METHOD FOR MEASURING MAGNETIC FIELD IN AREA OF WELL'S DRIVE PIPE AND METHOD FOR DECREASING MAGNETIC FIELD'S ATTENUATION (VERSIONS) Russian patent published in 2008 - IPC E21B47/12 G01N27/83 

FIELD: oil and gas industry.

SUBSTANCE: invention refers to oil industry and is meant for measuring or discovering magnetic field (MF) inside the well's drive pipe (DP) in order to determine DP parameters or medium parameters around well. Magnetic receiver with magnetic permeable core is located inside the well's DP and is operated in feedback mode in order to decrease the measured MF attenuation. Feedback device (FD) is used in receiver for decreasing the relationship between core and DP, which allows for decrease in normal attenuation of electromagnetic signals otherwise appearing inside DP. In this case FD can be made in the form of additional winding and feedback winding, which efficiently suppresses MF induced inside the core and decreases the attenuation otherwise induced by interaction of core and DP. Alternatively, amplifier circuit with feedback as to the current can be used as FD in magnetic receiver. It is designed for attenuating MF induced inside the core. In particular, this circuit is used for generating additional MF that basically suppresses MF inside the core.

EFFECT: increasing the efficiency of development and control of hydrocarbon sources.

41 cl, 12 dwg