Measuring device recording various well-related and reservoir-related data (called well logs) while travelling along the borehole.
Downhole logging tools are divided into two categories:
| Surface Read Out logging tools | Memory logging tools |
|---|---|
| which are powered and commanded via braided line from the surface and send the data readings to the surface in real-time | which are battery powered and record the data readings in built-in memory and only use wireline as the tool carrier |
The downhole logging tool consists of the following components (courtesy of ZSCAN):
| A pair of downhole logging tools in transportation case | A pair of fully assembled tools with two cable heads | ||
 |  | ||
| Partially Disassembled Tool | High Pressure Housing | ||
 | Protecting the tool electronics from mechanical, pressure and chemical impact |  | |
| Cable Head | Bullnose | ||
| Providing the connection to the cable, can be a removable component or a welded element of the housing |  | Protecting the sensors from mechanical exposure |   |
| Junction cross-over | Tool assembly without a Housing | ||
| Connecting one tool with another |  |
| |
| Sensors unit | Electrical Circuit Board | ||
| Providing the electrical response to the corresponding physical property of the surrounding media |    | Providing the recording of the sensors' data, primary processing and data transfer to desktop computer |  |
| Battery unit (in case of Memory Logging) | Modem unit (in case of Surface Read Out Logging) | ||
| Providing the electrical power for Electrical Circuit Board in case of |
| Providing the electrical power for Electrical Circuit Board and data transfer between the tool and surface and Surface Read Out Panel | |
See Also
Petroleum Industry / Upstream / Data Acquisition / Well & Reservoir Surveillance / Well Logging