JP7116418B2 - Magnetic measuring device and magnetic exploration system - Google Patents

Description

The present invention relates to a magnetic measurement device and a magnetic exploration system.

2. Description of the Related Art Conventionally, a magnetic measuring device using a superconducting quantum interference device (SQUID (Superconducting Quantum Interference Device) device) installed in an oil/natural gas observation well or on the seabed has been used. Magnetic measurement is a measurement method that explores underground or underwater resistance structures by using changes in the magnetic field generated by loop coils, etc., and is widely used as a method for measuring resistivity distribution under sea level or underground. ing. Patent Literature 1 discloses a magnetic measurement system that uses a superconducting quantum interferometer (hereinafter sometimes referred to as SQUID) as a magnetic sensor in a system used for metal mineral exploration in a range of about several tens of meters underground. there is

Japanese Patent No. 4272246

A SQUID can obtain a large amount of information due to its high sensitivity and wide observation band, but it operates only at low temperatures, so it must be cooled to the temperature of liquid nitrogen or liquid helium under normal pressure. When liquid nitrogen is stored in a vacuum insulation container (hereinafter referred to as a dewar) installed in a sealed pressure-resistant container, and when all the liquid nitrogen inside evaporates due to a malfunction of the refrigerator or breakage of the dewar. There is In this case, if the dewar filled with liquid nitrogen is damaged, the pressure inside the sealed pressure-resistant container will increase, and there is a risk of an accident such as an explosion of the container. Moreover, when magnetic measurement is performed in an observation well, there is a problem that the rapid volume expansion of liquid nitrogen leads to breakage of the well head.

Therefore, the present invention has been made in view of these points, and is a magnetic measurement apparatus capable of improving safety when measuring magnetism using a superconducting magnetic interferometer in a closed environment such as underwater. , a cooling device, and a magnetic exploration system.

In a first aspect of the present invention, an inner container that suppresses heat transfer between the inside and the outside, a superconducting quantum interferometer element accommodated in the inner container, and the superconducting quantum interferometer The superconducting quantum interference device has a liquid coolant for cooling an element, a heat storage body for accumulating cold heat generated by the liquid coolant, and a measurement unit for measuring magnetism detected by the superconducting quantum interference device. A magnetic measuring device is provided, characterized in that the metering element is mounted so as to be immersed in said liquid coolant in operation.

Further, the heat storage body may have a recessed accommodating portion, and the superconducting quantum interferometer element may be accommodated in the accommodating portion. Further, a hole penetrating through the heat storage element may be formed in the bottom of the accommodation portion.

Further, the heat storage body may have a first heat storage body and a second heat storage body coupled to the first heat storage body below the accommodation section. Further, the liquid coolant may be liquid nitrogen, and the heat storage medium may contain silicon or quartz glass.

Further, the cooling unit cools and liquefies the gaseous coolant obtained by vaporizing the liquid coolant, and the control unit operates the cooling unit based on the timing at which the measurement unit measures the magnetism. good too.

Further, a temperature detection unit for detecting a temperature of the superconducting quantum interferometer element is further provided, and the control unit determines that the temperature detected by the temperature detection unit is equal to or higher than a predetermined temperature, and that the measurement unit detects a magnetic field. The cooling unit may be operated when it is not the timing to measure the .

Further, the control unit determines the timing at which the measurement unit measures magnetism based on an intermittent magnetic field generation signal indicating the timing at which the magnetic field generation device generates magnetism, received from a magnetic field generation device that generates magnetism. The cooling unit may be intermittently operated based on the specified timing.

Further, the apparatus further includes an outer container that houses the inner container, and the inner container is formed with a hole for communicating the gaseous coolant obtained by vaporizing the liquid coolant with the outer container. good.

Further, a vibration absorbing material may be provided between the outer surface of the heat storage body and the inner surface of the inner container to absorb vibrations generated when the liquid coolant is vaporized.

In a second aspect of the present invention, there is provided a cooling device for cooling a superconducting quantum interferometer element, comprising: an inner container for suppressing heat transfer between the inside and the outside; a liquid coolant for cooling the superconducting quantum interferometer element, a heat storage medium for accumulating cold heat generated by the liquid coolant, and the superconducting quantum interferometer element fixed so as to be immersed in the liquid coolant during operation. A cooling device characterized by comprising a fixing portion for

In a third aspect of the present invention, a magnetic field generating device that generates a magnetic field, a magnetic measuring device that measures the magnetic field generated by the magnetic field generating device, and a system control device that controls the magnetic field generating device and the magnetic measuring device wherein the system controller generates a magnetic field generation signal indicating the timing at which the magnetic field generation device generates a magnetic field, and the magnetic field generation device generates a magnetic field based on the magnetic field generation signal The magnetic field measuring device has a magnetic field generating unit that generates an inner container that suppresses heat transfer between the inside and the outside, a superconducting quantum interferometer element housed in the inner container, and the A liquid coolant that cools the superconducting quantum interferometer element, a heat storage medium that stores the cold heat generated by the liquid coolant, and a magnetism detected by the superconducting quantum interferometer element is measured based on the magnetic field generation signal. and a measuring unit, wherein the superconducting quantum interferometer element is installed so as to be immersed in the liquid coolant during operation.

Further, the magnetism measuring device includes a cooling unit that cools and liquefies the gaseous coolant obtained by vaporizing the liquid coolant; and an actuating control unit.

Further, the magnetic field generation device switches between an energization period in which the magnetic field generation section is energized and a non-energization period in which the magnetic field generation section is not energized in synchronization with the magnetic field generation signal, and the system control device controls the magnetic field generation An advance notice signal may be further generated to give advance notice of the timing at which the apparatus switches from the energized period to the non-energized period, and the control section may stop the operation of the cooling section based on the advance notice signal.

The power storage unit stores electric power for operating the magnetism measuring device, and a storage amount measuring unit measures the storage amount of the storage unit. The storage amount obtained is less than a predetermined first lower limit value, and the storage unit may be charged at a timing when the measurement unit does not measure the magnetism.

Further, the power storage unit has a first power storage unit and a second power storage unit, and the control unit controls the power storage amount of the second power storage unit measured by the power storage amount measurement unit to be the predetermined first lower limit value. is less than a predetermined second lower limit value smaller than , the second power storage unit may be charged even at the timing when the measurement unit measures magnetism.

ADVANTAGE OF THE INVENTION According to this invention, it is effective in the ability to improve the safety|security at the time of measuring magnetism using a superconducting magnetic interferometer in a sealed environment.

1 shows the structure of a magnetic exploration system having a magnetism measuring device according to this embodiment. 1 shows the structure of a magnetic measurement device according to this embodiment. 4 shows a cooling control flow of the control unit; 4 shows a power storage control flow of the control unit. 4 shows the control flow of the system controller. An example of a control signal is shown. 4 shows a modification of the heat storage body.

[Overview of magnetic exploration system S]
The electromagnetic exploration method is expected to be applied to the exploration of seabed resources. For example, by applying a square-wave current to a cable installed on the seabed and observing the response from a magnetic sensor installed on the seabed away from the cable, it is possible to estimate the resistance value distribution under the seabed or in the sea. Become. In addition, as another application, it is used for enhanced recovery to recover the crude oil remaining in the oil layer by injecting an injection fluid such as water containing carbon dioxide or surfactant into the oil field where the pressure has decreased due to production. and monitoring the behavior of carbon dioxide in underground storage of carbon dioxide produced in industrial activities.

In these applications, since the stratum whose magnetism is to be measured is as deep as 1000 to 3000 m underground, it is preferable to install the magnetic sensor near the stratum whose magnetism is to be measured. In this case, it is required to install the sensor in an observation well dug up to the stratum whose magnetism is to be measured. These observation wells are filled with a water-based wellbore fluid so that the well walls resist the pressure from the surrounding ground. Therefore, it is necessary to house the magnetic sensor in a sealed pressure vessel and suspend the magnetic sensor from the mouth of the observation well to a defined depth.

When using a SQUID as a magnetic sensor, it is necessary to keep the SQUID cool. Therefore, in order to use the SQUID, for example, it is necessary to accommodate a cooling agent such as liquid nitrogen or liquid helium together with the SQUID in a pressure container. A magnetic exploration system S having a magnetic measuring device T having a pressure-resistant container capable of accommodating such a coolant will be described below.

FIG. 1 is a diagram showing the structure of a magnetic exploration system S having a magnetic measurement device T according to this embodiment.
The magnetic exploration system S is a monitoring system for detecting the behavior of water in the primary recovery process of injecting water into an oil layer of an oil field under the seafloor and recovering hydrocarbons in the oil layer in a production well. The magnetic survey system S is excited by blocking the magnetic field of the magnetic field generator V1 at the timing when the water-hydrocarbon interface generated by injecting water from the injection well passes under the magnetic measurement device T installed on the seabed. measured by the change in the secondary magnetic field. The magnetic survey system S measures the timing at which the water-hydrocarbon interface passes under the magnetic measurement device T, thereby identifying the position of the hydrocarbon.

By replacing part of the hydrocarbons such as crude oil in the oil layer with water, the resistance value of the replaced part decreases. In the magnetic exploration system S, the change in the eddy current pattern flowing through the oil layer due to the interruption of the primary magnetic field caused by the decrease in resistance value is treated as the change in the secondary magnetic field induced by this change. Detected by the magnetometer T. In addition, the magnetic exploration system S detects an object including metal that moves in the vicinity of the magnetic measurement device T based on a change in the secondary magnetic field according to the movement of the object including metal existing in the vicinity of the magnetic measurement device T. It is possible.

The magnetic exploration system S has a magnetic field generator V, a magnetometer T, and a system controller U. The magnetic field generator V generates a magnetic field. The magnetic field generator V has a magnetic field generator V1 and a power feeder V2. The magnetic field generator V1 generates a magnetic field based on a magnetic field generation signal generated by the system controller U. FIG. The power supply unit V2 applies a voltage to the magnetic field generation unit V1.

The magnetic measurement device T measures the magnetic field generated by the magnetic field generator V. FIG. The magnetic measuring device T is arranged apart from the magnetic field generating device V. As shown in FIG. The magnetic measurement device T is installed, for example, on the seabed about 2500 m away from the magnetic field generator V1, and is connected to a system control device U on the ground via a control cable 15 .

The control cable 15 has an optical fiber, a power supply line, a drive wiring for a backup charge control relay, a reset signal line for the controller 9, and the like, as will be described later. The control cable 15 is connected to the magnetic measuring device T at the connector 13 of the lid 12 of the outer container 1 . Details of the magnetic measurement device T will be described later.

The system controller U controls the entire magnetic exploration system S. Specifically, the system controller U controls the magnetic field generator V and the magnetometer T. FIG. Further, the system control device U stores data transmitted from the magnetism measuring device T. FIG. The system control device U is installed on the ground.

A system controller U generates a magnetic field generation signal. The magnetic field generation signal is a signal indicating the timing at which the magnetic field generator V generates a magnetic field, as described above.

[Structure of magnetic measurement device T]
FIG. 2 is a diagram showing the structure of the magnetic measurement device T according to this embodiment.
The magnetic measurement device T is used on the seabed or in wellbore filled with aqueous or oily liquids. The magnetic measurement device T includes an outer container 1, an inner container 2, a superconducting quantum interferometer element (SQUID element) mounting substrate (hereinafter referred to as a SQUID substrate) 3, a FLL (Flux Locked Loop) circuit 4, a cooling unit 5, and a power storage unit. 6, a holding member 7, a pressure detection unit 8, and a control unit 9. The magnetic measurement device T is a device for measuring magnetic field strength and changes in magnetic field strength with a superconducting quantum interferometer device (hereinafter referred to as SQUID device) 31 .

The outer container 1 is, for example, a sealed container having pressure resistance. The outer container 1 uses the SQUID substrate 3 mounted inside the outer container 1 to measure the magnetic field strength and the change in the magnetic field strength outside the outer container 1, so that the magnetism and conductivity of the outer container 1 itself are not affected. is required. Therefore, the outer container 1 is made of carbon fiber reinforced plastic or ceramic, for example. The outer container body 11 may be made of composite material including carbon fiber reinforced plastic. The outer container 1 has an outer container body 11 and a lid 12 . The outer container main body 11 is, for example, a cylindrical container with an outer diameter of 130 mm and a length of 1500 mm.

The lid 12 is a member that covers the opening formed above the outer container body 11 . The lid 12 is provided with a connector 13 and an internal pressure holding device 14 . The connector 13 is an interface for supplying power to the magnetic measurement device T and for transmitting and receiving information inside and outside the magnetic measurement device T. FIG. A control cable 15 is connected to the connector 13 . The control cable 15 includes two optical fiber cables, a 24V power line and a ground line.

The lid 12 and the joint portion of the outer container body 11 with the lid 12 are made of non-magnetic metal such as SUS304 stainless steel. An O-ring seals between the outer container main body 11 and the lid 12 .

The internal pressure holding device 14 has a function of releasing the internal pressure to the outside when the pressure in the outer container 1 becomes higher than the external pressure by a certain value or more. The internal pressure holding device 14 has, for example, a check valve. The internal pressure holding device 14 is provided with connection means with an analyzer for analyzing the gas released from the inside of the outer container 1 .

The inner container 2 is a container housed in the outer container 1 . The inner container 2 is, for example, a dewar, and has a function of suppressing heat transfer between the inside and the outside. The inner container 2 has an inner container body 21 and a lid 22 . The inner container main body 21 is, for example, a cylindrical container filled with a heat insulating material. The lid 22 is a member that covers the opening formed above the inner container body 21 . The lid 22 has a liquid coolant injection tube 24 . An opening into which the liquid coolant L is injected is formed in the liquid coolant injection pipe 24 . The liquid coolant injection pipe 24 is provided with a valve 241. By opening the valve 241, the liquid coolant L is injected from the upper opening of the outer container body 11 into the inner container 2 with the lid 12 removed. can be injected into Liquid coolant L is, for example, liquid nitrogen.

It should be noted that the liquid coolant L is indicated by halftone dots in FIG. As shown in FIG. 2, the liquid coolant L is contained in the inner space of the inner container 2 .

A hole 221 is formed above the inner container 2 . The hole 221 is a hole for communicating the gaseous coolant obtained by vaporizing the liquid coolant L with the outer container 1 . A discharge pipe 222 is attached to the lid 22 of the inner container 2 to discharge the gaseous coolant obtained by vaporizing the liquid coolant L into the outer container 1 . Specifically, one end of the discharge pipe 222 is provided in the hole 221 formed in the lid 22 of the inner container 2, and the other end of the discharge pipe 222 is positioned near the bottom of the outer container 1. there is The discharge pipe 222 is provided, for example, along the outer periphery of the inner container 2 , and the low-temperature gaseous coolant obtained by vaporizing the liquid coolant L moves from one end of the discharge pipe 222 to the other end, thereby moving the inner container 2 . After cooling the outer circumference, it is discharged from the other end of the discharge tube 222 and diffuses inside the outer container 1 .

A heat storage element 25 and a liquid coolant L are accommodated in the inner container 2 . The liquid coolant L cools the SQUID elements 31 of the SQUID substrate 3 on which the SQUID elements 31 are mounted. The heat accumulator 25 has a function of accumulating cold heat generated by the liquid coolant L so that the usage amount of the liquid coolant L can be reduced. That is, the magnetism measuring device T can reduce the amount of the liquid coolant L accommodated in the inner container 2 by accommodating the heat storage body 25 in the inner container 2 .

The outer diameter of the heat storage element 25 is smaller than the inner diameter of the inner container 2 . Specifically, the outer diameter of the heat storage element 25 is smaller than the inner diameter of the inner container 2 by, for example, about 2 to 10 mm. The heat reservoir 25 is substantially non-conductive in the operating temperature range of the SQUID element 31, and is selected from paramagnetic or diamagnetic, so-called non-magnetic materials, in order to prevent it from affecting the strength of the magnetic field in the surrounding environment. be done. The term "substantially non-conductive" means that fluctuations in the magnetic field to be measured do not excite a current in the heat storage medium 25 that affects the measurement results.

Further, the heat storage element 25 is required to have strength so as not to be damaged by a thermal shock due to injection of the liquid coolant L when it is housed in the inner container 2 . The material used for the heat storage body 25 is, for example, a compact obtained by subjecting an eleven nine semiconductor device grade single crystal silicon ingot to laser processing and alkali etching. More simply, the heat storage body 25 may be an object in which an adhesive silicone rubber sheet mixed with boron nitride, aluminum oxide, or the like used for heat dissipation from semiconductors is wound around a polyethylene pipe. The heat storage body 25 may be sapphire, quartz glass, or the like.

The heat storage body 25 has a housing portion 251 and holes 252 . The housing portion 251 is a recessed portion provided on the upper surface of the heat storage body 25 . The SQUID board 3 is accommodated in the accommodation portion 251 . The hole 252 is formed, for example, in at least a partial region of the bottom surface of the housing portion 251 , penetrates to the bottom of the heat storage body 25 , and allows the liquid coolant L to flow between the inside of the housing portion 251 and the outside of the heat storage body 25 . communicate.

The hole 252 in the heat store 25 allows the liquid coolant L contained inside the inner container 2, for example between the outer surface of the heat store 25 and the inner surface of the inner container 2, to pass through the hole 252. , and moves to the inside of the housing portion 251 of the heat storage body 25, and the liquid coolant L housed inside the housing portion 251 of the heat storage body 25 flows between the outer surface of the heat storage body 25 and the inner container 2. It becomes possible to move between the inner surfaces.

As a result, inside the inner container 2, the magnetic measuring device T measures the height of the liquid coolant L accommodated inside the accommodation portion 251 of the heat storage body 25, the outer surface of the heat storage body 25, and the inner container 2. It is possible to make it difficult to cause a difference in the height of the liquid coolant L accommodated between the inner surface of the inner surface and the height of the liquid coolant L, and to maintain it within a certain range. As a result, the state where the SQUID substrate 3 is always immersed in the liquid coolant L can be easily maintained.

Moreover, a plurality of through holes may be formed in the heat storage body 25 in the height direction of the heat storage body 25 . Specifically, the plurality of through-holes may penetrate from the upper surface to the lower surface of the heat storage element 25, for example. Since the heat storage body 25 is formed with a plurality of through holes in the height direction of the heat storage body 25 in this way, the liquid coolant L flows through the plurality of through holes of the heat storage body 25 inside the inner container 2 . It can enter inside and be in a state of being accommodated inside the plurality of through holes. As a result, the contact area between the liquid coolant L and the heat storage element 25 increases, so that the heat storage element 25 can be easily cooled by the liquid coolant L, and the temperature distribution in the heat storage element 25 cooled by the liquid coolant L It is possible to make it difficult to produce the bias of

In the magnetic measurement device T, the temperature inside the inner container 2 fluctuates as the pressure inside the outer container 1 fluctuates. Since the heat storage medium 25 has a large heat capacity, it also functions as a cold storage material, so as to mitigate temperature fluctuations and extend the continuous stop time of the refrigerator 51 . As a result, the magnetic measuring device T is continuously operated for a longer period of time than the magnetic measuring device without the heat storage 25, even if the same amount of liquid coolant L is used as the magnetic measuring device without the heat storage 25. It is possible to secure a sufficient observation time.

A SQUID element 31 , a temperature detector 32 , and a connector 33 are mounted on the SQUID board 3 . The SQUID element 31 is installed so as to be immersed in the liquid coolant L during operation.

The temperature detector 32 has, for example, a temperature sensor element. Temperature detector 32 detects the temperature of SQUID element 31 . The connector 33 is an interface for transmitting electrical signals from the SQUID element 31 and the temperature detector 32 to the outside of the SQUID board 3 . The connector 33 is provided on the upper surface of the SQUID board 3, for example. The connector 33 is connected to a connector attached to the tip of a third holding member 73, which will be described later. The third holding member 73 is, for example, a substrate mounting member formed by processing a round bar made of polyacetal resin. The SQUID board 3 is horizontally attached to the lower end of the third holding member 73 via the connector 33 and is inserted into the housing portion 251 of the heat storage body 25 .

The FLL circuit 4 is a circuit that applies a magnetic field to the SQUID element 31 that cancels out the magnetic field from the outside, and converts it into a current or voltage that linearly changes with the strength of the detected magnetic field. The FLL circuit 4 outputs the converted current or voltage to the controller 9 .

The FLL circuit 4 converts the magnetic field intensity detected by the SQUID board 3 into a voltage signal. The converted signal is A/D-converted on the control unit 9 and stored as digital information in the storage unit 92 on the control unit 9 in a state associated with the sampling time information by the clock signal on the control unit 9. . The FLL circuit 4 and control unit 9 are driven by a power storage unit 6 installed inside the outer container 1 .

The cooling unit 5 cools and liquefies the gas coolant in which the liquid coolant L is vaporized. The cooling unit 5 has a refrigerator 51 , a motor 52 , a cooling head 53 , a heat radiation head 54 and a heat pipe 55 . The refrigerator 51 is, for example, a Stirling refrigerator. Motor 52 drives refrigerator 51 . The cooling head 53 is positioned inside the inner container 2 and cools and liquefies the vaporized gaseous coolant L inside the inner container 2 . The heat dissipation head 54 is positioned outside the inner container 2 and inside the outer container 1 to discharge heat emitted from the refrigerator 51 . The heat pipe 55 transports and discharges waste heat from the refrigerator 51 .

Since the outer container 1 is sealed, the internal pressure increases as the liquid coolant L evaporates. Since the temperature of the liquid coolant L also rises along with this, if the temperature rises, the operation of the SQUID element 31 as a magnetic field sensor will soon become unstable, and eventually the superconducting state cannot be maintained. A critical temperature is reached and the magnetic field cannot be measured.

For this reason, the magnetic measuring device T detects the temperature of the liquid coolant L and the atmospheric pressure in the outer container 1 with the pressure detector 8 arranged in the outer container 1 and the temperature detector 32 arranged in the SQUID substrate 3. Monitor at least one. The pressure detector 8 is, for example, a pressure sensor. The magnetometer T lowers the temperature in the inner container 2 by driving the refrigerator 51 installed in the outer container 1 with a motor 52 at a constant temperature or pressure. The waste heat at this time is discharged into the outer container 1 and finally released to the external environment through the wall surface of the outer container 1 .

When the magnetic measuring device T is used in a high-temperature environment exceeding 90° C., such as in oil and natural gas production wells, the cooling unit 5 includes a Peltier element or the like in addition to the cooling unit 5. cooling means. In this case, the second cooling means may transport waste heat from the refrigerator 51 through a heat pipe 55 attached to the wall of the outer container 1 and discharge it to the outside of the outer container 1 .

The power storage unit 6 stores electric power for operating the magnetic measurement device T. As shown in FIG. The power storage unit 6 has a first power storage unit 61 and a second power storage unit 62 . The first power storage unit 61 is a ±15V analog power supply that drives the FLL circuit 4 and the like, which are made up of, for example, nickel-metal hydride batteries. The second power storage unit 62 is, for example, a +5V digital power supply. The voltage of each power source, that is, the first power storage unit 61 and the second power storage unit 62 is monitored by a power storage amount measuring unit (not shown) by the control unit 9, and when the voltage of the power storage unit 6 becomes less than a certain value, the refrigerator 51 charging is started in synchronization with the operation of

The holding member 7 is a member that holds the SQUID substrate 3 , the heat storage element 25 and the inner container 2 . As the holding material 7, a first holding material 71, a second holding material 72, a third holding material 73, a fourth holding material 74, and a fifth holding material 75 are provided. The first holding member 71 is made of a cushioning member made of melamine foam or the like. The first holding material 71 is provided between the outer surface of the heat storage body 25 and the inner surface of the inner container 2, and functions as a vibration absorbing material that absorbs vibrations generated when the liquid coolant L is vaporized. have

Specifically, the first holding member 71 partially or entirely covers the outer surface and the bottom surface of the heat storage element 25 and is accommodated in the inner container 2 so as to be in pressure contact therewith. Since the first holding member 71 is accommodated in the magnetic measurement device T in this way, the impact caused by the bubbles when the liquid coolant L boils on the inner wall surface of the inner container 2 is directly transmitted to the heat storage element 25. to prevent In addition, the liquid coolant L circulates in the first holding member 71 when bubbles generated at the bottom of the inner container 2 rise, and the flow of the liquid coolant L causes the liquid coolant L to flow around the SQUID substrate 3 . In order to suppress the reaching, it is possible to further suppress the noise caused by the vibration.

Like the first holding member 71, the second holding member 72 is made of a cushioning member made of, for example, melamine foam. A second holding member 72 is provided below the SQUID substrate 3 .

The third holding member 73 is, as described above, a substrate mounting member obtained by processing a round bar of polyacetal resin, for example. The third holding member 73 is attached to the lid 12 of the outer container 1 through the lid 22 of the inner container 2 . By closing the lid 12 of the outer container 1 , the lid 22 is placed on the inner container 2 to prevent the gaseous coolant, which is vaporized by heating the liquid coolant L in the outer container 1 , from entering the inner container 2 . In addition, the SQUID substrate 3 and the inner container 2 are pressed against the bottom of the outer container 1 . Specifically, the SQUID substrate 3 is pressed against the bottom of the inner container 2 by a third holding member 73 via a second holding member 72 provided below the SQUID substrate 3 . The wiring from the connector 33 of the SQUID board 3 is connected to the FLL circuit 4 inside the outer container 1 along the third holding member 73 .

The fourth holding member 74 has, for example, a cylindrical shape, but the shape of the fourth holding member 74 is arbitrary. The fourth holding member 74 is provided near the bottom of the inner container 2 between the outer surface of the inner container 2 and the inner surface of the outer container 1 and between the bottom surface of the inner container 2 and the bottom surface of the outer container 1. It is The fifth holding member 75 has, for example, a cylindrical shape, but the shape of the fifth holding member 75 is arbitrary. The fifth holding member 75 is provided between the outer surface of the inner container 2 and the inner surface of the outer container 1 near the upper portion of the inner container 2 .

At least one of an oxygen absorbent and a dehydrating agent (water absorbing agent) may be accommodated inside the outer container 1 . At least one of the oxygen absorbent and the dehydrating agent (water absorbing agent) may be placed, for example, in a space formed by the bottom surface of the inner container 2 and the bottom surface of the outer container 1, but is not limited thereto. Any position inside the outer container 1 may be used.

Since the oxygen absorbent is contained inside the outer container 1, the amount of oxygen inside the outer container 1 can be reduced. Combustion of hydrocarbons in oil and gas wells by oxygen can be prevented. In addition, since the dehydrating agent is stored inside the outer container 1, the amount of water inside the outer container 1 can be reduced. As a result, insulation failure due to dew condensation inside the outer container 1 is prevented, and cooling efficiency deterioration due to frost adherence to the surface of the cooling head 53 is prevented.

The control unit 9 is, for example, a CPU (Central Processing Unit) and executes programs stored in the storage unit 92 . The control unit 9 has a measuring unit 91 , a storage unit 92 and a refrigerator switch 93 . The measurement unit 91 has a function of measuring magnetism detected by the SQUID element 31 . Specifically, the measurement unit 91 measures the magnetism detected by the SQUID element 31 based on the magnetic field generation signal. The magnetic field generation signal is a signal that indicates the timing at which the magnetic field generator V generates a magnetic field.

The storage unit 92 includes ROM (Read Only Memory) and RAM (Random Access Memory). The storage unit 92 stores programs executed by the control unit 9 . The storage unit 92 stores, for example, measurement results measured by the measurement unit 91 . The refrigerator switch 93 is a switch that activates the motor 52 of the cooling unit 5 .

The control unit 9 operates the cooling unit 5 based on the timing at which the measurement unit 91 measures the magnetism, as will be described later. Specifically, the control unit 9 activates the cooling unit 5 when the temperature detected by the temperature detection unit 32 is equal to or higher than a predetermined temperature and when it is not the timing for the measurement unit 91 to measure magnetism. More specifically, the control unit 9 controls the measurement unit 91 to generate a magnetic field based on an intermittent magnetic field generation signal indicating the timing at which the magnetic field generation device V generates magnetism, received from the magnetic field generation device V that generates magnetism. is specified, and the cooling unit 5 is intermittently operated based on the specified timing.

The control unit 9 temporarily stores the magnetic flux density information measured by the measurement unit 91 in the storage unit 92 and transmits the information to the ground system control unit U, which will be described later, via the optical fiber included in the control cable 15 . The control unit 9 also receives control information from the system control unit U via the optical fiber included in the control cable 15 , and controls the voltage of the power storage unit 6 and the temperature inside the inner container 2 .

The control unit 9 A/D-converts the voltage corresponding to the intensity of the magnetism detected by the FLL circuit 4 and temporarily stores it in the storage unit 92 together with the sampling time. The control unit 9 transmits the magnetic field intensity information stored in the storage unit 92 to the system control unit U through the optical fiber included in the control cable 15 as data that can be matched with the sampling time during the operable period of the refrigerator 51. do.

The controller 9 appropriately controls the temperature inside the inner container 2 . The controller 9 operates based on the temperature detected by the temperature detector 32 . Based on the magnetic field generation signal, the control unit 9 operates the cooling unit 5 at the timing when the measurement unit 91 does not measure magnetism.

The inner container 2 , the liquid coolant L, the heat storage element 25 , and the fixing portion (for example, the connector 33 of the SQUID substrate 3 or the holding member 7 or the like) constitute a cooling device that cools the SQUID element 31 . The fixing part is a member that fixes the SQUID element 31 so that it is immersed in the liquid coolant L during operation.

[Cooling control of controller 9]
FIG. 3 is a diagram showing the cooling control flow of the controller 9. As shown in FIG.
The controller 9 measures the temperature of the SQUID element 31 with the temperature detector 32 (S11). Next, the controller 9 determines whether the temperature detected by the temperature detector 32 is equal to or higher than a predetermined threshold (S12).

When the control unit 9 determines that the temperature of the SQUID element 31 measured by the temperature detection unit 32 is equal to or higher than a predetermined threshold value (for example, 77 K) (YES in S12), the control unit 9 A magnetic field generation signal transmitted from the outside of the magnetometer T (for example, the system controller U) is received via an optical fiber (S13). Based on the received magnetic field generation signal, the control section 9 determines whether or not a certain period of time has elapsed since the energization of the magnetic field generation section V1 ended (S14). When the controller 9 determines that the temperature of the SQUID element 31 measured by the temperature detector 32 is not equal to or higher than the predetermined threshold value (NO in S12), the process returns to S11.

When the control unit 9 determines that a certain period of time has passed since the energization of the magnetic field generation unit V1 ended (YES in S14), the control unit 9 shifts to the refrigerator operable mode (S15), and the motor 52 that drives the refrigerator 51 to start cooling the inside of the inner container 2 (S16). When the controller 9 determines that the predetermined time has not elapsed since the energization of the magnetic field generator V1 was terminated (NO in S14), the controller 9 returns to S11.

As a result, the temperature of the cooling head 53 provided inside the inner container 2 decreases, and the gaseous coolant obtained by vaporizing the liquid coolant L in the inner container 2 liquefies on the cooling head 53 . The liquefied liquid coolant L drips onto the heat storage element 25 or the liquid surface of the liquid coolant L contained in the heat storage element 25 . The gaseous coolant obtained by vaporizing the liquid coolant L in the outer container 1 moves into the inner container 2 through the discharge pipe 222 . As a result, the pressure inside the outer container 1 is reduced.

The control unit 9 determines whether or not an advance notice signal has been received (S17). The notice signal is a signal indicating that it is a predetermined time before the termination of the energized state of the magnetic field generator V1. When the control unit 9 determines that the warning signal has been received (YES in S17), the control unit 9 turns off the refrigerator operable mode (S18) and stops the motor 52 (S19). Specifically, the controller 9 ends the refrigerator operable mode a predetermined time before the end of the energization time of the magnetic field generator V1. The predetermined time is, for example, 2 seconds. At the end of the refrigerator operable mode, the control unit 9 stops the motor 52 so that the piston of the refrigerator 51 is positioned on the heat absorption side. As a result, the magnetometer T prevents motor noise and vibration from affecting the magnetic field strength measurement. Further, when the controller 9 determines that the notification signal has not been received (NO in S17), the process returns to S15.

[Power storage control of control unit 9]
FIG. 4 is a diagram showing a power storage control flow of the control unit 9. As shown in FIG.
The control unit 9 causes the power storage unit 6 to store power at the timing when the power storage amount measured by the power storage amount measuring unit is less than a predetermined first lower limit and the measurement unit 91 does not measure magnetism.

Specifically, the control unit 9 measures the amount of electricity stored in the electricity storage unit 6 by the electricity storage measuring unit (S21). Next, the control unit 9 determines whether the voltages of the first power storage unit 61 and the second power storage unit 62 measured by the power storage amount measuring unit are less than the first lower limit values (eg ±13.3V and 4.81V). (S22). When the voltages of first power storage unit 61 and second power storage unit 62 become less than the first lower limit value (YES in S22), control unit 9 sets the power storage amount of second power storage unit 62 to the second lower limit value (for example, 4.75V). ) is determined (S23). The second lower limit is a value smaller than the first lower limit.

When control unit 9 determines that the amount of electricity stored in second power storage unit 62 is not less than the second lower limit value (NO in S23), it determines whether or not the refrigerator operable mode is on (S24). When the controller 9 determines that the refrigerator operable mode is on (YES in S24), the controller 9 stores power in the first power storage unit 61 and the second power storage unit 62 while the refrigerator operable mode is on (S25). ). Specifically, the control unit 9 connects the switching power supply of each voltage to the 24V power supply supplied from the system control device U through contact relays. The control unit 9 controls the first power storage unit 61 and the second power storage unit 62 to keep the first power storage unit 61 and the second power storage unit 62 in the ON state unless the respective upper limit values (for example, ±15.0 V and 5.5 V) are reached. 61 and the second power storage unit 62 are charged.

In the magnetic exploration system S, the magnetic field data measured by the magnetic measurement device T after the magnetic field generator V1 is energized is used as the magnetic field change measurement result. The magnetism measuring device T shifts to the refrigerator operable mode after a certain period of time has elapsed since the energization state of the magnetic field generator V1 is terminated, and performs the cooling or power storage operation. As a result, it is possible to prevent power source noise from the refrigerator 51, the motor 52, and the power storage unit 6 from being included in the data after the current interruption of the magnetic field generator V1, which is important as magnetic data. Improves accuracy.

When the amount of electricity stored in second electricity storage unit 62 measured by the electricity storage amount measuring unit is less than the second lower limit value smaller than the first lower limit value (YES in S23), control unit 9 causes measurement unit 91 to The second power storage unit 62 is charged even at the timing of measuring magnetism.

Specifically, when the voltage of second power storage unit 62 is less than the second lower limit value (YES in S23), control unit 9 controls the Charging of the second power storage unit 62 is started (S26). As a result, the magnetic measurement device T is prevented from becoming uncontrollable due to power shutdown.

[Effects of the magnetic measurement device T according to this embodiment]
The magnetic measurement device T according to this embodiment includes an inner container 2 that suppresses heat transfer between the inside and the outside, a superconducting quantum interferometer element 31 housed in the inner container 2, a superconducting quantum It has a liquid coolant L that cools the interferometer element 31, a heat storage body 25 that stores cold heat generated by the liquid coolant L, and a measurement unit 91 that measures the magnetism detected by the superconducting quantum interferometer element 31. , the superconducting quantum interferometer element 31 is in contact with the heat reservoir 25 via the liquid coolant L. FIG. The liquid coolant L is vaporized by the heat that flows in from the outside of the inner container 2, increasing the pressure inside the outer container 1, and the temperature of the liquid coolant L also increases accordingly. In this case as well, the volume of the heat storage medium 25 does not substantially change, and the heat capacity per volume of the heat storage medium 25 is greater than the heat capacity per volume of the liquid coolant L, so the temperature of the liquid coolant L rises. is alleviated.

In addition, since the heat storage body 25 occupies a large volume inside the inner container 2, the volume of the liquid coolant L required for immersing the superconducting quantum interferometer element 31 can be reduced. The magnetism measuring device T according to this embodiment has the heat storage body 25 in this way, so that the amount of the liquid coolant L per unit volume inside the inner container 2 can be reduced. Therefore, when the inner container 2 is damaged due to an accident or the like, the magnetic measuring device T is less likely to undergo rapid volumetric expansion of the liquid coolant L, and the pressure rise in the outer container 1 can be easily suppressed in terms of design. .

Further, when the magnetic measuring device T according to the present embodiment is used in a well, the outer container 1 breaks at a point near the well mouth where the pressure in the well is low, and the explosively vaporized liquid coolant L is released into the well. However, since the absolute amount of the liquid coolant L is small, the possibility of causing a serious accident such as breakage of the well head is reduced. Further, in the case of this embodiment in which the vaporized liquid coolant L is discharged into the sealed container, it is possible to control the temperature of the liquid coolant L low by extending the operation time of the refrigerator 51. , thereby improving the sensitivity of the superconducting quantum interferometer device 31 . When the characteristics of the superconducting quantum interferometer element 31 deteriorate, it is possible to temporarily operate it by lowering the operating temperature. The configuration allows the pressure rise to be maintained within an acceptable range for a longer period of time.

[Structure of magnetic exploration system S]
Details of the magnetic exploration system S will be described.
As described above, the magnetic exploration system S has the magnetic field generator V, the magnetic measurement device T, and the system controller U. The magnetic field generator V has a magnetic field generator V1 and a power feeder V2. The magnetic field generator V1 generates a magnetic field based on a magnetic field generation signal generated by the system controller U. FIG. The power supply unit V2 applies a voltage to the magnetic field generation unit V1.

The magnetic field generator V switches between an energized period in which the magnetic field generator V1 is energized and a non-energized period in which the magnetic field generator V1 is not energized in synchronization with the magnetic field generation signal. The magnetic field generator V1 has a covered electric wire that generates a primary magnetic field corresponding to the square wave current in the environment by applying a square wave current. The magnetic field generator V1 has a cable V11 and electrodes V12. The magnetic field generator V1 has a form called a line source, which has a cable V11 arranged substantially linearly on the seabed and electrodes V12 arranged at both ends or one end of the cable V11. The cable V11 is, for example, a cable with a length of about 2 km installed on the seabed. The electrode V12 is made of, for example, a galvanized steel plate.

An electrode V12, which is a feeding point provided somewhere on the cable V11, supplies a square-wave current having positive and negative amplitudes, and the electrode V12 discharges into the sea and under the seabed. A square-wave current is generated by switching a direct current supplied from a direct current power source V21, which is a power supply device, by a switch device V22 provided near the electrode V12, which is a feeding point.

The power supply unit V2 repeatedly applies a rectangular wave voltage to the magnetic field generator V1 in the order of positive direction-pause-negative direction-pause at arbitrary intervals (for example, 10 seconds). The power supply unit V2 applies a voltage so that the current flowing through the magnetic field generation unit V1 is 1 to 1000 [A], preferably about 40 to 400 [A].

The power supply unit V2 has a DC power supply V21 and a switch device V22. The DC power supply V21 is installed on land or at sea. The DC power supply V21 has the function of supplying a DC current to generate a magnetic field of the required strength, and includes, for example, a 50 or 60 Hz three-phase AC generator and inverter, and their attendant safety devices and control devices. have.

The switch device V22 generates a square wave current swinging in both positive and negative directions from the DC power supply V21. The switch device V22 switches the DC current from the DC power supply V21 based on the magnetic field generation signal (control signal) from the system controller U to generate a square wave current.

The switching device V22 has switching means (interrupting means), surge absorbing means (surge absorber), safety device, and switching device control means. Switch means are relays, SSRs (Solid State Relays), and other existing switching elements. An IGBT (Insulated Gate Bipolar Transistor) is particularly suitable for the switching means because it cuts off a current of 30 to 400 [A] flowing through an electric wire extending several kilometers in a transient time of about 1 millisecond. The switching device V22 generates square waves in the positive and negative directions with a transient time of about 1 millisecond at the time of interruption.

Information on the energization/cutoff timing and the positive/negative direction is stored with a clock signal by a GPS (Global Positioning System) clock or other synchronizing means for analysis of the received signal.

The switch device V22 is provided in the vicinity of the electrode V12, which is a feeding point, and generates a square wave current by switching the direct current supplied from the direct current power source V21. The switching device V22 switches the direct current based on a magnetic field generation signal (switching timing signal) generated by the system control device U. FIG. As a result, the direction of the current is repeated in the order of positive direction - off - negative direction - off, and 8 seconds after turning on in the positive and negative directions, an advance notice signal (that is, a signal a predetermined time before the end of the on state) ) is sent to the control unit 9 of the magnetism measuring device T. FIG.

The current value at this time is 10 to 1000 [A], usually 30 to 400 [A]. Also, the ON→OFF transient time is 10 milliseconds or less, preferably 1 millisecond or less.

In the case of this configuration, it is inevitable that a ripple current of about 1% of the amplitude is generated when both positive and negative are in the ON state. Therefore, in a so-called time domain analysis method using a square wave, the secondary magnetic field after the ON→OFF timing is analyzed. By doing so, it becomes possible to eliminate the influence of the ripple current in the magnetic measurement.

FIG. 5 is a diagram showing the control flow of the system control device U. As shown in FIG. FIG. 6 is a diagram showing an example of a control signal.

The system control device U transmits a magnetic field generation signal (switching signal) to the switching device V22 (S31). Next, the system control device U determines whether or not it is a predetermined time before the switch device V22 turns off the current flowing to the magnetic field generator V1 (S32).

When the system control device U determines that it is a predetermined time before the switch device V22 turns off the current flowing through the magnetic field generator V1 (YES in S32), the timing at which the magnetic field generator V switches from the energized period to the non-energized period. is generated (a signal indicating that it is a predetermined time before turning off the current flowing through the magnetic field generator V1). Then, the system control device U transmits the notice signal to the control section 9 of the magnetism measuring device T (S33). As described above, the control section 9 of the magnetism measuring device T stops the operation of the cooling section 5 based on the warning signal (S17 to S19 in FIG. 3). If the system control device U determines that it is not before the predetermined time before the switch device V22 turns off the current flowing to the magnetic field generator V1 (NO in S32), the process returns to S31.

In addition, the system control device U calibrates the time signal of the control unit 9 of the magnetic measurement device T with required accuracy, and activates the reset line when the magnetic measurement device T malfunctions, so that the magnetic measurement device It is possible to return the control unit 9 of T to the initial state and forcibly charge the second power storage unit 62 as necessary.
In the above, the magnetic field generator V that causes a rectangular wave current to flow through the substantially linear cable V11 has been described. can be changed and combined as appropriate, such as using

<Modification>
FIG. 7 is a diagram showing a modification of the heat storage body 25. As shown in FIG. FIG. 7(a) is a cross-sectional view in the height direction of the heat storage element 25a. FIG. 7(b) is a diagram showing the structure of the heat storage element 25a viewed from above.

The magnetic measuring device Ta is different from the magnetic measuring device T according to the present embodiment in that the SQUID element mounting substrate 3a is provided for three directions of XYZ, and the heat storage body 25a is divided into two. .

The heat storage body 25 a is a modification of the heat storage body 25 . The heat storage body 25a has a first heat storage body 253a and a second heat storage body 254a. The heat storage body 25a is formed by combining the first heat storage body 253a and the second heat storage body 254a. The second heat storage body 254a is coupled to the first heat storage body 253a below the accommodation portion 251 of the heat storage body 25a.

Since the heat storage body 25a is vertically divided into two at substantially the central portion, even in the superconducting quantum interference device (SQUID device) 31a having a complicated uneven shape for three-axis mounting, the heat storage body 25a It can be accommodated in the accommodation portion 251, and molding of the heat storage body 25a is facilitated.

Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of the gist thereof. be. For example, specific embodiments of device distribution/integration are not limited to the above-described embodiments. can be done. In addition, new embodiments resulting from arbitrary combinations of multiple embodiments are also included in the embodiments of the present invention. The effect of the new embodiment caused by the combination has the effect of the original embodiment.

S... Magnetic exploration system T, Ta... Magnetic measuring device 1... Outer container 11... Outer container main body 12... Lid 13... Connector 14... Internal pressure holding device 15. Control cable 2... Inner container 21... Inner container body 22... Lid 221... Hole 222... Release pipe 24... Liquid coolant injection pipe 241... Valve 25, 25a... Heat storage element 251... Housing part 252... Hole 253a... First heat storage element 254a... Second heat storage elements 3, 3a... Superconducting quantum interferometer element (SQUID element) mounted Substrate (SQUID substrate)
31, 31a ... superconducting quantum interferometer element (SQUID element)
32... Temperature detector 33... Connector 4... FLL circuit 5... Cooling part 51... Freezer 52... Motor 53... Cooling head 54... Radiation head 55... Heat pipe 6 Electric storage unit 61 First electric storage unit 62 Second electric storage unit 7 Holding material 71 Vibration absorbing material (first holding material)
72 Second holding member 73 Third holding member 74 Fourth holding member 75 Fifth holding member 8 Pressure detector 9 Control unit 91 Measurement unit 92 Storage unit 93 Chiller switch U System controller V Magnetic field generator V1 Magnetic field generator V11 Cable V12 Electrode V2 . . Power supply unit V21 .. DC power supply V22 .. Switch device L .. Liquid coolant

Claims (10)

an inner container that suppresses heat transfer between the inside and the outside;
a superconducting quantum interferometer element housed in the inner container;
a liquid coolant for cooling the superconducting quantum interferometer element;
a heat storage body for accumulating cold heat generated by the liquid coolant;
a measurement unit that measures the magnetism detected by the superconducting quantum interferometer element;
has
wherein the superconducting quantum interferometer element is positioned so as to be immersed in the liquid coolant during operation ;
The heat storage body has a concave accommodation portion,
A magnetic measurement apparatus , wherein the superconducting quantum interferometer element is housed in the housing section . characterized in that a hole penetrating the heat storage element is formed in the bottom of the housing part,
A magnetic measurement device according to claim 1 . The heat storage element is
a first heat storage element;
a second heat storage element coupled to the first heat storage element below the housing;
characterized by having
3. The magnetic measuring device according to claim 1 or 2 . the liquid coolant is liquid nitrogen;
The heat storage body is characterized by containing silicon or quartz glass,
The magnetic measuring device according to any one of claims 1 to 3 . a cooling unit that cools and liquefies the gaseous coolant obtained by vaporizing the liquid coolant;
a control unit that operates the cooling unit based on the timing at which the measurement unit measures magnetism;
characterized by further comprising
A magnetic measurement device according to any one of claims 1 to 4 . further comprising a temperature detection unit that detects the temperature of the superconducting quantum interferometer element,
The control unit operates the cooling unit when the temperature detected by the temperature detection unit is equal to or higher than a predetermined temperature and the measurement unit is not timing to measure magnetism,
The magnetic measuring device according to claim 5 . The control unit specifies the timing at which the measurement unit measures magnetism based on an intermittent magnetic field generation signal indicating the timing at which the magnetic field generation device generates magnetism, received from the magnetic field generation device that generates magnetism. , characterized by intermittently operating the cooling unit based on the specified timing,
The magnetic measuring device according to claim 5 or 6 . further comprising an outer container that houses the inner container;
The inner container is formed with a hole for communicating the gaseous coolant obtained by vaporizing the liquid coolant with the outer container,
A magnetic measurement device according to any one of claims 1 to 7 . A vibration absorbing material is provided between the outer surface of the heat storage body and the inner surface of the inner container, and absorbs vibration generated when the liquid coolant is vaporized.
A magnetic measurement device according to any one of claims 1 to 8 . A magnetic exploration system comprising a magnetic field generation device that generates a magnetic field, a magnetic measurement device that measures the magnetic field generated by the magnetic field generation device, and a system control device that controls the magnetic field generation device and the magnetic measurement device,
The system control device generates a magnetic field generation signal indicating the timing at which the magnetic field generation device generates a magnetic field,
The magnetic field generator has a magnetic field generator that generates a magnetic field based on the magnetic field generation signal,
The magnetic measurement device is
an inner container that suppresses heat transfer between the inside and the outside;
a superconducting quantum interferometer element housed in the inner container;
a liquid coolant for cooling the superconducting quantum interferometer element;
a heat storage body for accumulating cold heat generated by the liquid coolant;
a measurement unit that measures the magnetism detected by the superconducting quantum interferometer element based on the magnetic field generation signal;
a cooling unit that cools and liquefies the gaseous coolant obtained by vaporizing the liquid coolant;
a control unit that operates the cooling unit at a timing at which the measurement unit does not measure magnetism based on the magnetic field generation signal;
a power storage unit that stores power for operating the magnetic measurement device;
a power storage amount measuring unit that measures the power storage amount of the power storage unit;
has
wherein the superconducting quantum interferometer element is positioned so as to be immersed in the liquid coolant during operation ;
The control unit causes the power storage unit to store power at a timing when the power storage amount measured by the power storage amount measuring unit is less than a predetermined first lower limit and the measurement unit does not measure magnetism . magnetic survey system.

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