Know All About ‘measurement While Drilling’

Specific to the oil industries, ‘measurement while drilling’ is a system that is developed for the purpose of carrying out drilling connected measurements downhole as well as to transmit information to the surface while the activity of drilling is on. These systems take several measurements such as directional survey, borehole pressure, natural gamma ray, too face, torque, shock, vibration, temperature and much more. With the latest technology, now some of these tools can also be used to measure formation pressure and take some of their samples! Once the measurement is done, the results are stored in the tool while some results can also be transmitted to the surface digitally with the help of mud pulser telemetry.

These tools are either contained in a drill collar or are in-built in the drill itself. It is amazing to know that some of these systems also have the ability to receive encoded control-commands that are in turn sent by turning on and off the mud pumps or even by altering the rotation speed of the drill pipe.

The Kind Of Information Transmitted

As was mentioned earlier, these MWD tools not only take measurements but also help transmit information. By and large, there are three kinds or rather types of information that are transmitted by them viz. directional information, the drilling mechanics information and the formation properties! Talking of directional information, these tools are capable enough of taking directional surveys in real time. It uses the magnetometers and accelerometers in order to measure the inclination as well as the azimuth of the borewell and then this information is transmitted upward to the surface. These real-time surveys are helpful in directional drilling! So it is evident that the system comprises of tools that are extremely complicated pieces of high-tech electrical.

Then, the measurement while drilling tools also provide drilling mechanics information which mainly comprises of the conditions at the drill place. The information features knowledge of the rotational speed of the drill string, the smoothness of that rotation, the type and severity of any vibration detected downhole, the volume of mud flow, temperature conditions downhole as well as the torque and weight on bit. This information becomes extremely vital for the operator to ensure that the tools used downhole (such as rotary steerable systems, mud motors and LWD tools) are functioning within their technical abilities; this helps prevent any tool failure.

And then, information on the formation properties is also transmitted. Measurements of the formation properties assembled into a log are transmitted either by the tools themselves or in conjunction with distinct logging while drilling tools (also known as LWD tools). These latter tools measure the geological features such as the porosity, density, resistivity, inclination at the drill, acoustic-caliper, the formation pressure as well as magnetic resonance. It is the MWD tools that permit such measurements to be taken and transmitted while the well is drilled.

Talking of measurement while drilling on a whole, this can be economical and cost-effective in exploration wells, especially in places such as Gulf of Mexico where well are drilled in salt-diapirs areas!

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