Understanding underground geological conditions is an important part of planning construction, mining, water, environmental, energy, and infrastructure projects. While drilling provides access to the subsurface, additional measurements are often needed to understand what is happening beyond the visible core or borehole. This is where wireline borehole logging becomes an important investigation technique.

Robertson Geo has more than 45 years of experience developing, manufacturing, and supplying wireline borehole logging probes, technologies, and associated equipment. Its systems are used for applications including geotechnical investigations, hydrology, environmental studies, mineral evaluation, hydrocarbon exploration, and geoscience research.

Understanding Wireline Borehole Logging

Wireline borehole logging involves lowering specialised instruments into a borehole to collect measurements at different depths. Instead of relying exclusively on physical samples, geophysical probes can provide continuous information about the formations and conditions encountered along the borehole.

Different probes measure different properties. Depending on the project, logging can provide information about electrical resistance, natural gamma activity, borehole geometry, acoustic properties, fluid characteristics, geological structures, and other subsurface conditions.

This makes borehole logging a flexible technology that can be adapted to a wide range of investigation objectives.

Borehole Imaging and Structural Investigation

Understanding fractures and geological structures can be particularly important for geotechnical projects. Borehole imaging tools can create detailed representations of the borehole wall, allowing specialists to examine geological features that may not be fully understood through conventional sampling alone.

Robertson Geo's borehole structure logging portfolio includes the High Resolution Acoustic Televiewer, High Resolution Optical Televiewer, 4-Arm Dipmeter, Sonar Caliper, RGeo-eye borehole camera, and 4-Arm Caliper. These instruments are designed for different types of structural and geometric investigations.

For example, the High Resolution Acoustic Televiewer provides an oriented ultrasound image of the borehole wall, while the High Resolution Optical Televiewer provides an oriented optical image. Such tools can assist professionals in evaluating fractures, formation structures, and borehole conditions.

Electrical Borehole Measurements

Electrical logging is another important part of geophysical investigation. Electrical techniques measure properties associated with the formation surrounding a borehole and can help distinguish geological conditions.

Robertson Geo offers several electrical logging options, including Electric Log, Induced Polarisation, Focussed Electric, Magnetic Susceptibility, Microresistivity, and Dual Focussed Induction probes.

These tools can be selected according to the geology, borehole characteristics, and objectives of a particular investigation. Electrical measurements may be especially useful when investigating water-bearing formations, mineralised rocks, or geological boundaries.

Lithology Logging

Lithology logging focuses on identifying and characterising geological formations encountered by a borehole. Geophysical measurements can provide information that complements geological observations and other investigation data.

Robertson Geo's lithology logging range includes Natural Gamma, Spectral Gamma, and Ultra-Slim Gamma probes. These instruments measure radiation-related properties associated with formations surrounding the borehole.

Combining lithological information with other measurements can help create a more comprehensive subsurface dataset.

Applications in Geotechnical Engineering

Geotechnical investigations require an understanding of the physical characteristics and geological structure of the ground. Reliable information about rock strength, fractures, borehole geometry, and formation conditions can contribute to engineering assessments.

Robertson Geo states that wireline borehole logging can provide information relevant to rock strength and fractures, which can be important when determining locations and designs for new construction and foundations.

The company's PS Logger is another example of specialised geophysical technology. It is designed to measure P-wave and S-wave velocities in soils and rock formations. Robertson Geo describes applications in offshore wind development as well as other geotechnical investigations.

Supporting Water and Environmental Projects

Borehole logging is also valuable for water-well and environmental investigations. Understanding fluid movement, temperature, conductivity, water quality, and aquifer conditions can be essential when evaluating groundwater systems.

Robertson Geo provides probes for measuring fluid temperature and conductivity, vertical flow, water quality, and fluid or gas samples. Its fluid-property logging technologies are designed for applications including identifying aquifer locations, assessing flow rates, investigating contamination levels, and examining potential casing leaks.

These measurements can provide additional information that supports groundwater investigations and environmental assessments.

Mineral Exploration and Mining

Mining and mineral exploration projects often require detailed information about geological formations and mineralised zones. Geophysical logging can complement drilling and geological sampling by providing continuous measurements along the borehole.

Robertson Geo offers mineral logging technologies including Spectral Gamma, Formation Density, Gyro/Magnetometer, Induced Polarisation, Magnetic Susceptibility, and specialised density tools.

Borehole direction surveys, fracture analysis, hydrogeological investigations, and geotechnical studies can also form part of mining-related logging programmes.

Borehole Casing and Geometry

Borehole condition can influence the quality and interpretation of an investigation. Measuring borehole diameter, inclination, direction, and other geometric characteristics can therefore be an important part of a logging programme.

Robertson Geo's casing and geometry technologies include 3-Arm Caliper, Gyro, Borehole Geometry, Full Waveform Sonic, Verticality, and Sonar Caliper tools.

These technologies can help identify variations in borehole geometry and provide information required for more detailed analysis.

Equipment, Rental, and Professional Services

Not every organisation needs to purchase a complete logging system. Project requirements, duration, location, and available technical expertise can all influence whether equipment purchase, rental, or a professional logging service is appropriate.

Robertson Geo provides equipment for sale or rental as well as ground investigation services. Its enquiry process allows customers to specify project information such as borehole diameter, depth, casing type, borehole fluid, industry application, and required downhole measurements.

Training is another part of the service offering. Customers can seek support for equipment operation, logging techniques, data collection, and other practical requirements.

Calibration and Data Quality

The usefulness of geophysical measurements depends heavily on appropriate equipment performance and data quality. Calibration and verification are therefore important considerations when planning a logging programme.

Robertson Geo describes a dedicated test-well facility used to verify tool operation and measurement calibration before equipment is accepted for use. The company also states that verification reports and calibration records can be made available on request.

Its 2026 information on probe calibration describes the use of an on-site test borehole at its manufacturing facility and a conformance process for probes sold, rented, or used by its service teams.

Selecting the Right Logging Technology

The right logging equipment depends on the objectives of the investigation. A project focused on groundwater may require different measurements from a mineral exploration programme or an offshore geotechnical investigation.

Important considerations can include:

• Borehole diameter and depth
• Open-hole or cased-hole conditions
• Borehole fluid
• Geological formation
• Required measurements
• Project location
• Data processing requirements
• Equipment rental or purchase requirements
• Operator training and technical support

A clear understanding of the investigation objectives helps ensure that the selected probes produce information relevant to the project.

Conclusion

Wireline borehole logging provides a practical way to gather detailed subsurface information from drilled boreholes. By combining different geophysical measurements, investigators can develop a broader understanding of geological structures, formation properties, groundwater conditions, borehole geometry, and other underground characteristics.

Robertson Geo offers a broad portfolio of borehole logging probes covering structural imaging, electrical measurements, lithology, fluid properties, minerals, casing, and geotechnical applications.

With decades of experience in geophysical technology and a range of equipment, rental, training, and field-service options, Robertson Geo supports organisations carrying out subsurface investigations across multiple industries and geographical locations.