A total field magnetic measuring device and temperature drift suppression method suitable for downhole

Abstract

The invention provides a total field magnetic measuring device and temperature drift suppression method suitable for downhole. An omnidirectional structural fixed double gas chamber and an accessory device are arranged behind the glass plate assembly. The laser is connected with the optical fiber coupling head through an optical fiber, and the incident sequence Through the polarizer, the glass plate assembly, the omnidirectional structure fixed double air chamber and the accessory device, the omnidirectional structure fixed double air chamber and the accessory device are connected to the MCU controller after photoelectric signal processing A and photoelectric signal processing B. The invention can improve the service life of the instrument, increase the magnetic measurement parameters, avoid the blind area of ​​the magnetic measurement and suppress the temperature drift of the magnetic measurement data.

Description

technical field [0001] The invention relates to a downhole laser helium optical pump magnetic measuring device, in particular to a downhole total field magnetic measuring device and a method for suppressing temperature drift. Background technique [0002] There will be anomalies before earthquakes. The anomalies of the geomagnetic field and the occurrence of earthquakes have a good correlation and regularity. The abnormal changes of the geomagnetic field can be used to predict earthquakes. Therefore, long-term monitoring of the geomagnetic field is very important for the monitoring and prediction of earthquakes. It is of great significance, but the ground environment is relatively complex and there is a large magnetic interference. The magnetometer cannot judge whether the monitored magnetic anomaly is caused by an earthquake or magnetic interference. Therefore, the long-term monitoring of the underground magnetic field is of great significance. The magnetometer in the well ...

AI Technical Summary

Problems solved by technology

Similarly, in the downhole environment, the complex environment brings difficulties for the use of helium optically pumped magnetometers

First of all, the downhole ambient temperature is relatively high, and the temperature at a depth of 1,000 meters can be as high as 70°C. During long-term magnetic surveying, the helium absorption chamber of the sensitive unit in the magnetic surveying equipment has a short lifespan. Similar problems will also be encountered in satellite magnetic surveying; Secondly, according to "Analysis and Detection of Helium Optical Pump Magnetometer Signals", it can be seen that the optical pump magnetometer mainly locks the magnetic resonance point by detecting the voltage zero point of the fundamental wave signal, but in a high temperature environment for a long time, the electronic devices in the circuit and the magnetic field The measurement system will be affected by high temperature, and the magnetic measurement data has the problem of temperature drift; finally, according to F.D.Colegrove theory, when the angle between the sensor optical axis direction and the magnetic field direction is 90°, M z There is a dead zone in the magnetic force of the type helium optical pump, and the magnetic field cannot be measured normally. Due to the particularity of the structure, the dead zone cannot be avoided by adjusting the probe angle. When the optical axis direction of the sensor is parallel to the magnetic field direction, M z The output signal of the type magnetometer is the largest

[0004] For the third problem, the existing helium optical pump magnetic measurement device uses three orthogonal helium lamps as the pumping light method to eliminate the dead zone, but the power consumption of the instrument increases; using three orthogonal helium absorption chambers as the pumping light The method of photosensitive unit eliminates the dead zone, the size of the instrument is increased and the optical path is complicated; adopting four units in two vertical planes can eliminate the dead zone, but there are problems of complex implementation, single performance and non-optimal sensitivity

[0005] Regarding the first and second problems, for the time being, there is no precedent for putting the optical pump magnetometer into the well for long-term observation, so no effective solution has been proposed

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