Tachometer for a rotating control device

Abstract

A rotating control device (RCD) includes: a tubular housing having a flange formed at each end thereof; a stripper seal for receiving and sealing against a tubular; a bearing for supporting rotation of the stripper seal relative to the housing; a retainer for connecting the stripper seal to the bearing; and a tachometer. The tachometer includes a probe connected to the retainer and including: a tilt sensor; an angular speed sensor; an angular acceleration sensor; a first wireless data coupling; and a microcontroller operable to receive measurements from the sensors and to transmit the measurements to a base using the first wireless data coupling. The tachometer further includes the base connected to the housing and including: a second wireless data coupling operable to receive the measurements; and an electronics package in communication with the second wireless data coupling and operable to relay the measurements to an offshore drilling unit.

1 . A rotating control device (RCD) for use with an offshore drilling unit, comprising:
 a tubular housing having a flange formed at each end thereof;   a stripper seal for receiving and sealing against a tubular;   a bearing for supporting rotation of the stripper seal relative to the housing;   a retainer for connecting the stripper seal to the bearing; and   a tachometer, comprising:
 a probe connected to the retainer and comprising:
 a tilt sensor; 
 an angular speed sensor; 
 an angular acceleration sensor; 
 a first wireless data coupling; and 
 a microcontroller operable to receive measurements from the sensors and to transmit the measurements to a base using the first wireless data coupling; 
 
 the base connected to the housing and comprising:
 a second wireless data coupling operable to receive the measurements; and 
 an electronics package in communication with the second wireless data coupling and operable to relay the measurements to the offshore drilling unit. 
 
   
     
     
         2 . The RCD of  claim 1 , wherein:
 the stripper seal is an upper stripper seal,   the retainer is an upper retainer, and   the RCD further comprises a lower stripper seal and a lower retainer for connecting the lower stripper seal to the bearing.   
     
     
         3 . The RCD of  claim 2 , wherein the tachometer further comprises a pressure sensor in communication with a pathway for measuring pressure between the stripper seals. 
     
     
         4 . The RCD of  claim 1 , wherein the probe further comprises a battery. 
     
     
         5 . The RCD of  claim 1 , wherein the sensors are accelerometers. 
     
     
         6 . The RCD of  claim 1 , wherein the angular speed sensor is a gyroscope, comprising:
 an outer frame;   an inner frame;   a dither driver operable to dither the inner frame relative to the outer frame; and   a Coriolis sensor for tracking movement of the outer frame.   
     
     
         7 . The RCD of  claim 1 , wherein:
 the stripper seal, bearing, and retainer are part of a bearing assembly,   the bearing is part of a bearing pack having a self contained lubricant system,   the bearing assembly further comprises a catch sleeve,   the housing is part of a docking station, and   the docking station further comprises a latch operable to engage the catch sleeve, thereby fastening the bearing assembly to the docking station.   
     
     
         8 . The RCD of  claim 7 , further comprising a data sub, comprising:
 a second probe connected to the catch sleeve and comprising:
 a second tilt sensor; 
 a temperature sensor in fluid communication with the lubricant system; 
 a third wireless data coupling; and 
 a second microcontroller operable to receive measurements from the second tilt and temperature sensors and to transmit the measurements to a second base using the third wireless data coupling; 
 the second base connected to the housing and comprising:
 a fourth wireless data coupling operable to receive the measurements; and 
 an electronics package in communication with the fourth wireless data coupling and operable to relay the measurements to the offshore drilling unit. 
 
   
     
     
         9 . The RCD of  claim 8 , wherein:
 the second tilt sensor is a first accelerometer,   the second probe further comprises second and third accelerometers, and   the accelerometers are triaxially oriented.   
     
     
         10 . A method for drilling a subsea wellbore using the RCD of  claim 1 , comprising:
 injecting drilling fluid down a drill string while rotating the drill string having a drill bit located at a bottom of the subsea wellbore,   wherein the RCD is engaged with the drill string, thereby diverting returns from the wellbore to an outlet of the RCD; and   monitoring the measurements while drilling the wellbore.   
     
     
         11 . The method of  claim 10 , wherein the measurements are monitored by forecasting a remaining lifespan of the stripper seal. 
     
     
         12 . The method of  claim 11 , wherein the lifespan is forecast using the tilt measurement. 
     
     
         13 . The method of  claim 11 , further comprising adjusting a drilling parameter to optimize the remaining lifespan. 
     
     
         14 . The method of  claim 10 , wherein the measurements are monitored by comparing the angular speed of the RCD to the angular speed of the drill string. 
     
     
         15 . The method of  claim 10 , wherein the measurements are monitored by determining vibration of the drill string. 
     
     
         16 . The method of  claim 15 , wherein the determined vibration includes stick-slip, bit-bounce, and whirl. 
     
     
         17 . The method of  claim 10 , further comprising exerting backpressure on the returns. 
     
     
         18 . The method of  claim 10 , further comprising, while drilling the wellbore:
 measuring a flow rate of the drilling fluid;   measuring a flow rate of the returns; and   comparing the returns flow rate to the drilling fluid flow rate to ensure control of an exposed formation adjacent to the wellbore.