METHOD FOR ELECTRIC LOGGING OF CASED WELL Russian patent published in 2009 - IPC G01V3/20 

FIELD: physics, measurement.

SUBSTANCE: invention is related to the field of geophysical surveys of wells and may find application in determination of electric resistance of rock beds that surround well cased by metal column. Prior to logging performance, one or more breaks of electric connections are arranged between part of cased well in interval of logging performance and other parts of cased wells. In process of cased well logging, probe is installed in well, and probe consists of three or more equidistant metering electrodes and two or more current electrodes installed outside the limits of metering electrodes zone symmetrically relative to medium metering electrode. Electric current is supplied to column via every of two current electrodes alternately from one and the same pole of electric current source. During every session of current supply, potential of column electric field is measured in point of one of metering electrodes, as well as the first difference of potentials in column section between two extreme metering electrodes and the second difference of potentials at the same section of column, and specific electric resistance of rock behind column is defined. Metering electrodes are arranged in the form of cylinders and are freely placed in well without special pressing to cased well. Logging is performed continuously during upward motion of probe in well.

EFFECT: increased accuracy and faster performance of logging.

3 cl, 1 dwg