US2708000A - Apparatus for sealing a bore hole casing - Google Patents

Description

May l0, 1955 s. M. zANDMER APPARATUS FOR SEALING A BORE HOLE CASING Filed June 18, 1952 Fiel INVENTOR ATTORNEY United Statesl Patent() APPARATUS FOR SEALING A BORE HOLE CASING Solis Myron Zandmer, Calgary, Alberta, Canada Application June 18, 1952, Serial No. 294,251

6 Claims. (Cl. 166-100) This invention relates to improved apparatus for sealing a bore hole casing or liner in a bore hole, and more particularly to novel apparatus for providing ducts for the ow of iluids between selected earth strata and the interior of a bore hole casing or liner.

Heretofore, bore hole casings have been set in drilled bore holes by a cementing process in which fluid cement is forced down through the casing and then upwardly around -the outside of the lower portion of the casing to fill the space between the outside of the casing and the surrounding earth. It has then been customary to perforate the casing and the surrounding cement at the levels of producing strata by means of horizontal drilling or by means of gun-type perforators which re a projectile through the casing and cement to form passageways therethrough. Said known methods and apparatus have created various difculties such as a shattering of the cement, destruction of the sealing vbond between the casing or liner and the cement, and the formation of cracks in the cement making said cement subject to destructive attack by acids subsequently introduced to acidize and improve the ow of fluids from productive strata.

A novel method and apparatus for establishing communication between producing strata and the interior of a cemented bore hole casing or liner is shown in my joint application Serial No. 285,201 filed April 30, 1952, and the present application is a continuaton-in-part of said earlier application.

It is an object of the present invention to provide improved apparatus for establishing communication between producing strata and the interior of a cemented bore hole casing or liner.

-It is another object of this invention to provide economical ducts between producing strata and a bore hole casing or liner which do not damage in any manner the electiveness of a cement seal between the casing or lliner andthe surrounding earth lformations.

It is a further object of this invention to provide a novel bore hole casing or linerconstruction having a movable duct-forming sleeve or duct, the sleeve or duct being extendable laterally from the casing or liner into contact with producing strata either before cement is applied around the casing or liner or while such cement is in a fluid condition.

. It is a further object of this invention to avoid puncturin`g or perforating a casing or liner after it has been sealed in cement and hence to avoid damaging the sealing cement or the bond between the cement and the bore hole casing or liner and/or the bond between the cement and the bore hole wall.

It is a still further object of this invention to provide a bore hole casing or liner with a plurality of lateral duct-forming devices at various levels operable ,by uid pressure to establish or position the ducts between the casing or liner and different strata of the surrounding limestone formations without damaging the seal between ameten across between the outer surface of the casing 12 andJ the casing or liner and the surrounding formation and between the various levels or strata.

Other objects and advantages of this invention will become readily apparent from the following detailed description of a preferred arrangement of apparatus and its method of use. In the accompanying drawings forming a part hereof:

Figure 1 is a vertical section view, partly cut away and partly diagrammatic of a bore hole provided with a casing sealed in accordance with this invention.

Figure 2 is a fragmentary view, on an enlarged scale, taken on line 2--2 of Figure 1 before the duct-forming device is laterally extended and before the application of sealing cement to the space between the casing and the wall of the bore hole.

Figure 3 is a fragmentary view similar to Figure 2 but showing the duct-forming device extended to the wall of the bore hole and set in sealing cement.

Figure 4 is a fragmentary view similar to Figure 3 but showing the duct-forming device open to establish communication between a producing stratum and the interior of the hole casing or liner.

Referring to the drawings for the purposes of illustration, a bore hole 10 is drilled in the earth or limestone 11 by any conventional drilling apparatus. In

boring wells through limestone formations, for example,

the bore hole 10 may be of approximately nine inches in diameter and will have a substantially smooth and regular surface. A bore hole casing or liner 12 is positioned in the bore hole 10, and may be formed of steel or aluminum tubing of about seven inches outside di- This leaves an annular space about one inch the wall of the bore hole 10. The casing or liner 12 is sealed or set in the formation 11 by means of cement 13. The cement 13 may be Portland cement or any other composition or settable plastic material not affected by oil, gas, or bore hole treating chemicals.

Earth formations 11 usually have a plurality of oil or gas producing strata indicated in the drawings by the numeral 14. Some'of the strata 14 may be more porous than other adjacent strata. The porosity of the individother chemicals, it is desirable that the cement seal 13 between various strata be maintained unbroken so that upon application of acids under pressure there will 'be no leakage outside of the casing 12 from one strata 14 to another strata 14 of greater porosity. In actual practice the strata 14 may be found to be of relatively small thickness and spaced only a few feet apart.

The section of well casing or liner 12 adjacent -thestrata 14 is provided before its introduction into the bore hole with a plurality of duct-forming devices 15 mounted in the wall of the casing 12 at levels to correspond with: the indicated levels of the strata 14 to be tapped. 'One'- such duct-forming device will now be describedv first With v reference to its original position illustrated in Figure `2.

The device 15 comprises a bushing 16 mounted in an opening in the casing 12 by threads 17. The outer end of bushing 16 projects beyond the outer surface of casing 12 into the space between the casing 12 and the wall ofthe borehole 10. The duct-forming devices may be spaced around the circumference of casing 12 at the various levels to be tapped and serve as centering devicesv tending to keep the casing 12 approximately centered as it' is lowered into the bore hole 10. The 'outer surfaceof each bushing may be provided with a recess -18.to permit the application of a Spanner wrench to screw the bushing into the threaded opening of casing 12. A ductforming sleeve-like member 19 is slidably mounted in the bushing 16, and is initially provided with a closure disc 20 secured within the member. The member 19 has a peripheral flange 21 at its inner end engageable with an inwardly extending flange 22 on the outer end of bushing 16 to limit the outward sliding movement of member 19. A disc 24 having a restricted aperture 25 therethrough is secured in the inner end of bushing 16 by threads 26. A valve 27 is mounted on the outer face of closure disc 24 and acts as a check valve to prevent the back flow of fluids or cement through the aperture 25 into the interior of the casing 12. The valve 27 may be a resilient flap valve mounted by a screw 28, as illustrated, or may be a spring-pressed ball-type check valve or the equivalent.

The bushing 16 is preferably formed from aluminum or steel, the same as casing 12. The sleeve 19 is preferably made from bronze. The closure disc 20 and the apertured disc 24 are preferably die castings formed of pot metal containing zinc or of any other metal or substance easily dissolved by the application of conventional bore hole treating acids. It is to be understood that suitable packing material such as rubber or other self-sealing materials may be secured to the outer periphery of flange 21 and/or to the inner periphery of flange 22 to prevent the leakage of fluids under pressure into the space between the sleeve 19 and the bore of bushing 16. The valve 27 may be resiliently biased against the aperture 2S to maintain the aperture closed until a predetermined internal fluid pressure is applied within the casing 12.

The sleeve member 19 is adapted to be moved from its initial position within bushing 16, shown in Figure 2, to a final extended position projecting outwardly from the outer end of bushing 16, shown in Figure 3, by the application of fluid under pressure within the casing 12.

When it is desired to project the duct-forming sleeve 19 into contact with a porous stratum 14, fluid pressure is applied within the casing and flows through the aperture 25, opens valve 27, and engages the closure disc 20 to push the sleeve 19 outwardly. The bottom of the casing or liner 12 is initially closed by a releasable valve or plate 30, to open the apertures 32 to the flow of plastic sealing cement 13 under pressure from within the casing 12 outward and upward within the bore hole. The hollow portion of sleeve 19 may be initially filled with an acid soluble paste 33 to prevent the sleeve from becoming clogged with drill cuttings or other deleterious material within the bore hole when the casing 12 is lowered and positioned therein. As shown in Figure 3, sealing cement 13 is forced into the space between the outer sur- Y face of casing 12 and the inner surface of the bore hole 10.

The preferred method of operation will now be described. A bore hole 10 drilled in an earth formation, such as limestone 11, is surveyed by conventional methods to determine both the porosity and the actual level of the several porous strata 14 above the bottom of the bore 10. A casing or liner 12 is vthen prepared with a plurality of duct-forming devices 15 secured therein at levels corresponding to the levels of the several strata 14 to be tapped. The casing or liner 12 is then lowered into the bore hole 10 until it engages the bottom and the ductforming devices are opposite the strata 14 to be tapped. Fluid under pressure is then pumped into the casing 12 until the pressure is great enough to open valves 27 in duct-forming devices 15 and push the sleeve members 19 outward until the outer end of each member 19 firmly engages the wall of a porous stratum 14. Next, sealing cement 13 under a greater fluid pressure is forced into the casing so as to open or force downward the releasable bottom closure 30 of the casing 12 from position 30a to a position below the lateral passages 32, the fluid cement then passing through passages 32 and upwards filling the space between the outer surface of the casing 12 and the wall of the bore hole 10. The duct devices 19 are surrounded by the cement 13 and subsequently provide passageways from the casing l2 to the strata 14 before the cement 13 is hardened and set. After the cement 13 has firmly set and become thereby bonded to the outer surface of casing 12, to the wall of the bore hole 10 and to the surfaces of the duct devices 15, the apertured disc 24, closure disc 20, and filler paste 33 may be dissolved away by the application of an acid solution which does not dissolve the aluminum casing 12, the aluminum bushing 16 or the bronze duct-forming sleeve member 19. Conventional drilling tools may be used to cut away any cement remaining within the casing 12.

It will be apparent that the described method and apparatus provides novel means for setting and forming ducts or passageways through the casing 12 and cement 13, without in any way damaging the casing 12 or cracking or shattering the cement seal 13. It will also be apparent that the elimination of cutting or perforating the set cement seal eliminates any damage to the sealing bond between the cement 13 and the casing 12 and the bond between the cement 13 and the inner surface of the bore hole 10. This feature is of great importance because it prevents any subsequent leakage along the bore outside of the casing 12 of acids applied to acidize or treat a given strata 14, and hence eliminates possible loss of treating chemicals into the more porous strata. The use of packers within the casing 12 to confine the treating chemicals to a desired stratum is well known. It will also be apparent that the duct-forming devices used with the above-described method may vary in details from the embodiment shown without departing from the scope of this invention as defined in the following claims.

I claim:

1. In apparatus for use in a bore hole traversing a porous stratum to be tapped; a duct-forming device adapted to be supported by a bore hole casing, said device comprising supporting means mountable in the wall of said casing and projecting outward therefrom, a hollow tubular member movable outwardly in said supporting means to engage the outer end of said member with said porous stratum, closure means carried by said hollow member, and means carried by said supporting means defining an aperture providing communication between the interior of said casing and said closure means, said closure means being of a material dissolvable by chemical reaction.

2. In apparatus for use in a bore hole traversing a porous stratum to be tapped; a duct-forming device adapted to be supported by a bore hole casing of smaller diameter than the diameter of said hole, said device comprising a supporting bushing mountable in the wall of said casing, a hollow tubular member slidably mounted in said supporting bushing for movement outwardly therein, the outer end of said hollow member being open for engagement with said porous stratum, closure means mounted in the inner end of said member, and valve means mounted in said supporting bushing admitting fluid pressure from within said casing against said closure means, said closure means and a portion of said valve means being of material dissolvable by chemical reaction with an acid solution.

3. In apparatus for use in a bore hole traversing a porous stratum to be tapped; a casing of smaller diameter than the diameter of said hole, a duct-forming device supported by said casing, said duct-forming device including a tubular member slidably mounted in an aperture through the wall of said casing and projecting outward of the inner wall of said casing, said tubular member being slidable outwardly from said casing to engage the outer end of said member with said porous stratum, and dissolvable closure means mounted within said tubular member, said duct-forming device providing a duct from the interior of said casing to said porous stratum adapted to be embedded in sealing material in the space between the exterior surface of said casing and the wall of said bore hole, said closure means being of a material dissolvable by chemical reaction with bore hole acidizing solutions.

4. In 'apparatus for use in a bore hole traversing a porous stratum to be tapped; a duct-forming device adapted to be supported by a bore hole casing, said device comprising a supporting bushing mountable in an aperture in the wall of said casing and projecting 0utward from the outer surface of said casing, a hollow tubular member mounted within and slidable outwardly in said bushing to engage the outer end of said member with said porous stratum, flanges on said bushing and on said hollow member to limit the outward movement of said hollow member in said bushing, a removable closure in said hollow member, and check valve means supported by said bushing inward of said hollow member and admitting fluid pressure from within said casing to engage said closure, said closure and said valve means being ot a material dissolvable by chemical reaction with an acid solution.

5. In apparatus for use in a bore hole traversing a plurality of porous strata to be tapped; an aluminum well casing adapted to be lowered into said bore hole, a plurality of lateral duct-forming devices supported by said casing at spaced intervals corresponding t0 the distance between strata to be tapped, each of said duct forming devices comprising an aluminum supporting bushing mounted in an aperture in the wall of said casing and communicating with the interior of the casing, and a bronze tubular member slidably mounted in said bushing for lateral movement outwardly into contact with the wall of said one of said strata, and a closure disc of metal containing zinc secured in said tubular member and dissolvable by a bore hole acidizing solution.

6. ln apparatus for use in a bore hole traversing a plurality of spaced porous strata to be tapped; a Well casing of smaller diameter than said bore hole and adapted to be lowered into said bore hole, a plurality of duct-forming devices supported by said casing at spaced intervals corresponding to the distance between said porous strata to be tapped, each of said duct-forming devices comprising a tubular bushing mounted in an aperture in the Wall or said casing and communicating with the interior of said casing, a tubular member slidably mounted in said bushing for movement outward to engage the outer end of said tubular member with one of said porous strata, a closure disc mounted in said tubular member and being of a material dissolvable by a bore hole treating acid solution, and a filler material filling the outward portion of said tubular member and also dissolvable by said acid solution.

References Cited in the le of this patent UNITED STATES PATENTS 1,410,827 Muehl Mar. 28, 1922 2,196,652 Baker Apr. 9, 1940 2,330,144 Powers Sept. 21, 1943 2,546,669 Kirby Mar. 27, 1951

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