Downhole drilling system

Abstract

The present invention relates to a downhole drilling system, comprising: a drill string having a drill head configured to drill a borehole having a borehole wall forming an annulus between the drill string and the borehole, a plurality of sensor units forming a mesh network, wherein each one of said sensor units is distributed in a drilling fluid flowing in the annulus and in the drill string, and at least one of said sensor units is provided with a detector for measuring position data. The present invention also relates to a method for providing a downhole drilling system according to the present invention and to a method for determining drilling direction.

1 . A downhole drilling system, comprising:
 a drill string having a drill head configured to drill a borehole having a borehole wall forming an annulus between the drill string and the borehole,   a plurality of sensor units forming a mesh network, wherein each one of said sensor units is distributed in a drilling fluid, said drilling fluid flowing in the annulus and in the drill string, and at least one of said sensor units is provided with a detector for measuring position data of said sensor unit.   
     
     
         2 . A downhole drilling system according to  claim 1 , wherein all sensor units are provided with a detector for measuring position data. 
     
     
         3 . A downhole drilling system according to  claim 1 , wherein the detector comprises an accelerometer and/or a magnetometer, and position data comprises inclination and/or azimuth. 
     
     
         4 . A downhole drilling system according to  claim 1 , wherein at least one of said sensor units further comprises a sensor module comprising additional sensors. 
     
     
         5 . A downhole drilling system according to  claim 4 , wherein said sensor module comprises a temperature sensor and/or a pressure sensor. 
     
     
         6 . A downhole drilling system according to  claim 1 , wherein each sensor unit is configured to receive wirelessly transmitted data from an adjacent sensor unit, and to forward the received data to the adjacent sensor units. 
     
     
         7 . A downhole drilling system according to  claim 1 , further comprising a surface system configured to receive downhole data from said sensor units. 
     
     
         8 . A downhole drilling system according to  claim 7 , wherein said surface system is further configured to determine the position of at least one sensor unit in relation to the surface system, and to associate said determined relative position with associated position data. 
     
     
         9 . A downhole drilling system according to  claim 8 , wherein the surface system is configured to determine the relative position of at least one sensor unit by Monte Carlo simulation and/or Shortest Path simulation. 
     
     
         10 . A method for providing a downhole drilling system according to  claim 1 , said method comprising:
 entering a plurality of sensor units in a drilling fluid, and   entering said drilling fluid in a borehole annulus via a drill string during drilling, whereby each sensor unit is positioned in said annulus.   
     
     
         11 . A method according to  claim 10 , wherein each sensor unit is flowing randomly in said annulus. 
     
     
         12 . A method for determining drilling direction, comprising:
 providing a downhole drilling system by performing the method according to  claim 10 ,   activating at least one sensor unit for measuring position data of said sensor unit,   transmitting data corresponding to said measured position data from the activated sensor unit to a surface system via at least one adjacent sensor unit, and   analysing the received data in order to determine the drilling direction.   
     
     
         13 . A method according to  claim 12 , further comprising:
 determining the position of said activated sensor unit in relation to the surface system, and associating said determined relative position with the corresponding position data received by said surface system.   
     
     
         14 . A method according to  claim 12 , wherein activating at least one sensor unit comprises measuring inclination and/or azimuth. 
     
     
         15 . A method according to  claim 12 , further comprising comparing the determined drilling direction with an intended drilling direction, and optionally adjusting the current drilling direction based on the comparison.