Patent ID: 7010429

Claim:
A method for correcting skin effect in a induction logging system, said method comprising the steps of: measuring first, second and third apparent conductivities at first, second and third operating frequencies, respectively; determining first, second and third weighting coefficients; determining first, second and third weights; determining a first low-pass filtered conductivity difference between the measured first and second apparent conductivities; determining a second low-pass filtered conductivity difference between the measured second and third apparent conductivities; determining a third low-pass filtered conductivity difference between the measured first and third apparent conductivities; determining a first corrected conductivity from the measured first, second and third apparent conductivities, the first, second and third weighting coefficients, and the first weight; determining a second corrected conductivity from the first corrected conductivity, the second weight, the third low-pass filtered conductivity difference, and the first and third operating frequencies; determining a third corrected conductivity from the second corrected conductivity, the first low-pass filtered conductivity difference, the second low-pass filtered conductivity difference, the first, second and third operating frequencies, and the third weight; determining first, second and third compensated conductivities from the first, second and third corrected conductivities, respectively, and values from a look-up table; determining selection coefficients; and determining a formation corrected conductivity by summing the selection coefficients combined with the first, second and third compensated conductivities.