Guide device

Abstract

The present invention provides an active downhole cutting tool guide device 14 for use in a hole 17 with sides between which a hole-cutting tool 15 mounted on a drill string and provided with said device may be disposed. The guide device 14 comprises at least one elongate longitudinally extending hole-side engagement member 20 mounted on a body 19 disposable, in use of the device, in-line with the drill string, so as to be movable relative to said body 19 between a retracted position and a radially outwardly displaced position for hole-side engagement. Each engagement member 20 has pressurised-fluid operable actuator means 24 formed and arranged for driving said hole-side engagement member 20 between its retracted and hole-aide engagement positions. The guide device 14 includes preasurised fluid supply means 28,18 formmed and arranged for controlling the supply of pressurised fluid to the actuator means 28,18 for operation thereof. In use of the guide device 14 the hole-cutting tool 15 may be directed relative to the central longitudinal axis of the hole 17 in which the tool 15 is disposed.

What is claimed is:  
     
         1 . An active downhole cutting tool guide device for use in a hole with sides between which a hole-cutting tool mounted on a drill string and provided with said device may be disposed, said device comprising at least one elongate longitudinally extending hole-side engagement member mounted on a body, which body is disposable, in use of the device, in-line with the drill string, so as to be movable relative to said body between a retracted position and a generally radially outwardly displaced position for hole-side engagement, each said at least one engagement member having presourised-fluid operable actuator means formed and arranged for driving said hole-side engagement metber between said retracted and hole-side engagement positioned said device including pressurised fluid supply means formed and arranged for controlling the supply of pressurized fluid, in use of the device, to said actuator means for operation thereof, whereby in use of the device a said hole-cutting tool may be directed relative to the central longitudinal axis of the hole in which said tool is disposed.  
     
     
         2 . The guide device of    claim 1    wherein each said engagement member is captively secured to said body by at least one connector.  
     
     
         3 . The guide device of    claim 2    wherein said at least one connector is fixedly secured to said body and is formed and arranged so as to allow sliding movement of the engagement body relative to said at least one connector.  
     
     
         4 . The guide device of    claim 1    wherein the actuator means comprises piston means mounted in cylinder means provided in said body, said piston means having a proximal end in communication with said pressurised fluid supply means, and a distal end mounted in a respective said engagement member.  
     
     
         5 . The guide device of    claim 4    wherein said piston means distal end and said connector means are formed and arranged so as to guide movement of said engagement member between its retracted and outwardly displaced positions.  
     
     
         6 . The guide device of    claim 1    wherein are provided at least three angularly distributed engagement members.  
     
     
         7 . The guide device of    claim 6    wherein are provided at least 4 equiangularly spaced apart engagement rmembers.  
     
     
         8 . The guide device of    claim 1    wherein said pressurised fluid supply means comprises a chamber formed and arranged for fluid passage connection, in use of the guide device, to a drilling fluid exhaust passage at a said cutting tool.  
     
     
         9 . The guide device of    claim 1    wherein is provided a plurality of said engagement members and wherein said preasurised fluid supply means for each said engagement member comprises a respective chamber formed and arranged for fluid passage connection, in use of the guide device, via fluid passage means provided with selectively operable control valve means, to, alternately, high and low fluid pressure fluid passage means.  
     
     
         10 . The guide device of    claim 9    wherein is provided a Measurement and Control While Drilling Device including said control valves.  
     
     
         11 . A milling apparatus suitable for use in milling a window in a well casing and comprising a rotary milling bit, motor means for driving the milling bit, and a guide according to    claim 1    for positioning the milling bit in contact with a selected portion of the casing to be milled out.  
     
     
         12 . A method of milling a window in a selected portion of a hole casing comprising the steps of: 
 providing a milling apparatus according to    claim 11   ;    placing the milling apparatus within the casing;    operating the actuator means of the cutting tool guide device so as to position the milling bit in contact with the selected portion; and    driving the milling bit so as to form a window in the casing.    
     
     
         13 . A stabilised hole reboring apparatus suitable for use in reboring an asymmetrically obstructed hole, which apparatus comprises a rotary drilling bit, motor means for driving the drilling bit, and a guide device according to    claim 1    having at least two substantially symmetrically driven engagement members for stabilising the drilling bit against lateral deviation in use of the apparatus as it cuts through an obstruction.  
     
     
         14 . A method of reboring an asymetrically obstructed hole comprising the steps of: 
 providing a stabilised hole reboring apparatus according to    claim 13   ;    placing the stabilized hole reboring apparatus inside the asymmetrically obstructed hole;    operating the actuator means of the cutting tool guide device so as to forcibly engage the hole sides above an obstruction thereby stabilizing the drilling bit against lateral deviation; and    driving the stabilised drilling bit so as to cut through the obstruction.    
     
     
         15 . A directional drilling apparatus suitable for use in directional drilling, which apparatus comprises a rotary drilling bit, motor means for driving the drilling bit, and a guide device according to    claim 1    having at least three angularly distributed independently driven engagement members operable for directing the drilling bit away from an existing drilling axis.  
     
     
         16 . A method of directional drilling comprising the steps of: 
 providing a directional drilling apparatus according to    claim 15   ;    placing the directional drilling apparatus inside a hole;    independently operating the actuator means of the respective engagement members of the cutting tool guide device so as to forcibly engage the hole sides so as to direct the drilling bit in a desired direction; and    driving the directed drilling bit so as to bore a hole along a desired path.