GB2124676A - Pipe string protector - Google Patents

Abstract

A protector for a drill string comprises a sleeve (10) with an internal reinforcement (26) the sleeve being split at teeth an-when located on a drill string pipe the free ends are held together bye pin 20 passing through slots in the teeth. A V-shaped notch (24) lies diametrically opposite to the teeth and this notch facilitates opening of the protector to enable easy mounting on a drill pipe. <IMAGE>

Description

SPECIFICATION Drill pipe/casing protector This invention relates to drill pipe/casing protectors.

When drilling an oil or gas well it is conventional practice to employ a drill string pipe carrying at the operative end a cutting tool and pipe strings of this nature may be very lengthy, the maximum currently in use being about twenty-five thousand feet. For a variety of reasons, it is unusual for a pipe string to be rectilinear and indeed in many instances the drill hole frequently is deliberately made to follow a curved path so that from a given drilling platform a number of wells terminating in different producing areas can be formed. It is, of course, conventional practice that as drilling progresses the wall of the bore hole is lined with a steel pipe, known as a bore casing, and it will be understood that the filling pipe string is liable to contact that casing with resultant scuffing of the metal of the drill string, as well as likely damage to the casing itself.Indeed wear of the casing can be so severe that for many years the problem of scuffing has been overcome by the provision of protectors along the length of the pipe string, such protectors being made of an elastomer material, being of annular form and being, when in use, spaced along the pipe string at appropriate intervals.

It is important that once installed, the annular protectors should be firmly held to the periphery of the pipe since contact with the bore casing will tend to cause the protectors to rotate on the pipe. Clearly this must not be permitted and hence it is conventional for the protectors to be provided with an internal resilient metal reinforcement which serves, in use, to constrain a tight fit on the pipe.

In more detail, such protectors effectively take the form of a split annulus and at the join, interdigitating fingers are provided both in the reinforcement and in the moulded elastomer surrounding it. When in situ the interdigitating fingers are locked together by a pin and since the fit on the external surface of the pipe must be a tight one it is necessary to provide a special tool for tightly holding the interdigitated fingers together while the pin is inserted.

From this background relating to conventional protectors, which have been in widespread use for upwards of thirty years, it will not be difficult to appreciate that substantial force is necessary to open out the split annulus thus enabling it to be located at a desired position on the external surface of a drill string. Although the personnel employed to fit the protectors are strong, the amount of strength required is such that fatigue becomes a limiting factor in the rapidity with which the protectors can be fitted and it is clearly desirable to reduce the amount of force to effect fitting and removal necessary while at the same time maintaining the characteristics which ensure a tight fit when in situ.

According to the present invention there is provided a drill pipe/casing protector comprising a moulded split annulus of elastomer and a resilient metal reinforcement within the elastomer, the eiastomer having an axially extending notch in its external periphery, preferably diametrically opposite the split.

The invention will now be described, by way of example only with reference to the accompanying diagrammatic drawing in which: Figure 1 is a perspective external view of a protector in accordance with the invention with the protector in a semi-open configuration; Figure 2 is a perspective view showing the protector in a secure configuration; and Figure 3 is an end elevation of the protector of Figures 1 and 2.

The protector 10 illustrated in the drawing is of generally annular form as illustrated in Figures 2 and 3 and includes a plurality of interdigitating fingers 12 (three at each end of the split annular as shown) a pair of recesses 14 enabling a tool (not shown) to be applied which holds the two ends of the annulus together while a pin 16 is inserted in slots 18 when aligned in the configuration as shown in Figure 2.

The fingers 12 are complementary so that they mesh together somewhat in the manner of gear teeth. The pin 16 has a head 20 with an aperture 22 to assist removal. Diametrically opposite to the ends of the split annulus a V-section notch 24 is provided which effectively provides a hinge thus substantially reducing the amount of force necessary fully to open the split annulus to enabie application to a pipe.

This V-section notch will be conincident with one trough of an internal resilient, corrugated, reinforcement 26 (broken lines). It is desirable that there should be a thickness of approximately one eighth of an inch (3mm) between the trough of the notch and the closest portion of the reinforcement.

As will be understood, the notch effectively acts as a hinge but from a practical standpoint is a substantial improvement over conventional hinges provided in the reinforcement itself since such hinges not only add to the cost of manufacture but also having the disadvantage that the strength of the protector is liable to be appreciably reduced. In any event the stiffness of the reinforcement may provide a relatively low resistance to bending in comparison to the compressive effect on the elastomer.

While it has been proposed to provide a single V notch extending axially of the external periphery it is also possible under certain circumstances to provide a notch which extends obliquely with reference to the longitudinal axis and it is also possible to use two or more notches spaced around the outer periphery. In the latter case the angle of the V can be smaller. The cross-sectional profile of the notch 24 is clearly illustrated in Figure 3 in its preferred form but it will be understood that the angle of the V can range from forty-five degrees to one hundred and fifty degrees, while the preferred range is from fifty-five degrees to one hundred and fifteen degrees; the precise angle selected will, of course, depend upon the nature of the internal metal reinforcement.

In the preferred embodiment illustrated for a protector with an internal diameter up to 4", the V will be 1" across at the open end and " at the trough. At the trough the apex of the notch will be spaced by " from the corresponding trough of the reinforcement. If the protector has an internal dia meter in excess of 4" the V will be 1 1/W' across at the open end but the other dimensions remain the same.

The V-section notch 24 may be asymmetrical and under certain circumstances of intended use the walls of the V notch are not necessarily plane and may be slightly concave or convex.

CLAIMS (Filed on 4.2.83) 1. A drill pipe/casing protector comprising a split annul us of elastomer material and a resilient metal reinforcement within the annulus, the elastomer having a notch extending generally axially of the annulus.

2. A protector according to claim 1 wherein the notch extends in the outer surface of the elastomer substantially opposite to the split.

3. A protector according to claim 1 or claim 2, wherein the notch is of V section.

4. A protector according to claim 3, wherein the two faces of the V-section are concave.

5. A protector according to any one of the preceding claims wherein the metal reinforcement is corrugated and the notch is coincident with a trough of the corrugations.

6. A protector according to claim 5, wherein the thickness of elastomer at the notch is not less than 3mm.

7. A protector according to any one of the preceding claims comprising two said notches.

8. A protector according to any one of the preceding claims wherein the on each notch has an angle, in cross-section in the range 45" to 1500.

9. A protector according to claim 8, wherein the said angle is in the range 53" to 1150.

10. A protector according to any one of the preceding claims wherein the notch is asymmetrical.

New claims or amendments to claims filed on 8 June 83 Superseded claims 2,4 New or amended claims: 2. A protector according to claim 1 wherein the notch extends in the outer surface of the elastomer substantially diametrically opposite to the split.

4. A protector according to claim 3, wherein the two faces of the V-section notch are concave.

11. A drill pipe/casing protector comprising an annulus of elastomer material having a single split therein extending at least substantially parallel to the longitudinal axis of the annulus, a resilient, sheetmetal, reinforcement of corrugated form with the centre of curvature of the corrugations extending substantially parallel to the said longitudinal axis, the reinforcement having ends adjacent the split of the elastomer annulus, the elastomer annulus having a notch in the external surface extending generally parallel to the longitudinal axis of the annulus and disposed diametrically opposite the split whereby to facilitate the application to and the removal from the article to be protected, and means for securing together the ends of the annuli at the split when the protector is in situ.

12. A drill pipe/casing protector substantially as hereinbefore described with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (12)

**WARNING** start of CLMS field may overlap end of DESC **. reinforcement. If the protector has an internal dia meter in excess of 4" the V will be 1 1/W' across at the open end but the other dimensions remain the same. The V-section notch 24 may be asymmetrical and under certain circumstances of intended use the walls of the V notch are not necessarily plane and may be slightly concave or convex. CLAIMS (Filed on 4.2.83)

1. A drill pipe/casing protector comprising a split annul us of elastomer material and a resilient metal reinforcement within the annulus, the elastomer having a notch extending generally axially of the annulus.

2. A protector according to claim 1 wherein the notch extends in the outer surface of the elastomer substantially opposite to the split.

3. A protector according to claim 1 or claim 2, wherein the notch is of V section.

4. A protector according to claim 3, wherein the two faces of the V-section are concave.

5. A protector according to any one of the preceding claims wherein the metal reinforcement is corrugated and the notch is coincident with a trough of the corrugations.

6. A protector according to claim 5, wherein the thickness of elastomer at the notch is not less than 3mm.

7. A protector according to any one of the preceding claims comprising two said notches.

8. A protector according to any one of the preceding claims wherein the on each notch has an angle, in cross-section in the range 45" to 1500.

9. A protector according to claim 8, wherein the said angle is in the range 53" to 1150.

10. A protector according to any one of the preceding claims wherein the notch is asymmetrical.

New claims or amendments to claims filed on 8 June 83 Superseded claims 2,4 New or amended claims:

2. A protector according to claim 1 wherein the notch extends in the outer surface of the elastomer substantially diametrically opposite to the split.

4. A protector according to claim 3, wherein the two faces of the V-section notch are concave.

11. A drill pipe/casing protector comprising an annulus of elastomer material having a single split therein extending at least substantially parallel to the longitudinal axis of the annulus, a resilient, sheetmetal, reinforcement of corrugated form with the centre of curvature of the corrugations extending substantially parallel to the said longitudinal axis, the reinforcement having ends adjacent the split of the elastomer annulus, the elastomer annulus having a notch in the external surface extending generally parallel to the longitudinal axis of the annulus and disposed diametrically opposite the split whereby to facilitate the application to and the removal from the article to be protected, and means for securing together the ends of the annuli at the split when the protector is in situ.

12. A drill pipe/casing protector substantially as hereinbefore described with reference to the accompanying drawing.