METHOD OF DETERMINING FORMATION RESISTIVITY UTILIZING COMBINED MEASUREMENTS OF INDUCTIVE AND GALVANIC LOGGING INSTRUMENTS

摘要

A method of determining selected parameters of an earth formation (132) surrounding a borehole (135) by first obtaining at least one induction logging measurements of the selected parameters in a first predetermined volume (138-138') of the formation (132) surrounding the borehole (135) having known first radial and vertical dimensions, then obtaining at least one galvanic logging measurement of the identical selected parameters in a second predetermined volume (136) of the formation (132) surrounding the borehole (135) having known second radial and vertical dimensions that overlap the first radial and vertical dimensions of the first predetermined volume, whereby the overlapping volumes form a representative common volume (140) of the formati on (132), and then combining the induction and galvanic logging measurements using an inversion technique to obtain a measurement of the selected parameters of the earth formation (132) surrounding the borehole (135) in the representative common volume (140) of the formation (132).