US 3910348 A
The invention is an improved bridge plug device which uses shearable "O" rings as appropriate retainers to maintain the assembled component parts in proper relationship before the bridge plug is used in an earth well or the like. The device of this invention is more simply manufactured and assembled than known bridge plugs which utilize shear pins to hold the component parts in position.
Claims available in
Description (OCR text may contain errors)
United States Patent [191 Pitts Oct. 7, 1975 DRILLABLE BRIDGE PLUG  Inventor: Charles A. Pitts, Wichita Falls, Tex.
 Assignee: The Dow Chemical Company,
22 Filed: July 26, 1974 21 Appl. NO; 492,119
 US. Cl 166/134; 166/135  Int. Cl. E21B 23/06; E21B 33/129  Field of Search 166/135,134,123125, 166/206, 212, 216, 217, 237
 References Cited UNITED STATES PATENTS 3,091,293 5/1963 Fry 166/123 3,115,186 12/1963 Kline 166/135 3,250,331 5/1966 Boyle 166/135 X 3,303,885 2/1967 Kisling... 166/135 X 3,631,924 1/1972 McGill... 166/134 3,631,925 l/1972 Nutter.... 166/134 3,631,927 1/1972 Young 166/134 Primary Examiner-David H. Brown Attorney, Agent, or Firm-Earl D. Ayers  ABSTRACT The invention is an improved bridge plug device which uses shearable 0 rings as appropriate retainers to maintain the assembled component parts in proper relationship before the bridge plug is used in an earth well or the like. The device of this invention is more simply manufactured and assembled than known bridge plugs which utilize shear pins to hold the component parts in position.
3 Claims, 2 Drawing Figures US. Patent Oct. 7,1975
DRILLABLE BRIDGE PLUG BACKGROUND OF THE INVENTION This invention relates to bridge plugs and particularly to drillable bridge plugs for use in earth wells.
Drillable bridge plugs are well known in the well drilling and servicing arts. However, the usual practice is to employ shear pins to hold the various components of the bridge in predetermined relationship with respect to each other. This use of shear pins requires both precision sizing of the pins and the bores into which they fit, but also requires precise alignment of parts when the pins are inserted.
OBJECTS OF THE INVENTION A principal object of this invention is to provide an improved drillable bridge plug which is easy to assemble.
Another object of this invention is to provide an improved, economical to manufacture, drillable bridge plug.
STATEMENT OF INVENTION In accordance with this invention there is provided a drillable bridge plug comprising, disposed about a central mandrel, upper and lower slip elements, upper and lower slip cones, a packing element disposed between the cones, a fixed position bottom plate and a movable top plate positioned to bear against the upper slip elements. The top plate, upper slip elements, lower slip cone and lower slip elements are held in position until the bridge plug is to be set by shearable rings disposed in grooves along the outer surface of the mandrel and the inner surface of the parts named.
The bridge plug is set in the well bore by using an explosive setting tool whereby the outer part of the setting tool moves downwardly against the top plate of the plug while the mandrel is held in position by a tension stud which is connected to the setting tool. The down ward movement of the top plate moves the slips and cones and that movement compresses and expands the packing element to seal it against the well casing or well bore wall.
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 in section, of a drillable bridge plug in accordance with this invention, and
FIG. 2 is a sectional view taken along the line 22 of FIG. 1.
DETAILED DESCRIPTION OF THE DRAWING Referring to the drawing, there is shown a drillable bridge plug, indicated generally by the numeral 10, comprising an elongated inner mandrel 12 having a lower end 14 whose outer peripheral surface is threaded and an upper end 16 having a centrally disposed threaded bore 18 extending into it.
The outer peripheral surface of the mandrel 12 is its largest diameter at its upper end part, then is reduced in diameter somewhat from there until near the lower end of the mandrel 12 where the threaded part is of somewhat reduced diameter.
A top plate 22 having an axial bore 26 sized to fit closely but slidably around the larger diameter part of the mandrel 12. The top plate is held in position during assembly and until the plug is to be set by 0 ring 24 which fits in opposed grooves in the outer surface of the mandrel and inner wall of the top plate, respectively.
An upper slip member 30 having a horizontally toothed outer configuration and an inner wall part adapted to slide along the outer surface of the mandrel l2 abuts against the lower surface of the top plate 22.
The inner wall part of the slip member 30 which slides over the mandrel 12 extends along a minor part of the length of the member 30 and then, tapers outwardly at 56, for example, after a grooved part 66 permits insertion of the 0 ring 28 in a groove in the mandrel 12, until the slip member is rather thin at the end thereof which is remote from the top plate 22.
The slip member 30 contains a plurality of symmetrically arrayed longitudinal slits extending along its length and from the inner surface to near the toothed outer part of the member 30.
An upper cone member 32 having an outer peripheral surface adapted to bear against the tapered undersurface part 56 of the slip member 30, abuts against the upper end of the longer reduced outer diameter part of the mandrel 12. The lower end of the upper cone member 32 abuts against the upper end of the packing element 36 which fits slidably about the outer peripheral surface of the mandrel 12.
The packing element 36 is illustrated as having tapered ends, but ends which are perpendicular to the longitudinal axis of the plug are also practical.
A lower cone member 38 fits around the mandrel 12 with its upper end abutting against the lower end of the packing element 36. The cone member 38, like the cone member 32, has a tapered outer surface along which the tapered undersurface 54 of the lower slip member 44 is adapted to move.
The cone member 38 is held in position abutting against the packing element 36 by an 0 ring 40 which rides in a groove in the mandrel and abuts against a recessed part of the lower end of the cone member 38.
The lower slip member 44, of the same form as the upper slip member 30, fits around the mandrel 12 with its tapered surface 54 overlapping the tapered outer surface of the cone member 38. The slip member 30 has longitudinal slits 50 which are arrayed as the slits 48 are in slip member 30.
Upward movement of the slip member 44 is prevented by the 0 ring member 46 which fits into a groove in the outer surface of the mandrel and abuts against a recessed part of the member 30.
A retaining base member 20 is screwed over the threads 52 of the further reduced diameter lower end of the mandrel I2.
OPERATION The bridge plug of this invention is assembled by slipping the top plate 22 along the mandrel 12 with the 0 ring 24 in place so that the groove 26 extending downwardly from its top surface passes over the ring 24. The plate 22 is then retained by the ring 24 bearing against the wall of the groove 26.
The upper slip member 30 slides over the mandrel 12 and bears against the top plate 22. The slip member 30 is then held in place by inserting the 0 ring element 28 into the groove 64 in the mandrel through the open ended groove 66 in the inner part of slip member 30.
The upper cone member 32 then slips over the mandrel 12, coming to rest against the shoulder 34 between the larger and smaller diameter wall parts of the mandrel 12.
The packing element 36 is then slid over the mandrel 12 to bear against the end of the upper cone member 32.
The lower cone member 38 is then slid over the mandrel 12 to abut against the lower end of the packing element 36 and is held in place by an ring 40 in a groove in the mandrel 12 at the lower end of member 38.
The lower slip member 44 slips over the mandrel 12 with its tapered surface 54 bearing against the inclined surface of the conical member 38. Further advancement of the slip member 44 is prevented by the 0 ring 46 in a groove in the outer surface of the mandrel 12.
The base element 20 is then screwed onto the threaded lower end of the mandrel l2, bearing against the lower end of the lower slip member 44.
The bridge plug of this invention may be assembled in about ten minutes as compared with about an hour for a bridge plug using shear pins to hold its assembled parts in position. In addition, the cost of manufacture of this bridge plug is reduced over a similar bridge plug utilizing shear pins because no precision drilling or fitting for using shear pins is required.
Also, the shearing pressure of0 rings is more uniform than is the case with shear pins, so the operation of the bridge plug of this invention is more predictable.
The bridge plug is lowered down the bore hole, usually within a string of easing, on a cable to which is coupled an explosively actuated setting tool, as is well known in the art.
The setting tool (not shown) has a stud at its lower end which is coupled to the threaded bore 18 at the upper end of the mandrel 12. The setting tool also has an outer rim part which is adapted to be driven downwardly with respect to the above mentioned stud on firing of the explosive material in the setting tool.
Once the explosive material in the setting tool is fired, the rim part of the setting tool forces the top plate downwardly, shearing the 0 rings 28 and 40 as the upper slip member 30, upper cone 32, packing element 36 and lower cone 38 are driven downwardly with the top plate 22 by the rims of the setting tool.
As relative movement occurs between the slip members and cones, the pressure causes the slip members to break along the slots 48, 50, segmenting the advancing slip elements. The setting tool, once the packing element 35 and slip members 30, 44 have advanced to set the bridge plug 10 is separated from the bridge plug by breaking the tension stud which has been attached to the mandrel 12 during the setting operation.
Because precision fits are not required with most parts of the bridge plug 10, most parts may be cast rather than forged or machined, further reducing the manufacturing costs of the unit.
What is claimed is:
1. A bridge plug for use in well bores and the like comprising an elongated mandrel having an upper end including setting tool attachment means, and a lower end having threads on its outer peripheral part, a base element, said base element being threadedly engaged with said threads on said mandrel, and a lower slip member, lower cone member, packing element, upper cone member, upper slip member and top plate being disposed around said mandrel in the named order, said packing element having ends each of which abut against one of said cone members, each cone member having a tapered surface which tapers towards said mandrel from that part of its outer surface which is adjacent to said packing element, each of said slip members having a tapered under surface adapted to bear against the tapered surface of its adjacent cone member, said lower slip member abutting against said base element and said upper slip member abutting against said top plate, an array of 0 rings, each of said 0 rings lying in a groove in the outer periphery of said mandrel and abutting against an upper or lower inner edge of a retained part of said plug, said grooves being so disposed along said mandrel that, until the 0 rings contacting said upper slip member and said lower cone member are sheared, downward movement of said upper slip member, upper cone member, packing element and lower cone member is prevented.
2. A bridge plug in accordance with claim 1 wherein said 0 rings each contact an edge surface of the adjacent part which surrounds said mandrel.
3. A bridge plug in accordance with claim 1 wherein said upper cone member abuts against a shoulder on the outer peripheral surface of said mandrel.
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