Method and Apparatus for Installing a Cementing Float Shoe on the Bottom of a Well Casing

1. Field of the Invention

The invention relates to a method and apparatus for effecting the installation or replacement of a cementing float shoe, normally run into a well on the bottom of the well casing, without requiring the removal of the well casing from the well.

2. Description of the Prior Art

It is a common procedure in the completion of subterranean wells to effect the cementing of the bottom portions of the well casing in the well bore. Such cementing operations are normally conducted, at least insofar as a first cementing stage is concerned, by passing cement axially through a cementing float shoe which is carried into the well on the bottom of the casing and incorporates a conventional float valve to accommodate a required upward passage of well fluids during the insertion of the casing. It occasionally happens that after insertion of the casing, it is found that the well bore is not completed to the proper depth. Obviously, the withdrawal of the entire casing string, particularly when welded joints have been employed, is a time consuming and expensive procedure. Heretofore, the problem of casing removal had only been partially solved by drilling out the cementing float shoe valve apparatus, then inserting an expanding type drill to complete the well bore to the desired depth. This procedure however, meant that the cementing operation had to be conducted without the benefit of an inplace cement float valve at the bottom of the well casing.

This invention provides a method and apparatus for effecting a reliable, sealed securement of a cementing float valve in the bottom of a well casing either as an original installation, or as a replacement after the original cementing float valve has been drilled out in order to permit further drilling or completion operations on the well bore. The casing extension sleeve containing the originally installed cementing float valve is provided with an upwardly facing locating shoulder above the position of the cementing float valve and a seal bore is provided immediately below the locating shoulder. A replacement cementing float shoe is then provided comprising nested inner and outer sleeve elements connected by an annular layer of cement. The lower portions of the cementing layer support a conventional cementing float valve. The outer sleeve is provided with a downwardly facing locating shoulder and an external seal which respectively cooperate with the locating shoulder and seal bore provided in the casing extension sleeve when the replacement cementing float shoe is run into the casing on a tubular workstring. The upper end of the inner sleeve is provided with threads which in turn cooperate with external threads provided on a coupling sleeve which is secured in conventional fashion to the bottom of a tubular workstring. Thus the replacement float shoe apparatus may be run through the casing and positioned in sealing relationship with the casing bore, following which the tubular workstring may be disengaged from the installed float shoe apparatus by rotation in a direction opposite that of the direction of the threads. Obviously the casing may be run in with no float shoe installed and the replacement shoe installed as the original.

To effect the securement of the installed float shoe apparatus to the casing extension sleeve, an annular recess is provided in the outer wall of the outer sleeve of the replacement float shoe and such recess is provided with an downwardly and outwardly inclined bottom surface. A plurality of annular segment slips are then mounted in peripherally spaced relationship in the recess and such slips have bottom surfaces sloped to correspond with the bottom surface of the recess so that upward relative movement of the replacement float shoe apparatus with respect to the slips will effect a radial outward displacement of the slips into wedging engagement with the adjacent bore surface of the casing extension sleeve. Resilient means are provided urging the slips radially outwardly and, in order to permit the passage of the slips through the casing, a retaining sleeve is provided in surrounding relationship to the slips to maintain the slips in a radially retracted position. The retaining sleeve is mounted for axial comovement with the coupling sleeve.

Accordingly, an initial rotation of the workstring results in rotation of the coupling sleeve and an upward axial displacement of the coupling sleeve with respect to the replacement cement float shoe apparatus, thus elevating the retaining sleeve out of engagement with the slip elements which are urged outwardly by their spring biasing means to engage the wall of the casing sleeve extension. Since the coupling sleeve is still partially engaged with the internal threads of the inner sleeve of the float shoe apparatus, an upward force can be applied through the tubular workstring to the replacement cement float shoe apparatus to force the slips outwardly into gripping engagement with the casing sleeve extension wall. Further rotational movement of the coupling sleeve by the tubular work string will result in the disengagement of the coupling sleeve from the replacement float shoe apparatus, leaving the replacement apparatus sealingly secured to the bottom of the casing extension sleeve and hence, the replacement cement float valve is ready to be utilized for subsequent cementing operations.

FIG. 1 is a vertical sectional view of a conventional cement float shoe initially installed in the bottom of a well casing extension sleeve, which sleeve is constructed in accordance with this invention.

FIG. 2 is a view similar to FIG. 1 but illustrating the drilling out of the originally installed cement float shoe and the further drilling of the well bore below the bottom of the casing extension sleeve through the utilization of a conventional underreamer.

FIG. 3 is a view similar to FIG. 1 but illustrating the first step in the installation of a replacement cement float shoe apparatus constructed in accordance with this invention.

FIG. 4 is a view similar to FIG. 3 but illustrating the next step involved in the installation of the replacement cement float shoe apparatus.

FIG. 5 is a view similar to FIG. 3 but illustrating the completed installation of the replacement cement float shoe and the stabbing in of a drill pipe preliminary to initiating cementing operations.

Referring to FIG. 1, there is shown a well bore 1 in the bottom of which is disposed the bottom portions of a casing sleeve extension 2 which mounts a conventional cement float shoe 3. The cement float shoe 3 comprises an annular mounting layer of cement 3a which is adhered to an internally corrugated or threaded portion 2a of the bore of the casing sleeve extension 2. The cement float shoe 3 incorporates an inner sleeve 3b defining a seal bore 3c for reception of the seals of a drill pipe for subsequent cementing operations. Directly below the inner sleeve 3b there is provided a conventional float valve 3d.

Immediately above the cementing layer 3a of the cement float valve 3 the casing extension sleeve 2 is provided with an inwardly projecting rib 2b defining an upwardly facing locating shoulder 2c. Immediately above the locating shoulder 2c, a seal bore 2d is defined. It should be noted that the seal bore 2d is of greater internal diameter than the cement retaining corrugations 2a so that the drill out of the conventional cement float shoe 3 can be accomplished without damage to the seal bore 2c.

If it happens that the casing extension sleeve 2 cannot be lowered to the desired depth in the well bore 1, due to unconsolidated hole conditions, the utilization of the method and apparatus of this invention will permit further drilling of the well bore 1 and the replacement of any conventional cement float shoe apparatus on the bottom end of the casing extension 2 without requiring the pulling of the casing from the well.

The first step of the procedure is illustrated in FIG. 2 wherein a conventional underreamer 5 is insertedin the well casing and effects the drilling out of the internal components of the originally installed cement float shoe 3, following which the underreamer 5 may be extended through the bottom of the casing extension sleeve 2 to drill the well bore 1 to whatever depth is required. The underreamer 5 is then removed from the casing. Alternatively, the sleeve 2, may be run in the well with no float shoe installed.

Referring now to FIG. 3, the next step in the procedure is to run in a tubular workstring (not shown) carrying a replacement cement float shoe apparatus 10 and sealingly securing the replacement cement float shoe apparatus 10 in the bottom portion of the casing sleeve extension 2.

The replacement cement shoe apparatus 10 comprises a rigid nested assemblage of an outer sleeve 20, an inner sleeve 30 and an intermediate annular layer of cement 40. Inner sleeve 30 has the upper portion of its bore formed with internal lefthand square threads 31. These threads cooperate with corresponding external square threads 51 provided on the bottom portion of a coupling sleeve 50, which has its upper end conventionally secured to the tubular workstring (not shown). An annular seal 32 provided in the inner wall of the inner sleeve 30 provides a sealing engagement with a cylinder end portion 50a of coupling sleeve 50. Coupling sleeve 50 further provides a mounting for a slip retaining sleeve 60, a radial flange 61 of which rests on an upwardly facing shoulder 52 and is secured in that position by a ring 53 secured to coupling sleeve 50. Thus the retaining sleeve 60 is co-movable with the coupling sleeve 50 insofar as axial movements are concerned.

Below the threads 31, inner sleeve 30 defines a reduced diameter seal bore 33 for the subsequent sealing reception of the end of a drill pipe. Below seal bore 33, a conventional cementing float valve unit 34 is mounted communicating with the axial bore 41 defined in the annular cement layer 40.

The outer sleeve 20 of the replacement cement shoe apparatus 10 is provided with a lower cylindrical exterior surface 21 which freely clears the cement adhering corrugations 2a provided in the casing sleeve extension 2. The upper portion of outer sleeve 20 is radially enlarged as indicated at 22 and thus defines a downwardly facing shoulder 23 which seats on the upwardly facing locating shoulder 2c provided below the seal bore surface 2d of the casing sleeve extension 2. An annular external seal 24 is provided on the enlarged diameter portion 22 and sealingly cooperates with the seal bore surface 2d provided in the casing extension sleeve 2.

Above the external seal 24, the outer sleeve 20 is provided with an annular recess 25 within which are mounted a plurality of annular segment slips 26. Recess 25 has an outwardly and downwardly inclined bottom surface 25a and the bottom surfaces of the slips 26 are similarly shaped. Thus, upward relative movement of the outer sleeve 20 with respect to the slips 26 will produce a radially outward wedging action on such slips. Slips 26 are normally biased outwardly by any conventional resilient means, such as a C-ring 27. The outer surfaces of slips 26 are provided with gripping teeth 26a.

All components of the replaceable float shoe 10 remaining in the well are preferably formed from drillable material to permit subsequent drill out. As shown in FIG. 3, the slips 26 are normally maintained in a radially inwardly retracted position by the annular wall of retaining sleeve 60. Thus, the assemblage may be readily inserted through the casing and the casing extension sleeve 2 with the slips being shielded from contact with the casing walls.

After seating of the replacement cement float shoe apparatus 10 in the casing extension 2 in the manner illustrated in FIG. 3, the tubular workstring (not shown) is rotated clockwise for a few turns, but not sufficient to completely disengage the square threads of the coupling sleeve 50 from the inner sleeve 20. Such clockwise or righthanded rotation of the coupling sleeve 50 will result in an upward movement of the sleeve 50 relative to the cement float shoe apparatus 10 and hence will displace the retaining sleeve 60 in an upward direction and free the slips 26 to move radially outwardly into engagement with the adjacent wall of the casing extension sleeve 2, as shown in FIG. 4. The slips 26 may be further secured in their casing gripping position by applying an upward lifting force to the replacement cement shoe apparatus 10 through the workstring and the still connected coupling sleeve 50.

Following the securement of the slips 26, the workstring is rotated further in a clockwise direction sufficient to effect the complete disengagement of the coupling sleeve 50 from the replacement cementing shoe apparatus 10. The workstring with the coupling sleeve 50 and the retaining sleeve 60 attached thereto may then be removed from the casing.

The casing may then be moved downwardly to position the bottom end of the casing extension sleeve 2 at the desired distance above the new bottom of the well bore 1.

Referring to FIG. 5, a drill pipe 8 may then be inserted through the casing bore. The bottom end of drill pipe 8 is provided with a cylindrical sealing portion 8a incorporating external axially extending seal units 8b which sealingly engage the seal bore 33 defined in the lower portions of the inner sleeve 30. An external shoulder 8d provided on the lower portion of the drill pipe 8 seats on an upwardly facing internal shoulder 35 defined in the inner sleeve 30. The apparatus is then ready for the customary cementing operations with the cement being supplied through the drill pipe 8 and passing through the float valve 34 to flow axially out of the end of the replacement cementing float valve apparatus 10 and into the well bore 1.

Those skilled in the art will recognize that in some applications the original float valve may not be installed with the casing, in which case the casing sleeve extension 2 will be open and the replacement float shoe apparatus 10 will be installed as the first unit.

Although the invention has been described in terms of specified embodiments which are set forth in detail, it should be understood that this is by illustration only and that the invention is not necessarily limited thereto, since alternative embodiments and operating techniques will become apparent to those skilled in the art in view of the disclosure. Accordingly, modifications are contemplated which can be made without departing from the spirit of the described invention.