DEVICE FOR LOGGING WELLS ENCASED IN METAL COLUMN Russian patent published in 2013 - IPC G01V3/20 

FIELD: electrical engineering.

SUBSTANCE: device includes a ground-based part and a downhole device with a multielectrode probe. The ground-based part consists of an on-board computer, a switching unit, an interface unit, a logging winch, a depth unit and the probe power supply as well as electrodes B and N_ud. The probe is represented by a group of five or more electrode packages serially arranged along the well axis. Positioned within the end packages of the electrodes group are current electrodes A1 and A2. The other electrode packages within the group are measuring ones (M1…Mn). The probe power points can be pressed to the column walls with the help of the electric drive with clamping mechanisms and penetrate into the column body with the help of in-built impact mechanisms. The downhole device includes a gamma logging unit, a collar locator and an accelerometer. With the help of the accelerometer, one controls the impact mechanisms operation quality. The switching unit enables the opportunity to transmit current between the current electrodes A1 and A2 and to power electrodes A1 and A2 relative to electrode B in three measurement cycles. Based on digitised results of the three measurement cycles, one determines specific electric resistance from the formula accounting for, among other things, the casing column diameter and.

EFFECT: formation resistivity.

2 dwg