Drilling tool and method

Abstract

A drill tool comprising a drill pipe having a turbine and a hydraulic pump, wherein drilling fluid is passed through the turbine and into the hydraulic pump through a hollow shaft in the drill pipe. The drill tool also includes a high pressure jet at a distal end of the drill pipe for discharging drill fluid at a pressure which is between 20 and 40 MPa greater than the ambient pressure of the drill hole.

1 . A method for breaking rock at the bottom of a drill hole, characterized in that a local negative pressure area is created near the rock by a high-pressure and continuous jet stream of drilling fluid.  
   
   
       2 . The method of  claim 1 , characterized in that after the drilling fluid flows through a hollow shaft the drilling fluid is pressurized by a multistage centrifugal pump or an axial flow pump.  
   
   
       3 . The method of  claim 2 , characterized in that the pressure of said pressurized drilling fluid is 20-40 MPa.  
   
   
       4 . The method of  claim 1 , further comprising using a drill bit to mechanically break the rock.  
   
   
       5 . The method of  claim 1 , characterized in that before pressurizing the drilling fluid, a filter is used for filtering the drilling fluid.  
   
   
       6 . A method for breaking the rock comprising the following steps: 
 (a) providing the drilling fluid for a downhole-drilling tool with a high-pressure and continuous-flow jet by a drill pipe that is driven by a ground rotary table or a top driving unit;    (b) driving the drilling fluid by said the drilling tool, a portion of drilling fluid driving the multistage turbine sections rotary to drive a multistage centrifugal pump or an axial flow pump by using a turbine which has multistage turbine sections as a drilling motor, and the other portion of the drilling fluid flowing through a hollow shaft and directly flowing into the multistage centrifugal pump or axial flow pump to increase the pressure of the drilling fluid, said pressurized drilling fluid jetting the well bottom through a high-pressure jet nozzle of a drill bit to generate a local negative pressure area near the rock at the well bottom, in which the rock will be expanded and broken;    (c) breaking the non-broken rock using the bit in order to break the rock by hydraulic and mechanical means.    
   
   
       7 . The method of  claim 6 , characterized in that the non-pressurized drilling fluid is used for driving the turbine unit, and then jets the well bottom through a low-pressure jet nozzle ( 72 ) of the bit to carry the cuttings to the surface.  
   
   
       8 . The method of  claim 6 , characterized in that before the step of pressurizing the drilling fluid, a filter is used for filtering the drilling fluid.  
   
   
       9 . The method of  claim 6 , characterized in that the filtered drilling fluid is increased to between 20 and 40 MPa by the centrifugal pump or axial flow pump.  
   
   
       10 . A downhole-drilling tool with high-pressure and continuous-flow jet, comprising: 
 a drill pipe driven by a ground rotary table or a top driving unit,    a filter;    a turbine unit;    a centrifugal pump or an axial flow pump;    a drill bit mounted on the bottom of the drill pipe; and    both a high-pressure jet nozzle and a low-pressure jet nozzle provided on the drill bit, wherein    the filter, the turbine unit, a thrust bearing, and the centrifugal pump or axial flow pump are arranged sequentially along the axis of the drill pipe inside the drill pipe, the turbine unit having a hollow shaft for reducing the pressure loss of drilling fluid, the filter being connected with the hollow shaft.    
   
   
       11 . The downhole-drilling tool according to  claim 10 , characterized in that the shaft input end of the centrifugal pump or axial flow pump is connected with the output end of the hollow shaft.  
   
   
       12 . The downhole-drilling tool according to  claim 11 , characterized in that the output end on the hollow shaft is supported with a thrust bearing and the shaft input end of the centrifugal pump or axial flow pump is connected with the output end on the hollow shaft by the thrust bearing.  
   
   
       13 . The downhole-drilling tool according to  claim 10 , characterized in that the internal diameter of the hollow shaft is substantially aligned with the internal diameter of the housing of the centrifugal pump or axial pump.  
   
   
       14 . The downhole-drilling tool according to  claim 10 , characterized in that an annular space is formed between the inner wall of the drill pipe and the outer wall of the centrifugal pump or axial flow pump.  
   
   
       15 . The downhole-drilling tool according to  claim 10 , characterized in that the high-pressure jet nozzle on the drill bit is connected with the centrifugal pump or axial flow pump, the low-pressure jet nozzle on the drill bit is adapted to generate a circulating return flow and is mounted inside the cavity formed in the drill bit.  
   
   
       16 . The downhole-drilling tool according to  claim 10 , characterized in that said turbine unit is a multistage turbine, each turbine stage being connected serially on said hollow shaft.  
   
   
       17 . The downhole-drilling tool according to  claim 10 , characterized in that said centrifugal pump or axial flow pump is a multistage centrifugal pump or axial flow pump.  
   
   
       18 . The downhole-drilling tool according to  claim 10 , characterized in that the filter is a cyclone means, which includes screw blades fixed on the inner wall of the drill pipe.  
   
   
       19 . The downhole-drilling tool according to  claim 10 , characterized in that a filter of the drilling fluid is comprised of screw blades fixed on a drive shaft.  
   
   
       20 . A method of drilling, comprising: 
 (a) providing a drill in a drill hole, the drill having a first fluid outlet adjacent the drill bit for discharging a drill fluid; and    (b) discharging the drill fluid from the first fluid outlet at a pressure which is between about 20 and about 40 MPa greater than the ambient pressure at the first fluid outlet    
   
   
       21 . The method of  claim 20 , wherein the drill fluid is at a pressure which is between 23 and 33 MPa greater than the ambient pressure at the first fluid outlet.  
   
   
       22 . The method of  claim 20 , wherein the drill fluid is discharged from the first fluid outlet at a speed of between about 100 and 200 meters per second.  
   
   
       23 . The method of  claim 22 , wherein the drill fluid is discharged from the first fluid outlet at a speed of about 150 meters per second.  
   
   
       24 . A drilling tool, comprising: 
 a drill pipe having a proximal end and a distal end, wherein the proximal end is in mechanical communication with a driving unit for rotating the drill pipe;    a turbine in the drill pipe, the turbine having a proximal end and a distal end;    a hydraulic pump in the drill pipe located distally with respect to the turbine, the hydraulic pump having a proximal end and a distal end and comprising an inlet at the proximal end;    a hollow shaft in the turbine having a proximal end and a distal end, wherein the hollow shaft extends from a proximal end of the turbine to the inlet of the hydraulic pump, wherein the hydraulic pump is in fluid communication with the proximal end of the turbine by means of the hollow shaft;    a drill bit on the distal end of the drill pipe; and    a high-pressure jet nozzle adjacent the drill bit, the nozzle being in fluid communication with the distal end of the hydraulic pump.