c425b8c8d4041659ffff814cffffe41e Seismic Energy sources.ppt

Seismic Energy sources

1. Chapter 2 (Part 2)

2. 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. Types:
Magnetic and Electromagnetic Surveys
Gravity Surveys
Seismic Surveys

4. Basement rock typically has magnetic
properties
Typically Two Types of Surveys:
Magnetometer Surveys
Magnetollurics

5. -Magnetometer is
towed behind an
airplane or ship.
-Transmits data
to an onboard
computer that
records the data.
-Micromagnetic
Technique is used
to determine
micromagnetic
anomalies or
deviations

6. 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. 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. 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.

10. http://www.youtube.com/watch?v=f1GeNljM
0T8&feature=related

11. 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. http://www.youtube.com/watch?v=jc38hj9JQ
_4

14. Typically
same
methods as
on land, but it
uses
hydrophones
(marine
version of the
geophone)

15. 1.Define Geophysics.
2.List and describe the three types of surveys.
3.What are the two types of Magnetic Surveying?
4.Is basement rock typically magnetic (yes/No)?
5.What is a gravity survey?
6.Define seismology.
7.List three different methods of seismic surveying.
8.How do “Thumper Trucks” create seismic activity in
the earth’s surface?
9.What is a geophone called in offshore applications?
10.How do ships create the seismic “wave” in offshore
seismic surveying?