JP5453611B2 - Underground fluid observation device and measurement method - Google Patents

Description

The present invention relates to an underground fluid observation apparatus for observing a fluid flow state based on a flow current generated by a fluid existing underground such as groundwater, oil, natural gas, etc. flowing in the underground , and the flow of the fluid The present invention relates to a measurement method for measuring a state .

  Conventionally, when investigating underground structures and various resource deposits, a resistivity exploration method for exploring underground resistivity is often used. In the resistivity exploration method, an electromagnetic field source is required to generate a predetermined electromagnetic field in the survey area, and an appropriate electromagnetic field source is installed according to the size of the survey area and the survey depth. The specific resistance is measured.

  In such a specific resistance exploration method, there is also known an electromagnetic exploration method called the so-called MT method in which an underground field resistivity is obtained by measuring a geomagnetic variation caused by an electromagnetic field variation such as lightning discharge instead of providing an electromagnetic field source. (For example, refer to Patent Document 1).

  Since the MT method uses geomagnetism, it is necessary to measure a small electric field and a small magnetic field with a measured electric field of several tens mV / km and a magnetic field of several tens of nT. Since measurement is required, a certain level of skill is required for measurement work.

  Under these circumstances, the present inventors have been researching underground electric exploration using the fluid streaming potential method. In the fluid streaming potential method, a flowing current generated when a fluid flows underground is detected, and the fluid flow state is specified from the detected flowing current.

Therefore, it is known as an effective electric exploration method in investigations targeting fluids that flow underground, such as investigations aimed at the use of groundwater and investigations aimed at the forced recovery of oil using pressurized water. It was.
JP 05-323038 A

  However, in the fluid streaming potential method, since the flowing current is measured by the potential, it is necessary to provide a reference potential as a reference for potential measurement, and there is a problem that the setting work of the reference potential is extremely complicated. .

  In other words, the reference potential in such a case is theoretically a potential at infinity, but in practice it is impossible to set an electrode at infinity, and it is at a point as far as possible from the investigation area. The reference potential electrode is provided, and the larger the area of the survey area, the farther apart the reference potential electrode should be provided. Usually, the reference is located at a distance of several kilometers or more from the survey area. An electrode for potential was provided.

  Moreover, the reference potential electrode must be electrically connected to a potential difference measuring device provided in the investigation area, and the wiring must be installed over several kilometers, and this wiring is cut by a wild animal or the like. Since this often occurs, it was necessary to check whether the wiring was disconnected before measurement.

  The inventors of the present invention have made the present invention that can solve this problem while conducting further research and development of the fluid streaming potential method.

The underground fluid observation apparatus of the present invention, which is detected at a plurality of detection portions and, the plurality of detector for detecting the flow currents caused by the fluid flowing respectively installed underground in a predetermined position in the measurement area flow An underground fluid observation apparatus including an analysis unit that analyzes current data and identifies a fluid flow state, wherein the detection unit is a time variation of a potential difference between two points on a first virtual straight line passing through the detection unit. First potential fluctuation detecting means for detecting the first potential fluctuation detecting means, second potential fluctuation detecting means for detecting temporal fluctuation of the potential difference between two points on the second virtual straight line passing through the detecting section and intersecting the first virtual straight line, virtual straight line and the magnetic field variation detecting means for detecting a time variation of the magnetic field at the intersection portion between the second imaginary straight line possess respectively, the analysis unit, the first potential variation detecting means and the second potential variation detecting means Time variation of detected potential difference, normal To the magnetic field fluctuation detection means and to identify the flow state of the fluid based on time variation of the potential of the detecting portions identified by using the time variation of the magnetic field detected.

Further, the underground fluid observation apparatus of the present invention is characterized in that the magnetic field fluctuation detecting means is composed of three magnetic sensor elements arranged orthogonal to each other, and the first virtual line and the second virtual line are obtained. It is also characterized by being orthogonal.
Further, in the measurement method of the present invention, the flow current generated by the fluid flowing in the basement of the plurality of detection points respectively set at predetermined positions in the measurement area is detected, and the detection is performed at the plurality of detection points. A measurement method of analyzing flow current data to measure a flow state of the fluid, wherein a first step of detecting a time variation of a potential difference between two points on a first virtual straight line passing through the detection point; A second step of detecting a time variation of a potential difference between two points on a second virtual line passing through the detection point and intersecting the first virtual line; and the first virtual line and the second virtual line A third step of detecting time variations of the magnetic fields at the intersections, respectively, and the time variation of the potential difference detected in the first step and the second step, and the detection in the third step. Time variation of magnetic field, and it has the characteristics to measure the flow state of the fluid based on time variation of the potential of each detection point identified by using.

In the underground fluid observation apparatus of the present invention, not only the time variation of the potential by the first potential variation detection means and the second potential variation detection means in the conventional fluid streaming potential method but also the time variation of the magnetic field by the magnetic field variation detection means. by detecting the time variation of utilizing a time variation of the time variation amount reflecting the magnetic field of the potentials, so can be identified without using a reference potential, the arrangement of the detector reference voltage as required Work can be made extremely easy.

  In addition, since the potential at the installation point where each detection unit is installed can be specified individually, it is possible to perform multipoint simultaneous measurement independently for each installation point, and it is possible to monitor the fluid flow state in the basement in real time. it can.

  An underground fluid observation apparatus according to the present invention is installed at a predetermined position in a measurement area, detects a flowing current generated by a fluid flowing in the underground, and data of a flowing current detected by the detecting unit. An underground fluid observation device including an analysis unit that analyzes and identifies a fluid flow state, and detects a change in a magnetic field caused by a change in potential along with a change in potential in the detection unit. .

  As described above, the detection unit can detect the fluctuation of the magnetic field, and can generate more detailed fluctuation data in the fluctuation of the potential from the fluctuation data of the magnetic field based on the relational expression between the electric field and the magnetic field known as the Maxwell equation. Therefore, the direction and magnitude of the flowing current can be specified in more detail from the potential data thus obtained.

  The inventors of the present invention call the electric exploration method that detects and uses not only the fluctuation of the potential but also the fluctuation of the magnetic field as the “fluid flow electromagnetic method”.

  In the fluid flow electromagnetic method, unlike the conventional fluid flow potential method, it is not necessary to set a reference potential as a reference for potential measurement, so it is possible to save time and labor for setting and managing the reference potential. Can be

  Further, in the fluid flow electromagnetic method, the potential difference fluctuation specified by the magnetic field fluctuation detected by the magnetic field fluctuation detection means is different from the potential difference fluctuation detected by the first potential fluctuation detection means and the second potential fluctuation detection means. Based on this, it is possible to easily eliminate the influence of disturbances such as noise included in the detection results of the respective detection means, so that higher accuracy can be achieved.

  In particular, in the fluid flow electromagnetic method, the direction and magnitude of the flowing current at each measurement point can be accurately identified by configuring the magnetic field fluctuation detection means with three magnetic sensor elements arranged orthogonal to each other. In addition, the fluid flow state can be monitored in real time.

  In the magnetic field fluctuation detection means, the three magnetic sensor elements do not necessarily have to be arranged orthogonal to each other, and the three magnetic sensor elements may be arranged in a primary independent direction in the three-dimensional space, respectively. By placing them orthogonal to each other, it is possible to reduce the burden of analysis processing of detection results.

  Further, the first potential fluctuation detecting means and the second potential fluctuation detecting means do not necessarily need to make the first virtual line and the second virtual line orthogonal to each other, and the first virtual line and the second virtual line are each independently independent. Although it may be provided in the direction, by making the first imaginary straight line and the second imaginary straight line orthogonal to each other, it is possible to reduce the load of analysis processing of the detection result. Furthermore, the detection of the fluctuation of the potential difference may be measured using three or more electrodes that are not on the same straight line, and the detection accuracy of the fluctuation of the potential difference can be improved by increasing the number of electrodes.

  FIG. 1 is a schematic explanatory diagram of the underground fluid observation apparatus of the present embodiment. The underground fluid observation apparatus includes a plurality of detection units 10 installed at predetermined positions in the measurement area S, and an analysis unit that analyzes flow current data detected by the detection unit 10 and identifies a fluid flow state. It consists of 20 and.

  In the present embodiment, the analysis unit 20 includes a server 21 including a storage unit that temporarily records data detected by each detection unit 10, and an electrode supply unit that supplies power to each detection unit 10, and the server The personal computer 22 analyzes the data stored in the storage means 21. Note that the server 21 and the personal computer 22 may be configured integrally. In FIG. 1, reference numeral 23 denotes a wiring connecting the server 21 and each detection unit 10.

  The personal computer 22 has an analysis program installed. By analyzing predetermined data with this analysis program, the flow current at the observation point where each detection unit 10 is installed is specified and observed on the display of the personal computer 22 The flow state of the target fluid can be displayed.

  As shown in FIG. 2, the detection unit 10 includes a control circuit 12 accommodated in a required protective case 11, and a first circuit connected to the control circuit 12 via predetermined conduction wires a, b, c, d. The electrode 13a, the second electrode 13b, the third electrode 13c, the fourth electrode 13d, and the three-axis gradiometer 14 accommodated in the protective case 11 are configured.

  The detection unit 10 embeds a protective case 11 in the ground to make it easier to detect changes in the underground magnetic field by the triaxial gradiometer 14, and the protective case 11 prevents moisture from entering inside. It has a watertight structure. The protective case 11 is made of plastic so as not to affect the magnetic field detected by the triaxial gradiometer 14.

  In FIG. 2, 15 is a GPS antenna that synchronizes the measurement times at all measurement points with high accuracy. The antenna 15 is received from the protective case 11 of the detection unit 10 buried in the ground and exposed to the ground. The sensitivity can be improved and the embedded position of the detection unit 10 can be easily understood.

  The first to fourth electrodes 13a, 13b, 13c, and 13d are only required to have such a size that the installation position does not move after being installed at a predetermined position. It is a polarized electrode.

  In the present embodiment, the control circuit 12 includes the first electrode 13a and the second electrode 13b as a set to constitute the first potential fluctuation detecting means together with the control circuit 12, and the control circuit 12 includes the third electrode 13c and the fourth electrode 13d as a set. In addition, the second potential fluctuation detecting means is configured.

  The first electrode 13a and the second electrode 13b are on a first imaginary straight line passing through the detection unit 10 and are arranged at approximately equal distances from the detection unit 10, respectively, so that two points of the first electrode 13a and the second electrode 13b are provided. The control circuit 12 can detect fluctuations in the potential difference between them. In the present embodiment, the first electrode 13a and the second electrode 13b are disposed at a distance of 5 m from the detection unit 10 and the distance between the first electrode 13a and the second electrode 13b is 10 m.

  The third electrode 13c and the fourth electrode 13d are on the second imaginary straight line passing through the detection unit 10 and are arranged at approximately equal distances from the detection unit 10, respectively, and two points of the third electrode 13c and the fourth electrode 13d. The control circuit 12 can detect fluctuations in the potential difference between them. In the present embodiment, the third electrode 13c and the fourth electrode 13d are arranged at a distance of 5 m from the detection unit 10, respectively, and the distance between the third electrode 13c and the fourth electrode 13d is 10 m.

  The first virtual line and the second virtual line are orthogonal to each other, and the detection unit 10 is positioned at the intersection of the first virtual line and the second virtual line. By making the first virtual line and the second virtual line orthogonal to each other, it is possible to simplify the calculation in the analysis of the potential fluctuation data respectively detected by the first potential fluctuation detecting means and the second potential fluctuation detecting means. The analysis process can be speeded up.

  In addition, the detection unit 10 is positioned at the intersection of the first virtual line and the second virtual line, and the variation of the magnetic field is detected by the three-axis gradiometer 14 provided in the detection unit 10, thereby detecting the detected magnetic field. Since the calculation in the analysis of the potential fluctuation data obtained by the analysis of the fluctuation data and the potential fluctuation data respectively detected by the first potential fluctuation detecting means and the second potential fluctuation detecting means can be simplified, the analysis processing Can be speeded up.

  In particular, in the three-axis gradiometer 14, one of the three axes is parallel to the first imaginary line, and the other one of the three axes is parallel to the second imaginary line. The speed can be increased.

  In the present embodiment, the three-axis gradiometer 14 is arranged such that the sensor portion of the first magnetic sensor element 14e, the sensor portion of the second magnetic sensor element 14f, and the sensor portion of the third magnetic sensor element 14g are orthogonal to each other. Is configured.

  The first to third magnetic sensor elements 14e, 14f, and 14g are so-called MI (Magneto-Impedance effect) sensors, and each measures a magnetic field gradient in the present embodiment.

  In FIG. 2, 14e-B is a circuit part of the first magnetic sensor element 14e, 14f-B is a circuit part of the second magnetic sensor element 14f, and 14g-B is a circuit part of the third magnetic sensor element 14g. The control circuit 12 is connected through the wiring bundles e, f, and g. Each of the connection wiring bundles e, f, and g is composed of a plurality of conductive wirings, and can be supplied to each circuit section 14e-B, 14f-B, 14g-B, and output a signal to the control circuit 12. It is said.

  A wiring 23 connected to the server 21 is connected to the control circuit 12 so that a predetermined data signal to the server 21 can be output. In addition, power is supplied to the control circuit 12 via the wiring 23. Furthermore, in the present embodiment, the control circuit 12 can connect the detection units 10 adjacent to each other by the wiring 23 in series and can be connected to the server 21, thereby reducing the necessary amount of the wiring 23.

  As shown in FIG. 1, the detection unit 10 configured as described above does not necessarily have to be arranged vertically and horizontally in the measurement area S as long as the arrangement position of each detection unit 10 can be correctly specified. In particular, in the present embodiment, the position of the detection unit 10 is specified by the latitude information and the longitude information of the arrangement position of each detection unit 10.

  FIG. 3 shows measurement data obtained by actually measuring the fluctuation of the potential and the fluctuation of the magnetic field by the detection unit 10 described above. In this case, the three axes correspond to a decrease in the potential (the one-dot chain line in FIG. 3). Magnetic field fluctuations in the first magnetic sensor element 14e (solid line in FIG. 3), the second magnetic sensor element 14f (dotted line in FIG. 3), and the third magnetic sensor element 14g (dashed line in FIG. 3) of the gradiometer 14, respectively. It can be seen that is detected. From the detection results of the first to third magnetic sensor elements 14e, 14f, and 14g, the direction and magnitude of the flowing current can be identified based on the Maxwell equation.

  In addition, in the underground fluid observation apparatus composed of the detection unit 10 and the analysis unit 20 described above, the direction and magnitude of the flowing current can be detected, but this directly indicates the actual fluid flow rate. is not.

  Therefore, the measuring area S is provided with measuring means for performing boring and measuring the substantial flow rate of the fluid to be observed, and the measured value of the fluid flow state obtained by the measuring means and the flow current. The flow state of the fluid is monitored in real time from the observed values. In this case, the measurement means for measuring the substantial flow rate can be provided with high accuracy by being provided at a plurality of locations in the measurement area S.

  When the fluid flow electromagnetic method is used, usually at least in the measurement area S, such as pumping up groundwater, forcibly collecting oil using pressurized water, pumping up hot water for geothermal power generation, or subsurface reduction. Since boring is necessary at one place, a necessary measuring means can be provided in this boring hole.

  In the above-described embodiment, the server 21 of the analysis unit 20 and the detection unit 10 are connected by wire via the wiring 23. However, each detection unit 10 is provided with a power source such as a battery and wireless communication means. As shown in FIG. 4, the server 21 of the analysis unit 20 and the detection unit 10 may be connected by wireless communication. As described above, by making the server 21 of the analysis unit 20 and the detection unit 10 wirelessly connected, the installation work of the detection unit 10 can be further simplified. In FIG. 4, reference numeral 24 denotes a transmission / reception antenna device connected to the server 21.

It is a schematic explanatory drawing of the underground fluid observation apparatus which concerns on embodiment of this invention. It is a schematic explanatory drawing of a detection part. It is a graph of the detection result by a detection part. It is a schematic explanatory drawing of the underground fluid observation apparatus of other embodiment.

Explanation of symbols

S Measurement area
10 Detector
11 Protective case
12 Control circuit
13a First electrode
13b Second electrode
13c Third electrode
13d 4th electrode
14 3-axis gradiometer
14e First magnetic sensor element
14f Second magnetic sensor element
14g 3rd magnetic sensor element
15 Antenna
20 Analysis section
21 servers
22 Personal computer
23 Wiring a Conducting wiring b Conducting wiring c Conducting wiring d Conducting wiring e Connection wiring bundle f Connection wiring bundle g Connection wiring bundle

Claims (3)

A plurality of detection units for detecting a flowing current generated by a fluid flowing in the underground by being respectively installed at predetermined positions in the measurement area, and analyzing the data of the flowing current detected by the plurality of detection units An underground fluid observation device including an analysis unit for identifying a fluid flow state,
The detector is
First potential fluctuation detecting means for detecting time fluctuation of a potential difference between two points on a first virtual straight line passing through the detection unit;
Second potential fluctuation detecting means for detecting a temporal fluctuation of a potential difference between two points on a second virtual line that passes through the detection unit and intersects the first virtual line;
A magnetic field variation detecting means for detecting a time variation of the magnetic field at the intersection portion between the second imaginary straight line and the first imaginary straight line possess respectively,
Each of the analysis units specified using the time variation of the potential difference detected by the first potential variation detection unit and the second potential variation detection unit and the time variation of the magnetic field detected by the magnetic field variation detection unit. An underground fluid observation apparatus that identifies the flow state of the fluid based on a temporal variation amount of potential in a detection unit . The magnetic field fluctuation detecting means is composed of three magnetic sensor elements arranged orthogonal to each other ,
The underground fluid observation apparatus according to claim 1, wherein the first virtual line and the second virtual line are orthogonal to each other .   The flow current generated by the fluid flowing under the plurality of detection points respectively set at predetermined positions in the measurement area is detected, and the flow current data detected at the plurality of detection points is analyzed and the flow current is analyzed. A measurement method for measuring a fluid flow state,
  A first step of detecting time variations in potential difference between two points on a first virtual straight line passing through the detection point;
  A second step of detecting a time variation of a potential difference between two points on a second virtual line that passes through the detection point and intersects the first virtual line;
  A third step of detecting time variations of the magnetic field at the intersections of the first virtual line and the second virtual line,
Including
  Based on the time variation amount of the potential at each detection point specified using the time variation of the potential difference detected in the first step and the second step and the time variation of the magnetic field detected in the third step. A measurement method characterized by measuring a flow state of a fluid.

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