Patent Number: 060268980
Section: claims

1. A tubing head for accommodating a tubing rotator therein, the tubing head being of the type having an upper end, a lower end for attachment to a wellhead and an internal bore extending between the upper and lower ends, wherein the tubing rotator comprises a drive gear and a swivel tubing hanger for rotatably suspending a tubing string contained within a wellbore, the tubing hanger comprising an external surface for engaging the internal bore of the tubing head such that the tubing hanger may be suspended thereby and a driven gear for engaging the drive gear, the improvement which comprises: (a) the internal bore of the tubing head defining an internal surface for engaging the external surface of the tubing hanger such that the tubing hanger may be suspended by the tubing head and wherein the internal bore of the tubing head further defines a minimum diameter of the bore; and  (b) the tubing head defining a gear housing for containing the drive gear therein, wherein the gear housing communicates with the internal bore such that the drive gear may releasably engage the driven gear of the tubing hanger when the tubing hanger is suspended by the tubing head and wherein the gear housing is configured such that when the drive gear is contained within the gear housing, the drive gear does not protrude into the internal bore within the minimum diameter;  (a) a tubing head having an upper end, a lower end for attachment to a wellhead and an internal bore extending between the upper and lower ends, wherein the internal bore of the tubing head defines an internal surface and a minimum diameter of the bore and wherein the tubing head further defines a gear housing which communicates with the internal bore;  (b) a swivel tubing hanger for locating within the internal bore and for connecting to the tubing string, the tubing hanger comprising a driven gear and an external surface for engaging the internal surface of the tubing head such that the tubing hanger may be suspended by the tubing head; and  (c) a drive gear for containing within the gear housing and for releasably engaging the driven gear of the tubing hanger, wherein the gear housing is configured such that when the drive gear is contained within the gear housing, the drive gear does not protrude into the internal bore within the minimum diameter;  (a) a supporting member comprising the external surface of the tubing hanger; and  (b) a supported member rotatably supported within the supporting member such that the longitudinal movement of the supported member relative to the supporting member in a direction toward the lower end of the tubing head is inhibited, the supported member having an upper end and a lower end for connecting to the tubing string and wherein the supported member is associated with the driven gear such that rotation of the driven gear causes the supported member to rotate within the supporting member. 2. The tubing head as claimed in claim 1 wherein the internal surface of the tubing head defines a maximum diameter of the internal bore which is about equal to a maximum diameter of the tubing hanger and wherein the maximum diameter of the tubing hanger permits the tubing hanger to be removed from the internal bore by pulling it through a blowout preventer in order to service the well. 3. The tubing head as claimed in claim 2 wherein the drive gear and the driven gear engage each other between the minimum diameter and the maximum diameter. 4. The tubing head as claimed in claim 3 wherein the drive gear is comprised of a worm and the driven gear is comprised of a worm gear. 5. The tubing head as claimed in claim 4 wherein the worm and the worm gear are non-enveloping in order to facilitate the removal of the tubing hanger from the internal bore without first disengaging the worm from the worm gear. 6. The tubing head as claimed in claim 5 wherein the tubing head is further comprised of at least one adjustable holddown screw for engagement with the tubing hanger such that when the holddown screw is adjusted for engagement with the tubing hanger, longitudinal movement of the tubing hanger in a direction toward the upper end of the tubing head is inhibited. 7. The tubing head as claimed in claim 6 wherein the tubing head is comprised of at least two holddown screws located adjacent the upper end of the tubing head. 8. The tubing head as claimed in claim 6 wherein the tubing head is further comprised of means for mounting the tubing head on the wellhead. 9. The tubing head as claimed in claim 8 wherein the mounting means is comprised of a mounting portion of the internal bore of the tubing head adjacent the lower end. 10. The tubing head as claimed in claim 8 wherein the mounting means is comprised of a lower surface on the lower end of the tubing head. 11. The tubing head as claimed in claim 10 wherein the lower surface of the tubing head is comprised of a mounting flange. 12. The tubing head as claimed in claim 8 wherein the tubing head is further comprised of means for connecting the upper end of the tubing head to other wellhead equipment. 13. An apparatus for attachment to a wellhead for suspending and rotating a tubing string contained within a wellbore, the apparatus comprising: 14. The apparatus as claimed in claim 13 wherein the internal surface of the tubing head defines a maximum diameter of the internal bore which is about equal to a maximum diameter of the tubing hanger and wherein the maximum diameter of the tubing hanger permits the tubing hanger to be removed from the internal bore by pulling it through a blowout preventer in order to service the well. 15. The apparatus as claimed in claim 14 wherein the drive gear and the driven gear engage each other between the minimum diameter and the maximum diameter. 16. The apparatus as claimed in claim 15 wherein the drive gear is comprised of a worm and the driven gear is comprised of a worm gear. 17. The apparatus as claimed in claim 16 wherein the worm and the worm gear are non-enveloping in order to facilitate the removal of the tubing hanger from the internal bore without first disengaging the worm from the worm gear. 18. The apparatus as claimed in claim 17 wherein the worm gear is comprised of a plurality of worm gear teeth and wherein a lower end of each worm gear tooth is tapered inwardly towards a centre of the tooth in order to facilitate the feeding of the worm gear onto the worm. 19. The apparatus as claimed in claim 18 wherein the lower end of each worm gear tooth is sloped downwardly from a top face to a bottom face of the tooth in order to facilitate the feeding of the tubing hanger into the internal bore of the tubing head. 20. The apparatus as claimed in claim 19 wherein the worm is comprised of a plurality of worm teeth and wherein a crest of each worm tooth is tapered to facilitate the feeding of the worm gear onto the worm. 21. The apparatus as claimed in claim 17 wherein the tubing head is further comprised of at least one adjustable holddown screw for engagement with the tubing hanger such that when the holddown screw is adjusted for engagement with the tubing hanger, longitudinal movement of the tubing hanger in a direction toward the upper end of the tubing head is inhibited. 22. The apparatus as claimed in claim 21 wherein the tubing head is comprised of at least two holddownscrews located adjacent the upper end of the tubing head. 23. The apparatus as claimed in claim 21 wherein the tubing hanger is further comprised of: 24. The apparatus as claimed in claim 23 wherein the driven gear is fixedly mounted about the supported member such that the driven gear extends from the supported member towards the gear housing of the tubing head for engagement with the drive gear. 25. The apparatus as claimed in claim 24 wherein the tubing hanger further comprises means for inhibiting the longitudinal movement of the supported member relative to the supporting member in a direction toward the upper end of the tubing head. 26. The apparatus as claimed in claim 25 wherein the inhibiting means is comprised of an abutment of the driven gear and the supporting member. 27. The apparatus as claimed in claim 24 wherein the supported member is rotatably supported within the supporting member by at least one bearing located between the supported member and the supporting member such that the bearing is seated on the supporting member and the supported member is rotatably supported upon the bearing. 28. The apparatus as claimed in claim 27 wherein the bearing is comprised of a thrust bearing in combination with a bushing sleeve. 29. The apparatus as claimed in claim 21 wherein the tubing head is further comprised of means for mounting the tubing head on the wellhead. 30. The apparatus as claimed in claim 29 wherein the mounting means is comprised of a mounting portion of the internal bore of the tubing head adjacent the lower end. 31. The apparatus as claimed in claim 29 wherein the mounting means is comprised of a lower surface on the lower end of the tubing head. 32. The apparatus as claimed in claim 31 wherein the lower surface of the tubing head is comprised of a mounting flange. 33. The apparatus as claimed in claim 29 wherein the tubing head is further comprised of means for connecting the upper end of the tubing head to other wellhead equipment.