Borehole Logging
Drill and Well Logs are essential in civil engineering, hydrogeological, geological, and petrophysical projects, as they help supplement preliminary desk studies and provide key numerical, groundwater, and lithological data about a borehole. However, the information provided by these logs is often limited. Additional data is required to better understand subsurface changes, including the fluctuation of groundwater over time.
Logging geophysics offers a solution by enabling the monitoring of a borehole site over time without further disruption to the surface. This technique measures the petrophysical response of the well and evaluates factors such as fluid quality, temperature, pressure, groundwater flow, and migration pathways.
Geophysical methods like resistivity, magnetics, and radiometry can be used to scan the borehole dimensionally and gather measurements that supplement preliminary test results. These measurements can provide insight into the geological composition, environmental impact, and stability of the site, as well as determine if groundwater well sites are at risk. Additionally, these geophysical profiles can be combined with near-surface 2D geophysical profiles to enhance cross-correlation, yielding more detailed information about the construction of the wells and any changes in the borehole’s character over time.
Mount Sopris has designed both standalone and Quick Link sondes that allow users to collect multiple geophysical (e.g., resistivity, magnetic, and radiometric) and mechanical measurements within the borehole. By combining probe sub-sections, these sondes provide continuous point measurements in digital format. This data can then be related to the physical and chemical properties of the lithological formations as a function of depth, as shown in Fig. 1 (Logger, Winch, Borehole Probe).
To operate the borehole sondes, it is essential to assemble the equipment (as shown in Figs 1 and 2) and ensure that the operator is fully trained before collecting any data. Once assembled, data can be acquired using a portable logger (either the Scout or Matrix logger), which connects to a Getac laptop equipped with Logger Suite and WellCAD software. The logger is linked to the winch and borehole sonde through a network cable and a single-core conductor cable, which includes a depth encoder. Additionally, a cable-to-cable stainless steel head, located at the top of the probe, is part of the setup.
All equipment must be powered via an inverter and can be controlled by a voltage regulator.
Inside each of the borehole sondes are the source, detectors, power supply, and electronics for transmitting and receiving electronic signals (360° around the probe axis). These components are designed for complete isolation and robust signal transmission, and they are built to withstand high pressure and temperature conditions.
