Difference between revisions of "Dictionary:Apparent resistivity/es"

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1. Resistividad de una Tierra isótropa, homogénea que daría la misma relación voltaje-corriente medida. Resistividad aparente de corriente directa, ρsub>a es una relación de la ley de Ohm sobre el voltaje medido V aplicado a una corriente l, multiplicado por una constante geométrica k que depende en el arreglo de electrodos: ρa=kV/l. A menudo tiene unidades de ohm-metros. Ver resistivity.

2. With electromagnetic methods, quantities such as the moduli of the electric and magnetic field intensities (E and H) are measured at a certain frequency or time. If the subsurface were homogeneous and isotropic, these would yield the true resistivity via a certain equation. However, use of the same equation for a heterogeneous subsurface yields the ‘‘apparent’’ resistivity ρa:

${\displaystyle \rho _{\mathrm {a} }={\frac {\rho _{\mathrm {HS} }F(V)}{F(V_{\mathrm {HS} })}}}$

where ρHS=resistivity of a homogeneous half-space, F is a function of V=observed voltage, and VHS=voltage for a half-space. Asymptotic definitions such as late-time and early-time apparent resistivity are sometimes used for apparent resistivity values over a limited range of measurement parameters. For some EM models apparent resistivity may be undefined or multivalued. See Spies and Eggers (1986)[1] and Strack (1992)[2].

3. The resistivity recorded by an electrical log that differs from the true resistivity of the formation because of the presence of mud column, invaded zone, influence of adjacent beds, etc.

References

1. Spies, Brian R.; Eggers, Dwight E. (1986). "The use and misuse of apparent resistivity in electromagnetic methods". GEOPHYSICS (Society of Exploration Geophysicists) 51 (7): 1462–1471. doi:10.1190/1.1442194.
2. Strack (1992). Exploration with deep transient electromagnetics. Amsterdam New York: Elsevier. ISBN 978-0-444-89541-7.