Drill pipe tubing and casing protector

1. A protector assembly for a pipe string movable within the bore of a well, said protector assembly comprising:

a generally annular body internally dimensioned to fit around said pipe string;

an outer sleeve formed from at least two part-annular sections and located over the annular body so as to be rotatable relative thereto; and

a pair of substantially annular clamping means adapted to restrict longitudinal movement of the body and outer sleeve relative to the pipe string, each clamping means comprising a one-piece clamping ring and a fastener adapted to tighten the clamping ring around the pipe string; wherein the outer sleeve is formed from first and second part-annular sections, wherein the first section has male and female engagement portions each adapted to interlock with respective female and male engagement portions on the second section; wherein the first and second;

annular sections of the outer sleeve interlock using a dovetail fitting comprising a keyed profile extending from a first longitudinal edge of the first annular section which interlockingly engages a matching recess provided on an opposing longitudinal edge of the second annular section.

2. The protector assembly of claim 1 , wherein the body, outer sleeve, and clamping rings are formed from one or more sacrificial materials.

3. The protector assembly of claim 1 , wherein the body and outer sleeve are both formed from two part-annular sections, and the part-annular sections are secured together using fasteners formed from sacrificial materials.

4. The protector assembly of claim 1 , wherein each clamping means further comprises an end sleeve having an abutment surface adapted to restrict the longitudinal movement of the outer sleeve, and a channel adapted to receive its respective clamping ring.

5. The protector assembly of claim 4 , wherein each channel includes one or more retaining tabs adapted to retain the respective clamping ring within the channel.

6. The protector assembly of claim 4 , wherein one of the end sleeves is integrally formed with the annular body.

7. The protector assembly of claim 4 , wherein one of the end sleeves and the annular body are provided with co-operating interlocking portions which prevent axial movement of the end sleeve and annular body relative to one another.

8. A method of protecting a drill pipe string and casing when drilling the bore of a well, the method comprising the steps:

(a) selecting a plurality of protector assemblies, wherein the protector assemblies comprise:

a generally annular body internally dimensioned to fit around said pipe string;

an outer sleeve formed from at least two part-annular sections and located over the annular body so as to be rotatable relative thereto; and

a pair of substantially annular clamping means adapted to restrict longitudinal movement of the body and outer sleeve relative to the pipe string, each clamping means comprising a one-piece clamping ring and a fastener adapted to tighten the clamping ring around the pipe string;

wherein the outer sleeve is formed from first and second part-annular sections, wherein the first section has male and female engagement portions each adapted to interlock with respective female and male engagement portions on the second section;

(b) clamping said protector assemblies upon the drill pipe string, in spaced apart relation;

(c) running said drill pipe string into said bore and drilling a well;

(d) circulating fluid down the pipe string and up the annulus between the pipe string and bore;

(e) causing wear of the protector assemblies such that parts break away or separate from the assembly; and

(f) circulating the broken or separated parts out of the bore in the fluid;

wherein the first and second annular sections of the outer sleeve interlock using a dovetail fitting comprising a keyed profile extending from a first longitudinal edge of the first annular section which interlockingly engages a matching recess provided on an opposing longitudinal edge of the second annular section.

9. The method of claim 8 , wherein step (e) comprises initiating a grinding or milling action of the drill string within the bore such that the parts of the protector assemblies are broken down for ease of circulation out of the bore.

10. The method of claim 8 , wherein the body, outer sleeve, and clamping rings are formed from one or more sacrificial materials.

11. The method of claim 8 , wherein the body and outer sleeve are both formed from two part-annular sections, and the part-annular sections are secured together using fasteners formed from sacrificial materials.

12. The method of claim 8 , wherein each clamping means further comprises an end sleeve having an abutment surface adapted to restrict the longitudinal movement of the outer sleeve, and a channel adapted to receive its respective clamping ring.

13. The method of claim 12 , wherein each channel includes one or more retaining tabs adapted to retain the respective clamping ring within the channel.

14. The method of claim 12 , wherein one of the end sleeves is integrally formed with the annular body.

15. The method of claim 12 , wherein one of the end sleeves and the annular body are provided with co-operating interlocking portions which prevent axial movement of the end sleeve and annular body relative to one another.

16. A protector assembly for a pipe string movable within the bore of a well, said protector assembly comprising:

a generally annular body internally dimensioned to fit around said pipe string;

an outer sleeve formed from at least two part-annular sections and located over the annular body so as to be rotatable relative thereto, wherein each annular section has male and female engagement portions each adapted to interlock with respective female and male engagement portions on an adjacent annular section; and

a pair of clamps adapted to restrict longitudinal movement of the body and outer sleeve relative to the pipe string;

wherein the annular sections of the outer sleeve interlock using a dovetail fitting comprising a keyed profile extending from a first longitudinal edge of a first annular section which interlockingly engages a matching recess provided on an opposing longitudinal edge of a second annular section.

17. The protector assembly of claim 16 , wherein the clamps each comprise a clamping ring and a fastener adapted to tighten the clamping ring around the pipe string.