Geophysics Flashcards
a subject of natural science concerned with the physical processes and physical properties of the Earth and its surrounding space environment and the use of quantitative methods for their analysis
Geophysics
Sub discipline of Geophysics
- Global Geophysics
- Exploration Geophysics
- Geotechnical & Environmental Geophysics
Sample of Global Geophysics
Structure of the Earth
Samples of Exploration Geophysics
- Petroleum Geophysics
- Mining Geophysics
- Groundwater Studies
Samples of Geotechnical & Environmental Geophysics
- Site investigations
- Contaminant Studies
- Archaeological Investigation
geophysics that focus on structures that trap oil
Petroleum Geophysics
geophysics that focus on detection of ore bodies
Mining Geophysics
geophysics that focus on the depths, thickness
Groundwater studies
geophysics that focus on mechanical properties and depth
site investigations
geophysics that focus on detection and flow direction
Contaminant studies
its objective is to locate or detect the presence of subsurface structures or bodies and determine their size, shape, depth, and physical properties
Geophysics
detected when a survey encounters some geometric perturbation in the distribution of a particular physical property in the rocks
Geophysical Anomaly
Arise due to lateral perturbations in rock density, magnetic ones are caused by lateral changes in rock magnetization, and seismic anomalies indicate variations in acoustic impedance
Gravity Anomalies
objective of the survey; due to the causative or target body
Signal
Anything else measured but which may not contain useful information
Noise
is of most concern in geophysical surveys
S/N ratio
utilizes natural fields of the earth
Natural
Involves generation a field using an artificial source
Artificial
Fluctuating Measurements (e.g. lightning strokes, magnetic storms, earthquakes, typhoons)
Natural Disturbance
Man made structures (e.g. powerlines, buried metal pipes, metallic objects on the ground)
Artificial Disturbance
Variable thickness of overburden, presence of non-economical minerals in the overburden or overlying layers
Geological Noise
Remedy for Natural Disturbance
Discontinue Measurement
Remedy for Artificial Distubance
Stay away from source of noise
Remedy for Geological Noise
Mathematical Correction
best applied to flat or gently undulating terrain
Ground
For large or heavily forested areas
Airborne
For offshore Investigations
Marine
Records one or more physical properties as a function of depth
Borehole
