INDUCTION POSITION SENSOR Russian patent published in 2006 - IPC E21B47/24 G01B7/00 

FIELD: oil and gas industry, particularly oil and gas equipment necessary for well operation, particularly for instrument or tool lowering in well.

SUBSTANCE: position sensor comprises inductance coil arranged outside pipe at well head and receiving unit having the first input connected with inductance coil and output linked with executive device, which controls drive operation. Drive moves tool inside the well. Additional inductance coil is included in the sensor. Additional inductance coil is installed outside the pipe and is coaxial with main inductance coil. Additional inductance coil is spaced a distance of to not less than length of tool to be lowered and is linked to the second input of receiving unit. The receiving unit is made as input differential amplifier having output connected to the first input of synchronous detector and the second input connected with reference generator output. Reference generator is connected with sensor inductance coils. Synchronous detector output is connected to receiving unit output through low frequency filter.

EFFECT: increased simplicity and reliability, elimination of well head improvement.

2 dwg