GB1139908A - Well bore drilling apparatus - Google Patents

Abstract

1,139,908. Boring earth &c. DRILCO OIL TOOLS, Inc. 2 May, 1966, No: 19302/66. Heading E1F. Well-bore drilling apparatus comprises a hollow mandrel 14, Fig. 4, connected to a drill bit 16 and a. drill string 17, a directing barrel 18 slidable between end positions adjacent the bit and string, 'seals 30, Figs. 6A, 6B, defining a .chamber, 28, a port 42 ,to. transfer pressure fluid from the-interior of the mandrel into the chamber, the seals being on opposite sides of port 42 in all relative axial positions of band and mandrel, bore-well .engaging members 22 extendable from the barrel by the pressure fluid in chamber 28 while the mandrel is moved axially during drilling, and a .releas- 'able. latch 20 for holding the barrel.to the mandrel at the bit-end, said latch comprising interengaging pin and socket parts preventing relative axial movement of barrel and mandrel. In this arrangement, latch 20 comprises lugs each providing a socket part behind a circumferentially protruding pin part. Engagement is achieved by: turning the mandrel in the direction, opposite to drilling direction. The mandrel is, guided" in the barrel ;by bearings 40 with fluted bearing surfaces and made, e g of rub- 'ber. Part 42 is controlled by valve 62 which is removed by a grapple to admit pressure fluid to chamber 28. A relief valve 48 limits the pressure differential betweenchamber 28 and the bore-hole in both directions. When drilling has proceeded until barrel 28 is adjacent string 17, : rotation ,is stopped, bit. 16 is raised and mandrel turned to enagage latch 20, pressure in the mandrel is reduced to retrack members 22 and mandrel And barrel are lowered,;-whereupon, the. pressure is. increased to secure the barrel, latch 20 is released,- and drilling recommenced.. Members 22 may comprise toothed ' plate 44, Fig. 9, connected to a number of diaphragm persson 82 secured in the barrel wall. The barrel may be used to guide a straight hole with members 22 extended symmetrically, or to .return a hole to the vertical 'or to'"guide a curved or inclined hole with 'selected members 22 extended to position 'the barrel asymmetrically in the bore, those member 22 not required 'being removed and their barrel apertures being blanked off. Cam surfaces may be provided on the facing ends of string 17 and: barrel 18 to cause vibration at the end of the stroke. In another arrangement, the mandrel is provided with one or more piston .surfaces in chamber 28 whereby the fluid-pressure in the chamber urges the mandrel downwards. It is stated that the barrel may be used as a tubing anchor with the tubing connected to the barrel. In a modification, collars. Fig. 17, with toothed projections 271, 273, 275, 277 extending radially to various extents, are spaced along the barrel and orientated to govern the extension of members 22 to the required degree. In another modification, the pin and socket comprises a socket or slot 331, Fig. 19, in barrel portion 157, and a pin 333 slidable radially in mandrel 141 and urged into the slot by fluid pressure in the mandrel. Bar 347 is moved down by said fluid pressure against a spring to position recess 359 so that the pin can be moved mechanically by the barrel as the mandrel is 'raised. On reducing said pressure, the bar rises to prevent inward movement of the pin and hence disengagement of mandrel and barrel. A cam formed on the barrel co-operates with a cam formed on a part secured to the mandrel to align the pin and socket means. A pin 255 serves to align a string lowered down the mandrel and including a survey instrument which records the azimuthal direction of the hole.