Abstract
The recent introduction of a multiple depth of investigation Measurement While Drilling (MWD) resistivity tool has enabled several measurements and observations to be made that have previously not been possible utilizing either wireline or conventional 2 MHz MWD resistivity tools. The new sensor utilizes four transmitter-receiver spacings, which yield eight radial response characteristics; four using the phase-shift derived readings and four utilizing a combined phase/amplitude-attenuation method.