Patent ID: 9377555
Filing Date: 2016-06-28
CPC Classification: E21B,G01V

Claim Text:
1. A method for well logging, comprising: (a) a step of selecting homogeneous measurement point, wherein an apparatus for well logging is configured to select two sequential measurement points to take at least two sequential measurements at each measurement point; (b) determining whether said selected two sequential measurement points may serve as selectable points of homogeneous formation according to the measurements at said two sequential measurement points, if yes, then proceeds to step (c); (c) deriving the amplitude ratio essential value and phase difference essential value of the signal response generated by the apparatus for well logging, which corresponds to the formation resistivity of the measured target formation, from said two selectable points of homogeneous formation; (d) deriving the amplitude ratio standard value and phase difference standard value corresponding to the formation resistivity of the measured target formation from said amplitude ratio essential value and phase difference essential value; (e) setting a layer-out threshold of the formation for said measured target formation according to said amplitude ratio standard value and phase difference standard value; (f) selecting a next measurement point to take at least two measurements at said next measurement point; (g) deciding whether the amount of variation in amplitude ratio and/or the amount of variation in phase difference of the induced electromotive force between a pair of receiving antennas of the apparatus for well logging at the current measurement point are greater than said layer-out threshold; if yes, then proceed to step (h); (h) it is determined that a formation with low-resistivity appears in front of the apparatus for well logging.