MWD (Measurement While Drilling)

MWD (Measurement While Drilling, a method of measuring petrophysical properties of formations, drilling parameters (WOB, torque etc.) and environmental parameters downhole and sending the results to surface without interrupting routine drilling operations.
A special tool containing sensors, power supply and transmitter is installed as part of the BHA. The information is transmitted to surface by a telemetry system using mud pulses or signals through the pipe.