Document Type and Number:
Japanese Patent JPS5213761
Kind Code:
B1
Abstract:
1,249,582. Boring earth and rock. BYRON JACKSON Inc. 5 March, 1969 [6 May, 1968], No. 11830/69. Heading E1F. In the drilling of curved boreholes, an instrument I carried within 'the drill string signals an indication of the angle of torsional twist of the drill string by generating a number of pulses in the drilling fluid. The instrument comprises a body 30, 37 fixed within a drill collar sub D below which is an angled sub, a mud driven motor and a bit. The body contains an eccentrically weighted member 130 rotatably mounted on a housing 111 and provided with clutch teeth 133 engageable with projections 132 on a clutch sleeve 131 rotatably fixed relative to the body. The housing is non-rotatable relative to the body and is mounted on a slidable assembly comprising rod and tube members 60, 74, 117. The rod 60 slides in a fixed tube 61 having stop means, e.g. axially spaced sets of balls such as 75a, which are cammed outwardly by thimbles such as 72a to engage an inwardly extending ledge (not shown) in a sleeve 13 connected to a pulse producing member 14 to limit the upward travel according to an inverse function of the upward displacement of the rod 60. The member 14 is biassed upwardly by a spring 15 and is held on its seat 31 by drilling fluid pressure. When the drilling fluid pressure is reduced fractionally the member 14 rises releasing the members 60, 74, 117 which are displaced upwardly to lift the clutch sleeve 131 which locks the eccentrically weighted member 130 against further rotation. The drilling fluid is then cut off and the members 60, 74, 117 rise further lifting the housing 111 until a projection 135 on the member 130 abuts one of a series of steps 200 on a stop member 100. The member 14 rises until the ledge in the sleeve 13 abuts the first set of outwardly cammed balls. The drilling fluid is then restarted and the member 14 is returned to its seat, passing constrictions 7 (only two of which are shown) to produce a number of pulses. The rotation of the eccentrically weighted member is damped by fluid between closely concentrically spaced surfaces (152), (153) Fig. 4 (not shown). The upper surface of the projection 135 may be rounded. The stop member (100), Figs. 6, 7, 8 (not shown) may have various arrangements of steps 200, (200a- 200f) subtending different angles. The instrument may be used with a directional drilling bit.
Application Number:
JP799074A
Publication Date:
April 16, 1977
Filing Date:
January 18, 1974
Export Citation:
International Classes:
E21B7/06; E21B7/04; E21B47/024; E21B47/12; G01C9/00; G01C9/12; (IPC1-7): E21B7/06