JP2911695B2 - Underground electromagnetic induction survey method 3-axis magnetometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a three-axis magnetometer used for an underground electromagnetic induction survey and an invention of a data analysis method for confirming an underground crack in a monohole well using the magnetometer. About.

[0002]

2. Description of the Related Art Conventionally, as a typical example of metal ore exploration, there has been known an in-well electromagnetic induction exploration method using a vertical component magnetometer. On the other hand, as for the magnetometer used for the electromagnetic induction survey in the downhole, the one conventionally used for this type of survey is as follows.
It has an accuracy on the order of nT, and is not sufficient for use in deep exploration of petroleum, geothermal, and the like.

[0003]

2. Description of the Related Art This type of magnetometer is structurally composed of the following two types of sensors.

(1) Induction type horizontal magnetometer (2) Induction type vertical magnetometer Among these, the vertical magnetometer is a normal induction coil, but the horizontal magnetometer is assumed to be used in a geothermal well.
What can be stored in a pressure-resistant container having an outer diameter of 3.5 inches is required.

[0005] For this reason, a 3-inch length horizontal coil is used as the total length that can be stored in a heat container having an outer diameter of 3.5 inches. However, a single 3-inch length horizontal coil (induction type) is used. There is a drawback that the coil sensitivity is limited, that is, the obtained data is not reliable because the coil sensitivity is not good.

[0006] In transmitting data from the inside of a wellbore to the surface of the ground, a transmission device and a transmission cable with low attenuation and high reliability are desired.

[0007]

In order to solve the above problems, the present invention provides a three-axis magnetometer (two horizontal directions and one vertical direction), that is, a horizontal magnetic field magnetometer having a 3.5 inch outer diameter. Improve the sensitivity of a single-axis type small coil that can be stored inside the tool, make it a horizontal magnetic field magnetometer with a strong SN ratio, and connect multiple coils in an array to improve the sensitivity as a whole. The result is a horizontal magnetic field magnetometer with a strong ratio.

[0008] Similarly, the vertical magnetometer is also a three-axis magnetometer having an array-type configuration, the sensitivity of which is improved, and the vertical magnetometer has a strong SN ratio.

That is, in the three-axis magnetometer of the underground electromagnetic induction survey method, X, Y using the above-mentioned array type horizontal magnetic field sensor.
Regarding the component magnetometer, two sets of array-type horizontal magnetometers are arranged vertically above and below the array-type magnetometer to improve the cross-coupling of the X and Y component magnetometers. Is used as an array type vertical magnetometer as described above to improve the sensitivity and S / N ratio of the vertical magnetometer alone, and measure the cross-coupling, sensitivity and noise level of the entire three-component magnetometer through these arrangements. In addition, this is calibrated to provide a three-axis magnetometer capable of improving the sensitivity as a whole and increasing the SN ratio.

More specifically, a plurality of single-axis induction coils (hereinafter referred to as "coil elements") having a total length of 3 inches are arranged by being alternately combined in the X-axis direction and the Y-axis direction orthogonal to the horizontal direction. , To increase the coil sensitivity.

Incidentally, in order to increase the coil sensitivity, it is not sufficient to simply arrange a plurality of single-axis induction coils alternately in an orthogonal direction. That is, in order to measure the three-axis magnetic force, it is necessary to always provide a vertical magnetometer. For this purpose, in order to minimize the increase in noise due to mutual interference between these vertical and horizontal magnetometers, it is necessary to provide an optimal condition. Configuration must be determined.

In the present invention, a horizontal magnetic field sensor (upper components: X ₁ , Y ₁ , lower components: X ₂ , Y ₂ ) of two components (X axis and Y axis) is vertically symmetrical with respect to the vertical magnetometer. Sum (X ₁ +
X ₂ , Y ₁ + Y ₂ ).

In transmitting data from a wellbore logging probe to the ground surface, a transmission system for transmitting a control command from the ground surface to a tool is selected, and a multiplexing (signal multiplexing) method is used. Therefore, the total number of channels can be secured, and the synchronous detection circuit, the analog / digital converter, and the control microprocessor in the downhole electronic device are appropriately set accordingly.

[0014]

According to the present invention, a plurality of coil elements each having a total length of 3 inches are arranged in an array type in which a plurality of coil elements are alternately combined in the X-axis direction and the Y-axis direction orthogonal to the horizontal direction, so that the sensitivity of the horizontal coil is improved and the plurality of horizontal elements are increased. In order to prevent an increase in noise due to mutual interference between the coil and the vertical coil, the sum of the X-axis component and the Y-axis component is obtained symmetrically with respect to the vertical magnetometer. Furthermore, since the upper and lower components are symmetrical with respect to the vertical magnetometer, the upper components of the horizontal magnetic field coil elements are X ₁ and Y ₁ , and the lower components are X ₂ and Y _2.
, The upper component (X ₁ + X ₂ ) and the lower component (Y
₁ + Y ₂ ) can be measured.

In the downhole electronic device, a synchronous detection circuit, an analog / digital converter, and a control microprocessor are appropriately incorporated and used to reduce the attenuation of measurement data detected in the downhole. Therefore, it is transmitted to the ground surface with high accuracy, and it is easy to confirm underground cracks.

[0016]

An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view and a side view of a coil element for an array type horizontal magnetometer used in the present invention, and has an outer diameter of 20 mmφ and a length of 76 mm.

In FIG. 1, reference numeral 1 denotes an entire array type horizontal magnetometer coil element, 3 denotes a core, 4 denotes a main winding (main coil), and # 33AWG GAG
It is obtained by winding a lead wire of E (0.2 mmφ) 5000 times. 5 is a feedback winding (coil), 6 is a Teflon coil end, 7 is an electrostatic shield, 8 is a winding terminal, and 9 is a winding end. Also, 10
Is a set screw for locking the main winding 4 and others to the core 3.

FIG. 2 is a sectional view of a perpendicular magnetometer used in the present invention, which has an outer diameter of 25 mm in diameter and 457 mm in length. In FIG. 2, reference numeral 2 denotes an overall outline of the perpendicular magnetometer, 11 denotes a μ metal core, and 12 denotes
It is a single pie winding (coil) wound 11,180 times.

Reference numeral 13 denotes a feedback winding. A partition plate 14 is interposed at both ends of the single pie winding 12 and the feedback winding 13 to form a total of 16 single windings. One pie winding (coil) 1
2, the feedback winding 13, and the 17 partition plates 14, constitute the entire perpendicular magnetometer unit 2.

FIG. 3 is an overall schematic sectional view of an embodiment of the three-axis magnetometer according to the present invention. The vertical magnetometer unit 2 shown in FIG. 2 is disposed at the center, and FIG. Arrayed horizontal magnetometer coil elements 1
And a total of 20 pieces are arranged at right angles to each other, and are configured to have a total length of 1575 mm.

On the cable connection side of the three-axis magnetometer, a main output connector 15 for connecting a transmission cable to the ground is arranged, and the whole of the horizontal magnetometer element 1 and the vertical magnetometer section 2 are respectively connected to the main output connector 15. It is connected and transmits the measured magnetic field components in the horizontal, vertical X, Y, and Z directions to the ground equipment.

In FIG. 3, a part of the coil element unit 100 for the upper horizontal magnetometer is enlarged to be a portion A in the figure.
00 and the connecting portion of the vertical magnetometer section 2 are shown as an enlarged B section, and the connecting section between the vertical magnetometer section and the other horizontal magnetometer coil element section is shown as an enlarged C section.

As is clear from the enlarged views of these parts, the upper horizontal magnetometer coil element section 100 and the vertical magnetometer section 2 are connected by a connector 20. The connector 21 is connected to the lower horizontal magnetic coil element 200 at the other end.

FIG. 4 shows a state in which a plurality of the array type horizontal magnetometer coil elements 1 are arranged and arranged to form the upper horizontal magnetometer coil element section 100 or the lower horizontal magnetometer coil element section 200. .

The coil element 100 for the upper horizontal magnetometer or the coil element 20 for the lower horizontal magnetometer
The specific arrangement of 0 is perpendicular to each other so that when the three-axis magnetometer is suspended in a wellbore, it is possible to measure magnetic field components in two horizontal directions of X direction and Y direction. You.

FIG. 4 schematically shows this state. That is, X-axis array elements X ₁ , X ₂ ,
X ₃ , X ₄ and X ₅ are electrically connected in series, respectively, and Y-axis array elements Y ₁ , Y ₂ , Y ₃ , Y ₄ and Y ₅ arranged in each Y-axis direction are respectively , X-axis, and these Y-axis array elements Y ₁ , Y ₂ , Y ₃ , Y ₄ , Y ₅ are electrically connected in series. In FIG. 4, H _x represents the X-axis direction of the magnetic field, H _y is the Y-axis direction of the magnetic field, H _z represents a Z-axis direction of the magnetic field.

X ₁ , X ₂ , X ₃ , X ₄ , X ₅ are the coil axis directions of the respective X-axis array elements, and Y ₁ , Y ₂ , Y ₃ ,
Y ₄ and Y ₅ are the coil axis directions of each Y-axis array element.

In FIG. 4, reference numeral 16 denotes X-axis array elements X ₁ , X ₂ , X ₃ , X ₄ , X ₅ arranged in each X-axis direction.
Reference numeral 17 denotes an electrical series connection line for each of the Y-axis array elements Y ₁ , Y ₂ , Y ₃ , Y ₄ , and Y ₅ .

A schematic diagram of a three-axis magnetometer having a plurality of upper horizontal magnetometer coil element sections 100 and a lower horizontal magnetometer coil element section 200 disposed at both ends thereof and a vertical magnetometer section 2 disposed at the center thereof is shown. 5 and FIG.

FIG. 5 is a schematic diagram showing the arrangement of the above-described array type horizontal magnetometer coil element unit 100 and the lower horizontal magnetometer coil element unit 200 and the arrangement of the above-described vertical magnetometer unit 2. FIG. 6 is a schematic electrical connection diagram of the configuration of the three-axis magnetometer shown in FIG.

In FIG. 5, a plurality of reference numerals 1 denote coil elements for the above-mentioned individual array-type horizontal magnetometers.
These plurality of individual array type horizontal magnetometer coil elements 1 to horizontal magnetometer coil element units 100
And the coil element part 200 for lower horizontal magnetometers is formed. Reference numeral 2 denotes the above-described vertical magnetometer, and reference numeral 15 denotes the main output connector provided at the end of the three-axis magnetometer main body.

FIG. 6 shows a wiring connection diagram of each of the above-mentioned coil elements 1 for an array-type horizontal magnetometer. In FIG. In the arrangement, 4 is a main winding, 5 is a feedback winding, and 7 is an electrostatic shield that shields the winding and the wiring.

Reference numeral 15 is the connector, 16 is a preamplifier, 17 is the feedback winding network, 18 is a gain amplifier, and 19 is an output terminal.

In order to prevent mutual interference between end-axis induction coils (coil elements) having a total length of 3 inches in the array type element 1, each coil has a circumference of μ.
It is covered with metal foil (with slits) and is configured to be electrostatically shielded.

As is apparent from FIG. 6, each main winding 4 is connected in series, and its terminal is connected to the gain amplifier 18 via the preamplifier 16 and the feedback network 17, and the output terminal 19 to the ground equipment.

Next, the electrical connection configuration of the BH35 dual array type sensor according to the embodiment of the present invention will be described.

The sensor of this embodiment is capable of measuring X and Y components, and the electrical connection configuration is shown in FIGS.

FIG. 7 is a schematic connection diagram of the BH35 double array type sensor. The horizontal array sensors X ₁ , X ₂ and Y ₁ , Y ₂ are composed of two types of horizontal orthogonal arrays of X and Y.
It is a connection diagram of the whole sensor system including the vertical sensor Z.

That is, the multi-component receiving system is the same as the receiving system shown in FIGS.

As described above, the double array type sensor constituting each coil element comprises each coil element 1 having a unique feedback winding 5, and these windings 5 are connected in parallel. That, X ₁ and Y ₁ have a common shield wire, the receiving system is continuous to one or two connectors, each of which consists of three configurations are built as one unit.

That is, in FIG. 7, X ₁ and Y ₁ are:
This is a lower horizontal magnetometer coil element 200 comprising two types of orthogonal array type horizontal sensors 1 and 1 provided at the lower part of the receiving unit, each comprising a main coil of A and B and a feedback coil of A and B, respectively. ,
The start end (START end) and the same end (E
It has a connector terminal 21 connected to an ND end) and a shield end (SHIELD end).

The lower two types of array type horizontal sensors X
_1, of the Y _1, BMAIN of X1 is an output terminal of the main coil of H _x1, AFEED of Y ₁ is an output terminal of the feedback coil of H _y1.

Similarly, the BFEED of X ₁ is the output terminal of the feedback coil of H _x1 and the AMAIN of Y ₁
Is the output terminal of the _Hy1 feedback coil.

The two types of array-type horizontal sensors 1, 1 orthogonal to each other in the X and Y directions are connected to coupling shield wires 31, 32, 33, 34 via a connector 20.

The vertical sensor section 2 is arranged in parallel with the coil element section 200 for the lower horizontal magnetometer.

[0047] This vertical sensor unit 2, and outputs an output H _z of one type of C main coil (CMAIN) and one type of feedback coils in the same vertical direction Z for outputting a main coil output H _z the vertical Z-direction The open end, the end, and the shield end of the C feedback coil (CFEED) are coupled shield wires 31, 3 connected to the lower horizontal magnetometer coil element unit 200, respectively.
2, 33, and 34 are connected to the connector 21.

The other end of the connector 21 is connected to another coupling shield line 35, 36, 37, 38, 39, 40, and the coupling shield line 35, 36, 37, 3
A main coil and a feedback coil of two orthogonal D and E coils of the coil element unit 100 for the upper horizontal magnetometer are connected in parallel with 8, 39, and 40.

That is, the coil element unit 100 for the upper horizontal magnetometer via the connector 21 is similar to the coil element unit 200 for the lower horizontal magnetometer in that X ₂ and Y ₂ are:
An upper horizontal magnetometer coil element 100 comprising two sets of orthogonal array type horizontal sensors 1 and 1 provided at the upper part of the receiving unit, each comprising a main coil of D and E and a feedback coil of D and E, respectively. , Respectively, the start end (START end) and the same end (EN
D end) and a shield end (SHIELD end).

[0050] Of the array-type horizontal sensors X ₂ of two pairs of upper, Y _2, Emain of X ₂ is an output terminal of the main coil of H _x2, of Y ₂ DFEED the feedback coil of H _y2 an output terminal, likewise, EFEED of X ₂ is an output terminal of the feedback coil of H _x2, D MAIN of Y ₂ is an output terminal of the H _y2 feedback coil.

The start end (START end), the same end (END end) and the shield end (SHIELD end) of each of the coils D and E, and the coupling shield wires 25, 36, and 37 connected to the connector 21. 38, 39,
40 has a common shield end and is grounded.

The total output of the element coils of each type of A, B, C, D and E is transmitted to the ground equipment via a logging cable 60 composed of coaxial cables 41 to 50 via a main output connector 15 for connection. Connected.

To elaborate on the above, the first section is
It consists of two orthogonal horizontal array sensors, each consisting of ten elements (see FIG. 3), said two array sensors being meshed together to minimize the physical size of the sensor. Each coil element 1 is shielded by an electrostatic shield 7 connected by a shield wire in order to prevent electrostatic cross-coupling between the orthogonal array type horizontal magnetometer coil elements 1.

That is, the connection from the winding of the coil element 1 for the array type horizontal magnetometer to the connector at the last stage is shielded by a special means so as not to cause a ground loop. By making an open at one open end, the connection in a single connector is configured such that this first section terminates.

As a second section, including a vertical sensor, the entire connection from the first section has an arrangement extending towards the tip of the receiver body by means of shielded cable running over the sensor surface. The second section consists of a configuration in which the first two horizontal array sensors and the vertical sensor are connected by connectors.

The third (upper) section consists of two orthogonal array sensors, similar to what the first section did, ending with connectors that connect to all five sensors.

In addition, all cables are completely shielded with a single terminal shield.

The receiver case body composed of the three receiving systems used in this embodiment is made of a polycarbonate plastic material, which shows high dimensional stability against temperature changes and is easily machine-finished. And, since it is transparent, enables wiring inspection during assembly.

The circuit diagrams of these amplifiers, connected to a set of five amplifier receiver systems, are shown in FIGS.

These amplifiers were used in the standard BF6, except that the four arrays and the vertical sensors were slightly modified so that they could be measured correctly.

FIG. 8 is an amplifier circuit diagram of the vertical sensor unit used in this embodiment, and FIG. 9 is an amplifier circuit diagram of the horizontal sensor unit.

In this embodiment, the two amplifier circuits have the same shape. That is, the output from the main coil is input to the operational amplifier OPA111,
With C TRIM, the first-stage amplification is performed under bias adjustment.

After the first-stage amplification, the amplifier LM3
The second-stage amplification is performed at 56, and the result is fed back to the feedback coil connected to the signal input terminal for calibration together with the calculation result signal (CFE in FIG. 7).
Expressed as ED. ), And at the same time, the output of the other second-stage amplifier is adjusted by the amplifier LT10
The signal is further amplified by the output signal 12 and sent to the ground through the logging cable 60.

In the amplifier circuit of FIG. 9, A, B, D,
The outputs of the horizontal magnetic field components H _{x1 to} H _xn and H _{y1 to} H _yn from the main coils of E in two horizontal directions of X and Y orthogonal to each other are input to the operational amplifier OPA111 similarly to the amplifier circuit of FIG. After the first-stage amplification is performed under the bias adjustment described above, and after the first-stage amplification, the second-stage amplification is performed by the amplifier LM356 as in the amplifier circuit of FIG.
The result is fed back to each feedback coil connected to the signal input terminal for calibration similarly to the circuit of FIG. 8 (similarly, in FIG. 7, A FEED, B
Expressed as FEED, DFEED, E FEED. ), And at the same time, the output of the other second-stage amplifier (LM365) is adjusted by the amplifier LT after gain adjustment.
The signal is further amplified by 1012, output as a total horizontal two-directional component of each element coil, and sent to the ground through the logging cable 60.

The BH35 receiving system according to the present embodiment
It consists of five main sensors, each horizontal magnetic field component is 1
It is detected by two parallel arrays of zero elements.

These two arrangements are located at the two ends of the receiving system and have two main advantages:

1) When two signals are summed from two arrays, the sensitivity is increased by the factor of √2 of the natural logarithm of the uniform magnetic field, and the horizontal sensor having this configuration has a center at the center of the receiving system. And therefore coincides with the center of the vertical sensor.

2) Since five signals can be analyzed on the ground surface, the horizontal gradient of the transmission magnetic field can also be measured.

With respect to the three-axis magnetometer having the above-described configuration (two horizontal directions and one vertical direction), the sensitivity of a horizontal magnetic field magnetometer, that is, a single-axis type small coil that can be stored inside a tool having an inner diameter of 3.5 inches is determined. An improved horizontal magnetic field magnetometer having a high SN ratio and an improved overall sensitivity in which a plurality of the above-described coils are connected in an array manner, and a horizontal magnetic field magnetometer having a strong SN ratio in the entire connected coil. .

Next, the electrical connection of the vertical sensor will be described.

A schematic of the vertical sensor is shown in FIG.

In this case, a multi-winding (tube winding) structure that reduces the distributed capacitance and maintains a limited overall diameter is used.

The main winding 4 is wound 11,180 times or more and distributed to 16 tubes each 1/2 inch (12.7 mm) wide.

[0074] In the vertical sensor, the basic sensitivity of the coil is under the predicted noise about 1μγ / √H _z at 3000H _z, a _{S Hz = 2.5μV / γ / H} z.

Next, the configuration of a three-axis magnetometer sensor composed of the double array type horizontal sensor and vertical sensor will be described.

The multi-component receiving system, as described above,
It is composed of three parts shown in FIG.

The reason for this configuration is that it is easy to assemble and easy to disassemble for transportation and testing.

The sensor body is made of a polycarbonate plastic rod, and the individual array elements are inserted through holes made in the rod.

These array elements are shielded by an insert in front of them, away from the unshielded end connected to the winding end.

The wiring connection between the array element and the connector of the sensor section is arranged in a recess machined in the main body, so that the sensor main body is inserted into the pressure case without being caught, so that it does not protrude from the cylindrical surface.

By configuring so that all shielding at the common grounding point (place of generation) in the vicinity of the container ends, care is taken to avoid grounding closed circuits.

The following samples were obtained as the above three core materials and determined by a test.

1) Ad made by Advance Magnetics
-MU-78, a thin metal foil of magnetic permeability μ (0.000
6 "(.15 mm)).

This material has been cut and tempered to achieve high magnetic permeability.

2) Perfection Mica Co-N
Thick metal piece having a magnetic permeability μ of the ETIC AA alloy (.03)
0 "(.76 mm)).

This material is tempered according to EMI specifications in order to achieve the maximum magnetic permeability in a vacuum.

3) A metal wire (diameter: 0.025 (.63)) having a magnetic permeability μ of compounded alloy 25-8005 (manufactured by Sprung Industrial Co., Ltd.)
mm)).

This material has been heat-treated for magnetic properties in the production.

4) Ferrite rod 1/4 "ferrite material # 61 manufactured by Ferrite Products Co., Ltd. 6.3 m in diameter
m.

The specifications of these materials are attached to a separate sheet (see APPENDIX).

The outline of the construction of the test coil for testing these different materials has the following characteristics.

Length = 3 in. (76m
m) core cavity = 0.5 in. diameter. (12.2m
m) Winding = 2400 turns Wire dimension = # 32 The material was determined by a series of tests and subsequent calibration calculations.

The equation for calculating the coil sensitivity for the high magnetic permeability core is given by S _H = N × A × μ _ROD × μ ₀ × 790, and the core material must satisfy this equation.

Here, S _H = μ of the conductive region of the coil
V / γ / H _z sensitivity A = core area N = number of turns μ _ROD = permeability of material and execution μ of material by geometrical core, FIG. 1 shows core length versus core diameter with respect to change of material permeability Shows the relationship.

Μ ₀ = permeability of voids All materials tested showed geometric properties.

[0096] For example, the thickness of 0.76mm square section, is μ metal piece having a side face 9.5 mm, when guided into the test coil, the sensitivity of 0.05μV / γ / H _z was measured.

The formula for sensitivity is S _H =, which is consistent with the actual measurement.
It is given by 0.04μV / γ / H _z.

As a result of this test, a metal or ferrite with a permeability μ can be used to obtain the maximum permeability for a given coil geometry.

As a result, the ferrite core is ideal because the winding can be started from the surface of the rod, and is the core 3 having the configuration shown in FIG.

Next, the material of the winding was examined as follows.

Since this coil is used in the form of an array arrangement, the total diameter of the coil elements is determined by the length of each array arrangement. Increasingly, windings are added to each coil length.

As a result, the resistance of the coil (and hence its noise) which affects the sensitivity increases, so that a ferrite core capable of starting winding from the surface of the rod is ideal, and the coil element The diameter of
0.80 in. (20mm)
As shown in FIG. 1, for the coil element, Teflon is selected as an insulating material for coil ends and winding insulation, and this material is configured to withstand a maximum temperature of 250 ° C.

[0103] It may be made of a workable ceramic so that it can withstand higher temperatures.

The winding diameter used was a # 33 AWG gauge (0.2 mm), and a wire equivalent to ceramics of Fujikura Electric Wire Co., Ltd., capable of high-temperature insulation, was used.

The dimensions of the wire are determined by the coil resistance and the physical quantity, and are capable of 5,000 windings.

The following measurements were obtained as a result of making and testing three coil elements.

Field resistance = 134Ω Basic sensitivity S _H = O. 070μV / γ / H _z resonance frequency = 21kH _z noise generated in the coil element is computationally can be determined as follows.

[0108] _{N = I n / (S H} × F) , where, I _n is an amplification noise (μV / √H _z) (same as BF6 amplification degree), F denotes the frequency.

[0109] That is, the formula in 1000H _z, means to generate a noise of about 100μγ / √H _z.

The three-axis magnetometer of this embodiment is configured by arranging ten coil elements.

Therefore, the distance between the element arrays is
Determined by the diameter of the coil.

That is, the two horizontal sensors (x and y) are arranged on the main sensor body as shown in FIG.

The number of elements in the arrangement depends on the winding of the coil element and the number of amplifiers that can be used for it.

If each coil has its own amplifier, the sensitivity of the nth element array is only S _H √n, despite the slight residual noise from the winding resistance.

The resistance of a single amplifier arrangement and the resistance of all coil element windings connected in series, and the total resistance of the coil element resistances are, for example, R _TOT = n × R
_Represented by _element .

In the present embodiment, in order to measure the total sensitivity by arraying ten coil elements,
The measurement was performed using a test device as shown in FIG.

That is, a small coil sensor is used in FIG.
As shown in Fig. 7, an array composed of ten sensors located in an annular state was configured.

By using the test device having such a configuration, the sensitivity can be measured by a solenoid measuring device.

Further, according to this method, it is not necessary to consider the effect of the array type feedback coil.

That is, usually, an induction magnetic sensor (eg, BF
4, BF6) generally uses a solenoid coil that generates a uniform magnetic field at the center.

In this method, the sensors are arranged in an annular shape as shown in FIG.
H35).

However, this method has not been generally used in an array system of horizontal components because a solenoid magnetic field does not act on an unused coil element.

However, the measurement of the sensitivity of a single coil element and the measurement of a horizontal sensor could be performed using a special test facility as shown in FIG.

FIG. 11 shows an example of a horizontal component measuring apparatus as in this embodiment.

In FIG. 11, reference numeral 200 denotes a lower horizontal magnetometer coil element unit, 2 denotes a vertical magnetometer coil element unit, 100 denotes an upper horizontal magnetometer coil element unit, and 20 and 21 denote connectors; Is a main output connector, 71 is a five-component electronic device, 72 is a spectrum analyzer, 73 is a reference coil for test magnetic field measurement, 74
Is a transmitter and a transmission coil.

In the test apparatus shown in FIG. 11, the transmission coil 74 has a one-meter length metal core having a magnetic permeability μ and 1320 windings.

The transmitter 74 is capable of generating a 10 volt RMSAC signal, has an input from an experimental signal generator, and supplies a signal to the transmit coil Tx.
The magnetic field of about 0.2γ at 5 meter point at a frequency of 00H _z was used for outputting an easy signal generated.

At a frequency lower than this, since the magnetic field becomes strong, the receiving coil Rxs having the same sensitivity as that of the coil element of the BH35 array type horizontal sensor is required to accurately measure the magnetic field strength at a predetermined distance from the transmitter 74. Was used as the reference coil 73.

This reference coil 73 is measured inside the reference solenoid.

Since the magnetic field inside the solenoid is calculated from the winding geometry of the solenoid, the coil sensitivity of Rxs73 can be calculated as if it were absolute.

In addition, the size of the coil of Rxs73 is
It is the same size as the array coil element, so that
The measurement of the magnetic field generated by the transmitter Tx74 is considered to indicate a correct value.

Referring to FIG. 11, the magnetic field generated at the reception site of the experiment can be considered to be uniform within 1% of the horizontal array length.

The measurement of the array type horizontal sensor is performed according to the following procedure.

A) The reference coil Rxs73 is measured at various frequencies based on the measurement solenoid.

This determines an absolute reference place for magnetic field measurement.

B) The reference coil Rxs73 is used to measure a magnetic field generated at a measurement point by the transmission coil Tx74.

C) When the receiving sensor BH35 is arranged,
Each array element coil is centered on the transmission centerline and is positioned toward the transmitter 74.

The output of the array element coil is calculated and determined as a function of the magnetic field at the calculation point to obtain an absolute measurement of the array element coil. These calculations are made over various frequencies.

First, calibration of each sensor was performed.

For a vertical magnetometer, measurement is performed with a uniform magnetic field in a solenoid coil. For an array-type horizontal magnetometer, a solenoid coil cannot be used in view of its shape. In the generated magnetic field, the reference coil 73 and the array type horizontal magnetometer are placed at the same position away from the source, and the measured magnetic field at the reference coil 73 = the measured magnetic field at the array type horizontal magnetometer,
A measurement was made.

Specifically, using the device shown in FIG. 10, a transmitting coil (μ metal core, 1320 turns, approximately 0.5 mm at a position 5 m away from the magnetometer) at a position 5 m away from the magnetometer.
Place 2γ generating a magnetic field (oscillation frequency 3000H _z)), the solenoid coil, as a reference coil to coil elements single measured arrayed horizontally magnetometer, 5m
The magnetic field at a distant place was measured, and based on the measured value, the measurement result of the array-type horizontal magnetometer was calibrated.

[0142] Then, the generated magnetic field 10H _z ~3000
It was determined characteristics of the Amplitude and phase in the frequency band of H _z.

FIG. 12 shows the result.

[0144] From this result, in the above 100H _z, relatively and flat characteristics can be obtained and, 100H _z ~
In 10H _z, in particular the phase shift, but slightly larger, it is judged from the correction curve, considered practical use possible range.

Next, to measure cross-coupling due to non-orthogonality between the horizontal magnetometers (X, Y), one amplifier of the orthogonal magnetometer was disconnected, and an external signal was applied to its feedback coil. . This causes one magnetometer to operate as a transmitting coil.

At this time, assuming that the two magnetometers are completely orthogonal, the local signal input to the other magnetometer orthogonal to the transmitting coil is zero.

That is, it is considered that the signal actually measured by the magnetometer is influenced by the non-orthogonality and the electromagnetic coupling of the winding itself.

Therefore, it is considered that by measuring this effect, the cross coupling of the orthogonal magnetometer can be measured.

When the cross coupling of the horizontal magnetometer was evaluated using this method, it was 0.5 or less.

This result indicates that the angle detection capability of the device itself is
Since it is expected that it can only have an accuracy of about 1 mm,
It is considered to be a satisfactory value.

Next, the noise level was measured.

This measurement was performed using a high-precision induction magnetometer for AMT (model BF-6, manufactured by EMI, USA) and a BH35
The three-axis magnetometer is placed parallel to the field with little artificial noise, and the coherence of the two signals is measured by the spectrum analyzer 7.
2 was measured.

When the coherence is large, most of the input is considered to be a signal. When the coherence is close to 0, the signal can be considered to be due to noise of the sensor itself.

Therefore, while changing the frequency band, the output voltage (V / √) of the sensor when the coherence is close to 0 is obtained.
From _Hz ), the noise spectral density of the sensor can be measured.

In this case, it is assumed that the system noise generated in each of the two magnetometers is unique.

The signals input to each magnetometer are as follows:
Think the same.

At this time, the power having no correlation between the two magnetometers can be determined as the noise level of the entire measurement system including the sensor amplifier.

That is, the magnetic field H measured by the two magnetometers
Ordinary coherency between BH35 (three components) and HBF-6 (the same direction as the above three components): Coh (HBH
35, HBF-6) is represented by the following equation 1.

[0159]

(Equation 1)

In this equation, <> represents the self and mutual power spectra averaged over the frequency band, and * represents a conjugate complex number.

The noise of BH35 at this time is
It is expressed by the following equation (2).

[0162]

(Equation 2)

FIG. 13 shows the noise level of the horizontal and vertical magnetometers measured with respect to frequency using this method.

FIG. 13 also shows the magnitudes of both the horizontal and vertical magnetic fields induced in the MFT calculated by the simulation for reference.

[0165] 13 in the noise level of the sensor is a non-coherent electromagnetic signals, represented by nT / √H _z as noise spectral density.

On the other hand, in the EM method of the control source method, since the phase of the signal source is known and can be handled as a periodic function, the Fourier transform can be handled as a delta function.

In this case, it can be considered that the noise spectral density (nT / √H _z ) of the sensor and the magnitude of the magnetic field (nT) can be directly compared.

Regarding this measurement method, the BTBR measured with the layout of the downhole transmitter and the downhole receiver
(Borehole Transmitter-B
S measured in the layout of an orehole receiver or surface transmitter / underground receiver
The measurement may be performed by any of the TBR (Surface Transmitter-Borehole Receiver) method.

[0169] By the noise level measurement, as it is clear from FIG. 13, in the above band 200H _z, it was learned that achieve the following noise levels 1 × 10 ^{over 4} nT. Therefore, if this is analyzed by simulation, MFT can be sufficiently detected.

[0170] On the other hand, the noise level at 10H _z is, 1 ×
Is 10 ^over 2 nT, the current depth in STBR method in of 2000
The magnitude of the magnetic field required to probe m ( ^10-3
nT order). However, this is at the initial stage of designing the sensor force measurement test, probably because of using those frequency used was assumed above 100H _z, in the design phase of the sensor for high temperature testing, - the magnetic core material coil shape extent to make slight modifications to the feedback coil or the like, the coil characteristics, and shifts to a lower frequency range, the noise level 1 to 3 × 10 ^{chromatography} on 10H _z ³ n
Lowering to T is not a major technical problem.

On the basis of the above-mentioned calculation, sensitivity measurement and noise performance measurement were performed for this embodiment.

As expected, the total basal sensitivity of the annular arrangement of FIG. 4 is less than the sum of the basal sensitivities of the coils here,
The single coil sensitivity is S _H1 = 0.070 μV / γ / H _z
It is represented by

Here, the sensitivity S _H10 of the array is S _H10 = 0.
Represented by 60μV / γ / H _z.

This difference is due to the fact that several single elements are combined with one another and the total supplementary area is less than the sum of the single element supplementary areas.

When only one array is constructed, sensor noise cannot be measured at that time.

The results of measuring the above-mentioned cross-coupling, sensitivity, and noise in this embodiment will be described.

For the cross-coupling, sensitivity and noise measurements of this embodiment, five sensors are connected to five separate preamplifiers, and the vertical sensor circuit uses a device slightly different from the horizontal sensor amplifier. (Figure 5
And FIG. 6).

The amplifier is housed in a glass fiber pressure case section.

Next, the same measurement was performed for the vertical sensor.

The measurement by the vertical sensor is performed inside the measurement solenoid, and the results are shown in Table 1.

[0181]

[Table 1]

Table 1 shows that the response of this coil is exactly the same as that of the referenced BF-6 sensor.

That is, the basic sensitivity of the vertical sensor is as follows:
At the resonant frequency of the 2KH _z it can be said to be 2.5μV / γ / H _z.

Next, the result of measurement of the horizontal sensor of the device of this embodiment will be described.

As described above, the measurement of the horizontal sensor was performed by the apparatus shown in FIG. 11 over discontinuous frequencies. Table 2 shows the results of these measurements.

[0186]

[Table 2]

The basic sensitivity of this horizontal sensor is 1240H
It indicates that at the resonant frequency of the _z is _{0.65 × μV / γ / √H z} .

Next, the cross coupling of this example was measured.

Between the horizontal sensors (x and y),
There are two oscillation sources in the cross coupling.

A) Reference the horizontal sensor in the section of the receiving system.

[0191] They are knitted close to each other.

The first possible reason for cross-coupling is that each coil element has a feedback winding that generates a magnetic field.

If this magnetic field couples with the magnetic field of nearby orthogonal elements, it will retain cross-coupling, which, even in the absence of external magnetic fields, is noisy. In some cases, relying on coil elements alone is dangerous because the magnetic field of the coil elements induces other coil elements and causes higher potential noise.

To measure this cross coupling,
Driving the feedback winding of a sensor with a strong monochromatic signal at various frequencies and (1) measuring the same array response (which is a measurement of the magnetic field generated by the signal) and (2) the close orthogonal array Measuring the response, and measuring the ratio of these two responses, is a measure of the cross-coupling between the horizontal orthogonal sensors.

This measurement was performed with an HP3582A spectrum analyzer, and the results were very good.

[0196] That is, the frequencies above 1 kH _z, cross-coupling is always less than 60 decibels 1
In the KH _z following frequency, it was that can not be completely measured in any cross-coupling.

B) The second source of cross-coupling is non-orthogonal between the x and y horizontal sensors, and to measure it the following method was used. One of the two sensors between the cross-couplings to be measured was not connected to an amplifier, and the feedback coil was driven by an external signal.

There, the sensor functions as a kind of transmitter.

That is, the signal received by the quadrature sensor is
Knowing the non-orthogonal and capacitive and the magnetic coupling properties of the windings will allow the cross-coupling to be measured.

The inventors of the present application have obtained extremely good results. In any combination of orthogonal sensors, the equivalent of non-orthogonality is always better than 0.6 °.

Generally, an array-type sensor cannot perform accurate measurement at an angle of several degrees, so that the above-described cross-coupling measurement results are very satisfactory.

Subsequently, noise of the present example was measured.

At some frequencies, each sensor has a harmonic signal, especially at and near the power line frequency, even if it has very low noise.
It is extremely difficult to measure noise in a complete sense.

To eliminate this drawback and perform a complete noise measurement, the method used was as follows.

For each BH-35 sensor, an external B
An F-6 coil was used to monitor the surrounding magnetic field.

The outputs of the BH-35 sensor and the BF-6 coil were connected to a spectrum analyzer 72 capable of measuring coherence between the two signals.

If the sensors are placed in parallel, high coherence means that the received magnetic field is predominantly a signal, whereas if the coherence is low or zero. , It means that the signal at the sensor is due to noise.

Therefore, a frequency having a very low or zero coherence was selected, and noise was calculated from the measurement of the sensor output voltage with an HP spectrum analyzer.

[0209] The output voltage in this case is measured as V / √H _z is a voltage noise spectral intensity.

To calculate the equivalent magnetic noise spectrum intensity, simply calculate the voltage output of the sensor by multiplying it by the sensor scale at the measurement frequency (see Tables 1 and 2).

The results of these experiments are shown in Tables 3 and 4 together with the theoretical noise calculated based on the sensitivity of the basic coil and the amplifier noise.

[0212]

[Table 3]

[0213]

[Table 4]

Due to the inherent difficulty of noise measurements, all noise measurements have an error within ± 25%.

[0215] the lowest measurable noise level in the measurement system, at this stage, at 3000H _z, approximately 4μ
it can be said to be the γ / √H _z.

As a whole, the actual measurement noise was very close to the calculation noise.

Next, in this embodiment, in order to improve the data transmission system from the logging system in the wellbore to the ground surface,
The study was conducted.

Since the data transmission method used in this embodiment handles the frequency domain, the attenuation of signals in the data transmission system, in particular, the logging cable connecting the magnetometer and the ground is examined, and the result is used as a reference. Amplify the signal in the well and transmit it to the ground as time-series data (analog transfer)
Alternatively, data processing is performed in the downhole, and transmission is performed in a spectrum with respect to frequency (digital transmission).

Data is transmitted from the wellbore to the ground surface using a logging cable. Therefore, it is important to know the transmission characteristics of the logging cable in determining the data transmission rate (frequency).

As this sample, a standard outer diameter of 7/1 was used.
6 "7 core armored logging cable 60 (length 850
The transfer function of the logging cable 60 was measured using m).

The measuring method is as follows, using the apparatus shown in FIG.
Input signal and the transfer function of (V ₂ / V ₁₎ was measured using a spectrum analyzer.

The result is shown in FIG.

[0223] As FIG. 15 is clear, logging cable 60 (length 850 meters) is used in the test, 10.4KH _z
Shows that it is equivalent to a low-pass filter having a curved point.

[0224] From this result, in this short cable, indicates that it is not possible to use frequencies above 10KH _z.

If the cable becomes longer and C (capacitance) increases, this cutoff frequency is considered to shift to a lower frequency side. Therefore, a general logging cable having a length of 5000 m or more is considered. for many, the case of transferring a signal to the ground directly with it, the frequency 3KH _z, and it is difficult to transmit it is beyond the cut-off frequency, the time-series data placed on a direct cable to the other Conceivable.

In view of the test results, and assuming that various types of noise are mixed between the logging cables, the measurement data is amplified and digitized (digitized) in the wellbore, and then grounded through the logging cables. It is considered that transmission to the receiver is desirable from the viewpoint of improving accuracy.

Therefore, regarding the transmission diameter, the electronic circuit configuration in the downhole was selected by adopting digital transmission.

[0228] In order to amplify and digitize the data measured in the wellbore inside the measuring instrument and transmit it to the ground surface, it is preferable to perform multiplexing (signal multiplexing) of signals.

At the time of this multiplexing, the magnetic field data measured in the wellbore and other information to be transmitted are as follows.

(1) Magnetic field (x-component) in-phase (2) Magnetic field (x-component) out-of-phase (3) Magnetic field (y-component) in-phase (4) Magnetic field (y-component) out-of-phase (5) Magnetic field (z-component) in-phase (6) Magnetic field (z component) phase separation (7) Current value of transmitting coil (8) Declination to x-axis (absolute axis) (9) Declination to y-axis (absolute axis) (10) z-axis (absolute axis) (11) Electronic device temperature (12) Coil portion temperature = Downhole temperature (for temperature correction) A standard multiplexer that transmits these 12 types of data is considered to have 16 channels.

Therefore, the four channels are considered as a reserve when other data is added in the future, so that multiplexing of 16 channels can be performed.

For digitalization in the downhole, a synchronous detection circuit and an analog / digital converter / control microprocessor were used in the downhole apparatus.

Synchronous detection circuit (Synchronous)
Detection, S.M. D. ) For MF
Since the amplitude and phase of the measurement signal must be determined by a synchronous detector from each of the three axial components that can measure the fluctuation of the artificial AC magnetic field due to T, the configuration must be as follows: .

That is, the detected signal of the secondary magnetic field is
An in-phase component (a component having the same phase as the primary magnetic field) and a phase-separated component (a component having a phase difference of 90 ° from the primary magnetic field) can be considered separately. source)
A lock-in amplifier (l) that measures the amplitude of a signal of which frequency and phase is known by utilizing the fact that the frequency and phase of the
A method was adopted in which a signal was separated into an in-phase component and a phase-separated component and measured using one type of ock-in amplifier.

The synchronous detection circuit uses a combination of a tuning amplifier (lock-in amplification) and a phase-sensitive detector (heterodyne conversion).

Specifically, a weak signal is detected by performing a heterodyne conversion using a tuning amplifier having a high amplification factor in a narrow band and then passing through a low-pass filter having a long time constant.

FIG. 16 is a conceptual diagram showing the concept.

When the contents of the conceptual diagram shown in FIG. 16 are conceptually expressed by a mathematical expression, the cosine of the same period is given to the input signal Asin (ωt + э) (A is amplitude, ω is angular velocity, э is phase). Multiplied by the wave, it is expressed by the following equation.

[0239]

(Equation 3)

Further, by passing through a low-pass filter that removes the frequency of 2 × 2πω, the following expression can be obtained.

[0241]

(Equation 4)

Therefore, the in-phase component can be separated by this equation.

Similarly, the phase separation component can be expressed by the following equation by multiplying sine waves of the same period.

[0244]

(Equation 5)

Further, by passing through a low-pass filter that removes the frequency of 2ωt, the result is expressed by the following equation.

[0246]

(Equation 6)

Therefore, the phase separation component can be separated.

[0248] The results of the transmission test of the data transmission system from the well logging system to the surface of the well will be described.

[0249] This transmission test, in place of 1 kH _z which was considered originally a conventional frequency domain 16KH _z 10
Using a numerical model plan from H _z at a low frequency region 10KH _z, it is predicted that would results study performed separately, this change in the frequency band results in a better detectability of magnetic crack.

[0250] Thus, the low-frequency range of the equipment in the final stage was re-examined, such as reconfiguring the receiving electronic device that corrects, was studied transmission at a lower frequency range than 10H _z.

In the transmission in the lower frequency range, data can be collected using a high-resolution analog-to-digital converter without using the synchronization detection mode.

Furthermore, this means that the configuration functioning as a time-domain or frequency-domain device can be easily changed by simply changing the reception software without making many or slight changes to the hardware, and By running in software the sampled time of all the different transmitted waveforms used, such as square waves, triangle waves, sine waves, pseudo-random binary signals, through the many flexible results that are stacked, In contrast to the use of a sample that has been continuously sampled in the past, there is a merit that it can be added to this.

This device is a reliable, precise and low power consumption receiver electronics component, low power consumption being recognized as the best to minimize the high temperature type heat generation of this equipment. .

Changing to sampled time domain processing instead of synchronization detection is essential for many redesigns of the receiving electronics.

FIG. 17 shows an outline of the receiver, and its configuration and reception result will be described.

The structure of the channel multiplexer of the receiving apparatus according to the present embodiment is as follows.

The temporarily stored output from each magnetic channel and transmitter current monitor is directed to a segmented channel of a 16 channel multiplexer.

The multiplexers provide H _xlower , H _xupper , H _ylower , H _yupper and H _z for the magnetic channel.
5 channels in addition to the transmitter current monitor channel Txl and three channels holding a fluxgate or gyroscope compass.

The added three channels constantly monitor the temperature, and may include a transmitter, a receiver, etc., and may have four spare channels capable of monitoring and other parameters.

Next, the configuration of the analog / digital converter will be described.

This device has been developed and studied.
There are more than one kind of analog-to-digital converter, and based on these research results, a CS5102 16-bit analog-to-digital converter was selected.

This converter has very low power consumption (power of 40 mw) with low distortion, has no code error, is adjusted autonomously on the chip, and
The configuration is such that the power drops in the 1 mw mode.

This chip can withstand use at 125 ° C. as described in the specification.

The sampled analog-to-digital converter does not need to branch to the S / H amplifier of each channel, thus further reducing the slight power requirements and ignoring the heat generated by the receiver electronics. it can.

The evaluation of the converter at a high temperature, as well as the low power consumption, means that an ideal chip is formed for the receiving device.

The chip-CS5101 is a high-speed chip that uses 280 mw of power for a conversion time of 8 μs.

Then, this chip—CS5101
It is compatible with the same pin structure as S5102, and can be changed and replaced immediately if the device design needs to be changed to higher frequency or time-domain adaptation.

Both of these chips have a very short aperture time of 30 nanoseconds, which, in combination with an aperture jet of 100 picoseconds, facilitates what is done in underground survey radar systems. In addition, it is possible to continuously perform sampling.

In this operation mode, both chips are set at 10 kHz.
_It should be feasible at transmission frequencies above _z .

Regarding the high linearity and precision of the converter, FIG. 18 shows the waveform of an ideal 16-bit converter,
9 volt peak-to-peak input, the sine wave of 200H _z, perform 20 kHz _z sampling CS510
The results are shown in comparison with the measured reaction waveforms of the two converters.

That is, this chip achieves a 91 dB full-bandwidth signal (noise pulse distortion) ratio very close to the theoretical value of an ideal converter.

In order to measure the actual noise level of the fully constructed embodiment, the final stage receiving circuit first considers
Must be built.

Next, a microprocessor used in the system of this embodiment will be described.

Further, as a result of the measurement cable test, the following results were obtained.

The present inventors conducted two experiments using a measurement vehicle.

Two of these experiments were performed according to industry standard 7/16
The transmission performance of a 900-meter 7-core Armart cable was tested.

In the first test, HP3 was used as shown in FIG.
Using 582A spectrum analyzer to determine the transfer function between the input and the transmission waveform (V ₂ / V _1).

[0278] The transfer function for the white noise random signal inputs indicates that the cable is a cable that acts as a simple one pole low pass filter flexing essentially 10.4KH _z.

The results are shown in EM-2 for downhole.
(1) Confirmed by a secondary test in which a vertical sensor (manufactured by EMI) was measured, an output signal measured directly by the sensor was transmitted through a measuring cable and a receiver of a control board of a measuring vehicle, and this signal was compared.

The present inventors have also studied several digital transmission interfaces to determine the best one to use for communication between the downhole equipment and the terrestrial electronics.

[0281] They are RS-232 and RS-42.
2, ISDN user interface, and 960
0 baud modem standard protocol 32.

A 9600 baud V.D. 32 modems and RS
The -232 interface was ignored because of its lower baud rate and susceptibility to noise interference.

The RS-422 standard, on the other hand,
Identifies different line drivers with greater reliability and noise impairment than the H.232 standard, and yet supports high transmission baud rates.

Also, because the lower transmission frequency this time cannot support an ISDN user interface with a higher transmission baud rate (160K baud or more),
During the preliminary design phase, it was decided to use the RS-422 interface.

The RS-422 can make the surface electronic device simpler and less expensive, and can be compatible with a PC plug-in card.

There are many RS-422 line drivers and receiving chips, and when designing a high-temperature-compatible device, there is a fear that power consumption will be adversely affected later.

As a result of each of these experiments, the downhole (hanging type) microprocessor enables the final-stage equipment design and enables functionality that can be easily changed by changing software.

This arrangement of the microprocessor enables double buffering of the received data, and enables complete transmission which leads to transmission / reception error-free transmission of the ground connected to an inexperienced data system with extremely coarse precision. It is.

The inventors of the present invention have proposed a receiver capable of being flexibly designed and deformed, and a combination of the receiver and a highly accurate converter.
It has been found that such a multi-component receiver is achieved and allows for excellent processing.

[0290]

According to the present invention, in the array type three-axis magnetometer underground electromagnetic induction survey method (two horizontal directions, one vertical direction), a single-axis type magnetic field magnetometer capable of being stored inside a tool having an inner diameter of 3.5 inches. While improving the sensitivity of the small coil alone, a horizontal magnetic field magnetometer unit with a strong SN ratio, and connecting a plurality of the coil elements in an array,
As a whole, the coil sensitivity is improved, and a high-sensitivity, high-accuracy three-axis magnetometer can be achieved by using a horizontal magnetic field magnetometer having a large SN ratio.

Similarly, underground guidance exploration method array type 3
In the axial magnetometer, the vertical magnetometer of the three-axis magnetometer having the above-described configuration also improved the sensitivity and achieved a vertical magnetometer having a large SN ratio. Therefore, a plurality of the vertical magnetometers were incorporated. A plurality of horizontal coil elements are incorporated, and a plurality of horizontal coil elements are arranged at both ends of the vertical magnetometer. Cross-coupling of the X and Y component magnetometers is examined. Improve the sensitivity and SN ratio of a single unit, measure the cross-coupling, sensitivity and noise level of the entire three-component magnetometer, and calibrate them to improve the sensitivity and SN ratio of the entire three-axis magnetometer. It was something that could be improved.

In the data transmission device from the array type three-axis magnetometer underground guidance exploration method, when transmitting data from the wellbore logging probe to the ground surface, the best transmission method is selected and control from the ground surface to the tool is performed. Multiplexing (signal multiplexing) regarding the transmission method when transmitting instructions
As a result, the number of integrated channels can be ensured, and the synchronous detection circuit, analog / digital converter, and control microprocessor of the downhole electronic device are configured as appropriate. A small data transmission system could be achieved.

[Brief description of the drawings]

FIG. 1 is a sectional view and a side view of a coil element for an array type horizontal magnetometer used in the present invention.

FIG. 2 is a sectional view of a perpendicular magnetometer used in the present invention.

FIG. 3 is an overall schematic sectional view of an embodiment of a three-axis magnetometer according to the present invention.

FIG. 4 is a schematic view of an upper horizontal magnetometer coil element section 100 or a lower horizontal magnetometer coil element section 200, which is configured by arranging a plurality of array type horizontal magnetometer coil elements 1; It is.

FIG. 5 is a three-axis magnetic force in which a plurality of upper horizontal magnetometer coil element units 100 and another lower horizontal magnetometer coil element unit 200 are arranged at both ends, and a vertical magnetometer unit 2 is arranged at the center. It is a schematic diagram of a total.

FIG. 6 is a schematic electrical connection diagram of the configuration of the three-axis magnetometer shown in FIG. 5;

FIG. 7 is an electrical connection configuration diagram of the dual array type sensor according to the embodiment of the present invention.

FIG. 8 is an amplifier circuit diagram of a vertical sensor unit used in the present embodiment.

FIG. 9 is an amplifier circuit diagram of the horizontal sensor unit.

FIG. 10 is a schematic diagram of a test apparatus for measuring total sensitivity using an array of ten coil elements.

FIG. 11 is another example of the horizontal component measuring device of the present embodiment.

Figure 12, using the apparatus shown in FIG. 10, the generated magnetic field was measured by a solenoid coil obtained by the calibration of the measurement result magnetic field 10H _z ~
In the frequency band of 3000H _z is a characteristic diagram of the Amplitude and phase.

FIG. 13 is a noise level distribution diagram of the horizontal and vertical magnetometers with respect to frequency.

FIG. 14 is a diagram illustrating a logging cable test apparatus.

FIG. 15 is a view showing a result of measuring an input signal and a transfer function (V ₂ / V ₁ ) obtained by the apparatus shown in FIG. 14 using a spectrum analyzer.

FIG. 16 is a conceptual diagram of a synchronous detection circuit (SD).

FIG. 17 is a schematic configuration diagram of a channel multiplexer of the receiving device according to the present embodiment.

FIG. 18 is a comparison diagram of a waveform of an ideal 16-bit converter and a measured response waveform of a CS5102 converter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Coil element for array type horizontal magnetometer 2 ... Vertical magnetometer 3 ... Core 4 ... Main winding 5 ... Feedback winding 6 ... Teflon coil end 7 ... Static Electric shielding 8 ・ ・ ・ Winding terminal 9 ・ ・ ・ Winding end 10 ・ ・ ・ Set screw 11 ・ ・ ・ μ metal core 12 ・ ・ ・ Single pie winding 13 ・ ・ ・ Feedback winding 14 ・ ・ ・ Partition plate Reference numeral 15: Main output connector for connection 19: Output end 20: Connector 21: Connector 31 to 40: Coupling shield wire 41 to 50: Coaxial cable 60: Logging cable 71・ ・ ・ 5 component electronic device 72 ・ ・ ・ Spectrum analyzer 73 ・ ・ ・ Reference coil for test magnetic field measurement 74 ・ ・ ・ Transmitter and transmission coil 100 ・ ・ ・ Coil element part for upper horizontal magnetometer 200 ・ ・ ・ Lower Horizontal magnetometer coil element part BH35 reception sensor H magnetic field OPA111 operational amplifier LM356 second-stage amplification operational amplifier LT1012 third-stage amplification operational amplifier R reception coil S・ Sensitivity T ・ ・ ・ Transmission coil V ・ ・ ・ Standard protocol X ・ ・ ・ X-axis array element Y ・ ・ ・ Y-axis array element Z ・ ・ ・ Vertical sensor μ ・ ・ ・ Execution permeability

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-57-33377 (JP, A) JP-A-64-69979 (JP, A) JP-A-3-202587 (JP, A) JP-A-2- 302689 (JP, A) Special Table Hei 2-504071 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01V 3/28 G01R 33/02

Claims (3)

(57) [Claims] 1. A vertical magnetometer coil element disposed at the center and an array type horizontal magnetometer coil element disposed at both ends thereof, each having 10 coils at both ends, for a total of 20 coils.
, Each orthogonally arranged, a main output connector for transmission cable connection with the ground arranged on the transmission cable connection side, and a horizontal magnetometer element and a horizontal magnetometer connected to the vertical magnetometer composed of each of the combinations. Vertical X,
An array-based three-axis magnetometer that measures the magnetic field components in each of the Y and Z directions. 2. A vertical magnetometer coil element and an array type horizontal magnetometer coil element are orthogonal to each other to form a set of horizontal array type sensors, each of which is connected to a first connector. A second section comprising a section and a plurality of vertical sensors, each of which is connected to second and third connectors, wherein the first connector and the second connector are connected; and a first section. And a pair of orthogonal horizontal array sensors, each of which is connected to a fourth connector, and the third connector and the fourth connector are each connected to a third section. The array-based three-axis magnetometer according to claim 1, wherein: 3. A main winding of said plurality of arrayed coil elements, are connected in series, to claim 1 where the feedback winding of the plurality of array type coil elements, characterized in that connected in parallel An array-type three-axis magnetometer according to the above- described underground guidance method.