US 3489216 A
Description (OCR text may contain errors)
Jan. 13, G T ARMSTRONG ETAL BRIDGE PLUG WITH VALVED HOLLOW MANDREL BYPASS Filed Aug. 25, 1967 M 1% U K United States Patent O 3,489,216 BRIDGE PLUG WITH VALVED HOLLOW MANDREL BYPASS Gerald Turner Armstrong, Houston, and George E. Briggs, West University Place, Tex., assiguors to Halliburton Company, Duncan, Okla., a corporation of Delaware f j,
Filed Aug. 25, 1967, Ser. No. 663,264 Int. Cl. E21!) 33/136 U.S. Cl. 166-126 1 Claim ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION This invention relates to apparatus for plugging a well casing, and may be classified as packer or plug. In a known method of plugging back, a mechanical basket is placed at the desired level in the casing, and then a body of sealant material is placedfon` that basket. When the sealant material sets up or hardens, and bonds to the interior surface of the casing, a pressure resistant plug is formed. However, if the iluid in the well below the location of the plug is not in a completely static condition, the se'alant material may be subjected to pressure from below before it has hardened suciently or bonded suiciently to the casing to withstand the applied load. The sealant material may become channeled or otherwise disturbed before its full strength has been reached during the hardening process. In accordance with the present invention, the hollow mandrel provides a bypass to permit well fluid to pass therethrough during the time needed for the sealant to set up or harden and to bond to the interior of the casing. The passage through the mandrel is then closed by a valve, and the bridge plug structure is then complete.
SUMMARY BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a longitudinal sectional View in idealized form, showing a well casing containing a bridge plug embodying this invention.
FIGURE 2 is a longitudinal sectional View of a preferred form of shutoff valve device employed in connection with the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, the casing extends into the well bore 11 and a tubing 12 extends into the casing 10. A packer assembly between the tubing 12 and the casing 10 is shown diagrammatically at 13. When it is desired to plug the casing 10 at a location above the position of the perforations 14, a device generally designated 15 is lowered through the tubing 12 and into the casing 10 on a wire line, not shown. The wire line is of conventional type and serves to ignite an explosive squib when an electric current is furnished from the surface.
The device 15 includes a conventional expansible basket 17 mounted on a hollow axially extending mandrel 18. A lower slip assembly 19 and two upper slip assemblies 20 and 21, all of conventional design, are mounted on the mandrel and spaced by coil springs 22. The device 15 is initially contained within the metal cylinder, not shown, to the top of which is attached the electric wire line. The two upper slip assemblies 20 and 21 and the basket 17 are conned about the mandrel by the metal cylinder. The lower slip assembly 19 located just below the lower open end of the cylinder, is restrained by a seizing wire, not shown. The explosive squib is attached to the seizing wire in a manner to break the wire when an electric current is furnished from the surface. When the seizing wire is broken, the lower slip assembly 19 extends laterally to engage the interior wall of the casing 10. An upward pull on the line lifts the metal cylinder upward over the basket and upper slip assemblies 20 and 21. These upper slip assemblies then prevent downward movement of the device 15. The electric line and the metal cylinder are then removed from the well upward through the tubing 12.
`Sand 23, gravel 24 and sealant 25 dumps are deposited on the extended basket 17 by means of conventional equipment operating through the tubing 12. The sealant usually comprises cementitious cement of the type used in oil wells.
The shutoff valve assembly generally designated 28 is connected to the lower end of the mandrel 18 by means of the threaded connector 29. The mandrel 18 is open from end to end and its upper end extends above the body of cementitious material 25. The lower end communicates with the interior of the casing 10 through ports 31 in the wall of the valve housing 32. The movable closure 33 is slidably mounted within the housing 32 and is urged toward closed position yby means of the coil spring 34. A hollow rod 35 formed of magnesium is connected to the housing 32 by means of the threads 36 and the end plug 37. So long as the hollow rod 35 remains intact, the parts remain in the position shown in FIGURE 2, with the ports 31 open.
Fluid from the well passing into the casing 10 through the perforations 14 passes through the ports 31 and contacts the interior of the hollow magnesium rod 35. Chemical action between the well fluids and the magnesium rod 35 eventually dissolves enough of the rod 35 so that the force of the spring 34 breaks the rod 35 in tension at the location of a weakened zone 39. The spring then moves the closure member 33 upward, causing the axially spaced O-rings 40 to straddle the ports 31, thereby closing off the ports 31. This serves to close the bypass through the interior of the hollow mandrel 18. The size of the weakened zone 39 and the wall thickness of the rod 35 are chosen so that the time interval required before tension failure of the rod 35 occurs is suicient to enable the cementitious plug 25 to set and to bond to the interior of the casing 10.
If desired, the interior of the housing 32 may initially be lled with salt Water at the surface just before lowering the basket 17, mandrel 18, valve assembly 28, etc., into position in the well. This procedure is advantageous if the well is not known to contain liquids which will chemically attack the magnesium rod 35.
Having fully described our invention, it is to be understood that we are not to .be limited to the details herein set forth, but that our invention is of the full scope of the appended claim.
1. In a bridge plug for use in a well casing having a tubing extending therein, the combination of: a hollow mandrel having a passage therethrough and open at the top, an expansible basket secured to the mandrel and adapted to engage the inside of the casing, a valve assembly Xed to the hollow mandrel below said basket, eX- pansible means on the mandrel above the basket engageable with the inside of the casing to prevent downward movement of the expansible basket in the casing, the mandrel, basket, Valve assembly, and eXpansible means being adapted to be lowered as a unit into the casing through the interior of the tubing, whereby upon subsequent lowering of a body of material including cementitious material through the tubing to rest on the expansible ybasket and in direct contact with the inside of the casing and covering the eXpansible means, the valve assembly permits ow of well fluid from below the body to above the body through the hollow mandrel, the valve assembly having meansfor closing the passage after the cementitious material has hardened to form a rbond with the inside of the casing.
References Cited UNITED STATES PATENTS 2,717,644 9/1955 Bell et a1. 166-117 2,918,124 12/1959 spearow k- 166-21 3,064,734 11/1962 Toelke. t
3,070,163 12/1962 Colby et s1. 166-135X 3,078,862 2/1'963jMa1y 166-224X 3,118,503 1/1964 Rike et a1. 166-117X CHARLES E. OcONNELL, Primary Examiner IAN A. CALVERT, Assistant Examiner U.S. C1. X.R.