Downhole drilling sub with controllable stiffness

Abstract

Embodiments of a downhole drilling tool, system, and method are disclosed herein. In one embodiment, A downhole sub, comprising: a housing; and at least one tunable stiffness member integrated with the housing, the tunable stiffness member comprising a programmable stiffness material; wherein a stiffness of the tunable stiffness member is adjusted in response to instructions from a control unit of a wellbore system. In another embodiment, a method is provided for adjusting the stiffness of a sub having one or more tunable stiffness members while the tool on which the sub is placed remains downhole.

1 . A downhole sub, comprising:
 a housing; and   at least one tunable stiffness member integrated with the housing, the tunable stiffness member comprising a programmable stiffness material;   wherein a stiffness of the tunable stiffness member is adjusted in response to instructions from a control unit of a wellbore system.   
     
     
         2 . The downhole sub according to  claim 1 , further comprising a cavity within the housing, wherein the at least one tunable stiffness member is positioned in the housing, wherein the cavity is a longitudinal cavity extending along a length of the housing. 
     
     
         3 . The downhole sub according to  claim 2 , wherein the cavity is a longitudinal cavity extending along a length of the housing and wherein the tunable stiffness member is a longitudinal thread extending a length of the cavity. 
     
     
         4 . The downhole sub according to  claim 1 , further comprising a cylindrical opening around a channel extending a length of the housing. 
     
     
         5 . The downhole sub according to  claim 4 , wherein the tunable stiffness member is one of a cylindrical insert positioned within the cylindrical opening or a spiral thread winding through the cylindrical opening around the channel. 
     
     
         6 . The downhole sub according to  claim 1 , further comprising a plurality of cavities and a plurality of tunable stiffness members individually positioned within the plurality of cavities. 
     
     
         7 . The downhole sub according to  claim 6 , wherein each of the plurality of tunable stiffness members may be individually adjusted such that each tunable member may have a different stiffness. 
     
     
         8 . The downhole sub according to  claim 1 , wherein the control unit receives input from a telemetry element of the wellbore system, and the stiffness of the at least one tunable stiffness member is adjusted based on a signal received from the control unit via a pulser. 
     
     
         9 . The downhole sub according to  claim 1 , wherein the stiffness of the at least one tunable stiffness member is adjusted based on inclination and azimuth readings taken from sensors during an automated drilling operation. 
     
     
         10 . A downhole system, comprising:
 a tool string positioned downhole in a wellbore;   a control unit; and   a downhole sub coupled with the tool string and the control unit, the downhole sub comprising:   a housing; and   at least one tunable stiffness member integrated with the housing, the tunable stiffness member comprising a programmable stiffness material;
 wherein a stiffness of the tunable stiffness member is adjusted in response to instructions from the control unit. 
   
     
     
         11 . The downhole system according to  claim 10 , further comprising a cavity within the housing, wherein the tunable stiffness member is a longitudinal thread extending a length of the cavity. 
     
     
         12 . The downhole system according to  claim 10 , further comprising a cylindrical opening around a channel extending a length of the housing, and wherein the tunable stiffness member is one of a cylindrical insert positioned within the cylindrical opening or a spiral thread winding through the cylindrical opening around the channel. 
     
     
         13 . The downhole system according to  claim 10 , further comprising:
 a plurality of cavities and a plurality of tunable stiffness members individually positioned within the plurality of cavities; and   wherein each of the plurality of tunable stiffness members may be individually adjusted such that each tunable member may have a different stiffness.   
     
     
         14 . The downhole system according to  claim 10 , wherein the control unit is communicatively coupled with a telemetry element coupled with the tool string, wherein the control unit is configured to send a signal to adjust the stiffness of the at least one tunable stiffness member based on measurements received from the telemetry element. 
     
     
         15 . The downhole system according to  claim 10 , wherein the signal to adjust the stiffness of the at least one tunable stiffness member is based on inclination and azimuth readings taken from sensors during an automated drilling operation. 
     
     
         16 . A method of adjusting a stiffness of a downhole tool positioned within a wellbore, the method comprising:
 inserting the downhole tool into the wellbore, the downhole tool comprising:
 a tool string; 
 a control unit; and 
 a downhole sub coupled with the tool string and the control unit, the downhole sub comprising:
 a housing; and 
 at least one tunable stiffness member integrated with the housing, the tunable stiffness member comprising a programmable stiffness material;
 wherein a stiffness of the tunable stiffness member is adjusted in response to instructions from the control unit; and 
 wherein the stiffness of the downhole sub conforms to the stiffness of the tunable stiffness member; 
 
 
   receiving measurements at the control unit from one or more sensors positioned on the tool string as the downhole tool moves within the wellbore;   adjusting the stiffness of the tunable stiffness members based on the measurements.   
     
     
         17 . The method according to  claim 16 , wherein the control unit is configured to send a signal to adjust the stiffness of the at least one tunable stiffness member via a pulser. 
     
     
         18 . The method according to  claim 16 , wherein the measurements include at least inclination and an azimuth of the tool string. 
     
     
         19 . The method according to  claim 16 , wherein the downhole sub further comprises a plurality of cavities and a plurality of tunable stiffness members individually positioned within the plurality of cavities. 
     
     
         20 . The method according to  claim 19 , wherein each of the plurality of tunable stiffness members may be individually adjusted such that each tunable member may have a different stiffness.