MWD LWD Tools Video
MWD
"Measurement while drilling" (MWD) is a system developed to make drilling related measurements and transmit information to the surface while drilling the well. MWD tools are conveyed downhole as part of bottom hole assembly (BHA). The tools are either contained inside a drill collar or are built into the collars themseves.
MWD systems can take measurements of natural gamma ray, directional survey, tool face, borehole pressure, temperature, vibration, shock, torque etc. Some advanced MWD tools can even measure formation pressure and take formation samples. The MWD also provides the telemetry for operating rotary steering tools (RSTs).
The measured results are stored in MWD tools and some of the results can be transmitted digitally to surface using mud pulser telemetry or other advanced technology.
Certain MWD systems have the capability of receiving encoded control commands which are sent by turning on and off mud pumps and/or changing the rotation speed of drill pipe or by other advanced telemetry technology such as wired pipe.
LWD (Logging While Drilling) tools are able to measure a suite of geological characteristics including- density, porosity, resistivity, pseudo-caliper, inclination at the drill bit (ABI), magnetic resonance and formation pressure.
The MWD tool allows these measurements to be taken and evaluated while the well is being drilled. This makes it possible to perform Geosteering, or Directional Drilling based on measured formation properties, rather than simply drilling into a preset target.
Most MWD tools contain an internal Gamma Ray sensor to measure natural Gamma Ray values. This is because these sensors are compact, inexpensive, reliable, and can take measurements through unmodified drill collars. Other measurements often require separate Logging While Drilling tools, which communicate with the MWD tools downhole through internal wires.