US 11,988,800 B2
Common mode rejection method and apparatus for electromagnetic induction logging
Guoyun Guan, Chengdu (CN); Min Meng, Chengdu (CN); Jun Hu, Chengdu (CN); and Zaiping Nie, Chengdu (CN)
Assigned to University of Electronic Science and Technology of China, Chengdu (CN)
Filed by University of Electronic Science and Technology of China, Chengdu (CN)
Filed on Jun. 28, 2022, as Appl. No. 17/851,348.
Prior Publication US 2023/0305181 A1, Sep. 28, 2023
Int. Cl. G01V 3/28 (2006.01); G01V 3/30 (2006.01)
CPC G01V 3/28 (2013.01) [G01V 3/30 (2013.01)] 12 Claims
OG exemplary drawing
 
1. A method of reducing or rejecting common mode interference, comprising:
using a switch, separately placing a receiving coil in each of a forward connection mode and a reverse connection mode,
receiving a signal from a geological formation in the receiving coil,
outputting a formation signal and common mode interference from the receiving coil, wherein the formation signal is a differential signal and is output in real time,
amplifying the formation signal and the common mode interference using a differential amplifier,
receiving the amplified formation signal in a signal acquisition module,
outputting data from the signal acquisition module,
conducting phase-sensitive detection processing on the data using a processor connected to the signal acquisition module, wherein the processor:
separately places the receiving coil in each of the forward connection mode and the reverse connection mode,
obtains a forward measured value when the receiving coil is in the forward connection mode and a reverse measured value when the receiving coil is in the reverse connection mode, and
using the processor, calculating the formation signal and the common mode interference according to the forward measured value and the reverse measured value.