Patent EA-000513-B1 (EA)
Title: Drill string fitting
Inventor: MURREY GEOFFREY NEIL
IPC: E21B17/10
Filed: 1996-04-26
Abstract: 1. A fitting for reducing friction between a fitting and a section of a drill string or further fitting on a drill string, said fitting comprising a body having a tubular bore provided with a plurality of longitudinally extending recesses spaced circumferentially about the bore, dimensioned to lubricate the interface between the fitting and the drill string or further fitting with fluid in a drilling well, wherein rollers are provided about the periphery of the body to reduce friction in the axial direction. 2. A fitting as claimed in Claim 1 wherein the bore of the fitting is polygonal in cross-section. 3. A fitting as claimed in Claim 1 or Claim 2 wherein the recesses spiral along the length of the bore. 4. A fitting as claimed in any one of Claims 1 to 3 wherein rollers are provided in banks about the circumference of the body. 5. A fitting as claimed in Claim 4 wherein each bank of rollers includes a protective mounting assembly, which exposes only a portion of each roller. 6. A fitting as claimed in any one of the preceding Claims wherein the fitting is of two-part construction adapted to be secured about a drill string. 7. A fitting as claimed in any one of the preceding Claims wherein a filtering means is provided at either end of the fitting to prevent debris entering the longitudinal recesses. 8. A fitting as claimed in any one of the preceding Claims in combination with a sleeve having collars at either end adapted to be secured to a section of drill pipe with the fitting secured thereabout between said collars. 9. A fitting as claimed in Claim 1 having a bore of substantially circular cross section in combination with a sleeve for securement to a section of drill pipe wherein the sleeve has a substantially polygonal cross-section. 10. A fitting for engagement to a drill string or further fitting having a body with a bore therethrough provided with a plurality of roller means on the exterior of the body, each said roller means having one or more roller provided thereon and being rotatable relative to the body about an axis transverse to the axis of the bore, the arrangement being such that the roller means can rotate relative to said body to facilitate reduction of rotational and axial friction. 11. A fitting as claimed in Claim 10 wherein the rollers includes rollers positioned away from the transverse axis so as to rotate said roller means to keep the axis of said rollers substantially transverse to the direction of movement. 12. A fitting as claimed in Claim 11 wherein a plurality of rollers is provided on each said roller means. 13. A fitting as claimed in any one of Claims 10 to 12 wherein the roller means comprises a substantially disc-shaped member located within a corresponding recess in the body. 14. A fitting as claimed in Claim 13 wherein said disc-shaped member includes a central bore which locates with a pin extending outwardly from said body. 15. A fitting as claimed in Claim 13 or 14 wherein a plate is secured above the peripheral edge of each roller means to retain it within its recess. 16. A fitting as claimed in any one of Claims 10 to 15 wherein the rollers are formed of a nylon or ceramic material. 17. A fitting a claimed in any one of Claims 10 to 16 wherein the rollers have a substantially tapered cylindrical form and rotate about an axis transverse to the axis of rotation of the roller means. 18. A fitting as claimed in any one of Claims 10 to 17 wherein the body is of two-part construction so that it may be secured about a section of drilling pipe. 19. A fitting for engagement with a drill string or further fitting comprising an inner section for securement to a drill string or further fitting, an outer section for securement about said inner section, a bearing located between the inner section and outer section, seals provided at either end of the fitting between the inner section and outer section and pressure compensating means for maintaining the pressure within the bearing substantially the same as the external pressure. 20. A fitting as claimed in Claim 19 wherein the bearing comprises a layer of friction reducing material. 21. A fitting as claimed in Claim 20 wherein the layer of friction reducing material is formed of a plastics material. 22. A fitting as claimed in Claim 21 wherein the plastics material is nylon. 23. A fitting as claimed in any one of Claims 19 to 22 wherein the pressure compensating means is a diaphragm located between the bearing and the exterior of the fitting. 24. A fitting as claimed in Claim 23 wherein the bearing is filled with a lubricating fluid. 25. A fitting as claimed in any one of Claims 19 to 24 wherein the bearing comprises first journal surfaces on said inner and outer sections in the axial direction of said fitting and second and third journal surfaces on said inner and outer sections extending radially outwards to restrict movement of said outer section relative to said inner section in the axial direction. 26. A fitting as claimed in any one of Claims 19 to 25 wherein a plurality of fins project radially from said outer section which are profiled to reduce drag in the axial direction. 27. A fitting as claimed in Claim 26 wherein the fins have a curved profile. 28. A fitting as claimed in any one of Claims 19 to 27 wherein rollers are provided on the periphery of said outer section to reduce friction in the axial direction. 29. A fitting as claimed in any one of the preceding Claims constructed in such a manner as to allow the fitting to be rebuilt or reconditioned.