Gravity & Magnetic Data Acquisition, Processing, and Interpretation

Trainer(s): Jaap Mondt

Course content

What kinds of Geophysical Data could be used?

Various kinds of geophysical data are available. They are separated into Seismic and Non-Seismic data. Seismic is, without any doubt, the main method used in the oil and gas industry. But Non-Seismic data (gravity, magnetics, electrical, electromagnetics, spectral, etc.) is the main source of information in shallow subsurface applications (engineering, mapping pollution, archaeology). It is also used at the early reconnaissance of hydrocarbon plays and in mapping prospects below salt. However, seismic has its limitations and therefore also non-seismic methods are used successfully as complementary tools in subsurface evaluation. In combination with seismic data, they can significantly reduce the uncertainty of subsurface models as they measure different physical properties of the subsurface. Another important application is in determining the depth to basement.

The Course

The potential of gravity and magnetics will be discussed.

In part 1, various aspects of gravity will be discussed, based on an EAGE publication, such as the Earth gravity field, determining anomalies in the global field, establishing the depth of density anomalies, be it spherical or anticlinal and the resolution, which is limited because of it being a potential field described by a 1ste order differential equation. Most promising is the development of gravity gradiometry, whereby gradients in the gravity field can be directly measured. These are less sensitive to airplane and ship movement.

In part 2, the Earth's magnetic field will be studied. Being due to the internal dipole source, direct interpretation of magnetic (dipole) data is inherently more difficult than (monopole) gravity data. As different causative sources can produce the same surface measurements, non-uniqueness in the interpretation is even more severe than for gravity data. However, promising developments to mitigate these issues will be discussed.

The course

There are two types of courses, one F2F (classroom) and the other virtual using the internet. In both courses Gravity and Magnetic applications will be discussed using lectures and by making many practical exercises. In addition, you will benefit from Moodle facilitating interactions with other participants. In case of the virtual version you can submit your questions in the discussion panel or your solutions of the exercises and receive feedback.

Learning, methods and tools

Learning methods and tools

The course uses a Blended Learning approach based on a user-friendly Learning Management System, called Moodle. In Moodle different modules provide study material, videos, and exercises. The solutions to these exercises can be checked and if the exercise is not clear or the solution cannot be found you can submit your "solution" and ask for feedback. Also, each part contains a quiz which is meant to reinforce the learning. The quiz consists of multiple-choice questions.  For each question, all answers can be tried. The idea is that if the answer is not correct, one can go back to the course material to find out what the right answer should be. So, it is not an exam.

Day by day programme