Geosciences
Electrical Resistivity Methods
An applied programme in resistivity surveying: measurement principles, the design of vertical electrical soundings and 2D and 3D electrical resistivity tomography, processing and inversion, and the interpretation of results in groundwater exploration and engineering and environmental studies.
Overview
About the programme
Duration
3 days
Delivery
Training room with field work
Language
Arabic or English
Objectives
Training outcomes
- Understand the resistivity of rocks and soils and what controls it: porosity, saturation, water salinity and clay content.
- Select the right electrode array (Wenner, Schlumberger, dipole-dipole, pole-dipole and gradient) and spacing for the required depth and resolution.
- Design a vertical electrical sounding or a 2D or 3D resistivity profile and carry it out in the field with quality control of the measurements.
- Clean the data, run the inversion and assess the model by data misfit and depth of investigation.
- Interpret the models against geological information and borehole data, and write the survey report.
Content
What the programme covers
Day 1: physical basis and vertical sounding
- Ohm’s law, apparent resistivity and the geometric factor of the electrode array.
- Resistivity of rocks, soils and water, and Archie’s law.
- Vertical electrical sounding: sounding curves and their interpretation with layered models.
- Induced polarisation (IP): measuring chargeability and what it indicates about clays and metallic minerals.
Day 2: electrical resistivity tomography
- Electrode arrays compared for sensitivity, resolution, depth of investigation and signal-to-noise ratio.
- Planning profiles and 3D grids, contact resistance, stacking, and reciprocal measurements to estimate error.
- Field exercise: acquiring a resistivity tomography profile and documenting its data.
Day 3: processing, inversion and interpretation
- Data cleaning, removal of outliers and topographic correction.
- Smoothness-constrained least-squares inversion, data misfit and the depth of investigation index.
- Case studies: aquifers, saline intrusion, karst cavities, depth to bedrock and landfill leachate.
- Writing the survey report, followed by the assessment.
Who it is for
Target audience
Geophysicists, geologists and hydrogeologists, geotechnical and environmental engineers, and technicians who carry out resistivity surveys or review their reports in government bodies and consultancies.
Method
Delivery method
A short theoretical introduction followed by field acquisition of at least one profile, then processing and inversion on the computer. Field work uses the organisation’s equipment where available; equipment and site arrangements are agreed with the organisation before delivery. Participants may bring data from earlier surveys for analysis. Delivered in Arabic or English.
Questions
FAQ
How does this programme differ from Fundamentals and Applications of Geophysical Surveying?
The fundamentals programme presents the main geophysical methods and how to specify a survey, for those who commission surveys or use their results. This programme goes deep into the resistivity method alone: design, acquisition, processing, inversion and interpretation.
Can we work on data from our own earlier surveys?
Yes. The organisation’s survey data can be used in the processing and inversion exercises if it reaches the centre before delivery, together with any available borehole logs and geological information.
What background is needed?
A grounding in general geology or geotechnical engineering is enough; the programme starts from the physical principles of the measurement.
A programme tailored to your organisation
The duration and topics of the programme are adjusted to the organisation's needs, and it is delivered at its site, in a training hall arranged by the Center, or virtually.