Learning objectives
The Course aims to introduce students to knowledge and understanding of the "theory" at the base of the main geological and geophysical techniques for Subsurface Geology that, nowadays, represents one of the most important topic for the Earth Sciences and for Petroleum Exploration and for the subsurface in general.
Then, it aims to introduce to apply these knowledge to the reconstruction and representation of subsurface geological model.
Finally, it intends to make students able to compare, evaluate and criticize geological models reconstructed by means of different techniques either known during the course (Subsurface exploration methodologies - geophysical exploration and geological exploration) or known during previous years of education (surface geological techniques).
Prerequisites
Knowledge of Geophysics or Applied Geophysics
Course unit content
Introduction.
Subsurface exploration methodologies: seismic Reflection Survey; Seismic Refraction survey; Gravity and Magnetic Surveying; Introduction to Geophysical Borehole Logging.
Interpretation of seismic reflection profile: seismic stratigraphy; seismic structural styles.
Subsurface Geological Mapping.
Integration of Surface and Subsurface Geology.
Full programme
Introduction: aims and scope of the course; importance of the Suburface Geology in the Earth Sciences; main arguments treated; managing/planning of the lessons, exercises, study materials and field work; textbooks and suggested texts; modes for the final exam and evaluation criteria.
Subsurface exploration methodologies
- Geophysical vs geological exploration.
Geophysical exploration
- Seismic Reflection Surveying
Theory basis: elastic properties of the rocks; propagation of acoustic waves through rocks that are stratified and with different elastic properties;
The seismic reflection profile: reflectors and reflections; seismic waves and their description; horizontal and vertical resolution; coherent and non-coherent noise; signal/noise ratio; multiple, pegleg, diffractions.
The seismic profile: a) acquisition (technologies for land and marine acquisition; environmental impact and solution proposed); b) processing [signal processing; imaging (normal move out, static correction, velocity analysis; stacking)]; filtering, deconvolution; migration; c) display (variable area, wiggle, variable density).
- Seismic refraction Basic theory and case study
- Gravity Survey Basic theory and case study
- Magnetic Survey Basic theory and case study
- Introduction to Geophysical Borehole Logging. Basic theory on resitivity and electrical conductivity in rocks; diffetnt types of geophysical logging in boreholes: electric, nuclear, acoustic;
- Spontaneous potential log (SP) and its interpretation.
- Resistivity log (normal, lateral, induction and microresistivity/microlog) and its interpretation;
- Other geophysical logs and their use.
Geological exploration
- Well drill; different techonologies used for drilling wells; infrastructure and organization of well rigs.
- Composite/final log of exploration well and how to read it.
Interpretation of seismic reflection profile (with exercises on digitized seismic profile with the aid of drawing software)
- Seismic stratigraphic interpretation:
seismic facies;
seismic sequence;
seismic facies e seismic sequence in siliciclastic depositional system;
seismic facies e seismic sequence in carbonate depositional system;
principles of seismic sequence stratigraphy;
- Seismic interpretation of structural styles:
seismic reflection profile in extensional tectonics;
seismic reflection profile in compressional tectonics;
seismic reflection profile in transcurrent tectonics;
seismic reflection profile in salt tectonics and diapiric structures;
- Integration of stratigraphic and structural interpretation with well logs.
Subsurface Geological Mapping (with exercises carried out with the aid of dedicated software)
- Subsurface mapping of stratigraphic horizons;
- Subsurface mapping of isochronopach;
- Subsurface mapping of fault surfaces;
- Other types of subsurface maps.
Integration of Surface and Subsurface Geology (with fieldwork)
- Exercise on a case study with a) collection and synthesis of geological and geological maps, b) geological survey, c) interpretation of seismic reflection profile, d) integration of well logs. Definition of a geological model integrating surface-subsurface geology.
Bibliography
References Books
Bischke R. E., Metzner D., Tearpock D. J., Brenneke J. 2021. Applied Three-Dimensional Subsurface Geological Mapping: With Structural Methods, 3rd Edition. Pearson Editor.
Withjack M.A., Bally A.W. et al., Seismic Expression of Structural Styles,
Geol. Soc. Of America Short Course, USA.
Mussett A.E., Aftan Khan M., Looking into the Earth. Cambridge University Press
Asquit G. 2006. Basic Well Log Analysis for Geologists. AAPG,
USA.
Teaching methods
The course consists of oral lectures and practical activities concerning the interpretation of seismic reflection lines in different tectonics and stratigraphic frameworks.
Assessment methods and criteria
The final grading will be based on:
1) Practical exercises. Grades from 0 to 30.
The practical exercises will be carried out all along the duration of the course and they have to be submitted in their final form at least one week before the date of the oral examination.
2) oral examination of 30-45 minutes about the following topics:
a) knowledge and understanding of the theoric bases of the Subsurface Geological and Geophysical techniques. Grades from 0 to 30.
b) discussion concerning a practical exercise equal or very similar to practical exercise carried out during the course. For the evaluation of this part of the oral exam, it is taken into account the participation to the course during classes (frequencies of attendance, questions, participation to discussions). Grades from 0 to 30.
Online registration is requested for the oral examination.
The final grades is the calculated arithmetic mean of the grades obatined in the practical exercises (grade in point 1) and oral examination (grade in point 2a, 2b).
The final grade will be noticed at the end of the oral examination.
Other information
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2030 agenda goals for sustainable development
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