A Gentle Introduction to Electromagnetics (EM) in Geophysics

Course Description

Although in the search for hydrocarbons seismic plays the dominant role, complementary data can be very useful. A clear example is that seismic can clearly determine reservoir geometries based on acoustic impedance changes but is less sensitive to the pore-fluids. Electromagnetic measurements, such as Controlled Source EM (CSEM) measures resistivity directly and hence can discriminate between brine and hydrocarbon fill.

You might wonder about the poorer resolution of EM compared with seismic. Indeed, that is the case, but by combining the two independent sources of information, then seismic will give the structure (container) which then can be used as a constraint for the inversion of EM. Another application is in the realm of determining the shape of allochthone salt bodies below which hydrocarbons can be present. Numerous applications can be mentioned in relation to shallow seismic. An obvious one is the use of Ground Penetrating Radar (GPR) for investigating archaeological sites or determining the depth to upwelling deep salt-water due to severe pumping of fresh water for irrigation.

This course is unique in its hands-on exercises and its use of an open- source software Apps developed at UBC.

Course Objectives

Upon completion of this course, participants will be able to:

1. Interpret heuristically the basic equations governing EM phenomena;
2. Explain that EM characteristics/properties and uses depend on the frequency of the electromagnetic “wave”;
3. Define the realms of EM diffusion and EM wave propagation;
4. Understand how EM can be used in the search for hydrocarbons, investigating the shallow subsurface for the extend of pollution or salt water penetration;
5. Relate Induced Polarization to the presence of a working hydrocarbon system in the deeper subsurface.

Participants’ Profile

All those who are interested in understanding the use of Electromagnetic (EM) methods in Geophysical Applications. These are the geoscientists working in hydrocarbon exploration and exploitation as well as those applying shallow surface geophysics for detecting ore bodies, determining the extend of shallow pollution, foundation engineering, etc.

Prerequisites

Prerequisite is an intermediate level of understanding of physics and geophysics in the context of exploration and production of hydrocarbons and mitigation of pollution, including the issue of salt water penetration.

About the Instructor

Jaap Mondt acquired a MA Bachelor’s degree in Geology (University of Leiden), Master’s degree in Geophysics (University of Utrecht), PhD in Utrecht on “Full wave theory and the structure of the lower mantle”. He then joined Shell Research to develop methods for Quantitative Interpretation. Subsequently he worked in Shell Expro in London where he was actively involved in acquiring, processing and interpreting Offshore Well Seismic data. After his return to the Netherlands he headed a team for the development of 3D interpretation methods using multi-attribute statistical and pattern recognition methods. After a period of Quality Assurance of “Contractor” software for seismic processing, Jaap became responsible for Geophysics in the Shell Learning Centre. During that time, he was also part-time professor in Applied Geophysics at the University of Utrecht. From 2001 till 2005 he worked on the development of Potential Field Methods (Gravity, Magnetics) for detecting oil and gas. Finally, he became a champion on the use of EM methods and became involved in designing acquisition, processing and interpretation methods for Marine Controlled Source EM (CSEM). After his retirement, he founded Breakaway, providing courses on acquisition, processing and interpretation of geophysical data (seismic, gravity, magnetic and electromagnetic data).

In the last couple of years, Jaap developed a keen interest in the use of Machine Learning for Geophysical Applications and developed a practical Machine Learning course for Geophysicists and Interpreters.