces of the slips which are adapted to contact a pipe wall are normally shaped in the form of cylindrical segments which have a generally rectangular shape in elevational View, in order to provide maximum area for contact with the pipe. It will be obvious, of course, that any transverse cross section through the conical expander and the adjacent faces of the ring of slips which is normal to the axis of the expander, `will be a circle, and that such circles will have different radii at different elevations along the conical surfaces. As a result, as the expander is moved axially relative to the inner faces of the slips, the relative circular radii will change, so that it becomes practically impossible to maintain the inner faces of the slips in continuous bearing contact with the expander surface throughout the full area of the inner slip surfaces. As a result, although the inner faces of the slips may be in full contact with the expander surface at one position, at any other position the contacting surfaces become substantially a line contact extending longitudinally of the slips intermediate the side edges thereof, the remainder of the slip area on each side of the center line being caused to stand away from the expander surface. Since the slips have substantial length and breadth, the resulting separation is greatest at the corners of the slips, so that when the outer faces of the slips are expanded into gripping contact with the pipe wall, a substantial portion of the inner surfaces of the slips will be unsupported by the expander. When heavy expansive pressures are applied thereto, as is the common condition, the slips will very often be broken. To reduce this diniculty, conventional conical slip expanders and slips are designed for. setting in one particular ize of pipe so as to require a minimum of expansive movement to set the slips, and one such slip and expander assembly may not be used successfully in pipes of different sizes or having varying internal diameters.

Also, conventional slip and expander assemblies normally employ a variety of relatively complicated hinge linkages between the slips and the slip cage in order to provide the requisite degree of flexibility for expansive and retractive movements of the slips contemporaneous with the relative longitudinal movement between the cage and expander. This makes for a large number of loosely interconnected parts which, under the great stresses to which such packers are subjected in ordinary use, renders them very liable to breakage or severe damage, particularly when attempting to release the packer after it has once been set. Very often heavy jarring blows must be applied to the packer assembly to release it, and the loose linkages conventionally used will frequently be shattered by such blows, with the result that the packer will become stuck in the well pipe, and may then be withdrawn or removed only with great difficulty and by costly procedures.

Accordingly, it is a primary object of this invention to provide a slip and expander assembly for well tools of the hook-wall type which eliminates or obviates the principal disadvantages, such as above enumerated, to which more conventional constructions are commonly subject.

In accordance with an illustrative embodiment of this invention, an expander is employed which is in the form of a regular polygonal pyramid or frustum thereof, that is, a pyramidal body having a base in the form of a regular polygon, such as a triangle, square, pentagon, hexagon and the like. There is thus provided a tapered body having avplurality of contiguous flat trapezoidal faces. A corresponding plurality of slip segments are mounted for longitudinal sliding movement on these faces. The inner contact faces of the slip segments may, therefore, also be made flat and tapered longitudinally to complement the slope of the expander faces. The4 outer faces of the slips may be cylindrical and generally vertical, as well as rectangular in elevation, Acorresponding in these respects to the more conventional types of slips. By employing this novel geometric form of expander and complementary slips,.the full areas of the inner faces of the slips will remain in continuous contact with expander surface, irrespective of the degree of relative longitudinal movement be'- tween them.

Additionally, the described construction permits an arrangement of the slips such that, when in fully'retracted position, they are in substantial edge-to-edge abutment about the periphery of the expander and present a substantially continuous cylindrical surface, with the result that, when expanded, minimum separation of the slips will occur and the gripping load will be distributed over a maximum area of the pipe gripped thereby.

Further in accordance with an embodiment of this invention, there is provided a novel form of collar member for connecting the slip segments to the slip cage. This collar member is constructed of interfltting arcuate segments which may be assembled with the slips and connected to the cage in such a manner as to eliminate the need for the troublesome multi-part wrist pin and linkage types of connections employed in conventional types of packers for connecting the slips to the slip cage.

Other and more specific objects and advantages of this invention will become apparent from the following detailed .description when read in conjunction with the accompanying drawings which illustrate an embodiment in accordance with this invention.

In the drawings:

Fig, l1 is an elevational view of a packer in accordance with an embodiment of this invention having some of 'the parts broken away and shown in position 'in a Ywell casing prior to being set therein;

Fig. 2 is a view similar to Fig. 1 showing the packer set in a well casing;

Fig. 3 is an'enlarge'd vquarter-'sectional elevation of a portion ofthe packer including lthe slips, slip expander and "cage portions, in the unset position corresponding to that shown in Fig. 1;

Fig. 4, is a view similar to Fig. 3 showing the same parts in the set position;

Fig. 5 is a cross-sectional view looking upwardly along line KV5--5 of Fig. 3, through the slip and expander elements, having some of the slips removed therefrom for purposes of clearer illustration Fig. 6 is a Vquarten-*sectional elevational view of theslip expander;

Fig. 7 is a perspective view showing the connections between the slips, fslipcollar and cage elements;

Fig. 8 is a cross-sectional view looking down along line 8-8 of Fig.'4;

Fig. 9 is a cross-sectional view along line 9-9 of Fig. 4;

Fig. 1-0 is a 4bottom exploded view of the slip collar; and Y Fig. lljis `a cross-sectional elevational view along `line -I -I-I I lof-Fig. V10.

Referring to `the drawings, and to Figs. 1 and 2, in particular, there is shown, vby way of example, a packerof-the "hook-wall type, designated generallyiby the lnumeral I-5, Vinserted vin a well casing I6, in which the `packer is to be set. As illustrated, the packer comprises'a tubular operating pipe -I1jadapted to be connected at its upper end to a string of tubing or -pipe I8 by which the packer is lowered'and raised in the well and by means of which the operations of setting and releasing the packerare eifected. Concentrically mounted'on'operating'pipe I1 is the packer structure proper whichfcomprises a tubular sealing sleeve lyconstructedvof rubber or other suitable and conventional flexible, resilient material which when subjected to end-wise compression is adapted "to be radially expanded into sealing engagement with casing I6. The upper end of sealing sleeve I9 carries a metal seat ring 2B which isradapted to be engaged by an annular valve 2| 'carried on the upper end of the exterior of operating pipe I1, when tubing string I8 carrying operating pipe I I is lowered. Seating of valve 2| on seat ring 20 serves'to close the annular space between the "sealing sleeve and operating pipe I1 and also acts to transfer the weight of the tubing string to the upper end of the sealing sleeve when the latter is supported from below by the means to be described hereinafter.

Rigidly connected to the lower end of sealing sleeve I9 is the assembly of parts which constitutes the principal subject matter of this invention. This assembly comprises a mandrel or expander, designated generally by the numeral 22, a plurality of slips 23 which are circumferentially arranged about the expander, a sleeve cage, designated generally by the numeral 24, which is connected to the lower ends of the slips 23, by means of a slip collar, designated generally by the numeral 25. The lower end of cage 24 carries a pair of lugs 26-26 which lare adapted to cooperate with la pair of slots 21 (only one shown) formed in elongated lug plates 28 larranged on opposite sides of the lower end of operating pipe I1. Lugs 26 and slots 21 form bayonet-type releasable connections between the packer structure and the operating pipe. It will be understood that when lugs 26 engage slots 21 the elements of the packer structure will be held in the inoperative or retracted position, and the lugs are releasable from the slots in response to appropriate rotation of operating pipe I1 relative to the packer structure to release the packer structure for setting inthe casing. The operations in these respects are entirely conventional.

Expander 22 comprises a downwardly and inwardly tapering body 30, having the general form of a regular polygonal pyramid or frustum thereof. In the embodiment illustrated the body is in the form of a frustum of a regular hexagonal pyramid, its base being in the form of a regular hexagon (see Fig. 5). It will be understood that although this is a convenient shape, the geometric form of the base may lbe that of a triangle, square, pentagon or other regular polygon. Accordingly, each of Vthe sides 3| are in the form of regular trapezoids presenting a series of nat downwardly and inwardly tapering surfaces about the exterior of the expander. Expander 30 is provided axially with a cylindrical bore 32 concentric with operating pipe I1 which is freely movable rotatively and longitudinally therethrough. The upper end of bore 32 is internally threaded at 33 for threaded `engagement with a metalinsert 'ring 34 carried by the lower end of sealing sleeve I1 (see Figs. 3 and 4). Set screws 35 extend through the wall of the expander adjacent its base to lock the expander to insert ring 34. A plurality of p'assageways 35 extend radially through the wall of expander 3H at the junctions of sides 3| and are spaced slightly below threaded connection 33 to provide communication between bore 32 and the exterior of the expander.

Slips 23 comprise generally rectangular sectors cf a cylinder, the external diameter of which is normally slightly less than the internal diameter of casing I6. The slips will preferably be formed by cutting a cylindrical blank `along an appropriate number of radii to form the requisite number of slips, whereby the slips, whenvin retracted position, will have their side edges in relatively close contact to form a substantiallycontinuous cylindrical exterior surface. The Vexternal faces of the slips are provided with series of rows of downwardly faced gripping teeth 31. In longitudinalsection slips 23 are wedge-shaped having inner faces 38 which are at and taper upwardly and outwardly at an angle complementary to that of the adjacent faces 3| of the expander. Each of the faces 3| carries a dove-tail'spline 39 extending longitudinally of its medial portion which is engageable with a, complementary groove 40 out in faces 38 of the slips. The splined connection thus formed permits relative longitudinal movement between the slips and the expander while holding the slips locked to the expander. It will be understood that the splines may be on the slips and the grooves on the expander faces without altering the essential operating characteristics of the structure. The lower end or base ci' each of the slips 23 is provided with an integral tongue 4| having a T-shaped head which is adapted to be received in a complementary T-slot 42 formed or out in the upper edge of slip collar 25. lThe relative dimensions of heads 4| and 42 are made such that heads 4| fit somewhat loosely in slots 42 and may engage in some movement relative thereto, particularly in the radial direction. Collar 25 comprises a plurality of inter-tting circular segments 43 (see Fig. 1) particularly) adapted to be connected together by means of dowel pins 44, one of which is screwed into one end of each of the segments and is adapted to be slidably received in a suitable socket 45 in the adjacent end of the contiguous segment. In assembling the slips on the expander, the grooves 49 in the slips are engaged with splines 39 on the expander. Segments 43 of the slip collar are then connected to tongues 4| by slipping the segments laterally about the tongues with T-slots 42 engaging the T-heads in the manner illustrated. As the segments are thus moved radially inwardly, the dowel pins are brought into engage- -ment with their cooperating sockets and the collar thus locked about the tongues and slips to lock them about the expander. The lower end of collar 25 is provided with an externally threaded extension 45 of somewhat smaller external diameter than the body of the collar.

Gage 24 comprises a tubular body 41 concen trically arranged on operating pipe |1 and internally threaded at its upper end so that it may be screwed on extension d5 of the slip collar after the latter is assembled and connected to the slips as above described. With this arrangement the upper end of cage body 41 forms a rigid circular keeper or lock for the collar segments which will prevent their separation in use and additionally assure positive locking of the r slips about the expander. Cage body 41 is provided with a plurality of T-shaped radial sockets 48 (see Fig. 8) in which are mounted correspondingly shaped blocks 49 having projections or ribs 50 on their outer faces. springs 5| are arranged between the inner faces of blocks 49 and the bottom of sockets 48 and are adapted to normally urge blocks 49 outwardly to force ribs 50 into frictional engagement with the inner wall of casing lli. Blocks 49 have longitudinal edge anges 52 which cooperate with the inner edges of sockets 48 to retain the blocks within the sockets. The lower end of cage body 41 is externally threaded at 53 for connection thereto of a sleeve 54 which carries lugs 26 on its inner surface. A plurality of ports 55 provide communication between the bore of sleeve 54 and the exterior thereof. It will be understood that the described form of cage 24 and friction blocks 49 is intended to be merely illustrative of the various types of cages conventionally used in well packer structures for providing frictional engagement with a casing wall. Other suitable and conventional forms of friction cages may be employedfor this particular portion ofthe A plurality of coil I described structure, the detailed construction of such cages forming no essential part of this invention.

Operation of the above-described structure is as follows: The packer structure is assembled on operating pipe I1 with lugs 26 engaged in slots 21 to hold the slips 23 and sealing sleeve |9 in their retracted positions as illustrated particularly in Figs. 1 and 3. The upper end of operating pipe |1 will be connected to pipe string I8 and the packer structure lowered thereby into casing I5. It will be understood that other well tools may be connected to the lower end of oper ating pipe |1 if desired and in accordance with conventional practice. Also, mud fluid or other fluids may be circulated through the pipe string and up outside the packer during the lowering operation. Passageways 55 will allow fluidto enter the annular space between the packer and operating pipe |1 and discharge back into the annular space outside the packer through passageways 36 and through seat ring 29. This is a more or less conventional arrangement to permit the packer to move through the casing with minimum resistance from any fluid in the casing and to maintain circulation while the packer is in movement. When the packer has been lowered to the desired position in the well, pipe string 8 and operating pipe |1 will be rotated in the appropriate direction a sufdcient amount to release lugs 26 from slots 21. The frictional engagement maintained between blocks 49 and the casing wall under the pressure of coil springs 5| will hold the packer structure stationary while permitting relative rotation of operating pipe I1 to eiect release of lugs 26 fro-m slots 21. Fig. 1 illustrates generally the position of the parts of the structure just following the withdrawal of the lugs from the slots. Upon release-of the pins from the slots pipe string I9 and operating pipe |1 are lowered relative to the packer structure until valve 2| contacts seat ring 20. As the weight of the pipe string is thus transferred to the upper end of sleeve I9, the latter will drive expander 39 downwardly relative to slips 23 which will be held stationary through their connection to cage 24 which is, in turn, held in stationary position by the fri-ctional engagement of blocks 49 with the casing. The movement of the expander relative to the slips will cause the latter to slide upwardly over the descending faces 3| of the expander, the wedging action of the complementary surfaces forcing the slips radially outwardly until teeth 31 engage the wall of casing I6. This effectively stops further downward movement of the expander and sealing sleeve and continued application of the weight of pipe string I8 will increase the expansive pressure on the slips to cause the slips to grip the casing more tightly. Also the resistance to further downward movement, resulting from engagement of the slips with the casing, will cause the weight applied to the upper end of sealing sleeve |9 to expand the latter radially and thereby effectively seal the annular space between casing I9 and operating pipe l1, thus providing the pack-oft which is the primary purpose of the structure. Figs. 2 and 4 illustrate the positions of the parts when the packer has thus been set. Contact of of valve 2| with seat ring 29 will cut off uid communication between the sections of casing |6 above and below sealing sleeve I9, thus eiectively isolating the sections lfrom 'each other. Passageways 36 and 55 will also serve as relief ports t0 prevent entrapment of fluid between the parts of the packer during ,relative movement thereof which might otherwise hinder its proper functioning.

It will be evident that by virtue of the novel construction of the expander and slips herein described, -the slips will be fully ksupported over the entire area of their inner lfaces by the expander surfaces irrespective of the degree of relative longitudinal movement between them. Thus, one suitably dimensioned set of slips and expander may be employed in casings of considerably varying size while maintaining this full surface contact, and maximum expansive pressures may thus be applied to the slips without danger of breakage. Also by the selection of an expander having a suitable number o f polygonal faces and of suitable slope, a number `of slips may be employed such that minimum separation will occur between the contracted and fully expanded positions and thereby provide a maximum area of toothed surface for gripping the casing. Since the outer periphery of the ring of slips is circular, this permits a uniform distribution of the slip pressure about the entire circumference of the casing and obviates a difficulty common to the more conventional types o f hookwall packers in which the slip segments become rather widely spaced when expanded to their set positions and, therefore, are caused to concentrate their pressures at rather widely spaced vpoints on the casing wall. This frequently has the result that, under the very high pressures to which the packers are subjected, such separated slips -bulge the relatively limited casing areas against which the kslip faces are pressed. Such bulging may not only damage the casing but may cause the slips to become locked into the-bulged portions so that they become diiicult to release.

To eiect release of the packer, pipe string I8 is raised to release the pressure on sealing sleeve, allowing it to retract -while the operating pipe is drawn upwardly. The upward movement of operating pipe `I-l will bring the upper ends of plates `28 into contact with the apex of expander 3l). The upper ends of plates .28 form shoulders or abutments which coact with the lower Aend of the expander to force the latter in the upward direction relative'to slips 23. This movement will act through the splined connections of the expander with the slips to positively retract the latter out of engagement with the casing wall and thereby7 e'ect release of the packer. The entire packer may then be withdrawn from the well. Plates 28 may be used as jar lugs to strike upward blows `against the'lower end of the expander in the event-such blows are necessary to effect release of the slips and sealing sleeve from the casing wall. `Various other and more conventional forms of such jarring mechanisms may be employed for this purpose. By the described construction of slip collar 25 and its connections to the 'slips vand cage, it will be seen the conventional looselinkages commonly employed for hngedly connecting the slips to the cage have been eliminated, and replaced by a single connection formed -by T-heads 4I and slots 42, the T-heads being generally radially movable in the slotsduring relative movement between the slips and expander. The relatively massive and unitary construction thus provided permits the packer structure to be subjected to extensive vjarring action, whenvnecessary,.with no danger of breakage-orserious damage.

It willbe understood that .various valterations and changes may be made lin the details of the illustrative embodiment without departing from the r scope of the appended claims but within the spirit of this invention. In particular, it will be understood that the described slip and expander assembly may be employed for upward setting, as well as in the downward setting arrangement herein described by minor reversal and suitable rearrangement of the parts in a manner which will be clearly evident to those skilled in this art. While the slips and expander assembly has been illustrated as used with a well packer, this is merely by way of illustration and it will be understood that the invention may be employed with other forms of hook-wall well tools, such as spears, various fishing tools, and the like.

What I claim and desire to secure by Letters Patent is:

1. In well tools of the hook-wall type, an improved slip and slip-expander assembly, comprising, an expander shaped in the form of a regular polygonal pyramid, slip members disposed for longitudinal sliding movement on the several faces of said expander, the inner surfaces of said slip members being generally at and of complementary slope to said faces, interlocking longitudinally splined connections between said slip members and said faces, a segmental collar member having at one end thereof radially movable inter-locking tongue-and-slot connections with the base of each of said slip members and an externally threaded extension at its other end, an internally threaded tubular keeper member threadedly engageable about said extension, said collar member being composed of a plurality of separable arcuate segments having radially abutting end faces, a socket having a closed end in one of said end faces of each of said segments, and a dowel embedded in the other end face of each of said segments and slidable into the opposed socket in the adjacent end face for circularly joining said segments.

2. In well tools of the hook-wall type, an improved slip-expander assembly, comprising, a tapered slip expander, a plurality of slips annularly disposed about the exterior of said expander for longitudinal sliding movement thereon, and a slip-retainer collar member having radial tongue-and-slot connections at one end thereof with said slips and an externally threaded extension of smaller diameter than the body of said collar member at its other end, and an internally threaded tubular keeper member enclosing said extension, said collar member being composed of a plurality of separable arcuate segments having radial abutting end faces, a socket having a closed end in one of said end faces of each of said segments, and a dowel embedded in the other end face of each of said segments and-slidable into the opposed socket in the adjacent end face-for circularly joining said segments CICERO c. BROWN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,428,385 Meredith et al Sept. 5, 1922 2,275,935 ABaker g, Mar. 10, 1942 2,331,185 Gordy Oct. 5, 1943 12,343,075 .Otis Feb. 29, 1944 :2,368,401 Baker Jan. 30, 1945

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