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Geophysical Surveys. Geophysics: the study of the physics of the earth, its oceans, and its atmosphere.What are petroleum geologists looking at?Earth's magnetismGravitySeismic vibrations / Vibrations of the earth. Geophysical Surveys. Types:Magnetic and Electromagnetic SurveysGravity Surveys
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1. Geophysical Surveys and Reservoir Development Tools Chapter 2 (Part 2)
2. Geophysical Surveys Geophysics: the study of the physics of the earth, its oceans, and its atmosphere.
What are petroleum geologists looking at?
Earth’s magnetism
Gravity
Seismic vibrations / Vibrations of the earth
3. Geophysical Surveys Types:
Magnetic and Electromagnetic Surveys
Gravity Surveys
Seismic Surveys
4. Magnetic and Electromagnetic Basement rock typically has magnetic properties
Typically Two Types of Surveys:
Magnetometer Surveys
Magnetollurics
5. Magnetometer Survey
6. Magnetotellurics The theory that rocks of differing composition have different electrical properties.
Geologist record and measure flow of electricity between rocks or across salt water.
Analyze and interpret the data to reveal subsurface structures.
7. Gravity Surveys Scientist look for slight variations in the earth’s gravitational field caused by the varying weight of rocks.
Very Dense rocks (Weigh more) near the surface exert a higher gravitational force than those of lower density.
Salt domes are associated with minimum gravity
Ordinary Domes and Anticlines are associated with maximum gravity
Tools of the trade:
Torsion Balance
Gravimeter ‘or’ Gravity Meter
8. Seismic Surveys (Seismology) Surveys taken by small artificial “seismic events” bounce energy through the earth’s surface.
Different layers in the earth “bounce” differently such as sand vs. rock.
Sensors “Geophones” pick up the reflected seismic waves and send them to a recorder.
Recorder “Seismograph” amplifies and records their characteristics called a seismogram
Seismogram generates a two dimensional slice of the earth from the surface downward called a seismic section.
9. Seismic Surveys (Seismology)
10. 3D Seismic Surveys http://www.youtube.com/watch?v=f1GeNljM0T8&feature=related
11. Early Methods Dr. L. Mintrop:
German Scientist who developed one of the first practical uses of seismic data.
He invented a portable seismograph.
Used it during World War 1
Determined the position of the allies artillery by setting up three seismographs opposite the enemy.
Later came to the Texas Gulf Coast and started the Gulf Production Company specializing in seismic exploration
12. Explosive Methods http://www.youtube.com/watch?v=jc38hj9JQ_4
13. Thumper Trucks (Vibroseis)
14. Marine Seismic Methods Typically same methods as on land, but it uses hydrophones (marine version of the geophone)
15. Questions Define Geophysics.
List and describe the three types of surveys.
What are the two types of Magnetic Surveying?
Is basement rock typically magnetic (yes/No)?
What is a gravity survey?
Define seismology.
List three different methods of seismic surveying.
How do “Thumper Trucks” create seismic activity in the earth’s surface?
What is a geophone called in offshore applications?
How do ships create the seismic “wave” in offshore seismic surveying?