Glossary of Geophysical Terms
A |
B |
C |
D |
E |
F |
G |
H |
I |
J |
K |
L
M |
N |
O |
P |
Q |
R |
S |
T |
U |
V |
WXYZ
E
Effective porosity
The amount of interconnected pore space through which fluids can pass. Effective porosity is usually less than total porosity because some dead-end pores may be occupied by static fluid.
Elastic moduli (elastic constants)
Elastic moduli specify the stress- strain properties of isotropic materials in which stress is proportional to strain. They include bulk and shear moduli.
Electric field
A vector field describing the force on a unit electrical charge [newtons/coulomb = volts/meter].
Electrical logs
Provide information on porosity, hydraulic conductivity, and fluid content of formations drilled in fluid-filled boreholes. This record is based on the dielectric properties (e.g., electrical resistivity) of the aquifer materials measured by geophysical devices lowered down boreholes or wells.
Electrode
A piece of metallic material (typically stainless steel) acting as an electric contact with a non-metal substance.
Electromagnetic-casing inspection log
The effects of eddy currents on a magnetic field are used to provide a record of the thickness of the casing wall.
Electromagnetic method
A method which measures magnetic and/or electric fields associated with subsurface currents.
Electron volt
The energy acquired by an electron passing through a potential difference of one volt (eV); used for measuring the energy of nuclear radiation and particles, usually expressed as million electron volts (MeV).
Equipotential map
A plot in which points of equal hydraulic head are connected.
