Discharge circuit, discharge chip and nuclear magnetic resonance logging instrument

Abstract

The invention discloses a discharge circuit, a discharge chip and a nuclear magnetic resonance logging instrument. A second output end of a first output winding at the secondary side of an isolation transformer is connected with the drain electrode of a JFET, and is connected with the source electrodes of first and second MOSFETs through a first capacitor. A first output end of a second output winding is connected with the second output end of the first output winding. A second output end of the second output winding is connected with the grid electrode of the JFET and the source electrode of a third MOSFET, and is connected with the drain electrode of the JFET through a second capacitor. A first output end of a third output winding is connected with the source electrode of the third MOSFET, and the grid electrode of the JFET. A second output end of the third output winding is connected with the grid electrode of the third MOSFET. The drain electrode of the third MOSFET is connected with the drain electrode of the JFET. The drain electrode of the first MOSFET is connected with an antenna. The scheme can effectively suppress ringing and dead time of an instrument probe under a high-temperature environment, thereby ensuring higher instrument resolution and signal-to-noise ratio.

Description

technical field [0001] The invention relates to the technical field of high-temperature well logging, in particular to a relief circuit, a relief chip and a nuclear magnetic resonance logging instrument. Background technique [0002] With the reduction of easy-to-exploit oil resources, the depth of exploration and development of oil fields is deepening, and the temperature of some high-temperature and high-pressure downholes has exceeded the highest temperature resistance index of all relevant commercial nuclear magnetic resonance logging tools. At present, nuclear magnetic resonance logging tools (including Halliburton's MRIL-P, MRIL-XL and Baker Hughes' MREX series instruments) that use integrated transceiver probes need to use a bleeder circuit module to quickly eliminate the antenna after high-voltage excitation. The remaining energy reduces the dead time of the instrument, thereby reducing the echo interval of the instrument to improve the measurement resolution of the ...

AI Technical Summary

Problems solved by technology

At present, the discharge module of nuclear magnetic resonance logging tools is mostly designed with soft switches such as high-voltage bulk silicon MOSFETs. When this solution is higher than 175 degrees Celsius, the conduction resistance of the soft switch will increase due to the temperature limit of the bulk silicon process, and the conduction will maintain If the time becomes shorter, the performance of the bleeder circuit will decrease or fail, and the repeated opening and closing of the bleeder circuit module will cause the probe impedance to change and introduce an oscillating signal, which greatly increases the ringing and ringing of the NMR logging tool in a high temperature environment. Dead time, and may cause damage to the power amplifier circuit of the instrument due to the failure of the discharge function

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