Inversion of two-dimensional resistivity and induced-polarization data
- Phoenix Geophysics Ltd., Willowdale, Ontario
A fast ridge regression inversion technique was devised for the interpretation of simple two-dimensional resistivity and induced-polarization data. The program will determine the rectangular source under a single layer of overburden which best fits the observed data. Unfortunately, each ridge regression inversion requires a great many forward problem evaluations. One method to reduce the calculation time is to store in the computer a data bank containing solutions for the entire range of expected parameter combinations. The forward problem then reduces to numerical interpolation between these precalculated data sets. For compilation of the data bank of forward solutions, two main numerical methods were investigated: the finite element and transmission-surface algorithms.The efficiency of either method depends mainly on the scheme chosen for solving the resultant large system of linear equations. Once the data bank has been created, it is possible to obtain inverse solutions for less cost than the computation of one finite element or transmission-surface forward problem. Tests on theoretical data and field data show the inversion technique to be reasonably accurate, stable, and fast. The statistics estimated by the inversion program provide additional useful information on the uncertainty in the parameters of the derived model and on high correlations between parameters. The most highly correlated parameters are the resistivity and the width of thin conductive bodies. Two practical methods for carrying out inversion in spite of highly correlated parameters are, preferably, to add extra data sets which provide more information on some of the parameters or, alternatively, to fix some of the parameters at geologically reasonable values and invert to a more restricted model. 23 figures, 1 table.
- OSTI ID:
- 5828571
- Journal Information:
- Geophysics; (United States), Vol. 43:4
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ELECTRICAL SURVEYS
DATA PROCESSING
ALGORITHMS
ARGENTINA
BRITISH COLUMBIA
ELECTRIC CONDUCTIVITY
ELECTRIC IMPEDANCE
EXPERIMENTAL DATA
FINITE ELEMENT METHOD
GRAPHS
INTERPOLATION
NORTHWEST TERRITORIES
POLARIZABILITY
QUEBEC
TWO-DIMENSIONAL CALCULATIONS
WESTERN AUSTRALIA
WISCONSIN
AUSTRALASIA
AUSTRALIA
CANADA
DATA
DATA FORMS
ELECTRICAL PROPERTIES
GEOPHYSICAL SURVEYS
GREAT LAKES REGION
IMPEDANCE
INFORMATION
LATIN AMERICA
MATHEMATICAL LOGIC
NORTH AMERICA
NUMERICAL DATA
NUMERICAL SOLUTION
PHYSICAL PROPERTIES
PROCESSING
SOUTH AMERICA
USA
580203* - Geophysics- Geophysical Survey Methods- (1980-1989)