JPH09297182A - Excavating pipe body transmission plastic wave generating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an excavating pipe body transmission elastic wave generating device that can generate elastic wave of size and frequency required to transmit information to an excavating pipe body using magnetostrictive material while withstanding excavating vibration and high temperature and can be miniaturized. SOLUTION: An exciting face 26a of a magnetostrictive vibrator 26 with the same resonance frequency as an excavating pipe body is brought into contact with an excited face 52d, and the other face is made a vibrating free end to mount the magnetostrictive vibrator 26 on an elastic wave generating pipe body provided at the pit bottom and connected to the excavating pipe body. Pit bottom information of equipment, a stratum, and the like is modulated to vibrate the magnetostrictive vibrator 26 so as to generate elastic wave to the excavating pipe body, thus transmitting the information. An excavating pipe body transmission elastic wave generating device compact, efficient and withstanding high temperature environment can thereby be obtained. The required length of the magnetostrictive vibrator is half of the wavelength of an n-th resonance mode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to information transmission for transmitting information from the bottom of a well in a well such as oil or natural gas to the ground, or from the ground to the bottom of the well, or from the bottom to another bottom of the well. The present invention relates to an elastic wave generating device for transmitting excavated pipes used in the device (hereinafter, may be simply referred to as an elastic wave generating device).

[0002]

2. Description of the Related Art In recent years, for the purpose of reducing the cost of excavation and improving the safety of excavation work, MWD that transmits information on the stratum and the state of the excavator to the ground in real time while excavating.
(Measurement While Drilling) system has been developed. The practical MWD system uses a. Mud pulse method, b.
There were two methods of electromagnetic wave method. However, it is not practically sufficient due to the limitation of the transmission rate, the reliability of the device, or the applicable operating environment. Therefore, in order to solve such a problem, M by an acoustic method in which information is transmitted by acoustic elastic waves using a pipe body used for excavation as a medium.
WD systems are receiving attention.

As a conventional acoustic MWD system, there is a tubular body transmission device using a piezoelectric ceramic as a transmission source. FIGS. 12 to 16 show a conventional tubular body transmission device described in, for example, Japanese Patent Application Publication No. 0552833 A1 issued by the European Patent Office.
FIG. 12 is a side view showing the configuration of the tubular body transmission device using acoustic elastic waves, and FIG. 13 is an exploded perspective view showing the structure of the oscillator. FIG. 14 is a cross-sectional view showing a mounted state of the oscillator. FIG. 15 is a waveform diagram for explaining the operation.
15A is a waveform diagram showing the waveform of the driving current of the oscillator, FIG.
(B) is a waveform diagram showing an acoustic elastic wave generated in the drill collar. FIG. 16 shows a drive current modulation method of the oscillator. FIG. 16 (a) is a binary code “1”, FIG. 16 (b).
FIG. 3 is a signal waveform diagram showing a binary code “0”.

12 to 16, reference numeral 301 denotes an acoustic elastic wave oscillator using a piezoelectric ceramic, which is installed in a recess provided in a drill collar 306 described later. 3
02 is a receiver side receiver sub, and 303 is a receiver sub 3
The receiving transducer closely attached to the inner wall of 02, 304 is an MWD tool, 305 is a drill pipe, 3
06 is a drill collar. The receiver sub 302 is provided in the middle of the drill collar 306.

Here, a detailed configuration of the oscillator 301 is shown in FIG.
3 and FIG. In these figures, 31
1 is a vibrator formed by stacking piezoelectric elements 311a, 3
Reference numeral 12 is a coupling portion provided on one end side of the vibrator 311. 321 is an elastic body composed of a spring or the like. The oscillator 301 is installed in the recess provided in the drill collar 306 as shown in FIG.
By pressing the drill collar 306 at 1, the coupling portion 312 is mounted so as to be pressed against the drill collar 306. The elastic body 321 applies a bias force to the vibrator 311 so as to transmit the vibration of the oscillator 301 to the drill collar 306. A voltage lead 314 is for applying a voltage to the vibrator 311.

Next, the operation will be described. Oscillator 30
The acoustic elastic wave generated from 1 is a tubular body (drill collar 30
6, transmitted to the drill pipe 305) and propagates upward. The acoustic elastic wave is received by the receiving transducer 303 in the receiver sub 302 installed in the middle of the drill collar 306. In addition, MWD Tool 304
For example, information is transmitted to the ground via a method such as a mud pulse system in which elastic waves are generated in mud for excavation to transmit information.

The acoustic elastic wave transmitted to the drill collar 306 is generated as follows. As the drive current of the oscillator 301, an alternating burst current J of a sinusoidal wave as shown in FIG. 15A, for example, having a cycle matching the resonance frequency of the vibrator 311 is applied. Since the piezoelectric element 311a forming the vibrator 311 has a characteristic of causing distortion according to the magnitude of the applied current, the vibrator 311 generates vibration according to the cycle of the applied current J. At this time, when the frequency of the applied current is applied in conformity with the resonance frequency peculiar to the vibrator 311, the vibrator 311 starts resonance vibration and vibration of large amplitude is obtained, and the drill collar 306 is shown in FIG. Such an acoustic elastic wave SW can be generated. In addition, the acoustic elastic wave SW causes a delay of a time td with respect to the exciting current J.

Next, the modulation method of transmitted information will be described. The information to be transmitted is, for example, binary coded and modulated into elastic waves. Therefore, the tube is vibrated by making the binary code to be transmitted correspond to the interval of the acoustic elastic wave generated by the oscillator 301. For example, information is transmitted by associating the excitation interval of T1 with the binary code “1” to be transmitted and the excitation interval of T2 with the binary code “0” to be transmitted. That is, when the binary code to be transmitted is "1", the drive current is supplied at intervals of T1 as shown in FIG.
As shown in (b), a drive current is caused to flow at intervals of T2 to generate and modulate elastic waves having different vibration intervals.

The acoustic elastic wave transmitted from the oscillator 301 propagates upward in the drill collar 306 and is detected by the receiving transducer 303. Receiving transducer 303
Outputs a voltage according to the magnitude of the detected vibration and converts the transmitted acoustic elastic wave into an electric signal.

In the acoustic elastic wave signal converted into an electric signal by the receiving transducer 303, after removing a noise component by a filter or the like, when the time interval is T1, the binary code is "1", and when the time interval is T2. Is transmitted to the binary code "0" to demodulate the transmitted signal. The demodulated digital signal is input to the MWD tool 304, and is further transmitted upward by a mud pulse type MWD system, for example.

[0011]

As described above, the oscillator 311 in the oscillator 301 of the conventional tubular body transmission device is configured to generate an acoustic elastic wave by using the piezoelectric effect of the piezoelectric element 311a. , There were the following problems.

(1) The mechanical strength of the piezoelectric element is weaker than that of a metal material. (2) Piezoelectric elements, such as piezoelectric ceramics, have a Curie temperature of about 120 [° C.], and distortion cannot occur above this temperature, so they cannot be used in high temperature environments. (3) Since the crystal strain axis matches the direction in which the electric field is applied,
When the vibration is applied, stress is applied to the electrode part due to the distortion of the piezoelectric element itself, and there is concern that the electrode may be damaged. (4) Since the oscillation frequency is fixed according to the thickness of the piezoelectric element, in order to realize the low-frequency vibration necessary for the information transmission of the tubular body, the vibrator 311 is set to 1 m or more. Length is required. Moreover, the energy required for driving such a large vibrator is too large, and it is extremely difficult to secure a power source in the downhole system.

The present invention has been made in order to solve the above-mentioned problems, and a magnetostrictive material is used to withstand the vibration of excavation and high temperature, and the size required for transmitting information by the excavating pipe. It is an object of the present invention to obtain an elastic wave generator for excavation pipe body transmission, which can generate elastic waves of frequencies and frequencies with low power and can be downsized.

[0014]

According to a first aspect of the present invention, there is provided an elastic wave generator for electric power transmission for excavation pipes based on a propagation speed of an elastic wave propagating in the excavation pipe body and a length of the excavation pipe body. An elastic wave that has a resonance frequency that matches the determined resonance frequency and that has the same period as the resonance frequency and that propagates through the excavation pipe by exciting the magnetostriction vibrator with an exciting current that modulates the information to be transmitted. Is generated.
According to the first aspect of the invention, the magnetostrictive oscillator has a high Curie point, and thus can be used even in a high temperature environment. Also,
Since the magnetostrictive oscillator has the same resonant frequency as the resonant frequency of the drill pipe, it can efficiently generate elastic waves and consumes less power.

An elastic wave generator for transmitting excavation pipe body according to a second aspect of the present invention generates an alternating elastic wave having the same period as the period of the resonance frequency of the excavation pipe body in the magnetostrictive vibrator by an exciting current. is there. According to the second aspect of the present invention, since the cycle of the alternating elastic wave and the cycle of the resonance frequency of the excavating pipe are the same, the excavating pipe causes resonance vibration, and an elastic wave having a large amplitude is generated.

According to a third aspect of the present invention, there is provided an elastic wave generator for electric power transmission for excavating pipe body, wherein the magnetostrictive oscillator is formed by laminating thin plates made of a metal-based magnetostrictive material, and the exciting current causes resonance of the excavating pipe body. An alternating current or pulsating component having a half period of the frequency is a pulsating current having the same period as the resonant frequency. According to the third aspect of the present invention, the thin plate made of the metal-based magnetostrictive material has a high Curie point and operates even in a high temperature environment. In the case of a metal-based magnetostrictive material, such as nickel, it distorts only in the direction of contraction, regardless of the polarity of the excited magnetic field.Therefore, when the polarity of the exciting magnetic field is alternated around the zero point, the magnetostrictive material is distorted every time the polarity changes. , The vibration of the double cycle of the exciting current occurs. In order to avoid this, a DC magnetic bias is applied to form a pulsating current, or, when AC is applied, an AC having a frequency half the resonance frequency is used.

According to a fourth aspect of the present invention, in the elastic wave generator for electric power transmission for excavation pipe body, the exciting current is a pulse train having the same period as the period of the resonance frequency of the excavation pipe body.
According to the fourth aspect of the present invention, the pulsed exciting current is supplied in a cycle that matches the cycle of the resonant frequency of the magnetostrictive vibrator, so that the resonant vibration of the excavated pipe is efficiently generated.

According to a fifth aspect of the present invention, in the elastic wave generator for electric power transmission for excavation pipe body, the excitation surface of the magnetostrictive oscillator is located between the nodes of the axial resonance mode in the excavation pipe body. Then, an elastic wave is generated in the excavated pipe body. According to the fifth aspect of the present invention, the resonance vibration of the excavating pipe is efficiently generated by providing the excavating pipe between the nodes of the resonance mode of the excavating pipe transmitting the excitation surface of the magnetostrictive oscillator. .

According to a sixth aspect of the present invention, there is provided an elastic wave generator for electric power transmission in excavated pipes, wherein one surface of a magnetostrictive oscillator in a vibration direction is a vibration surface and the other surface is a free vibration end. An elastic wave is generated in the drill pipe. Claim 6
In the one described, only one surface in the vibration direction of the magnetostrictive vibrator is fixed, and the elastic wave is generated with the other surface as a free vibration end. Therefore, even if the length of the magnetostrictive vibrator is shortened, the amplitude is large. Resonant vibration occurs.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION

First Embodiment of the Invention 1 to 7 show an embodiment of the present invention, FIG. 1 is a configuration diagram showing a pipe body power transmission device which is an MWD system, FIG. 2 is a cross-sectional view of an excavation pipe body, and FIG. 3 is an elastic wave. It is a block diagram which shows the structure of a generator. FIG. 4 is a plan view showing a state where the elastic wave generator is mounted on the elastic wave generating tube. 5A and 5B show a magnetostrictive oscillator. FIG. 5A is a perspective view of the magnetostrictive oscillator, FIG. 5B is a perspective view of the magnetostrictive element, and FIG. 5C is a plan view of the magnetostrictive element. FIG.
FIG. 7 is a model diagram showing a result of modeling the vibration system of the excavation pipe and performing the vibration analysis, and FIG. 7 is a diagram showing a transfer function of vibration in the axial direction of the vibration system.

In FIG. 1, 10 is a drill bit and 11
Is a tube for mounting a pit bottom sensor, 12 is a tube for elastic wave generation, 1
Reference numeral 3 is an excavation pipe, and 14 is a receiving pipe, which are connected in series as shown. The receiving pipe body 14 is provided above the excavation pipe body 13. In this embodiment, the excavation pipe body 13 includes ten single pipes 13 as shown in FIG.
a is connected in series. As shown in FIG. 2, the single pipe 13a has a length A of 9 [m] and joints 13b and 13c (the lengths of which are B and C, respectively) having different outer dimensions at both ends thereof. There is.

A demodulator 16 demodulates the acoustic elastic wave signal converted into an electric signal by a receiving transducer (not shown) (similar to the receiving transducer 303 in FIG. 12) provided in the receiving tube body 14. In FIG. 3, reference numeral 21 is a bottom hole sensor provided in the tube body 12 for mounting the bottom hole sensor. Reference numeral 22 denotes an elastic wave generator, which is provided in the elastic wave generating tube body 12 as shown in FIG. 4 in this embodiment. In the vibration generator 25, the magnetostrictive vibrator 26, which is not shown in cross section in FIG. 4 but is hatched for easy understanding, is applied to the elastic wave generating tube body 12 in the same manner as the conventional vibrator 311 in FIG. It is installed. That is, one surface of the vibrating surface abuts on the elastic wave generating tube body 12 via the coupling portion 28, and the other surface side is attached to the elastic wave generating tube body 12 with the spring 29 compressed. One side of the vibrating surface is pressed against the elastic wave generating tube body 12 by the elastic force of the spring 29.

Next, the detailed structure of the elastic wave generator 22 will be described with reference to FIGS. The elastic wave generator 22 is shown in FIG.
As shown in FIG. 3, it has a control device 23, an exciting current supply device 24, and a vibration generator 25. The vibration generator 25 is the magnetostrictive vibrator 2
6. It has an exciting coil 27. The magnetostrictive oscillator 26 is shown in FIG.
As shown in (a), a predetermined number of thin magnetostrictive elements 31 are laminated and adhered, and the exciting coil 27 is provided on both sides facing each other.
Is wound.

The magnetostrictive element 31 has a hollow rectangular shape as shown in FIG. 5 (b), is made of a thin nickel plate, and has the dimensions shown in FIG. 5 (c). There is.
If a metal-based magnetostrictive material having a high material strength and a high Curie point, for example, nickel having a Curie point of 358 [° C.] is selected as the magnetostrictive element 31, the magnetostrictive vibrator 26 that can withstand a high temperature excavating environment can be obtained.

In the magnetostrictive vibrator 26, the element wire of the exciting coil 27 is wound around the magnetostrictive element 31 at right angles to the strain direction of the magnetostrictive element 31 (arrow S in FIG. 5), and a current is supplied to the exciting coil 27. Generates a magnetic field to excite the magnetostriction phenomenon. The feature of this structure is that the magnetostrictive material (magnetostrictive element 31) and the electric system (excitation coil 27) that excites this magnetostrictive material are in an interlinking relationship and are mechanically independent without contact. That is, there is no stress on the electrodes such as the piezoelectric element, and there is no fear of damage.

Further, in order to reduce the eddy current loss due to the excitation, the magnetostrictive oscillator 26 is generally made of a laminated structure of thin plates, but the laminating direction and the vibrating direction are orthogonal to each other, and the The phase and amplitude expand and contract in synchronization. Therefore,
The strength of the magnetostrictive vibrator 26 can be secured without applying a large stress such as peeling off the adhesive surface of each magnetostrictive element 31.

The commonly used magnetostrictive oscillator 26 has a prismatic structure in which the magnetostrictive elements 31 rolled into thin plates are laminated in order to reduce the eddy current loss as described above. The resonance frequency is determined by the shape and size of the magnetostrictive element 31.
For example, in the case of a generally known prismatic magnetostrictive oscillator 26, the wavelength λ of the primary resonance frequency satisfies the following characteristic equation (1) from the dimensions of each part shown in FIG. It is approximately an integral multiple of 1/4 wavelength of the resonance frequency. tan (α · 2 / π) · tan (β · 2 / π) = k (1) where k = Sc (area of pillar) / St (area of end face) α = 4 · a (end) (Length of part) / λ (wavelength) β = 2 · b (length of column) / λ (wavelength) That is, by changing the shape of the magnetostrictive oscillator 26, resonance vibration in an arbitrary band can be obtained. .

Next, the result of vibration analysis of the excavated pipe body 13 will be described. FIG. 6 is a diagram showing a result of modeling a vibration system in the case where the excavating pipe body 13 is configured by connecting 10 single pipes 13a having a length of 9 [m] and performing the vibration analysis. A vibration mode in the axial direction of the model of the excavated pipe body 13 in which ten single pipes 13a having such a structure are connected is analyzed. The result has the transfer function shown by the curve G in FIG. 7, and at the resonance frequency with good transfer efficiency, the integral multiple of the half wavelength and the total length A of the single tube 13a match. That is, the excavation pipe body 13 has a resonance mode M at a frequency determined by the propagation velocity of the elastic wave and the entire length of the excavation pipe body 13, that is, the resonance vibrations in the primary resonance mode M1, the secondary resonance mode M2, and the tertiary resonance mode M3 shown in FIG. Cause For example, if the tertiary resonance frequency has a wavelength that is ⅔ times that of the excavated pipe body 13, the propagation speed of the elastic wave is 5000 [m / s], and the length of the single pipe is 9 [m], then it is 833 [Hz].

Therefore, by making the resonance frequency of the magnetostrictive oscillator 26 match the resonance frequency of the excavation pipe body 13, it becomes possible to efficiently generate vibration with a large amplitude in the excavation pipe body 13 and to obtain information from a larger depth. Transmission becomes possible.
The control device 23 is configured to generate the third resonance frequency 833 [Hz] which is such a frequency. Since the carrier frequency of several hundred hertz, which is several tens of times higher than that of the conventional one, is used, the information transmission rate is improved several to several tens of times.

In the case of nickel, it is distorted only in the contracting direction, regardless of the polarity of the excited magnetic field. Therefore, when the polarity of the exciting magnetic field is alternated around the zero point, the magnetostrictive material is distorted every time the polarity changes, and vibration having a double cycle of the exciting current is generated. To avoid this, a DC magnetic bias is applied. For this purpose, the control device 23 controls the exciting current supply device 24 to superimpose the direct current on the exciting current to form a pulsating current. It should be noted that the magnetostrictive vibrator 26 is prestressed to be preliminarily distorted by external stress, or the magnetostrictive element 3
In some cases, a method of magnetizing 1 to give a residual magnetism may be adopted. When applying alternating current, the alternating current has a frequency half the resonance frequency.

Next, the operation will be described. This equipment is an MWD configured for use in oil and gas well drilling.
(Measurement While Drilling) system, which transmits information such as the stratum at the bottom of the hole, excavation status, and direction to the ground by acoustic acoustic waves propagating through a drill string connected to a single pipe. It aims to improve the safety and efficiency of the drilling and reduce excavation costs.

The information obtained by the bottom hole sensor 21 is modulated by the elastic wave generator 22 mounted on the elastic wave generating tube body 12, and an elastic wave including information to be transmitted is generated in the excavating tube body 13. To do. The acoustic wave transmitted on the ground is received by the receiving tube body 14, and the demodulation device 16 demodulates the signal to obtain the bottom hole information.

The magnitude of strain due to the magnetostrictive phenomenon is proportional to the magnitude of the exciting current, and its response speed is several tens of microseconds (μ
s) It is sufficiently faster than the following, which is the transmission speed of necessary information. Therefore, when the frequency, phase, amplitude, etc. of the exciting current are changed according to the signal to be transmitted, an elastic wave corresponding to the information is generated from the magnetostrictive vibrator 26, and the information can be transmitted. Further, the resonance frequency of the magnetostrictive oscillator 26 is matched with the resonance frequency of the excavation pipe body 13 as described above, so that vibration with a large amplitude can be efficiently generated in the excavation pipe body.

Here, the dimensions of the piezoelectric ceramic vibrator and the magnetostrictive vibrator and the power required to generate an elastic wave will be calculated. As a material characteristic of the piezoelectric ceramic, when the frequency constant of the thickness elongation characteristic (TE) mode is H, the thickness δ [m] has a frequency of f1 [H
z] is obtained by the following equation. δ = H / f1 As a piezoelectric material, for example, the frequency constant of TE mode of PZT-4 (trade name of Claybyte Co., USA) is 2000.
It is given as [Hz · m], and the thickness of ceramics reaches several meters at frequencies below 1000 [Hz], which is necessary for tube transmission (Negishi and Takagi “Ultrasonic Technology”).
The University of Tokyo Press, pages 32 to 36).

Next, the required power is estimated. For example, a vibrator (Bolt-clamped L) for a cleaning machine that uses piezoelectric ceramics.
The maximum electric input power P of the angevin type transducer: BLT is a capacity coefficient K (usually 0.4 to 0.5), a piezoelectric ceramic volume V [cc], and a frequency 1 [kHz].
Then, it can be estimated by the following equation ("Ultrasonic Engineering" edited by Japan Society of Mechanical Engineers, published by Corona Publishing, pages 10 to 17). P = K · V / f Now, assuming that the frequency required for transmission is 1 [kHz], the ceramic length is 1 [m], and the bottom area is 100 [cm x cm], the required power is 50 [kW]. become. On the other hand, in the case of a magnetostrictive oscillator, it is possible to generate vibration of 1 [kHz] or less at a maximum of 50 [W], and it is possible to significantly reduce power consumption.

Further, as described above, the magnetostrictive vibrator 26 and the exciting coil 27 for exciting are in a non-contact interlinking relationship and are mechanically independent, so that there is no stress on the electrodes such as the piezoelectric element, Highly reliable with no risk of damage. Further, since the lamination direction of the magnetostrictive element 31 is perpendicular to the vibration direction and the phase and amplitude of the vibration of each magnetostrictive element 31 expands and contracts in synchronization, a large stress is applied such that the adhesive surface of the magnetostrictive element 31 peels off. It is possible to maintain the strength as a vibrator. Therefore, it can be used in harsh environments such as high temperature, high pressure at the bottom of the pit, excavation impact, for example, 175 [° C], 1400 atmospheric pressure, 250 [G].

The magnetostrictive vibrator 26 is generally a magnetostrictive element 31.
It has a rectangular structure in which the resonance frequency is (1)
It is determined by the shape and size of the magnetostrictive material 31 as shown in the equation. Therefore, by changing the shape of the magnetostrictive oscillator 26, it is possible to obtain resonance vibration in an arbitrary band. Therefore, by matching the resonance frequency of the magnetostrictive oscillator 26 with the resonance frequency of the excavation pipe body 13, it is possible to efficiently generate vibration with a large amplitude in the excavation pipe body and to transmit information from a larger depth. It should be noted that the magnetostrictive oscillator 31 may use other metal-based magnetostrictive material instead of nickel, such as Alfero alloy (87% iron, 13% aluminum).

Second Embodiment of the Invention FIG. 8 is a waveform diagram showing an output waveform of the exciting current supply device in the elastic wave generator according to another embodiment of the present invention. By supplying an alternating current such as a sine wave to the exciting coil 27 of the magnetostrictive oscillator 26 in FIG. 3 and matching its frequency with the resonant frequency of the magnetostrictive oscillator 26, the resonant vibration is excited and a large amplitude vibration is generated. It can be generated in the drill pipe 13. Therefore, by modulating a code transmitted as a sinusoidal wave as the alternating current, for example, as shown in FIG. 8, it is possible to efficiently transmit information on the bottom of the well.

For example, the ASK system (amplitude shift keying system,
When modulating a binary code by Amplitude-shift keying modulation method), the code string "1011" is associated with the code "1" corresponding to the vibration "present" and the code "0" corresponding to the vibration "absent".
Is modulated, the exciting current waveform J1 shown in FIG. 8 is obtained.

Embodiment 3 of the Invention FIG. 9 is a waveform diagram showing an output waveform of the exciting current supply device in the elastic wave generator according to another embodiment of the present invention. The magnetostrictive vibrator 26 in FIG. 3 generates distortion of amplitude corresponding to the magnitude of the exciting current at a response speed of several tens of microseconds (μs) or less. Therefore, by instantaneously supplying a large current to the exciting coil 27, a large amplitude distortion can be generated with low power consumption.

In this embodiment, the magnetostrictive vibrator 2
The pulsed exciting current is supplied to the exciting coil 27 of No. 6, and the time interval for applying the current, that is, the pulse interval is made to coincide with the cycle of the resonance frequency of the magnetostrictive vibrator 26, so that the resonance vibration is generated. Excitation causes the excavation pipe body 13 to generate a vibration having a large amplitude. That is, as shown in FIG. 9, if the code transmitted by the pulse train is modulated, the information on the bottom hole can be efficiently transmitted. For example, when a binary code is modulated by the ASK method, the code “1” is associated with the excitation “with” and the code “0” is associated with the excitation “absence”, and the code string “101” is associated.
If "1" is modulated, an exciting current waveform J2 is obtained.

Fourth Embodiment of the Invention FIG. 10 is a schematic diagram showing a mounting state of a magnetostrictive vibrator and a waveform of an elastic wave in an elastic wave generator according to another embodiment of the present invention. In the figure, ND is a node of the resonance vibration W of the drill pipe 13. In the resonance mode of the drill pipe 13, vibration nodes ND are provided at regular intervals depending on the resonance frequency. The node ND of the resonance vibration is that it does not vibrate even if it is excited. For example, in the case of a single tube 13a having a length of 9 [m], in the primary resonance mode M1 in FIG. Next resonance mode M
2 has a node ND every 4.5 m and in the third resonance mode M3 every 3 m.

Therefore, in order to generate the resonance vibration W in the excavation pipe body 13, avoid this node ND and use the node N as shown in FIG.
An excited surface (spotting point) 12d is provided between D and the node ND, and is excited by the exciting surface 26a of the magnetostrictive vibrator 26. In addition, the greater the distance D from the surface to be excited 12d to the node ND is and the closer to the antinode of the vibration, the higher the efficiency of generating the resonant vibration in the excavated pipe body 13.

Embodiment 5 of the Invention 11A and 11B show a mounting state of a magnetostrictive vibrator according to another embodiment of the present invention on an elastic wave generating tube body. FIG. 11A is a sectional view and FIG. 11B is a plan view. Is. In these drawings, reference numeral 52 denotes an elastic wave generating tube body, which is similar to the elastic wave generating tube body 12 in FIG. 1, and has a rectangular recessed portion 52a, two grooves 52b, and two grooves on its side surface. Is provided with a box hole 52c, and the side wall of the recessed portion 52a is a surface to be excited 52d. The left side in FIG. 11 is the ground side.

Reference numeral 61 denotes a fixing member, which has a gate-like shape when viewed from the vibration direction of the magnetostrictive vibrator 26. Fixing member 61
The bolt 62a housed in the groove 52b of the elastic wave generating tube 52 is fixed by the nut 62b in the box hole 52c, so that the exciting surface 26a of the magnetostrictive oscillator 26 is moved to the elastic wave generating tube as shown in the figure. The surface to be excited 52d of the body 52 is pressed. Although not shown in FIG. 11B, the magnetostrictive vibrator 26 is hatched.

Magnetostrictive vibrator 2 mounted as described above
6 is a primary resonance mode M1 as shown in FIG.
It has first and second resonance modes M22. Magnetostrictive oscillator 26
Is determined by the frequency that satisfies the characteristic equation (1), and the half-wavelength of the primary resonance frequency is substantially equal to the entire length of the single tube 13a (see the waveform M1 in FIG. 6). Also,
For example, in order to match the primary resonance frequency having the longest wavelength among the resonance frequencies of the magnetostrictive vibrator 26 with the tertiary resonance frequency of the single tube 13a, the magnetostrictive vibrator 26 having a total length of about 3 m is required.

Therefore, the exciting surface 26a of the magnetostrictive oscillator 26 is pressed and fixed to the excited surface 52d of the elastic wave generating tube body 52 by the fixing member 61, and the other surface is used as a free vibrating end for the elastic wave generating tube body. It is mounted on 52. In this case, as shown in the primary and secondary resonance modes M11 and M22 of FIG. 11A, resonance vibration is generated in a mode in which the vibration surface 26a is a node of vibration and the other surface is a vibration antinode. At this time, 1 of the primary resonance frequency
The / 4 wavelength substantially matches the entire length of the magnetostrictive oscillator 26.

When the total length of the magnetostrictive oscillator 26 is matched with the third resonance frequency of the single tube 13a, the total length of the magnetostrictive oscillator 26 is 1.
It only takes 5m. That is, by adopting the mounting method in which only the vibration surface 26a is fixed, it is possible to make the resonance frequency of the smaller magnetostrictive vibrator 26 match the resonance frequency of the excavation pipe body and efficiently generate large vibration. Become.

In this case, when prestress is applied to the magnetostrictive oscillator 26, the resonance frequency is doubled, so that the exciting coil 2
It is necessary to excite 7 (FIG. 5) with a pulsating current on which a direct current is superimposed, or to magnetize the magnetostrictive element 31 itself in advance.

In the embodiment shown in FIGS. 4, 10, and 11, the vibration generator 25 is provided on the elastic wave generating tube 12,
Although the elastic wave generating tube body 12 is connected to the excavating tube body 13 for vibration, the magnetostrictive vibrator 26 may be directly provided on the single tube 13a. The elastic wave is not limited to the one generated by the excitation current having the waveform shown in each of the above-described embodiments, and may be a triangular wave or the like, and the modulation method may be another digital modulation method.

[0051]

As described above, according to the elastic wave generator for excavating pipe body transmission of the first aspect of the present invention, the propagation speed of the elastic wave propagating in the excavating pipe body and the length of the excavating pipe body are set. Has a resonance frequency that matches the resonance frequency that is determined based on, and excites the magnetostriction vibrator with an excitation current that modulates the information to be transmitted, and propagates through the excavated pipe with the same cycle as the resonance frequency. Since it generates elastic waves that are generated, it is possible to withstand the vibration of excavation and high temperatures and to generate elastic waves that propagate through the excavation pipe with low power.

According to the elastic wave generator for excavating pipe body transmission of the second aspect of the present invention, an alternating elastic wave having the same period as the period of the resonance frequency of the excavating pipe body is generated in the magnetostrictive vibrator by the exciting current. Therefore, the resonance of the magnetostrictive vibrator can be efficiently induced, and an elastic wave having a large amplitude can be generated in the excavated pipe body.

According to another aspect of the present invention, there is provided the elastic wave generator for transmitting excavation pipe body, wherein the magnetostrictive oscillator is formed by laminating thin plates made of a metal-based magnetostrictive material, and the exciting current is the excavation pipe body. Since the alternating current or pulsating component having half the period of the resonant frequency is the pulsating current having the same period as the resonant frequency, elastic waves with large amplitude are generated in the drill pipe even in high temperature environment. be able to.

According to the elastic wave generator for excavating pipe body transmission of claim 4 of the present invention, since the exciting current is a pulse train having the same period as the period of the resonance frequency of the excavating pipe body,
Resonance of the magnetostrictive oscillator can be induced with low power, and elastic waves with large amplitude can be generated in the excavated pipe body.

According to the elastic wave generator for excavating pipe body transmission of the fifth aspect of the present invention, the excitation surface of the magnetostrictive oscillator is located between the nodes of the resonance mode in the axial direction of the excavating pipe body. Since the elastic wave is generated in the excavation pipe body as described above, the resonance of the excavation pipe body can be efficiently generated.

According to the elastic wave generator for excavating pipe body transmission of the sixth aspect of the present invention, one surface of the magnetostrictive oscillator in the vibration direction is used as the excitation surface and the other surface is used as the free vibration end. Since the elastic wave is generated in the excavation pipe body by the surface, it is possible to make the resonance frequency of the small magnetostrictive oscillator match the resonance frequency of the excavation pipe body.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a tubular body transmission device showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the excavation pipe body in FIG.

FIG. 3 is a block diagram showing a configuration of an elastic wave generator according to an embodiment of the present invention.

FIG. 4 is a plan view showing a state where the elastic wave generating device of FIG. 3 is attached to an elastic wave generating tube.

5A and 5B show a magnetostrictive vibrator according to an embodiment of the present invention, wherein FIG. 5A is a perspective view of the magnetostrictive vibrator, FIG. 5B is a perspective view of the magnetostrictive element, and FIG. FIG.

FIG. 6 is a model diagram showing a result of modeling a vibration system of the excavated pipe in FIG. 1 and performing a vibration analysis thereof.

FIG. 7 is a diagram showing a transfer function of axial vibration of the vibration system of the excavation pipe in FIG.

FIG. 8 is a waveform diagram showing an output waveform of an exciting current supply device in an elastic wave generator according to another embodiment of the present invention.

FIG. 9 is a diagram showing an output waveform of an exciting current supply device in an elastic wave generator according to another embodiment of the present invention.

FIG. 10 is a schematic diagram showing a mounted state of a magnetostrictive oscillator and a waveform of an elastic wave generated in an elastic wave generator according to another embodiment of the present invention.

11A and 11B show a mounting state of a magnetostrictive vibrator according to another embodiment of the present invention on an elastic wave generating tube body. FIG. 11A is a sectional view and FIG. 11B is a plan view. Is.

FIG. 12 is a side view showing a configuration of a conventional tubular body transmission device using acoustic elastic waves.

FIG. 13 is an exploded perspective view showing the structure of a conventional oscillator.

FIG. 14 is a cross-sectional view showing a mounted state of the oscillator of FIG.

15A and 15B are waveform diagrams for explaining the operation, FIG. 15A is a waveform diagram showing a waveform of a driving current of an oscillator, and FIG. 15B is a waveform diagram showing an acoustic elastic wave generated in a drill collar. .

16 shows a drive current modulation method of the oscillator in FIG. 13, FIG. 16 (a) is a binary code “1”, and FIG.
FIG. 3 is a signal waveform diagram showing a binary code “0”.

[Explanation of symbols]

12: elastic wave generating tube, 12d: surface to be excited, 13: excavation tube, 13a: single tube, 14: receiving tube, 16: demodulator, 22: elastic wave generator, 23: controller , 24:
Exciting current supply device, 25: Vibration generator, 26: Magnetostrictive oscillator, 26a: Exciting surface, 27: Exciting coil, 31: Magnetostrictive element, 52: Elastic wave generating tube, 52d: Excited surface, 6
1: Fixed member.

Claims (6)

[Claims] 1. A resonance frequency that is formed of a magnetostrictive material that generates an elastic wave by the magnetostriction phenomenon and that matches a resonance frequency determined based on the propagation speed of the elastic wave propagating in the excavation pipe and the length of the excavation pipe. A magnetostrictive vibrator having the following, wherein by exciting the magnetostrictive vibrator with an exciting current that modulates information to be transmitted, the elasticity that propagates through the excavating pipe body has the same cycle as the cycle of the resonance frequency. An elastic wave generator for transmitting excavation pipes that generates waves. 2. The elasticity for excavating pipe body transmission according to claim 1, wherein the exciting current causes an alternating elastic wave having the same period as the period of the resonance frequency of the excavating pipe body to be generated in the magnetostrictive oscillator. Wave generator. 3. The magnetostrictive vibrator is formed by laminating thin plates of a metal-based magnetostrictive material, and the exciting current is an alternating current or a pulsating component having a half cycle of the resonant frequency of the drill pipe. The elastic wave generator for excavating pipe body transmission according to claim 2, wherein the pulsating current has the same cycle as the cycle of the resonance frequency. 4. The elastic wave generator for excavating pipe body transmission according to claim 1, wherein the exciting current is a pulse train having the same period as the period of the resonance frequency of the excavating pipe body. 5. The magnetostrictive oscillator is a device for generating an elastic wave in the excavation pipe body such that the excitation surface is between the nodes of the resonance mode in the axial direction of the excavation pipe body. The elastic wave generator for excavating pipe body transmission according to claim 1. 6. An elastic wave is generated in the excavation pipe body by using one surface in the vibration direction of the magnetostrictive oscillator as a vibration surface and the other surface as a free vibration end. The elastic wave generator for transmitting a drill pipe according to claim 1.