GB1114849A - A well drill pipe string - Google Patents

Abstract

1,114,849. Boring earth &c. JOY MANUFACTURING CO. 31 May, 1965 [5 June, 1964], No. 23033/65. Heading E1F. In a drill string having a sliding joint adjacent the bit, or fishing tool, the joint comprises a pair of telescopic members arranged for rotation together, the outer member having shoulders forming in conjunction with the inner member an axially extending chamber, the inner member having a piston dividing the chamber into upper and lower portions, and ducts connecting the portions respectively with the interior and the exterior of the string. The inner telescopic member 12 is connected to the drill pipe, and the outer telescopic member 16 carries the bit and has a splined connection 22 with the member 12. The chamber 36 is divided into portions by the piston 43 the upper portion bein connected to the interior of the member 12 by ducts 52, and the lower portion being connected by ducts 42 to the.exterior of the member 16. The splines are immersed in oil maintained at the pressure of the exterior of the member 16 (by ducts 37 and a slidable seal ring 40. When drilling mud is supplied to the bit through the bore 50 the tendency of the joint to extend is reduced or balanced by the construction and the weight on the bit is substantially the weight of the string below the joint. The invention may be applied to a string having reversed circulation, and the bit may be attached to the inner member and the drill pipe to the outer member.