Basic Geophysical Data Acquisition and Processing
Course Description
This course treats various geophysical methods, from gravity to magnetics, electrical, electro-magnetic, refraction and reflection seismic. It will be taught not only by explaining and discussing the methods, but above all by applying the theory in mainly Excel based assignments. Various kinds of geophysical data are available. They are usually separated into Non-seismic and Seismic data. Non-seismic data (gravity, magnetics, electrical, electromagnetics, spectral, etc.) is the main data used in shallow subsurface applications (engineering, mapping pollution, archaeology, etc.) and at the early exploration stage in the search for oil, gas or minerals. Seismic is the main subsurface evaluation tool for the EP industry, but it has its limitations. Therefore, non-seismic methods are used successfully as complementary tools at the more mature exploration stages and even for production. In combination with seismic data they can significantly reduce the uncertainty of subsurface models as they measure different physical properties of the subsurface. Controlled Source EM, for example, responds to reservoir resistivity and can thus be used to differentiate between hydrocarbons and brine in a geological structure mapped by seismic. The main topics covered by the programme are: • Gravity surveying • Magnetics surveying • Electrical surveying • Electro-Magnetic surveying, including Ground Penetrating Radar • Acquisition of shallow refraction seismic data • Acquisition of reflection seismic data • When to use 2D, 3D and 4D seismic / non-seismic • Principles of wave propagation • Basic designs of 2D and 3D seismic acquisition • Processing of seismic and GPR data with the objectives of improving signal-to-noise ratio, vertical and lateral resolution • From simple migration to Imaging • Result in depth (Time-to-Depth conversion) • What to spend on a new survey, be-it a new survey or a reprocessing or re-interpretation project. Hence, to determine whether the expected reward (increase in value) is higher than the cost of the project. In short, what is the value of the new information obtained (VOI: Value Of Information)
Course Objectives
At the end of the course, participants will have a good understanding of what information various geophysical data can give and for what purposes it can be used. This will enable them to specify the requirements for a survey or a reprocessing or interpretation project, either done in-house or by a specialised service provider. Other benefits include: • Place and value geophysical activities in a multi-disciplinary context • Judge the merits of various geophysical techniques • Better liaise and collaborate with staff in related disciplines • Recognise artefacts and direct hydrocarbon indications on seismic • Value novel developments such as time lapse methods for hydrocarbon reservoir monitoring or pollution control.
Course Outline
• Part 1: The principles and limitations of Geophysical methods • Part 2: Gravity surveying, Magnetic surveying, Electrical surveying • Part 3: Electro-Magnetic surveying • Part 4: Seismic Refraction surveying • Part 5: Seismic Reflection surveying • Part 6: Value of undertaking a new project (VOI)
Participants’ Profile
The course is designed for Geologists, Geophysicists and Petroleum Engineers involved in exploration and development of oil and gas fields and for those involved in projects related to the shallow subsurface (monitoring pollution). In addition, it would be useful for those dealing with the effects of production of a field (subsidence, earth tremors).
Prerequisites
A reasonable level of understanding of mathematics and physics is assumed.
Recommended Reading
An Introduction to Geophysical Exploration, Kearey, Brooks, Hill, ISBNB0-632-04929
About the Instructor
Dr Jaap C. Mondt obtained a Bachelors degree in Geology at the University of Leiden followed by a Masters degree in Theoretical Geophysics and a PhD on “Full wave theory and the structure of the lower mantle” at the University of Utrecht. Dr Mondt then joined Shell Research in The Netherlands to develop methods to predict lithology and pore-fluid based on seismic, petrophysical and geological data. Subsequently he worked at Shell Expro in London to interpret seismic data from the Central North Sea Graben. After his return to The Netherlands, he headed a team for the development of 3D interpretation methods using multi-attribute statistical and pattern recognition analysis on workstations. After a period of Quality Assurance of “Contractor” software for seismic processing, he became responsible for Geophysics in the Shell Learning Centre. During that time he was in addition 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) and EM methods (CSEM) for detecting oil and gas. After his retirement from Shell, he founded his own company (Breakaway), specialised in courses on acquisition, processing and interpretation of geophysical data (seismic, gravity, magnetic and electromagnetic data). In addition to providing support to the Shell Learning Centre, he gives his own courses to International as well as National energy companies.