Shock downhole measurement

Measurements while drilling are made with sensors and downhole electronics that must operate in an environment where vibrations and shocks are sometimes extremely severe. A brief study of vibrations and shocks will be made to understand better the meaning of the specifications mentioned earlier. 

Downhole Shocks Measurements. An accelerometer in the MWD telemetry tool measures transverse accelerations, or shocks, that may be damaging for the bottomhole assemblies. When acceleration exceeds a certain threshold, the event is signaled to the surface as being a shock. These events versus time or depth are displayed as shock count. This information is used as a warning against excessive downhole vibrations and to alert the driller to change the rpm or weight on the bit [106]. 

Bit efficiency calculated in real time gives an indication that the drill bit is damaged and that cones may be lost. Downhole vibration and shock measurements are also valuable indicators used to avoid damaging the drillstring. 

Drilling surface data such as weight-on-bit and torque were difficult to interpret because they were loosely related to downhole values. MWD for the first time in the history of drilling gives values of parameters measured at the bit or close by. Rock strength, bit wear, drag and friction can be calculated in real time. Shocks, temperature and pressure can also be measured. 

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