US3048227A - Releasable bumper block - Google Patents

Description

Aug. 7, 1962 Filed July 24, 1958 Tluz l- 1.. D. CASON ETAL 3,048,227

RELEASABLE; BUMPER BLOCK 3 Sheets-Sheet 1 Aug, 7, 1962 Filed July 24, 1958 L. D. CASON ETAL RELEASABLE BUMPER BLOCK 3 Sheets-Sheet 2 D. CASON ETAL 3,048,227

RELEASABLE BUMPER BLOCK Aug. 7, 1962 3 Sheets-Sheet 3 Filed July 24, 1958 United States harem @fifire 3,048,227 Patented Aug. 7, 1962 3,048,227 RELEASABLE BUMPER BLOCK Lloyd D. Cason and Kennedy J. Dugas, Erath, La., as-

. signors to Texaco Inc a corporation of Delaware Filed July 24, 1958, Ser. No. 750,791 11 Claims. (Cl. 166114) This invention is generally concerned with a downhole tool for deep wells. More specifically, it is concerned with a disconnectable tubing support. Such tubing support is applicable for work-over operations in wells that have been completed with reduced diameter tubing at the bottom of the string.

A procedure is known, which is employed in working over a permanently completed well, i.e. a Well that has been cased and tubed, without pulling the tubing of the well. This known procedure avoids the use of a wireline operated tail pipe for such work over operation.

The foregoing known procedure, briefly, involves cemen-ting-oif a given producing zone prior to re-perforating and commencing production anew from the same or a higher zone. In the course of such operation, it is necessary to wash out the old producing zone that is to be cemented. This may be done by fluid circulation accompanied by lowering the tubing down into the zone that is being washed. Following such washing the old zone is cemented under pressure, which is known as squeeze cementing. The squeeze cementing operation involves applying cement to the zone, using forward circulation out through the bottom of the tubing. After the cement slurry has been applied thus, excess cement is reversed out by reverse circulation, i.e. from the annulus into the tubing. Then some pressure is held on the cement while it is given time to set. To apply these pressures, the annulus is sealed around the tubing by employing a seal nipple on the tubing and locating it within a packer that has been set in the casing above the zone being squeezed.

Since the pressures involved in the squeeze operation mentioned above, are quite high, the force tending to raise the seal nipple and tubing up out of the packer becomes quite substantial. For this reason it has been found difficult to carry out the squeeze cementing operation without loss of pressure (due to the forcing of the seal nipple or nipples, up out of the packer). It is not feasible to apply tubing weight on the string, in order to counteract this upward force. This is because the string is suspended from the surface, and to attempt this would mean that the tubing string would be released and tend to be lowered, which would force the seal nipple out of the packer in a downward direction, and again create a loss of pressure by breaking the seal. The reason this is so is because of the length of the tubing string involved, which is relatively so great that compression on the tubing from the lower end, can create substantially large changes in the length thereof. Thus for example, the seal nipple or nipples can be moved several feet upward under the force involved duringthe squeeze operation, without moving the top of the tubing string at the well head, at all.

Consequently, it is an object of this invention to provide a method and apparatus for overcoming the above mentioned difficulties.

It is another object of this invention to teach a method of releasably latching a bumper block to the tubing string, so that the tubing string may be lowered through the block (and a packer underneath) for carrying out desired operations.

Another object of this invention is to provide a bumper block which has releasable latching structure so that tubing may be unlatched from direct supporting contact therewith, andbe lowered through the block. Thereafter such tubing may be raised again and relatched into positive contact with the bumper block.

Briefly the invention is concerned with a downhole releasable bumper block, for use in at least partially supporting a tubing string on a packer. Such bumper block comprises a latching head adapted to be connected to said tubing string, and a hollow cylindrical body member, having friction means exteriorly thereof for engaging the walls of said hole. The bumper block also comprises a bowl assembly in said body member which includes means for releasably engaging the latching head. The said hole assembly and said latching head, are so constructed and arranged that said latching head may be lowered axially relative to said body member for any desired distance after unlatching, and may be relatched after raising the latching head back within said bowl assembly.

The invention may be also briefly described as a method that is applicable in a permanent type well completion. Such completion being one that has a pre-determined length of reduced'diameter tubing at the bottom of the tubing string in said well. The method is one that is involved in a work-over procedure. The work-over procedure involving a lowering of said tubing string, relative to a packer located adjacent to said reduced diameter tubing. The method includes the steps of unlatching said tubing from a hollow cylindrical body member adapted to rest on said packer, and lowering said tubing through said packer and body member to carry out circulation of fluid through said tubing, Also the step of raising and relatching said tubing to said body member, and also releasing suificient of the weight of said tubing string to withstand the pressure involved in a squeezing operation.

The foregoing and other objects and benefits of this invention, are set forth in the detailed description that follows, and are illustrated in the drawings, in which:

FIG. 1 is an elevation assembly partly in cross section, showing the bumper block in place, resting on a packer that is schematically shown in cross section, and with a tubing string shown passing through the bumper block and packer;

FIG. 2 is an enlarged fragmentary elevation, largely shown in longitudinal cross-section along the line 22 of FIG. 1, illustrating the elements of the bumper block according to a preferred embodiment of the invention;

FIG. 3 is an enlarged detail showing of certain of the elements that go to make up the upper portion of the bumper block;

FIG. 4 is an enlarged detail elevation view showing the coil spring that is employed within the bowl assembly of the bumper block;

FIG. 5 is an enlarged detail elevation partly broken away in cross-section and illustrating a spring guide on which the bottom of the coil spring shown in FIG. 4, rests;

FIG. 6 is an enlarged detail elevation, partially broken away in cross section, illustrating the expanding thread segments that have the load bearing female threads on the inner periphery thereof;

FIG. 7 is another enlarged detail elevation, partially broken away'in cross-section, illustrating the stabilizer ring, that is located beneath the expanding-thread seg ments;

FIG. 8 is an enlarged detail elevation partially broken away in cross-section, illustrating the latching head that is adapted to be connected into the tubing string; 7

FIG, 9 is an enlarged fragmentary detail elevation of the lower pontion of the bumper block at the bowl assembly portion thereof. This showing is broken away in crosssection to show the internal structure including an axially extending key that co operates with the thread segments illustrated in FIG. 6;

FIG. 10 is a transverse cross-section view, taken along 3 the lines -10 of FIG. 2 looking in the direction of the arrows;

FIG. 11 is another transverse cross-section view taken along the lines 1111 of FIG. 2 looking in the direction of the arrows; and

FIG. 12 is a fragmentary cross-sectional view, showing a modified form for the elements of the bumper block that provide frictional engagement with the walls of the hole.

Referring to FIG. 1, it is pointed out that there is illustrated a fragmentary portion of a deep well 21, which has been drilled into the earth to reach under-lying strata such as formations 22 and 23 illustrated. Such a deep well is ordinarily lined with a casing 24, although if the formations are sufliciently hard a casing might not always be required.

Throughout this description, wherever the walls of the hole are referred to, it is contemplated that such walls include the casing, if the hole is cased, or the walls of the hole formed by the formation, if the hole is uncased.

There is a conventional type of production packer 25, schematically illustrated. This packer 25 has been expanded to provide a tight high pressure seal with the casing 24. There is shown situated within packer 25 a conventional seal nipple that is connected into a reduced diameter tubing string 31, which passes through the bumper block 32 that is shown resting upon the top edge of the packer 25.

The type of operation in which this invention is employed, has been briefly indicated above. Such operation (when applied to the apparatus shown in FIG. 1) includes a lowering of the tubing string 31 through the bumper block 32 and the packer 25, after the tubing string has been unlatched from the bump r block internally thereof. It will be appreciated that the reduced diameter tubing string 31 is attached at the lower end of the normal sized, full diameter tubing string (not shown) in the well. Such reduced diameter tubing string will have been attached to the main tubing string as the well is completed, in order that the procedures for re-working the well may be carried out, without removing the tubing from the well.

The operation involves a lowering of the reduced diameter tubing string 31, sufliciently to move the seal nipple 30 out of contact with the packer 25 in order to provide free passage for fluids from the annulus above the packer 25 to the annulus beneath the packer. Thus a circulation of fluids may be carried out under such circumstances; and any accumulation of sand or debris may be washed clear, prior to a squeeze cementing operation. A squeeze cementing operation involves applying pressure to the cement following injection thereof through the tubing 31. And, in order to apply and maintain such pressure, the tubing string 31 is raised until the seal nipple 30 again rests within the packer 25 (in the manner illustrated in FIG. 1). When this condition exists, and the tubing string 31 has been re-latched into positive contact with the bumper block 32, squeezing pressures may be applied to the cement, and will be maintained without forcing the seal nipple 30 up out of the packer 2 5. This is so because tubing-string-weight may be applied to the bumper block 32, since the string 31 is now latched into positive connection with the bumper block 32.

Ordinarily the full weight of the tubing string 31 will not be applied, for fear of causing a buckling in the tubing string. However, by reason of the bumper block being attached to the string 31 with a positive connection, sufficient tubing weight may be applied to insure that the squeeze pressure will not be able to lift the seal nipple 30 up out of the packer. The excess of such tubing weight will be carried in a supporting manner by the upper edge of the packer 25, upon which the bumper block 32 rests. Referring to FIGS. 2ll, the details of the structure of the bumper block 32 will be described.

There is a latching head 35 (FIG. 2 and FIG. 8) that may be called a tubing support or latching nipple and is connected into the tubing string 31, as indicated by the broken line showing of the tubing string in FIG. 2. Such connection with the string 31, by the latching head or tubing support 35, is made by means of upper internal pipe threads 36 for the upper portion of the tubing string, and lower pipe threads 37 for the tubing string connected below the tubing support or latching head 35. On the outer surface at the upper end of the tubing support 35, when viewed as shown in the drawings, there is a set of male buttress type load bearing threads 38. At the other end of the latching head or tubing support 35, there is an enlarged cylindrical collar section 39.

The structure of the bumper block proper (that acts to support the latching head or tubing support 35) includes a hollow cylindrical body portion, or body member 43 (FIG. 2). This is made up of two separable portions, including an upper sleeve-like unit 44 (FIGS. 2 and 3) that has a relatively short, thick walled hollow cylinder 45 surrounding part of the lower end thereof. Cylinder 45 is welded to a sleeve 47, at the upper edge of the cylinder 45 as indicated at reference number 46.

The lower portion of the body member 43, includes a lower eylinder-and-sleeve unit 48 (FIGS. 2 and 9) that includes an outer sleeve 56 that has internal threads 51 at one end thereof, adapted for meshing with threads 53 on the outside lower portion of the hollow cylinder 45 of the upper unit 44. The lower end of the sleeve 50 surrounds, and is securely attached to, the upper end of a lower cylindrical portion 54. This attachment may be accomplished in any feasible manner, such as by means of a weld 52 illustrated.

Attached .to the thick walled portion of cylinder 54, there is a plurality of hole-wall-engaging bowed springs 56. Springs 56 are attached to the cylinder 54 in any feasible manner, such as by employing cap bolts 57, as illustrated. At the other end of the springs 56 there is a supporting ring 58, to which the bowed springs 56 are attached by means of flush head bolts 59, as illustrated.

Generally within the sleeve 50, there are located the elements of a bowl assembly. These bowl assembly elements include the main element of the latching structure, viz. a plurality of frusto-conical annularly situated segments 63 (FIGS. 2 and 6). These segments 63 have on the inner peripheral surface thereof, female buttress type threads 64, which are cut for engagement with the male buttress threads 38 on the tubing support or latching head 35. Segments 63 rest within a frusto-conically walled chamber 65, that is formed by the widening portion of the upper extremity of cylinder 54, where it extends within the outer sleeve 50. Underneath the segments 63 in the bowl assembly, there is a stabilizer ring 66 (FIGS. 2 and 7), which rests upon a shoulder 67 formed in the cylinder 54. On top of the segments 63 there is a spring-guide ring 70 (FIGS. 2 and 5). Guide ring 70 supports a coil spring 71 (FIGS. 2 and 4). The other end of spring 71 rests against the lower edge of the upper cylinder 45.

It is pointed out that the threads 51 and 53 which join the upper and lower portions of the body member 43 together, are a tight fit so that when assembled, the entire bumper block 32 acts as a unitary whole.

Referring to FIGS. 10 and 11 it will be observed that the segments 63 are so proportioned as to be in contact with one another at the edges thereof, with the exception of a space 74 that is formed between segments 63a and 6312. This space 74 is provided to accommodate a key 75 that is welded to the upper extension of the cylinder 54, above the shoulder 67. Key 75 thus prevents relative rotation between the cylinder-and-sleeve unit 48 and the segments 63. However, the segments 63 are free to move longitudinally (i.e. parallel to the axis of the bumper block 32) against the spring pressure of spring 71. Such longitudinal axial movement of the segments 63,

aoaaaav Operation Referring especially to FIGS. 1 and 2, the operation may be explained in accordance with the following. With the elements in the relative positions illustrated, the tubing string 31 is connected to the tubing support or latching head 35, and the tubing string is therefore latched to the bumper block 32. When it isdesired to unlatch the tubing string 31, it will be raised to lift the bumper block 32 off of the packer 25, so that the bumper block 32 is supported by means of the buttress threads 38 and 64 in addition to the large collar section 39 on the latching head 35. Now when the tubing string 31 is rotated, the latching head 35 will of course rotate therewith. However, by reason of the bowed springs 56, the bumper block 32 and particularly the cylinder 54 thereof, will tend to remain stationary by reason of the drag friction between bowed springs 56 and the casing 24 of the well 21. Thus, by rotating the latching head 35 by means of the tubing string 31, in the proper direction, the body member '43 of the bumper block will become disconnected from the string on account of unscrewing the thread connection at the loose fitting buttress threads 38 and 64.

Ifthe tubing string 31 is held vertically stationary while it is rotated, body member 43 will climb upward as the threads are unscrewed from one another. After the buttress threads have become completely unscrewed from one another the tubing support or latching head 35 may be lowered along with the tubing string 31, as far as desired, depending upon the length of the reduced diameter tubing that has been installed and the depth to the bottom of the hole. When the tubing string 31 is thus lowered, carrying tubing support 35rtherewith, the bottom edge of cylinder 54 of the bumper block 32, will contact the packer 25 once more and remain there as the tubing is lowered therethrough. Lowering of the tubing will, of course, lower the seal nipple 30 out of the packer 25 and permit flow of fluids through the annulus past the packer.

After the completion of a washing operation, or other steps that may be. taken while the tubing string is unlatched from the bumper block 32, the tubing string may be again raised to bring the latching head 35 into contact once more with the threads 64 of the segments 63. Following such contact, the tubing string will be raised sufficiently to lift .the body member 43 for a distance above the packer 25 that is s'ufiicient to allow for the downward movement of the body member 43, as the relatching operation takes place. Such re-latching is accomplished by merely reversing the earlier steps, i.e. by-

rotating the tubing string 31, and the latching head 35 therewith, in the proper direction to screw the loose fitting buttress threads'of latching head 35 and of segments '63, back together.

As explained above, the body member 43 will not rotate, freely with the latching head 35 as it is rotated, because of the friction drag effect at the walls of the hole that is created by the bowed springs 56.

In order to be sure that the threads 64, of all of the segments 63, are properly meshed with the threads 38 of the latching head 35, it is advisable to rotate the latching head 35 for a full revolution in the opposite (or unscrewing) direction prior to the rotation in the forward, or screwing direction, when proceeding to relatch the string to the bumper block.

It will be noted that, by reason of the expanding thread structure of segments 63 and the tapering chamber walls 65, latching head 35 may be re-latched to the body member 43 without any rotation thereof. In other words,

the mere straight lifting action of latching head or tubing support 35 will cause the segments 63 to rise and spread, so that the meshing of the threads on latching head or tubing support 35 may be accomplished bythe ratcheting action of the buttress threads over one another. However, in any event, it is most advisable to rotate the tubing string 31 for a full revolution in the backward or unscrewing direction prior to a release of the tubing string Weight for support thereof on the packer 25. Such reverse rotation will make sure that the threads of all of the segments 63 are properly meshed at the same level without any cross threading.

Method Steps It will be observed that the apparatus which has been described may be employed to carry out a method that is applicable to the procedure that is involved in a permanent type Well completion operation. volved in the working over of the well following the aforementioned permanent type completion. The procedure has been described in general terms above.

It will be clear that in such a procedure the apparatus may be employed to carry out the following steps, including unlatching the tubing from the hollow cylindrical body member that is adapted to rest on a packer, lowering said tubing through the packer and body member in order to be able to carry out fluid circulation opera tions where fiuid is circulated either down the annulus between the casing and the tubing and up inside of the tubing or the reverse. In addition, the procedure may include the additional steps of raising and re-latching the tubing string to the body member, as well as releasing sufficient of the weight of the tubing string so as to provide downward force to withstand the pressure involved in a squeezing operation when the tubing string is latched in position (the seal nipple is located within the packer).

Modified Friction Springs FIG. 12 illustrates a different hole-Wall engaging friction drag means, to replace the bowed springs 56 of the modification described in the previous figures.

Referring to FIG. 12 it will be observed that there is a plurality of friction blocks at} that are mounted partially recessed in the lower cylindrical portion 54a of the body member. These friction blocks 30 are designed to provide more frictional force against the walls of the hole than would be applied with the other style friction wall engaging springs 56. Thus the friction blocks are spring biased radially outward into extended positions as illustrated in FIG. 12, by means of a double set of coil springs 81 and 82 located in each of a set of three re cesses 85, 86 and 87, in turn located in each of the friction blocks 80. Each of the friction blocks 80 is held in position in an elongated recess 90 in the wall of the cylinder 54a. Each block 80 is held in position in its recess 90, against the force of the coil springs 81 and 82,

.by means ofa pair of flat headed machine screws 91 and 92. The heads of these screws 91 and 92 overlap the edge of the recess 90, and make contact with the block 80 in notches 93 and 94 respectively.

All of the other elements of the bumper block, remain the same as already illustrated and described above.

It is pointed-out that while FIG. 12 illustrates only two friction blocks 80 it will be clear that more than two (preferably four) could be employed if desired.

While certain embodiments of the invention have been illustrated and described in considerable detail in accordance with the aplicable statues, this is not to be taken as in any Way limiting the invention, but merely as being descriptive thereof.

What is claimed as the invention is:

1. For use in a well bore having an internal packer fixedly mounted therein, a tubing string adapted to pass freely through the packer, and said tubing string being provided with a seal nipple engageable with the packer in sealing relationship; means for selectively holding the seal nipple in the packer comprising a bumper block about the tubing string above the packer and adapted to rest thereon, a tubing support connected into said tubing Such operation is instring, and means controlled from the well head for latching said tubing support to said bumper block when said seal nipple is engaged in said packer to hold said seal nipple therein, said latching means being selectively releasable to permit downward movement of the tubing string in the well.

2. In the combination according to claim 1, the said latching means including load bearing means on said tubing support, and complementary means on said bumper block for meshing with said load bearing means.

3. The invention according to claim 2 further including friction means on said bumper block for restraining the bumper block against rotation in the well.

4. The invention according to claim 3 wherein said load bearing means comprises machine threads.

5. The invention according to claim 4 wherein said complementary means comprises a plurality of segments having threads on the inner surfaces thereof matching with said machine threads.

6. The invention according to claim 5 wherein said plurality of segments include a tapered outer circumferential configuration to allow for diametrical expansion thereof.

7. The invention according to claim 6 further including a bowl assembly integral with said bumper block for housing said segments, and bias means for urging the segments into diametrically contracted position.

8. A disconnectable tubing support assembly for use in deep well operations, comprising in combination a tubing support adapted to be connected into a tubing string, a bumper block freely embracing said tubing support for permitting free downward movement of said tubing support relative to said bumper block when disconnected therefrom, said bumper block including a frusto-conically Walled chamber, machine threads on said tubing support for latching and unlatching with said bumper block, and a plurality of segments having a tapered outer circumferential configuration to allow for diametrical expansion thereof and being located within said chamber and having threads on the inner surfaces thereof matching with said machine threads, said bumper block being so constructed and arranged that by surface manipulation of said tubing string said tubing support may be connected and disconnected relative thereto as desired.

9. The invention according to claim 8 further including bias means for urging the segments into diametrically contracted position.

=10. A down hole releasable bumper block for use in at least partially supporting the weight of a tubing string on a packer, comprising a latching nipple adapted to be connected to said tubing string, load bearing threads on said latching nipple for carrying said tubing string load, a hollow body member adapted to receive said tubing string extending therethrough, said body member having friction means exteriorly thereof for engaging the walls of said hole, a bowl assembly in said body member, said assembly comprising a plurality of tapered thread segments adapted for threaded cooperation with said load bearing threads, a tapered chamber for receiving said segments, and key means for preventing relative rotation between said segments and said body member, said tapered chamber having an axial dimension greater than the corresponding axial dimension of said segments to provide for radial expansion of said tapered thread segments, spring bias means for urging said segments axially into radially contracted position within said tapered chamber, said tapered chamber being relatively situated in said body with the minimum diameter of the taper at the lower end when said bumper block is in place above said packer.

11. A down hole releasable bumper block for use in at least partially supporting the weight of a tubing string on a packer, comprising a hollow body member, hole wall engaging friction drag means mounted exteriorly on said body member and having means for biasing said drag means radially outward against the walls of said hole, a bowl assembly on the interior of said body member, said bowl assembly comprising a frusto-conical walled chamber with the minimum diameter at the end nearest said packer, a plurality of frusto-conical annular segments within said chamber having load bearing female threads on the inner surfaces thereof and including a predetermined circumferential space between two of the segments, a key attached to said body member and located in said circumferential space for insuring against rotation of said segments relative to said-body member, a spring for urging said segments toward the minimum diameter end of said chamber, a latching nipple adapted for connection into said tubing string, said latching nipple having load bearing male threads thereon for engagement with said female threads on said segments, the outside diameter of said male threads being less than the inside diameter of said body member below said bowl assembly, so that said tubing string may be unlatched and lowered out of said body member for reversing operations and relatched thereafter for squeeze operations and the like.

References Cited in the file of this patent UNITED STATES PATENTS 1,824,283 Marr Sept. 22, 1931 2,156,939 Fulkerson May 2, 1939 2,187,480 Baker Ian. 16, 1940 2,187,483 Baker Jan. 16, 1940 2,644,524 Baker July 7, 1953 2,687,774 Hodges Aug. 31, 1954 2,737,248 Baker Mar. 6, 1956 2,751,009 Wooddy June 19, 1956 2,893,492 Brown July 7, 1959

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