WO2020151235A1

WO2020151235A1 - Underground acoustic system

Info

Publication number: WO2020151235A1
Application number: PCT/CN2019/106163
Authority: WO
Inventors: 王东; 赵刚
Original assignee: 中科云声(苏州)电子科技有限公司
Priority date: 2019-01-25
Filing date: 2019-09-17
Publication date: 2020-07-30
Also published as: CN109594977A

Abstract

An underground acoustic system, comprising a transmitting acoustic system nipple and a receiving acoustic system nipple. The transmitting acoustic system nipple comprises a first acoustic system unit (1) and a second acoustic system unit (11); the first acoustic system unit (1), the second acoustic system unit (11), and the receiving acoustic system nipple (23) are connected to a measuring instrument by means of connecting joints, respectively. The structure and specification size design of the underground acoustic system satisfies the measurement environment of an acoustic remote detection imaging and evaluation system for offshore wind power tower footing; the acoustic system adopts an elastomer encapsulated high-power monopole longitudinal wave transmitting transducer; optimized design of an elastomer encapsulated low-frequency broadband orthogonal dipole transmitting transducer is provided; a receiving acoustic system integrated with a high-sensitivity receiving transducer and a receiving control circuit is selected; high power, low frequency and sufficient broadband of acoustic system transmission, and high sensitivity of the receiving acoustic system are guaranteed.

Description

An underground sound system

Technical field

The invention relates to the technical field of offshore wind power exploration design and offshore exploration logging equipment, in particular to an underground acoustic system.

Background technique

Offshore wind power exploration and design is a necessary link in the preliminary work of offshore wind power, and is the foundation for the construction and construction of offshore wind power tower foundations. The design evaluation of offshore wind power tower foundation mainly includes several technical approaches, namely conventional geophysical prospecting technology, downhole measurement technology and borehole sampling technology. Each technology includes different implementation methods and forms a variety of measurement and implementation instrument products. Among them, downhole measurement technology is one of the very important technologies. Similarly, downhole measurement technology also includes a variety of measurement methods and measuring instruments, such as downhole resistivity measuring instruments, downhole radioactivity measuring instruments, borehole diameter measuring instruments, and downhole acoustic measurement Instruments and other products.

The downhole acoustic wave measuring instrument means that after the drilling of the offshore wind power tower base is completed, the downhole acoustic wave measuring instrument equipped with the acoustic system of the sensor or probe and the control unit is placed in the borehole to complete the measurement. The instrument completes the power supply of the ground system through the cable and tele Control and lifting or lowering, etc., when the instrument implements logging, the acoustic emission sensor emits acoustic waves. The acoustic waves are coupled through the borehole fluid, and the acoustic signals propagate in the borehole stratum, and transmission, refraction, and reflection occur at different interfaces. Energy and mode conversion, and then the acoustic signal is received by the receiving sensor (stratum echo signal), the echo signal is uploaded to the ground acquisition and control system through cable and network transmission protocol, the ground system manages and processes the data, and calculates the various types of stratum The characteristic data (velocity and attenuation, etc.) of the mode wave are extracted and analyzed using relevant algorithms to complete the acquisition of the characteristic parameters of the lithology of the downhole formation and the detection and evaluation of the geological structure near the borehole.

At present, there are two main methods for downhole emission sound system, monopole sound system and dipole sound system emission. Among them, the monopole sound system realizes the excitation of monopole longitudinal wave measurement, and the dipole sound system completes the excitation of bending transverse wave measurement. , The receiving sound system completes the reception of various mode waves such as longitudinal waves and transverse waves. At present, the main problems faced by the underground sound system unit include: First, the sound system has a high operating frequency and a narrow bandwidth. The emission working frequency of the existing instrument sound system is relatively high. The monopole is between 10-15kHz and the dipole is between 1-6kHz. The working bandwidth is realized by the combination of resonance peaks, and the emission bandwidth is obviously limited. The stratum at the base of the wind power tower is very loose and highly porous. It may contain gas or a variety of complex structural geological bodies. The high-frequency acoustic signal of the emission sound system is attenuated very seriously. Therefore, the current emission sound system design , Can not meet the comprehensive evaluation and detection of the stratum in the tower base area and the geological structure in the stratum. Second, the sensitivity of the receiving sound system is low. The current receiving sound system is limited to the limitations of the underground environmental conditions. The receiving sound system sensitivity is low, generally in the range of -230dB to -200dB, due to the loose nature of the base layer of the wind power tower , The received acoustic signal is very weak, and the low-sensitivity receiving acoustic system cannot obtain signals of multiple modes related to the evaluation of stratum and geological structures. Third, the acoustic system has large specifications and uses complex and cumbersome silicone oil sealed packaging. The boreholes for offshore tower base detection are small. The borehole diameter is generally in the range of 90-150mm. The existing acoustic system diameter is generally greater than 108mm. For coupling and sealing requirements, generally the acoustic system is filled with vacuumed silicone oil, which is time-consuming and labor-intensive for packaging, installation and maintenance.

Summary of the invention

The purpose of the present invention is to provide a downhole acoustic system unit, which uses a low-frequency emission acoustic system with a frequency lower than 1kHz, so that low-frequency acoustic signals can propagate in loose formations with less attenuation, and adopt a composite structure to expand the emission bandwidth design The sound emission system is suitable for the detection of various complex formations at the base of the wind power tower, and the excitation control of the emission sensor in the low frequency band can maximize the efficiency of the sensor.

In order to solve the above technical problems, the technical solution of the present invention is:

A downhole acoustic system includes a transmitting acoustic system short section and a receiving acoustic system short section. The transmitting acoustic system short section and the receiving acoustic system short section are respectively connected to a measuring instrument through a connecting joint.

The transmitting acoustic system short section includes a first acoustic system unit and a second acoustic system unit. The first acoustic system unit includes a first housing, a first frame arranged in the first housing, and a plurality of monopole transmitting transducers arranged on the first frame. The first skeleton includes a first skeleton main body, a top cover provided at one end of the first skeleton main body, and a first terminal post is arranged on the top cover, and the first skeleton main body is provided with a first main body for mud circulation Channel, the monopole transmitting transducer is encapsulated on the first skeleton body by using an elastomer. The monopole transmitting transducer adopts a circular tube type piezoelectric element. There are two or four monopole transmitting transducers, and they are connected in parallel.

The second sound system unit includes a second shell, a second frame arranged in the second shell, and a plurality of dipole transmitting transducers arranged on the second frame, and the second frame is arranged to A frame connecting plate separated by a plurality of the dipole emission transducers, the dipole emission transducers are encapsulated on the second frame by an elastomer, and the second frame includes the second frame body , Density blocks arranged at both ends of the second skeleton body, and a second connecting column arranged on the density block at one end. The dipole transmitting transducer adopts a piezoelectric element with a three-stack structure. The three-stack structure includes a metal substrate and piezoelectric ceramic sheets arranged on both sides of the metal substrate. There are grooves on both sides. The dipole emitting transducer includes a dipole emitting long piece transducer and a dipole emitting short piece transducer. There are eight dipole transmitter transducers, four dipole long chip transducers and four dipole short chip transducers, two in each of the X and Y directions. The dipole emitting long chip transducer and the dipole emitting short chip transducer are arranged orthogonally.

The receiving sound system short section includes a receiving sound system housing, a receiving sound system skeleton arranged in the receiving sound system housing, a receiving circuit module and a plurality of receiving transducers arranged on the receiving sound system skeleton. The receiving transducer and the receiving circuit module are encapsulated in the receiving acoustic system skeleton by an elastic body. The receiving transducer adopts a five-stack structure, which includes three layers of metal substrates and two layers of piezoelectric ceramics, and a layer of piezoelectric ceramics is arranged between the two layers of metal substrates. The receiving acoustic system skeleton is provided with a mud channel penetrating the receiving acoustic system skeleton. The receiving sound system frame is provided with a receiving sound system connection post. There are 32 receiving transducers, with eight stations, four in each station, and the combination of orthogonal installation.

Compared with the prior art, the present invention has the following advantages: the downhole acoustic system of the present invention adopts a low-frequency emission acoustic system with a frequency lower than 1kHz, so that low-frequency acoustic signals can propagate in loose formations with less attenuation. The expanded emission bandwidth design of the composite structure makes the emission sound system suitable for the detection of various complex formations at the base of the wind power tower. The excitation control of the emission sensor in the low frequency band can optimize the efficiency of the sensor. The downhole acoustic system adopts a high-sensitivity receiving acoustic system design. The sensitivity of the receiving acoustic system is closely related to the piezoelectric material. Within the working temperature range of the instrument, the piezoelectric ceramic material with high receiving efficiency further improves the receiving sensitivity. In order to achieve the effectiveness of remote detection of acoustic signals and reduce the signal attenuation in circuit control, the receiving control circuit and the receiving sensor are integrated into a module unit. In this way, the receiving acoustic system pup is more conducive to receiving small and weak signals, which can ensure To obtain shear wave information in low-velocity seafloor formations, the most important thing is to obtain information on reflection waves of geological bodies in a large area beside the well. The downhole acoustic system is specially designed for the instrument products of offshore wind power tower base acoustic wave remote detection imaging and evaluation. The specifications of the transmitting and receiving acoustic system are smaller. At the same time, a new coupling and sealing design is carried out for the transmitting and receiving acoustic system. , Transmitting and receiving acoustic systems are packaged with elastomers (such as rubber and polyurethane, etc.). On the basis of solving the coupling and sealing, the acoustic system is easier to install and maintain, and the failure rate is reduced. At the same time, it is aimed at wind power tower foundation survey drills In the case of a smaller hole, a smaller design and scale of the transmitting and receiving sound system can meet the requirements of offshore operation conditions for wind power tower foundation detection while ensuring the effectiveness of detection.

Description of the drawings

The drawings described herein are only for explanatory purposes, and are not intended to limit the scope of the present disclosure in any way. In addition, the shape and proportional size of each component in the figure are only schematic, which are used to help the understanding of the present invention, and do not specifically limit the shape and proportional size of each component of the present invention. Under the teaching of the present invention, those skilled in the art can choose various possible shapes and proportional sizes according to specific conditions to implement the present invention. In the attached picture:

Figure 1 is a schematic structural diagram of a downhole acoustic system according to a specific embodiment of the present invention;

2 is a schematic structural diagram of a first acoustic system unit of a downhole acoustic system according to a specific embodiment of the present invention;

3 is a schematic structural diagram of a second acoustic system unit of a downhole acoustic system in a specific embodiment of the present invention;

Fig. 4 is a schematic structural diagram of a receiving acoustic system short section of a downhole acoustic system according to a specific embodiment of the present invention.

As shown in the figure: 1-first sound system unit, 2-first shell, 3-slurry, 4-first skeleton body, 5-elastomer, 6-tube type piezoelectric element, 7-first channel, 8-top cover, 9-first terminal, 10-connector, 11-second sound system unit, 12-second shell, 13-second skeleton body, 14-framework connecting plate, 15-density block, 16 -Dipole transmitting long piece transducer, 17-Dipole transmitting short piece transducer, 18-metal substrate, 20-piezoceramic piece, 21-notch, 22-second connecting post, 23-receiving Acoustic short section, 24-receiving sound system shell, 25-receiving sound system skeleton body, 26-receiving transducer, 27-receiving circuit module, 28-receiving transducer substrate, 29-receiving piezoelectric ceramic sheet, 30-epoxy resin, 31-receiving circuit board, 32-receiving sound system binding post, 33-second channel.

detailed description

In order to enable those skilled in the art to better understand the technical solutions in the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described The embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

It should be noted that when an element is referred to as being "disposed on" another element, it can be directly on the other element or a central element may also exist. When an element is considered to be "connected" to another element, it can be directly connected to the other element or an intermediate element may be present at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and are not meant to be the only embodiments.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The term "and/or" as used herein includes any and all combinations of one or more related listed items.

The downhole acoustic wave measuring instrument refers to the downhole acoustic wave measuring instrument equipped with the downhole acoustic system and the control unit of the sensor or probe after the completion of the drilling of the offshore wind power tower foundation to complete the measurement. The instrument completes the power supply of the surface system through the cable. Transmission control and lifting or lowering, etc. When the tool is logging, the acoustic emission sensor emits acoustic waves. The acoustic waves are coupled through the borehole fluid, and the acoustic signals propagate in the borehole stratum, and transmission, refraction and reflection occur at different interfaces. The sound wave energy and mode are converted, and then the sound wave signal is received by the receiving sensor (stratum echo signal). The echo signal is uploaded to the ground acquisition and control system through the cable and network transmission protocol. The ground system manages and processes the data and calculates the ground level. The characteristic data (velocity and attenuation, etc.) of a mode wave are extracted and analyzed using related algorithms to complete the acquisition of the characteristic parameters of the downhole formation lithology and the detection and evaluation of the geological structure near the borehole.

Please refer to Figure 1, a downhole acoustic system, including a transmitting acoustic system short section and a receiving acoustic system short section. The transmitting acoustic system short section and the receiving acoustic system short section are respectively connected to a measuring instrument through a joint. The section and the receiving sound system short section are connected to the power supply provided on the measuring instrument through a cable.

Referring to FIG. 2, the transmitting acoustic system short section includes a first acoustic system unit 1 and a second acoustic system unit 11. The first sound system unit includes a first housing 2 and a first skeleton arranged in the first housing 2, a monopole transmitting transducer is arranged on the first skeleton, and the first skeleton A common axis at one end is threadedly connected to the first housing 2. The first frame includes a first frame body 4, a top cover 8 arranged at one end of the first frame body 4, and a first terminal 9 arranged on the top cover 8. The first sound system unit 1 The first terminal 9 is connected to the cable to connect to the power source. The first skeleton is provided with a first channel 7 for circulating the mud 3, and the monopole transmitting transducer is encapsulated on the first skeleton body 4 by an elastic body 5. The elastic body 5 may be rubber or Polyurethane. There are two or four monopole transmitting transducers, and they are connected in parallel. The monopole transmitting transducer adopts a circular tube type piezoelectric element 6, and a high-power circular tube structure transducer is selected, and the working frequency is 10kHz-30kHz.

3, the second sound system unit 11 includes a second housing 12, a second frame arranged in the second housing 12, and a plurality of dipole transmitting transducers arranged on the second frame , The second frame is provided with a frame connecting plate 14 separating the plurality of dipole transmitting transducers. The second skeleton includes a second skeleton body 13, density blocks 15 respectively arranged at two ends of the second skeleton body 13, and a second connecting column 22 arranged on the density block 15 at one end. The tie unit 11 is connected to the cable through the second terminal 22 to connect to a power source. The dipole transmitting transducer adopts a piezoelectric element with a three-stack structure, and the three-stack structure is composed of a metal substrate 18 and piezoelectric ceramic sheets 20 respectively arranged on two surfaces of the metal substrate 18 , The three sheets are bonded together with epoxy resin. The metal substrate 18 can be made of aluminum, copper or metal alloy. The metal substrate 18 has grooves 21 on both sides, and the structure of the groove 21 is expanded The bandwidth of the transducer. By selecting the size of the metal substrate 18 and controlling the operating frequency, the dipole transmitting transducer includes a dipole transmitting long piece transducer 16 and a dipole transmitting short piece transducer 17. There are eight dipole emitting transducers, four dipole emitting long chip transducers 16 and four dipole emitting short chip transducers 17, which are arranged orthogonally, specifically, in X and Y Two dipole emitting long chip transducers 16 and dipole emitting short chip transducers 17 are set in each direction. For the short dipole emitting section, it contains 32 emitting transducers as an expected design launch On the whole, unlike the monopole short section, its two ends are provided with density blocks, which are made of alloy materials with a density far greater than its metal skeleton. This high-density arrangement at both ends limits the dipole transmitting transducer to one The relatively closed acoustic system ensures that the dipole subsystem is not interfered by external systems. The dipole transmitting transducer is encapsulated on the second skeleton main body 13 by an elastic body 5 to ensure sealing, coupling and a small pressure buffer. The elastic body 5 may be rubber, polyurethane, or epoxy resin. Choose according to the temperature resistance of the transducer.

4, the receiving sound system pup 23 includes a receiving sound system housing 24, a receiving sound system skeleton provided in the receiving sound system housing 24, and a receiving circuit module 27 provided on the receiving sound system skeleton. And a number of receiving transducers 26. The receiving circuit module 27 performs real-time processing such as pre-amplification, automatic gain control, and filtering on the signal received by each of the receiving transducers 26, which effectively improves the receiving transducer. The receiver sensitivity of the energy device 26 can reduce interference and signal attenuation during transmission. The receiving acoustic system skeleton includes a receiving acoustic system skeleton main body 25 and a receiving acoustic system binding post 32 arranged on the receiving acoustic system skeleton main body 25, and the receiving acoustic system puppet 23 passes through the receiving acoustic system binding post 32. Connect with the cable to connect the power source. The receiving transducer 26 and the receiving circuit module 27 are encapsulated and arranged on the receiving sound system skeleton body 25 through the elastic body 5. First, the receiving sound system circuit module 27 is potted with waterproof epoxy resin, and then, The elastic body 5 is used to encapsulate the receiving transducer 26 and the receiving sound system circuit module 27 on the receiving sound system skeleton body 25, and the receiving sound system skeleton body 25 is provided with a second channel 33 for the passage of the mud 3 . The receiving transducer 26 adopts a five-stack structure. The five-stack structure includes three layers of receiving transducer substrates 28 and two layers of receiving piezoelectric ceramic plates 29. The receiving transducer substrate 28 and the receiving The piezoelectric ceramic sheets 29 are alternately arranged and bonded together. The receiving transducer substrate 28 is used as the polarity control of the transducer, the receiving piezoelectric ceramic sheet 29 is located in the middle layer, and the receiving piezoelectric ceramic The thickness of the sheet 29 determines the resonance performance of the transducer. There are 32 receiving transducers 26, which are set to eight stations, four in each station, and are installed in an orthogonal manner.

The first housing 2, the second housing 12 and the sound receiving system housing 24 are all provided with a connecting joint 10, and the connecting joint 10 is connected to other parts of the measuring instrument.

The monopole transmitting transducer excites a unipolar longitudinal wave signal, and the dipole transmitting transducer excites a bending shear wave signal. The acoustic wave signal propagates in the bottom layer of the borehole and is finally received by the receiving transducer 26. The downhole acoustic system is specially developed for the instrument products of offshore wind power tower base acoustic wave remote detection imaging and evaluation. First, the downhole acoustic system adopts a low-frequency emission acoustic system with a frequency lower than 1kHz, so that the low-frequency acoustic signal can be In the loose stratum, the propagation attenuation is smaller, and the composite structure is adopted. The first sound system unit adopts a monopole transmitting transducer for the sound source excitation of a monopole longitudinal wave signal, and the second sound system unit adopts a dipole. The transmitting transducer is used to excite the sound source of the dipole transverse wave signal. The design of expanding the transmitting bandwidth makes the transmitting sound system suitable for the detection of various complex formations of the wind power tower base. The excitation control of the transmitting sensor in the low frequency band can make the sensor's efficiency reach optimal. Then, the downhole acoustic system adopts a high-sensitivity receiving acoustic system design, using piezoelectric ceramic materials with higher receiving efficiency to improve the sensitivity of the receiving acoustic system, and piezoelectric ceramic materials with higher receiving efficiency. In order to realize the effectiveness of remote detection of acoustic signals and reduce the signal attenuation in circuit control, the receiving control circuit and the receiving sensor are integrated into a modular unit. In this way, the receiving acoustic system pup is more conducive to receiving small and weak signals, which can ensure To obtain shear wave information from low-velocity submarine formations, the most important thing is to obtain information on reflection waves of geological bodies in a large area beside the well. Finally, the downhole acoustic system is specially designed for offshore wind power tower base acoustic wave remote detection imaging and evaluation instrument products. The transmitting and receiving acoustic systems have smaller specifications and at the same time, a new coupling of the transmitting and receiving acoustic systems is carried out. Sealing design, the transmission and receiving sound system chooses to adopt elastomer (such as rubber and polyurethane, etc.) encapsulation. On the basis of solving the coupling and sealing, the sound system is easier to install and maintain, and the failure rate is reduced. At the same time, it is aimed at wind power tower foundation In the case of small survey boreholes, the design and scale of the transmitting and receiving sound system are smaller, and under the condition of ensuring the effectiveness of detection, it can meet the requirements of offshore operation conditions for wind power tower foundation detection.

It should be understood that the above description is for illustration and not for limitation. By reading the above description, many embodiments and many applications beyond the examples provided will be apparent to those skilled in the art. Therefore, the scope of the present teaching should not be determined with reference to the above description, but should be determined with reference to the foregoing claims and the full range of equivalents possessed by these claims. For comprehensive purposes, all articles and references including the disclosure of patent applications and announcements are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the foregoing claims is not to abandon the subject matter, nor should it be deemed that the applicant has not considered the subject matter as part of the disclosed subject matter of the invention.

Claims

A downhole acoustic system, characterized in that it comprises a transmitting acoustic system short section and a receiving acoustic system short section, the transmitting acoustic system short section includes a first acoustic system unit and a second acoustic system unit, the first acoustic system unit , The second sound system unit and the receiving sound system short section are respectively connected to the measuring instrument through the connecting joint.
The downhole acoustic system according to claim 1, wherein the first acoustic system unit comprises a first shell, a first frame arranged in the first shell, and a plurality of frames arranged on the first frame. Monopole emission transducers, each of the monopole emission transducers adopts a circular tube type piezoelectric element, and the first frame is provided with a first channel for circulating mud.
The downhole acoustic system according to claim 2, wherein the first frame includes a first frame body, a top cover provided at one end of the first frame body, and a first wiring line provided on the top cover Column, the monopole transmitting transducer is encapsulated on the first skeleton body through an elastic body.
The downhole acoustic system according to claim 1, wherein the second acoustic system unit comprises a second shell, a second frame arranged in the second shell, and a plurality of frames arranged on the second frame. For the dipole emitting transducer, the second frame is provided with a frame connecting plate separating the plurality of dipole emitting transducers.
The downhole acoustic system according to claim 4, wherein the second frame comprises a second frame body, density blocks respectively arranged at two ends of the second frame, and a second density block arranged on one end of the density block. Connect the column.
The downhole acoustic system according to claim 4, characterized in that there are eight dipole transmitting transducers, including four dipole transmitting long chip transducers and four dipole transmitting short chip transducers. The dipole transmitting transducer adopts a piezoelectric element with a three-stack structure, and the three-stack structure is composed of a metal substrate and two sides of the metal substrate. Composed of piezoelectric ceramic sheets.
The downhole acoustic system according to claim 1, wherein the receiving acoustic system short section comprises a receiving acoustic system shell, a receiving acoustic system skeleton arranged in the receiving acoustic system shell, and a receiving acoustic system skeleton arranged in the receiving acoustic system. A receiving circuit module and a number of receiving transducers on the skeleton, and the receiving acoustic system skeleton is provided with a second channel for mud to pass through.
The underground acoustic system according to claim 7, wherein the receiving acoustic system skeleton comprises a receiving acoustic system skeleton body and a receiving acoustic system binding post arranged on the receiving acoustic system skeleton body, and the receiving transducer The receiver and the receiving circuit module are arranged on the main body of the receiving sound system skeleton through an elastic body encapsulation.
The downhole acoustic system according to claim 7, characterized in that there are 32 receiving transducers, arranged as eight stations, four in each station, orthogonally arranged.
The downhole acoustic system according to claim 7, wherein the receiving transducer adopts a five-stack structure, and the five-stack structure includes three layers of metal substrates and two layers of piezoelectric ceramics, and the metal The substrate and the piezoelectric ceramic sheet are alternately arranged.