MEASUREMENTS WHILE DRILLING (MWD) BASICS
Measurement While Drilling (MWD) Is a term used to describe drilling related measurements made at the surface or made downhole and transmitted to the surface while drilling a well. The terms MWD and LWD are sometimes used interchangeably, but we like to think of LWD as the process of obtaining information about the rocks (porosity, resistivity, etc) and MWD as obtaining information about the progress of the drilling operation (rate of penetration, weight on bit, wellbore trajectory, etc). MWD today often refers to geosteering measurements made to help decide on changes to the wellbore path.
The measured data are stored in LWD and MWD tools and some of the results can be transmitted digitally to surface using mud-pulse telemetry. 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 the drill pipe. These messages allow the drill bit to be steered in a desired direction. Most MWD tools contain an internal gamma ray sensor.
MWD tools are generally capable of taking directional surveys in real time. The tool uses accelerometers and magnetometers to measure the inclination and azimuth of the wellbore at a location, and they then transmit that information to the surface. With a series of surveys at appropriate intervals, anywhere from every 30 ft (10 m) to every 500 ft, the location of the wellbore can be calculated.
The primary use of real-time surveys is in directional drilling. For the directional driller to steer the well towards a target zone, he must know where the well is going, and what the effects of his steering efforts are.
Use of this information can allow the operator to drill the well more efficiently, and to ensure that the MWD tool and any other downhole tools, such as mud motors, rotary steerable systems, and LWD tools, are operated within their technical specifications to prevent tool failure.
Petro Tech M.E Team is planning to acquire the latest technology in this field to serve the best service to clients.