Glossary of Terms
EM MWD - Electromagnetic Measurement While Drilling System. Transmits data to the surface via electromagnetic wave propagation. Typically includes the inclination and azimuth angles of the borehole, the drilling system tool face (roll angle), and the tool temperature. The system can also be conﬁgured to transmit accelerometer and magnetometer sensor values, which can then be used to calculate the borehole angles.
FSK - Frequency-shift keying is a frequency modulation scheme in which digital information is transmitted through discrete frequency changes of a carrier signal.
LCM - Solid material intentionally introduced into a mud system to reduce and eventually prevent the flow of drilling fluid into a weak, fractured or vugular formation.
LWD - Abbreviation for logging while drilling. The measurement of formation properties during the excavation of the hole, or shortly thereafter, through the use of tools integrated into the bottom hole assembly. Shock and vibration is transmitted to the surface and logged.
MWD - Measurement While Drilling
MD - Measured Depth
MTBF - Mean Time Between Failures
NPT - Non-Productive Time
TVD - True Vertical Depth