Measurement While Drilling (MWD)
Definition - What does Measurement While Drilling (MWD) mean?
Measurement While Drilling (MWD) is the measurement of the physical properties including temperature, pressure and the wellbore-trajectory in the three-dimensional space, while drilling the wellbore. The measurements are done downhole, stored for some time in solid state memory and then transmitted to the surface. The MWD tools are referred to as logging while drilling (LWD) tools when they are used to measure the formation parameters. The MWD tools are used to take measurements while the well is drilled. This helps in performing geosteering based on the measurements instead of simply drilling into a target that was preset.
Petropedia explains Measurement While Drilling (MWD)
When a wellbore is drilled, the trajectory of the hole is measured. The information collected is then used in pre-planned direction drilling to form a well which contains water, gas or oil. Natural gamma rays emissions are also measured to find out the type of rock formation being drilled. After the downhole measurements are done, they are stored in solid state memory for a short time and then transmitted to the surface. These data transmission methods are different in every petroleum manufacturing organization, but the organizations usually use digitally encoding data. They also transmit the measurements to the surface as the pressure increases in the mud system. The pressure could be negative or positive, or continuous sine waves.