Downhole tool

Abstract

A downhole tool comprising: an axial drive unit ( 10 ) having a connection for an electric power cable extending up the borehole, and including an anchoring mechanism ( 12, 16 ) operable in the borehole between a first configuration in which the anchoring mechanism resists rotational and axial movement of the unit, and a second configuration in which the anchoring mechanism is moveable axially in the borehole, an axial drive mechanism that moves the anchoring mechanism axially down the borehole when in the second configuration; a motor ( 28 ) mounted on the drive unit at the downhole end thereof; an hydraulic pump ( 30 ) connected to the motor, the pump providing a source of hydraulic power; and a functional unit connected below the hydraulic pump and powered thereby, operation of the axial drive mechanism acting to move the functional unit axially down the borehole.

1 . A downhole tool comprising: 
 (i) an axial drive unit ( 10 ) having a connection for an electric power cable extending up the borehole ( 14 ), and including 
 anchoring mechanism operable in the borehole between a first configuration the which resists rotational and axial movement of the unit, and a second configuration in which the anchoring mechanism is moveable axially in the borehole,  
 an axial drive mechanism that moves the anchoring mechanism axially down the borehole when in the second configuration;  
 wherein the downhole tool further comprises:  
   (ii) a motor mounted on the drive unit at the downhole end thereof;    (iii) an hydraulic pump connected to the motor, the pump providing a source of hydraulic power; and    (iv) a functional unit connected below the hydraulic pump and powered thereby, operation of the axial drive mechanism acting to move the functional unit axially down the borehole.    
   
   
       2 . A tool as claimed in  claim 1 , further comprising an orienting unit that allows axial rotation of at least part of the tool below the drive unit.  
   
   
       3 . A tool as claimed in  claim 1 , further comprising a diverting member positioned below the functional unit and which acts to urge the functional unit in a predetermined direction on operation of the drive mechanism.  
   
   
       4 . A tool as claimed in  claim 1 , wherein the hydraulic pump uses fluid in the borehole to provide the source of hydraulic power.  
   
   
       5 . A tool as claimed in  claim 1 , wherein the functional unit is a well construction device.  
   
   
       6 . A tool as claimed in  claim 5 , wherein the well construction device comprises a drilling assembly.  
   
   
       7 . A tool as claimed in  claim 6 , wherein the drilling assembly includes a drilling motor that is powered by the hydraulic power supply from the pump.  
   
   
       8 . A tool as claimed in  claim 7 , further comprising a drill bit that is drive by the drilling motor.  
   
   
       9 . A tool as claimed in  claim 7 , the drilling motor is connected to the pump by a hollow drill shaft through which the hydraulic fluid flows.  
   
   
       10 . A tool as claimed in  claim 9 , further comprising at least one support member mounted o the drill shaft to support against buckling when drilling.  
   
   
       11 . A tool as claimed in  claim 6 , further comprising at least one baffle arranged to direct drilled cuttings down the well below the tool.  
   
   
       12 . A tool as claimed in  claim 6 , further comprising a cuttings catcher positioned below the drilling unit and attached to the tool for catching material drilled by the drilling unit.  
   
   
       13 . A tool as claimed in  claim 12 , further comprising diverters located above and below the drilling unit to force the cuttings into the catcher.  
   
   
       14 . A tool as claimed in  claim 13 , further comprising a circulation tube extending between the diverters to allow fluid to circulate back up the borehole one the cuttings have been removed.  
   
   
       15 . A tool as claimed in  claim 6 , further comprising a measurement unit located in the drilling unit.  
   
   
       16 . A tool as claimed in  claim 6 , further comprising an inflatable packer above the drilling tool which, when inflated, allows pressure isolation of at least the portion of the borehole in which the drilling tool is located.  
   
   
       17 . A tool as claimed in  claim 5 , wherein the well construction unit comprises a completion unit.  
   
   
       18 . A tool as claimed in  claim 17 , wherein the well construction unit comprise a tubular completion member that can be advanced into the borehole by operation of the drive unit and disconnected so as to remain in place when the tool is withdrawn from the borehole.  
   
   
       19 . A tool as claimed in  claim 18 , wherein the completion member is filled with a completion fluid that is pumped out of the completion member and into the borehole around the completion member by means of the hydraulic pump.  
   
   
       20 . A tool as claimed in  claim 1 , further comprising a storage unit located in the borehole in which at least one functional unit can be stored when not in use.  
   
   
       21 . A tool as claimed in  claim 20 , further comprising a latching system for disconnecting the functional unit stored in the storage unit from the remainder of the tool.  
   
   
       22 . A tool as claimed in  claim 1 , further comprising an imaging device for locating the portion of the borehole at which the tool is to operate.