Temperature measurement at one or more cutting elements of a drill bit

A method for detecting and monitoring at least one condition of a wellbore and/or drill bit while drilling, the method comprising:

• drilling the wellbore with the drill bit, wherein the drill bit is instrumented with a temperature sensor configured to measure temperature associated with a cutting element of the drill bit over time while drilling;
• using the temperature sensor to generate time-series temperature data representing temperature of the cutting element of the drill bit over time while drilling;
• and
• processing the time-series temperature data to determine at least one condition of the wellbore and/or the drill bit while drilling, wherein the at least one condition relates to detecting backwards whirling while drilling, which involves detecting a drop in the time-series temperature data for one or more cutting elements of the drill bit together with an increase in the time-synchronized rotational speed (RPM) of the drill bit.

A drilling system comprising:

• a drill bit for drilling a wellbore through a formation, wherein the drill bit is instrumented with a temperature sensor configured to measure temperature associated with a cutting element of the drill bit over time while drilling;
• and
• a processor configured to:
• generate or obtain time-series temperature data representing temperature of the cutting element of the drill bit over time while drilling as measured by the temperature sensor;
• and
• process the time-series temperature data to determine and monitor at least one condition of the wellbore and/or the drill bit while drilling, wherein the at least one condition relates to at least one of:
• i) detecting that a steering tool of a bottom hole assembly (BHA) of the drill bit is active and operating to control the direction of drilling, which involves detecting oscillations in the time-series temperature data for one or more cutting elements of the drill bit, and ii) detecting backwards whirling while drilling, which involves detecting a drop in the time-series temperature data for one or more cutting elements of the drill bit together with an increase in the time-synchronized rotational speed (RPM) of the drill bit.