阅读说明：本技术 一种适用于井下的总场磁测装置及温度漂移抑制方法 (Total field magnetic measurement device suitable for underground and temperature drift suppression method ) 是由 王言章 张�杰 王超 周志坚 于 2020-05-28 设计创作，主要内容包括：本发明提供了一种适用于井下的总场磁测装置及温度漂移抑制方法,在玻璃片组件后设有全向结构固定双气室及附件装置,激光器通过光纤与光纤耦合头相连,入射依次经过偏振片、玻璃片组件、全向结构固定双气室及附件装置,全向结构固定双气室及附件装置通过光电信号处理A和光电信号处理B后与MCU控制器相连。本发明可以提高仪器的使用寿命、增加磁测参数、避免磁测盲区以及能抑制磁测数据温度漂移。(The invention provides a total field magnetic measurement device suitable for underground and a temperature drift suppression method. The invention can prolong the service life of the instrument, increase magnetic measurement parameters, avoid magnetic measurement blind areas and inhibit the temperature drift of magnetic measurement data.)

1. A total field magnetic measurement device adapted for use downhole, comprising: laser instrument (1), optic fibre (2), optical fiber coupling head (3), polaroid (4), glass piece subassembly (5), photoelectric signal processing A (27), photoelectric signal processing B (28), MCU controller (13) and aviation plug (14), wherein, be equipped with fixed double air chamber of omnidirectional structure and accessory device (6) behind glass piece subassembly (5), laser instrument (1) links to each other with optical fiber coupling head (3) through optic fibre (2), incident light signal passes through polaroid (4), glass piece subassembly (5), fixed double air chamber of omnidirectional structure and accessory device (6), photoelectric signal processing A (27), photoelectric signal processing B (28) in proper order, and fixed double air chamber of omnidirectional structure and accessory device (6) are passed through photoelectric signal processing A (27), photoelectric signal processing B (28) and are continuous with MCU controller (13).

2. The total field magnetic measurement device applicable to the underground according to claim 1, characterized in that a lens (7), a balance detector (8), a signal conditioning circuit A (9), a signal selection module (10), a subtraction circuit A (11) and a data collector A (12) are connected in sequence in the photoelectric signal processing A (27), and a lens (7), a balance detector (8), a signal conditioning circuit B (15), a subtraction circuit B (16) and a data collector B (17) are connected in sequence in the photoelectric signal processing B (28), wherein the photoelectric signal processing A (27) and the photoelectric signal processing B (28) share the lens (7) and the balance detector (8).

3. A total field magnetic logging device suitable for use downhole according to claim 1, wherein the omnidirectional structural fixed double plenum and attachment means (6) comprises: a reflector and beam splitter group (18), a helium absorption chamber A (19), a radio frequency coil A (20), a reflector group A (21), a helium absorption chamber B (22), a radio frequency coil B (23) and a reflector group B (24).

4. The total field magnetic measuring device suitable for the underground according to the claim 1, characterized in that the controller (13) controls the electronic switches to make the non-inverting terminal of the subtraction circuit A (11) and the inverting terminal of the subtraction circuit B (16) grounded, and one circuit is working and the other is not working, that is, two circuits are working alternately.

5. The total field magnetic measuring device suitable for downhole according to claim 1, wherein the omnidirectional structure fixed double air chambers and the accessory (6) have a reflector and a beam splitter group (18) at the origin to split the incident light into two beams of circularly polarized light with equal light intensity, the optical axis of one beam of circularly polarized light is in the YZ plane, the optical axis of the other beam of circularly polarized light is in the XZ plane, the MCU controller (13) controls the rotating device a (25) to rotate the reflector and the beam splitter group (18), the helium absorption chamber a (19), the rf coil a (20) and the rotating device B (26) respectively to rotate the reflector group a (21), the helium absorption chamber B (22), the rf coil B (23) and the reflector group B (24) around the origin until the maximum fundamental wave signal appears, and the sensitivity of the helium pump magnetic measuring device is optimal.

6. The method for suppressing the temperature drift of the total field magnetic measurement device suitable for the underground according to the claim 1, is characterized by comprising the following steps:

1) firstly, in a given magnetic field direction, the sensitivity of a magnetic measuring device is optimized by controlling a rotating device A (25) and a rotating device B (26);

2) the A, B two paths are debugged under different temperature conditions, and the circuit parameters and the fine adjustment optical lens angle are adjusted to ensure that the output signals of the data acquisition unit A (12) and the data acquisition unit B (17) are completely consistent in size and phase;

3) changing the direction of the magnetic field to ensure that the magnitudes of the two magnetic fields are consistent, controlling a rotating device A (25) and a rotating device B (26) through an MCU (13) to improve the sensitivity of magnetic measurement, and adjusting rotation control parameters to ensure that the magnitudes and phases of output signals of a data acquisition unit A (12) and a data acquisition unit B (17) are completely consistent when the sensitivities are optimal;

4) fixing the frequency of the radio frequency field of the reference air chamber at a point C outside the resonance area, and sweeping the frequency of the other radio frequency field to obtain the acquisition results S of the data acquisition unit A (12) and the data acquisition unit B (17)_AAs a baseline value and S related to temperature_BAs a fundamental wave signal related to temperature;

5) the results of data collector A (12) and data collector B (17) are subtracted: s ═ S_B-S_AThe influence of temperature drift on the magnetic measurement result can be eliminated.

7. The method for suppressing temperature drift of a total field magnetic measurement device in a well according to claim 6, wherein the circuit parameters adjusted in the step 2) comprise bias, amplification factor and circuit phase of the circuit.

Technical Field

The invention relates to an underground laser helium optical pump magnetic measurement device, in particular to an underground total field magnetic measurement device and a temperature drift suppression method.

Background

The abnormal phenomenon can occur before the earthquake, the abnormality of the geomagnetic field and the occurrence of the earthquake have good correlation and regularity, and the earthquake can be forecasted by utilizing the abnormal change phenomenon of the geomagnetic field, so that the long-term monitoring of the geomagnetic field has important significance for monitoring and forecasting the earthquake, but the ground environment is complex and has larger magnetic interference, and a magnetometer cannot judge whether the magnetic abnormality caused by the earthquake or the magnetic interference is caused by the earthquake on the monitored magnetic abnormality, so that the long-term monitoring significance of the underground magnetic field is important. The in-well magnetometer is high in sensitivity, can respond to weak magnetic anomaly and low in baseline drift, and can stably work in a high-temperature environment in a well for a long time.

The laser helium optical pump magnetometer is total field magnetic detection equipment which has extremely high sensitivity and can detect magnetic anomaly, has a great application potential and a wide application prospect, is increasingly applied to the fields of geological exploration, geophysical exploration, mineral deposit exploration, military magnetic detection, satellite magnetic detection and the like, particularly the fields of geology, military and space detection, wherein in the field of satellite magnetic detection, satellite magnetic detection data is used as a high-resolution geomagnetic chart to be drawn as one of main data sources, and the requirements of detecting high-precision and long-service-life equipment in a special temperature environment exist. Also, in a downhole environment, the complex environment presents difficulties for the use of helium optical pumping magnetometers. Firstly, the temperature of underground environment is high, the temperature of the well depth of 1000 meters can reach 70 ℃, the problem of short service life of a sensitive unit helium absorption chamber in magnetic measurement equipment during long-term magnetic measurement is solved, and the similar problem can be encountered in satellite magnetic measurement; secondly, according to analysis and detection of signals of the helium optical pump magnetometer, the optical pump magnetometer mainly locks a magnetic resonance point by detecting a voltage zero point of a fundamental wave signal, but when the optical pump magnetometer is in a high-temperature environment for a long time, electronic devices and a magnetic measurement system in a circuit are affected by high temperature, and the magnetic measurement data has the problem of temperature drift; finally, according to the F.D.Colegrove theory, when the included angle between the optical axis direction and the magnetic field direction of the sensor is 90 degrees, M is calculated_zThe magnetic force of the helium optical pump cannot normally measure the magnetic field due to the dead zone, the dead zone cannot be avoided by adjusting the angle of the probe due to the structural particularity in the well, and when the optical axis direction of the sensor is parallel to the magnetic field direction, M is equal to M_zThe output signal of the model magnetometer is maximum.

Aiming at the third problem, the existing helium pump magnetic measurement device adopts a method of using 3 orthogonal helium lamps as pump light to eliminate dead zones, but the power consumption of the instrument is increased; the dead zone is eliminated by adopting a method of using 3 orthogonal helium absorption chambers as pumping light sensitive units, the size of the instrument is increased, and the light path is complicated; the dead zone can be eliminated by adopting four units in two vertical planes, but the problems of complex realization, single performance and non-optimal sensitivity exist.

For the first and second problems, no effective solution has been proposed for the time being, since there has been no precedent to put the optical pumping magnetometer downhole for long term observation.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a total field magnetic measurement device suitable for underground. Another object of the present invention is to provide a method for suppressing temperature drift of a total field magnetic measurement device suitable for use downhole.

The technical scheme provided by the invention is as follows: the utility model provides a total field magnetism surveys device suitable for in pit, laser instrument, optic fibre, optical fiber coupling head, polaroid, glass piece subassembly, photoelectric signal processing A, photoelectric signal processing B, MCU controller and aviation plug, wherein be equipped with fixed double air chamber of omnidirectional structure and accessory device behind the glass piece subassembly, the laser instrument passes through optic fibre and links to each other with the optical fiber coupling head, and incident light signal passes through polaroid, glass piece subassembly, the fixed double air chamber of omnidirectional structure and accessory device, photoelectric signal processing A, photoelectric signal processing B in proper order, and the fixed double air chamber of omnidirectional structure and accessory device pass through photoelectric signal processing A, photoelectric signal processing B and link to each other with the MCU controller.

Preferably, the photoelectric signal processing a is sequentially connected with a lens, a balance detector, a signal adjusting circuit a, a signal selecting module, a subtracting circuit a and a data acquisition unit a, and the photoelectric signal processing B is sequentially connected with 9 lenses, a balance detector, a signal adjusting circuit B, a subtracting circuit B and a data acquisition unit B, wherein the photoelectric signal processing a and the photoelectric signal processing B share the lens and the balance detector.

Further preferably, the omnidirectional structure fixed double air chamber and accessory device comprises: the device comprises a reflector and beam splitter group, a helium absorption chamber A, a radio frequency coil A, a reflector group A, a helium absorption chamber B, a radio frequency coil B and a reflector group B.

Preferably, the controller controls the electronic switches to make one of the two paths work and the other does not work when the same-phase ends of the subtraction circuit a and the subtraction circuit B are both grounded, that is, the two paths work alternately.

Preferably, the double air chambers and the accessories are fixed by the omnidirectional structure, a reflector and a beam splitter group are arranged at the origin to split incident light into two beams of circularly polarized light with equal light intensity, the optical axis of one beam of circularly polarized light is in a YZ plane, the optical axis of the other beam of circularly polarized light is in an XZ plane, the MCU controller respectively controls the rotating device A to enable the reflector and the beam splitter group, the helium absorption chamber A, the radio frequency coil A, the reflector group A and the rotating device B to enable the helium absorption chamber B, the radio frequency coil B and the reflector group B to respectively rotate around the origin until the maximum fundamental wave signal appears, and the sensitivity of the helium pump magnetic measurement device is optimal at the moment.

A temperature drift suppression method suitable for a total field magnetic measurement device in a well comprises the following steps:

1) firstly, under a given magnetic field direction, the sensitivity of a magnetic measurement device is optimized by controlling a rotating device A and a rotating device B;

2) the A, B two paths are debugged under different temperature conditions, and circuit parameters and the angle of the optical lens are adjusted to ensure that the magnitude and the phase of the output signals of the data acquisition unit A and the data acquisition unit B are completely consistent;

3) changing the direction of the magnetic field to ensure that the magnitudes of the two magnetic fields are consistent, controlling the rotating device A and the rotating device B through the MCU controller to improve the sensitivity of magnetic measurement, and adjusting rotation control parameters to ensure that the magnitudes and phases of output signals of the data acquisition device A and the data acquisition device B are completely consistent when the sensitivities are optimal;

4) fixing the frequency of the radio frequency field of the reference air chamber at a point C outside the resonance area, and sweeping the frequency of the other radio frequency field to obtain the acquisition result S of the data acquisition unit A_AAcquisition results S as a temperature-dependent baseline value and data collector B_BAs a fundamental wave signal related to temperature;

5) subtracting the acquisition results of the data acquisition unit A and the data acquisition unit B: s ═ S_B-S_AThe influence of temperature drift on the magnetic measurement result can be eliminated.

Preferably, the circuit parameters adjusted in step 2) include the offset, amplification factor and phase of the circuit.

Through placing two magnetism survey units that the parameter is the same in YZ and XZ plane, and its light path and subassembly accessible rotary device are rotatory in YZ and XZ plane, simple structure easily realizes, and can avoid the device dead zone to appear and guarantee sensitivity optimum simultaneously. The MCU controller controls the in-phase input signals of the two subtraction circuits, so that the working modes of the equipment can be switched. When no magnetic anomaly exists, the two air chambers alternately and independently work, so that the service life of the equipment can be prolonged, and the power consumption of the magnetic detection device can be reduced. When the differential subtraction circuit works alternately, the reference gas chamber signal can be selected as the in-phase end of the differential subtraction circuit, so that the temperature drift of the magnetic measurement data can be inhibited, and the error interpretation of the magnetic measurement data can be avoided. When magnetic anomaly is caused by earthquake, the system can work in a magnetic gradient measurement mode, so that magnetic measurement information is richer, and analysis and explanation of magnetic measurement data are facilitated.

Compared with the existing laser helium optical pump magnetic measurement device, the service life of the instrument is prolonged, the measured parameters are increased, the problem of sensor blind areas is avoided, the problem of magnetic measurement data drift can be effectively restrained, and the device can be suitable for underground special environments.

Drawings

FIG. 1 is a block diagram provided by the present invention;

FIG. 2 is a diagram of the structure of the fixed double air chambers and accessories of the omnidirectional structure provided by the present invention;

FIG. 3 is a graph comparing the temperature drift of magnetic measurement data before and after a high temperature environment.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

As shown in fig. 1, a total field magnetic measurement device and a temperature drift suppression method suitable for use in a well include: laser instrument 1, optic fibre 2, optical fiber coupling head 3, polaroid 4, glass piece subassembly 5, photoelectric signal processing A27, photoelectric signal processing B28, MCU controller 13 and aviation plug 14, wherein, be equipped with fixed double air chamber of omnidirectional structure and accessory device 6 behind the glass piece subassembly 5, laser instrument 1 passes through optic fibre 2 and links to each other with optical fiber coupling head 3, and incident light signal passes through polaroid 4, glass piece subassembly 5, fixed double air chamber of omnidirectional structure and accessory device 6, photoelectric signal processing A27, photoelectric signal processing B28 in proper order, and fixed double air chamber of omnidirectional structure and accessory device 6 pass through photoelectric signal processing A27, photoelectric signal processing B28 and MCU controller 13 links to each other.

The photoelectric signal processing A27 is sequentially connected with a lens 7, a balance detector 8, a signal adjusting circuit A9, a signal selection module 10, a subtraction circuit A11 and a data collector A12, the photoelectric signal processing B28 is sequentially connected with the lens 7, the balance detector 8, a signal adjusting circuit B15, a subtraction circuit B16 and a data collector B17, and the photoelectric signal processing A27 and the photoelectric signal processing B28 share the lens 7 and the balance detector 8.

The magnetic measuring device of the invention is that a laser 1 after frequency stabilization enters an optical fiber coupling head 3 through an optical fiber 2, and is converted into a circular polaroid after entering a lens 4 and a circular polaroid 5, transmission light signals of a fixed double air chamber with an omnidirectional structure and an accessory 6 are converged on a balanced photoelectric detector 8 through the lens and converted into electric signals, and fundamental wave signals S of 2 corresponding air chambers are respectively obtained through signal conditioning circuits 9 and 15 including amplification, band-pass filtering, phase sensitive detection and low-pass filtering_AAnd S_B. Then S_AThe differential part of the reference air chamber consisting of the signal selection module 10 and the subtraction circuit A11 is transmitted to the MCU controller 13 by the data acquisition A12 for feedback and calculation of the magnetic field, and similarly, S_BThe differential part of the reference air chamber consisting of the signal selection module 10 and the subtraction circuit B16 is transmitted to the MCU controller 13 by the data acquisition B17 to be fed back to the fixed double air chambers of the omnidirectional structure and the accessories 6 until the magnetic field is calculated after the locking.

As shown in fig. 2, the omnidirectional structure fixed double air chamber and attachment device 6 includes: mirror and beam splitter set 18, helium absorption chamber A19, radio frequency coil A20, mirror set A21, helium absorption chamber B22, radio frequency coil B23 and mirror set B24. The omnidirectional structure fixes the double air chambers and the accessory 6, a reflector and a beam splitter group 18 are arranged at the origin to split incident light into two beams of circularly polarized light with equal light intensity, the optical axis of one beam of circularly polarized light is positioned on a YZ plane, the circularly polarized light in the YZ plane penetrates through a helium absorption chamber A19 and is emitted to a lens 7 through a reflector group A21, and a radio frequency coil A20 is connected to the helium absorption chamber A19 to provide a radio frequency magnetic field to cause magnetic resonance. The other circularly polarized light beam has its optical axis in the XZ plane, where it is transmitted through helium absorbing chamber B22 and exits to lens 7 via mirror set B24, and radio frequency coil B23 is connected to helium absorbing chamber B22 to provide a radio frequency magnetic field to induce magnetic resonance.

The reference air chamber differential signal selection module 10 is controlled by the MCU controller 13 through an electronic switch, and when the controller 13 controls the electronic switch to ground the non-inverting terminals of the subtraction circuit a11 and the subtraction circuit B16, one of the two circuits works and the other does not work, i.e., the two circuits work alternately, the service life of the device can be prolonged.

A temperature drift suppression method suitable for a total field magnetic measurement device in a well comprises the following steps:

1) firstly, under a given magnetic field direction, the sensitivity of a magnetic measurement device is optimized by controlling a rotating device A and a rotating device B;

2) the A, B two paths are debugged under different temperature conditions, and the offset, the amplification factor, the circuit phase and the fine adjustment optical lens angle of the circuit are adjusted, so that the output signal size and the phase of the data acquisition unit A and the output signal size and the phase of the data acquisition unit B are completely consistent;

3) changing the direction of the magnetic field to ensure that the magnitudes of the two magnetic fields are consistent, controlling the rotating device A and the rotating device B through the MCU controller to improve the sensitivity of magnetic measurement, and adjusting rotation control parameters to ensure that the magnitudes and phases of output signals of the data acquisition device A and the data acquisition device B are completely consistent when the sensitivities are optimal;

4) fixing the frequency of the radio frequency field of the reference air chamber at a point C outside the resonance area, and sweeping the frequency of the other radio frequency field to obtain the acquisition result S of the data acquisition unit A_AAcquisition results S as a temperature-dependent baseline value and data collector B_BAs a fundamental wave signal related to temperature;

5) subtracting the acquisition results of the data acquisition unit A and the data acquisition unit B: s ═ S_B-S_AThe influence of temperature drift on the magnetic measurement result can be eliminated.

When magnetic anomaly exists, the MCU controller 13 controls the electronic switches to enable the same-phase ends of the subtraction circuit A11 and the subtraction circuit B16 to be grounded, and the two paths A and B work independently to form a gradient measurement mode.

When the controller 13 controls the electronic switch to make the non-inverting terminal S of the subtracting circuit A11_BWhen the in-phase end of the subtraction circuit B16 is grounded, the circuit B works in a normal mode, and the output signal is influenced by temperature and long-term use; in the path A, the output end of the reference air chamber B is connected to the in-phase end of the subtraction circuit A11, so that the magnetic measurement data have no offset; similarly, the A path can also be used as a reference air chamber.

When no magnetic anomaly exists, the two air chambers work alternately, so that the service life of the equipment can be prolonged, and the power consumption of the magnetic detection device can be reduced. As shown in FIG. 3, Δ B due to the temperature drift of the magnetic field_tdThe magnitude changes with the temperature change, and when the temperature-dependent resonant cavity works independently, the frequency of the radio frequency field of the reference gas chamber can be fixed at a point C outside the resonant region, so that the output signal does not generate a fundamental wave signal, only contains a temperature drift signal with fixed magnitude related to the temperature, and the output signal S is obtained_AAnd as a baseline value, the signal is output by selecting the reference gas chamber as the non-inverting terminal of the differential subtraction circuit. And the other air chamber radio frequency field is normally swept until a fundamental wave signal S appears_BIn the resonance area, the measured fundamental wave signal containing the temperature drift subtracts a baseline value output by the reference gas chamber: s ═ S_B-S_AThe temperature drift of the magnetic measurement data can be inhibited, and the wrong explanation of the magnetic measurement data is avoided. When magnetic anomaly is caused by earthquake, the system can work in a magnetic gradient measurement mode, so that magnetic measurement information is richer, and analysis and explanation of magnetic measurement data are facilitated.

Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

It will be understood that the invention is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the invention is limited only by the appended claims.