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Oil well logging is a technique for finding hydrocarbon zones in the geological formations below the Earth's crust. As the well is being drilled, a probe that contains both an energy source (neutron or gamma ray) and a detector (photomultiplier with scintillator) is lowered into the well. The detector measures the amount of radiation that scatters back from the well's surroundings. This will indicate the porosity and permeability of the rock, and help determine whether oil can be removed. In addition to this task, the photomultiplier tube can also detect gamma rays that naturally occur in shale deposits, which in turn indicate the presence of oil or gas.
The depth of a well can range from 300 to over 7,000 meters. At these depths, temperatures may reach up to 200 degrees Celsius, which means that the detector in the probe must be able to withstand high heat. The detector must also be very robust because the probe is lowered into the well as it is being drilled, so there are extreme levels of vibration to contend with.
Hamamatsu has designed dozens of ruggedized photomultiplier tubes that can handle such harsh operating conditions. These special-purpose PMTs include special heat-resistant photocathodes and dynodes, and an electrode structure that is fortified against the effects of thermal expansion, shock, and vibration. Some models are further reinforced to withstand the higher levels of shock and vibration associated with measurement-while-drilling (MWD) applications.
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"Ruggedized High Temperature Photomultiplier Tubes" catalog in PDF format.
Contact us for information on other products which can be used for this application.
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