US 3705624 A
This invention relates to a slip and drag block assembly for use with a packer or bridge plug, for example, in the casing of an earth well.
Description (OCR text may contain errors)
United States Patent Pitts  SLIP AND DRAG BLOCK ASSEMBLY  Inventor: Charles A. Pitts, Wichita Falls, Tex.
 Int. Cl. ..E2lb 43/10, E21b 23/06, E2lb 33/129  Field of Search ..166/138, 140,216, 217, 210
 References Cited UNITED STATES PATENTS 3,043,372 7/1962 Davis ..l66/140 3,045,758 7/1962 Muse ..l66/2l6 3,074,484 l/l963 Conrad ..166/216 3,282,343 11/1966 Tausch 166/138 3,352,362 11/1967 Lebourg ..166/140 3,374,841 3/1968 Current ..166/l38 3,520,361 7/1970 Lewis ..l66/l38 X Primary Examiner-David H. Brown Attorney-Earl D. Ayers et a1.
[5 7] ABSTRACT This invention relates to a slip and drag block assembly for use with a packer or bridge plug, for exam- [451 Dec. 12,1972
ple, in the casing of an earth well.
The drag block elements are spring loaded and held within a. slotted tubular cage member which is a cast 1 ing. The slip elements, spring loaded, are pivoted from Insertion of the drag block elements into the cage is accomplished by means of a rotatable tubular ring contiguous to the drag block end of the cage and having a notch in its end facing the cage whereby each drag block element is inserted in a slot in the cage as the notch in the rotatable ring is aligned therewith. The notch is then successively rotated to the next cage slot assembly for insertion of the drag block element. After the drag block elements are inserted, the rotatable ring is secured with the notch located between a pair of cage slot arrays.
Because the slip elements are pivoted from the drag block elements, the movement required to set the slips is the same regardless of the weight rating of the nominal size of the casing used.
7 Claims, 2 Drawing Figures BACKGROUND OF THE INVENTION 7 This invention relates to a slip and drag block assembly for use with a packer or bridge plug, for example, in earth wells.
The use of packers in the earthwell industry is well known. Packersare typically utilized in a well casing to divide the interior of the easing into two zones, that is, a zone below the packer and a zone above the packer. Packers are run into well casings on the lower end of a string of tubing. When the packer has been lowered to the desired position in the well casing, means is provided for setting the packer, that is, fixing it into position and expanding a packing element to seal the interior of the casing to divide the easing into the two mentioned zones.
Slip and drag block assemblies are commonly employed as the means for setting the packer in its predetermined position in the well casing.
One problem in connection with slip and drag block assemblies is economic, e.g., the high cost of machining and assembly of the parts of the devices.
Another problem is that of keeping the teeth of the slip elements in a position parallel to the casing wall to be engaged by the teeth. While this problem has in certain instances been solved, the higher production costs of such assemblies is, as mentioned above, an economic problem in a highly competitive industry.
Accordingly, a principal object of this invention is to provide an improved slip and drag block assembly.
Another object of this assembly is to provide an improved, more economical to manufacture, slip and drag block assembly.
Still another object is to provide a slip and drag block combination wherein either the slip or the drag block may be replaced independently of the other.
' A further object of this invention is to provide an improved slip and drag block assembly in which the slip biting elements are parallel with the casing wall.
STATEMENT OF THE INVENTION In accordance with this invention there is provided a slip and drag block assembly which is adapted to be disposed adjacent to and in alignment with a packer or bridge plug unit which is to be set at a predetermined location along and within a string of casing in an earth well, for example.
The invention comprises, disposed around an inner tube-like mandrel, a tubular cage assembly having spring loaded drag block elements extending through slots in the wall of the cage. An array of slip elements, each one pivotally coupled to a drag block element and spring loaded with respect thereto, is held in predetermined two dimensional position by the cage assembly unit. The tapered underside of each slip element is urged outwardly by the advancing tapered cone surface of the packer or bridge plug as the packer or bridge plug is being set in position in a cylindrical area suchv as a string of easing, tubing, pipe or borehole.
BRIEF DESCRIPTION OF THE DRAWING The invention, as well as additional objects and advantages thereof, will best be understood when the following detailed description is read in connection with the accompanying drawing, in which:
FIG. 1 is a side elevational view, partly broken away andin section, of a slip and drag block assembly in accordance with this invention, and 7 FIG. 2 is a sectional viewtaken along the line 2-2 of FIG. 1.
DETAILED DESCRIPTION OF THE DRAWING Referring to the drawing, there is shown an assembly, indicated generally by the numeral 10, in accordance with this invention, comprising an upper mandrel 12 and a lower mandrel 14 coupled together in end-to-end relationship by means of threads 16. A packer assembly, indicated generally by the numeral 18, is threadedly coupled to the lower end of the lower mandrel 14 by threads 20. The upper end of the packer assembly 18 comprises a cone element 22 whose inner surface abuts against a detent 24 in the outer surface of the lower mandrel 14.
. An elongated sleeve part, indicated generally by the numeral 26, has a thick walled lower part 28 and a thin walled upper part 30 and extends over the upper mandrel 12 and lower mandrel 14 at the upper part thereof.
The upper end of the thick walled lower part 28 has a threaded rod-like element 32 extending into a so-called J slot 34 whose long arm part is parallel to the longitudinal axis of the lower mandrel 14.
The sleeve 26 fits slidably around the upper mandrel l2 and lower mandrel 14.
A cage part, indicated generally by the numeral 36, is generally tubular in configuration and has a threaded upper part 38 by means of which it is rigidly mechanically coupled to the lower end of the thick walled lower part 28 of the sleeve 26.
The cage 36, fabricated by casting, machining or injection molding is a part having an outer wall part 40 and a shorter inner wall part 42 extending. axially downwardly from the threaded end part 38.
The outer wall part 40 contains an array of pairs of in-line slots44, 46, which are symmetrically disposed around the periphery of the cage part 36.
Each of the slots, indicated generally by the numeral 44, contains a drag block element 48 which is generally shaped as a regular parallelepiped block having rounded upper end edge surface 50, 52 and outwardly extending flanges 54, 56 extending from the lower end parts thereof. Each drag block element 48 contains three spring receiving bores 58, 60, 62 extending inwardly from its bottom surface '64. The bore 62' is disposed near the flange 54. In addition, a groove 66 which is arcuate in cross section when viewed along a longitudinal cross section of the drag block element 48, is disposed in the bottom of each drag block element between the bore 60 and the bore 62 with the closed end of the groove facing the end having the flange 56.
The drag block elements 48 are held in position against a retaining ring 68 which covers the end of the slots 44 which faces the flange 56 and against the cage outer wall at the end having the flange 54. Springs 70, 72, fitted into bores 58, 60 and bearing against the inner cage wall 42, holds the drag block elements 48 in a spring loaded outward position in the cage.
The ring 68, which holds the flanges 56 of the drag block elements 48 in position in the cage part 40, contains a notch 74 whose width and length correspond to the width and length of the flanges 56. The ring 68 is rotated to align the notch 74 with each slot 44. After unann mm:
the drag block is inserted with the flange 54 under the outer wall of the cage, the ring 68 is rotated to align the notch with another slot. After all the drag block elements 48 are all mounted in the cage 36, the ring 68 is rotated until the notch 74 lies between a pair of slots 44 and is then secured in position by means of the screw 76, for example.
A slip element, indicated generally by the numeral 78, is pivotally mounted in the arcuate groove 66 on the underside of each drag block element 48.
Each slip element 78 has a teeth bearing upper surface part 80 which extends below the cage 36 and a lower end surface 82 which is tapered upwardly towards the lower end 84 of the slip element-78, the taper being adapted to match the mating taper of the conical part 22 of the packer assembly 18. The pivot arm part 84 of the slip element 78 is an elongated barlike part having an upwardly and rearwardly extending arcuate end part 86 which mates with the arcuate groove 66.
A bar-like element 88 extends upwardly from the pivot arm part 84 through the slot 46 to hold or assist in holding the slip element in proper lateral and longitudinal position.
The spring 90, extending into the bore 62 and bearing against the upper surface of the pivot arm part 84, presses the slip element downwardly towards the lower mandrel as the slip and drag block assembly is being lowered down the casing 21.
OPERATION In operation, as the assembly is lowered down the casing 91, the J-mechanism is held with the element 32 in the cross slot position so there is no relative movement between the packer assembly and the slip and drag block assembly. The drag block elements 48, each urged outwardly by its springs 70, 72, ride in frictional dragging contact along the casing 91 until the location is reached where the packer assembly is to be set, e.g., expanded to seal off the casing except for flow through the inner mandrel and tubing usually attached above the below the apparatus shown in FIG. 1.
When the slips are to be set against the casing, the tubing (not shown, but coupled to the upper end of the upper mandrel 12 at the threads 92) is rotated to move the element 32 into the vertical part of the J slot 34.
Tension is placed on the upper mandrel l2 and the packer assembly, attached to the inner mandrel 14, moves upwardly with respect to the drag blocks 48 which are held in position by friction at least until the conical part 22 of the packer assembly 18 forces the slips 78 outwardly to engage the teeth 80 with the wall of the casing 91.
Once the teeth 80 of the slip elements 78 bite into the casing wall, the conical surface 22 is advanced further to bring all of the teeth 80 into biting position with respect to the wall of the casing, and the limited friction of the drag block elements 48 is no longer necessary to set the slips.
Continued tension on the tubing above the apparatus after the slips are set expands the packer (or bridge plug) and seals off the annulus between the lower mandrel and the wall of the casing.
The tubing above the assembly 10 is continuously held under tension after the packer is expanded by slips at a suitable control head (not shown), for example.
When the packer is to be released and recovered from the casing, tension on the tubing is released and the element 32 is moved up the J-slot into the side position (by rotation of the tubing). This movement releases the packer and withdraws the conical part 22 sufficiently from underneath the slip elements 78 to 48 and slip elements 78 are readily made by casting and require little skill on the part of workmen doing further machining andassembly of the parts, this slip and drag block assembly is, though very effective and efficient for the purpose it is to be used, economical to produce. Further, any damaged parts may easily be replaced in the field.
Because the slip elements 78 are mounted on the drag block elements 48 whose position is predetermined with relation to the inside diameter of any weightcasing used, the slips maintain a parallel position to provide an even bite of all their teeth 80 against the casing wall.
The assembly is also well suited, as stated above, to be cleaned by circulating liquid through it to dislodge and wash away particulate materials.
The device of the invention has been described as a tension actuated device. If the apparatus were reversed end-to-end, however, the packer could be set by compression means rather than tension as described herein; the slip and drag block assembly would function equally well in an inverted position.
What is claimed is:
1. An earth well tool assembly comprising a tube-lik inner mandrel having a first end, a second end and a side wall, a device having a frustoconical surface disposed contiguous with the second end of said mandrel with the smaller diameter of said frustoconical surface facing towards said first end of said mandrel, a slip and drag block assembly disposed adjacent said frustoconical surface and including a hollow generally cylindrically shaped cage member having a shorter inner wall and a spaced apart longer outer wall, the outer wall having an array of first and second end-toend longitudinally aligned slots disposed symmetrically around the periphery thereof, the first slots being disposed more distant from said frustoconical surface and being longer than said second slots, each of said first slots having a casing wall contacting part of a drag block element protruding therethrough, each drag block element having an elongated block-like body with end flanges extending from the lower edges of its ends and having a bottom surface opposed to said contacting part, each of said drag block elements being spring loaded between itself and said inner wall of said cage, one of said end flanges extending under the outer wall of said cage adjacent to said first slot and the other of said end flanges being retained in said longer slot by ring means extending around said cage member, a plurality of toothed slip members, one of said slip members being pivotally coupled from each of said drag block elements and having a rod-like retainer part extending into the second slot of each of said first and second aligned slots in said outer wall, each of said slip members having a toothed part facing outwardly from said inner mandrel and an opposed tapered surface adapted to bear against said frustoconical surface.
, 2. Apparatus in accordance with claim 1, wherein said slip members are each spring loaded with respect to the drag block element to which it is coupled.
3. Apparatus in accordance with claim 1, wherein said slip members are coupled to said drag block elements by means of a bar-like part having an upwardly and rearwardly curved male part which mates with a similarly arcuate female part in the bottom surface of said drag block element.
4. Apparatus in accordance with claim 1, wherein I each slip member has a protuberance extending into one of said second slots.
5. Apparatus in accordance with claim 1, wherein each of said drag block elements is spring loaded between itself and said inner wall of said cage by a plurality of coil springs fitting into recesses in the bottom of said drag block element.
6. An earth well tool assembly comprising a tube-like inner mandrel having a first end, a second end and a side wall, a device having a frustoconical surface, said device being rigidly coupled to the second end of said mandrel with the smaller diameter of said frustoconical surface facing towards said first end of said mandrel, a sleeve having a first end, second end, and side walls and a slip and drag block assembly, said sleeve and said assembly being rigidly joined together in end-to-end relationship over said mandrel, said mandrel having a slot in the side wall thereof adjacent to said sleeve and said sleeve having a protuberance extending into said slot, said slip and drag block assembly being disposed between the lower end of said sleeve and a said frustoconical surface and including a hollow generally cylindrically shaped cage member having a shorter inner wall and a spaced apart longer outer wall, the outer wall having an array of first and second end-toend longitudinally aligned slots disposed symmetrically around the periphery thereof, the first slots being disposed closer to said sleeve and being longer than said second slots, each of said first slots having a casing wall contacting part of a drag block element protruding therethrough, each drag block element having an elongated blocklike body with end flanges extending from the lower edges of its ends and having a bottom surface opposed to said contacting part, each of said drag block elements being spring loaded between itself and said inner wall of said cage, one of said end flanges extending under the outer wall of said cage adjacent to said first slot and the other of said end flanges being retained in said longerslot by a notched rotatable ring extending around said cage member, a plurality of toothed slip members, one of said slip members being pivotally coupled from each of said drag block elements and having a rod-like retainer part extending into the second slot of each of said first and second aligned slots in said outer wall, each of said slip members having a toothed'part facing outwardly from said inner mandrel and an opposed tapered surface adapted to bear a ainst said frustoconical surface,
. Ap aratus m accordance with claim 6, wherem said slot in the wall of said mandrel is a J -shaped slot.