A multi-frequency multi-mode acoustic logging instrument and its use method

Abstract

The present invention relates to the field of mine geophysical technology, specifically to a multi-frequency multi-mode acoustic logging instrument: the multi-frequency multi-mode acoustic logging instrument includes two parts: an acoustic wave transmitting probe and an acoustic wave receiving probe. The transmitting probe is composed of a high-power multi-mode transmitting transducer and a receiving transducer, and the multi-frequency transmission covers 100Hz-20kHz, and the multi-mode transmission covers four modes: monopole longitudinal wave, dipole shear wave, quadrupole wave and supermagnetic mode; the receiving probe is composed of an acoustic wave pushing device and a plurality of high-precision receiving transducers, and the receiving frequency range is 0-30kHz. The receiving acoustic system has a plurality of pushing arms, and the pushing arms are controlled by the acoustic wave pushing device. The present invention solves the problem of azimuth detection of geological anomalies or cracks around the wellbore.

Description

Technical Field

[0001] The invention relates to the technical field of transmitting multi-frequency and multi-mode sound waves into strata in mine geophysics and then receiving and collecting sound wave reflection waves, and specifically relates to a multi-frequency and multi-mode sound wave logging instrument. Background Art

[0002] Traditional acoustic reflection logging instruments include: longitudinal wave long-range detection logging instruments and shear wave long-range detection logging instruments. Both instruments mainly use centered measurement in detection, and use complex sound insulation structures between transmission and reception. The characteristic of this instrument is that it can correctly collect surface sliding waves propagating along the well wall only when the wellbore is relatively regular and the lithology of the formation is dense, and then compare it with the reflected waves collected from the abnormal body outside the well, and then calculate and determine the direction and shape of the abnormal body and other information, providing powerful parameters for formation evaluation. However, in the case of irregular wellbore and loose formation, these instruments have weak first waves and multiple peaks. Therefore, it is difficult to obtain reliable sliding direct waves due to the inability to accurately collect the first wave, and it is also difficult to determine and calculate the reflected wave. In addition, in reflection wave logging, due to the serious influence of the wellbore, various useless mode waves, tube waves, Stoneley waves, etc. will be excited. These useless waveforms are much larger in amplitude than the transmitted waves from the abnormal body. Therefore, it is difficult for traditional reflection wave logging instruments to judge and identify the abnormal body outside the well, and it is also difficult to describe and characterize it. Summary of the invention

[0003] The purpose of the present invention is to provide a multi-frequency multi-mode acoustic logging instrument in view of the deficiencies in the prior art.

[0004] The technical solution is as follows:

[0005] A multi-frequency multi-mode reflection wave logging instrument comprises an acoustic wave transmitting probe and an acoustic wave receiving probe; the acoustic wave transmitting probe is composed of a downhole capacitor short section, a downhole transmitting control electronic circuit, and a downhole transmitting acoustic system; the acoustic wave receiving probe is composed of a downhole acquisition control electronic circuit, a downhole receiving acoustic system, and an acoustic wave pushing device; the downhole capacitor short section, the downhole acquisition control electronic circuit, the downhole receiving acoustic system, the acoustic wave pushing device, the downhole transmitting acoustic system, and the downhole transmitting control electronic circuit are sequentially connected from top to bottom to form an instrument string, wherein the downhole capacitor short section is electrically connected to the downhole acquisition control electronic circuit, the downhole receiving acoustic system, the acoustic wave pushing device, the downhole transmitting acoustic system, and the downhole transmitting control electronic circuit, respectively.

[0006] Furthermore, the downhole receiving acoustic system includes a well wall measurement acoustic system and an acoustic wave pushing device, and the well wall measurement acoustic system is arranged on the acoustic wave pushing device. The acoustic wave pushing device includes a plurality of pushing arms arranged circumferentially around the instrument string. The pushing arms are 3-6 in number. The pushing arms are symmetrically distributed in the circumferential direction. The well wall measurement acoustic system includes a receiving transducer arranged on the pushing arm. The number of the receiving transducers is 6-12. The downhole transmitting acoustic system is composed of a plurality of multi-mode transmitting transducers and receiving transducers.

[0007] Furthermore, the transmitting frequency bands of the transmitting transducer and the receiving transducer cover the frequency bands of 100 Hz-1.5 kHz, 1.5 kHz-3 kHz, 3 kHz-5 kHz, 5 kHz-10 kHz, and 10 kHz-20 kHz, and the frequency band resolution is 100 Hz.

[0008] Furthermore, a method for using a multi-frequency multi-mode reflection wave logging instrument comprises the steps of:

[0009] (1) The winch uses a cable to lower the instrument consisting of a downhole capacitor short section, a downhole acquisition control electronic circuit, a downhole receiving acoustic system, a downhole transmitting acoustic system, and a downhole transmitting control electronic circuit to the target depth;

[0010] (2) Power the acoustic reflection logging instrument through the 7-core cable and replenish energy for the downhole capacitor short section;

[0011] (3) The ground system sends the encoded control signal to the downhole receiving and collecting control electronic circuit in the receiving probe through a 7-core cable. The downhole receiving and collecting control electronic circuit decodes the control signal, forms an acoustic wave transmission control signal and sends it to the transmitting control electronic circuit, and forms a push control signal. The push control signal drives the servo mechanism to open its legs, so that the receiving transducer in the receiving acoustic system is close to the well wall. The acoustic wave transmission control signal is driven by the transmitting control electronic circuit to control the multi-frequency and multi-mode transducer in the transmitting acoustic system to emit regular acoustic wave signals into the formation to reach the abnormal reflector outside the well. The energy during the acoustic wave transmission is completed by the ground panel through the 7-core cable and the downhole capacitor short section to ensure stable energy supply.

[0012] (4) After the sound wave is transmitted, the receiving transducer in the transmitting probe receives and collects the direct wave mainly from the instrument housing. At the same time, the high-precision receiving transducer located in the receiving acoustic system close to the wellbore wall receives and collects the sound waves reflected from the abnormal bodies and interfaces in the formation and the mode waves excited in some parts of the wellbore. The various signals collected are encoded downhole and uploaded to the ground system via a 7-core cable.

[0013] The beneficial effects of the present invention are:

[0014] It is capable of measuring acoustic reflection waves within 160 meters away from the wellbore. The downhole instrument can withstand a temperature of 175 degrees Celsius and a pressure of 140MPa. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of an embodiment of the present invention;

[0016] In the figure: 1 downhole capacitor short section, 2 downhole receiving and collecting control electronic circuit, 3 downhole receiving acoustic system, 4 acoustic wave pushing device, 5 transmitting acoustic system, 6 transmitting control electronic circuit, 7 winch, 8 well wall, 9 interface, 10 receiving acoustic system close to well wall, 11 transmitting transducer. DETAILED DESCRIPTION

[0017] See also Figure 1 A multi-frequency and multi-mode acoustic logging instrument comprises an acoustic wave transmitting probe and an acoustic wave receiving probe.

[0018] The transmitting probe is composed of a downhole capacitor short section 1, a downhole transmitting control electronic circuit 6, and a downhole transmitting acoustic system 5, and is responsible for exciting multi-frequency and multi-mode acoustic wave signals.

[0019] The receiving probe is composed of a downhole acquisition control electronic circuit 2, a downhole receiving sound system 3 and an acoustic wave pushing device 4, and is responsible for the acquisition and processing of acoustic wave signals.

[0020] The downhole capacitor nipple 1, the downhole acquisition control electronic circuit 2, the downhole receiving acoustic system 3 and the acoustic wave pushing device 4, the downhole transmitting acoustic system 5, and the downhole transmitting control electronic circuit 6 are all composed of a shell and a core shaft. The upper part of each component is a multi-core female plug, the bottom is a pressure-bearing multi-core male pin, and the head has a rotatable threaded ring for connecting the components.

[0021] The connection order from top to bottom is the downhole capacitor short section 1, the downhole acquisition control electronic circuit 2, the downhole receiving acoustic system 3 and the acoustic wave pushing device 4, the downhole transmitting acoustic system 5, and the downhole transmitting control electronic circuit 6. The connection between each component is internally connected by the multi-core pressure-bearing male pin located at the bottom of each component and the multi-core female plug at the head of the connected component below, and the outside is connected by a threaded ring. For example, the multi-core pressure-bearing male pin at the bottom of the mandrel of the downhole capacitor short section 1 is plugged into the multi-core female plug at the head of the mandrel of the downhole acquisition control electronic circuit 2, and the shell of the downhole capacitor short section 1 is rotatably connected to the shell of the downhole acquisition control electronic circuit 2 through the threaded ring located at the head of the downhole acquisition control electronic circuit 2.

[0022] The downhole capacitor short section 1 is responsible for providing sufficient energy to the transmitting acoustic system 5 under the control of the transmitting control electronic circuit 6, so as to meet the transmission of high-power acoustic wave signals into the formation and reach the reflector outside the well. The downhole receiving and collecting control electronic circuit 2 is responsible for collecting and controlling the sound signals from the receiving acoustic system 3, and forming a transmitting logic signal to send to the transmitting probe. The downhole receiving acoustic system 3 receives the sound signal, and the acoustic wave pushing device 4 is responsible for pushing the receiving transducer to the well wall. The transmitting control electronic circuit 6 decodes the transmitting logic from the receiving probe, and then generates various frequency or broadband transmitting signals by the DDS circuit. After the transmitting signal is driven, the transmitting acoustic system 5 is controlled to send multi-frequency and multi-mode waves into the formation.

[0023] The transmitting acoustic system 5 is composed of multiple high-power multi-mode transmitting transducers and receiving transducers. The transmitting frequency band covers 100Hz-1.5kHz, 1.5kHz-3kHz, 3kHz-5kHz, 5kHz-10kHz, 10kHz-20kHz, and the frequency band resolution is 100Hz. The multi-mode transmission covers four modes: monopolar longitudinal wave, dipole shear wave, quadrupole wave and supermagnetic mode. The transmitting acoustic system 5 has a sound-transmitting window at the transmitting transducer. The transmitting transducer bracket is made of high-strength heavy metal, which is convenient for multiple mode waves to be effectively transmitted into the formation to reach the abnormal body outside the well. Compared with the single-frequency single-mode acoustic wave signal, the multi-frequency multi-mode acoustic wave signal has different penetration power and different resolution at different distances, which is conducive to measuring the reflected wave to describe the geological abnormal body outside the well. The transmitting acoustic system 5 does not have a special sound insulation device, so that the original acoustic wave waveform of the multi-mode transmitting transducer can be collected and monitored without being affected by the wellbore. The acoustic wave signal is directly transmitted through the instrument housing and received by the receiving transducer next to the transmitting transducer. The receiving transducer has a frequency band covering 0Hz-30kHz and is mainly used for instrument monitoring and direct wave measurement.

[0024] Optional solution for underground transmission control electronic circuit 6: It is composed of DC-DC high-voltage stabilized power supply module, transmission control and drive module. The instrument is sensitive to AC, and here we choose to use DC-DC high-voltage stabilized power supply module to convert the DC power from the logging surface system into high-voltage stabilized DC power used by the instrument, preferably including: +360V high-voltage power supply, whose operating frequency is above 300kHz, far from the instrument's 0-30kHz processing range, and has little interference to the instrument as a whole. The transmission control and drive module is responsible for decoding the commands from the communication control module in the underground receiving and acquisition control electronic circuit 2, using DDS to generate various frequencies or pulse signals, and then driving them to the transmission sound system 5 to transmit sound wave signals of multiple frequencies and multiple modes.

[0025] Optional solution for downhole acquisition control electronic circuit 2: It consists of a low-noise DC-DC low-voltage power supply module, a power filter module, a communication control module and an acquisition module. Since the instrument is sensitive to AC power supply, a DC-DC low-voltage power supply module is selected here to convert the high-voltage DC power from the logging surface system into the low-voltage DC power used by the instrument. It is preferably composed of three low-voltage power supplies: +5V and + / -12V. Its operating frequency is above 300kHz, which is far from the instrument's 0-30kHz processing range. It has little interference to the overall instrument and is easy to filter out. The power filter module is responsible for further filtering the ripple and interference of the low-voltage power supply to reduce power supply fluctuations. The acquisition module is responsible for filtering, signal conditioning and regularizing the acoustic wave signal from the receiving acoustic system 3 after pre-amplification, and then digitizing the information, performing digital signal processing, and then packaging it and transmitting it to the communication control module. After modulation by the communication control module, it is transmitted to the logging surface system via the logging cable.

[0026] The receiving acoustic system 3 includes two parts: a measuring acoustic system attached to the well wall and an acoustic wave pushing device 4. The measuring acoustic system attached to the well wall and the acoustic wave pushing device 4 are composed of an acoustic wave pushing device and 6-12 receiving transducers located on the acoustic wave pushing device. The receiving frequency range is 0-30kHz. The receiving acoustic system 3 has 3-6 pushing arms, which are controlled by the acoustic wave pushing device. There is no special sound insulation device in the receiving acoustic system 3. The optional schemes of the receiving transducer located on the pushing arm are: a high-precision three-component receiving transducer or a high-sensitivity round tube or a three-layer transducer. The receiving transducer is integrated with a high-sensitivity preamplifier circuit.

[0027] The receiving acoustic system 3 coordinates the downhole transmitting control electronic circuit 6 to collect the acoustic wave signal under the control of the downhole collection control electronic circuit 2. The process of collecting and transmitting the acoustic wave signal is as follows: the capacitor short section 1 is charged, and the capacitor discharge circuit is opened. The transmitting acoustic system 5 transmits the acoustic wave signal under the control of the transmitting control electronic circuit 6, and then the charging circuit of the capacitor short section 1 is turned off and the acoustic wave signal is collected at the same time. After the acoustic wave signal is collected, the charging circuit is connected to charge the capacitor short section 1, and this is repeated continuously.

[0028] Implementation method: The multi-frequency and multi-mode acoustic logging instrument is lowered to the target formation underground by the winch power system through a standard 7-core cable for logging, and the acoustic reflection wave logging instrument is powered through the 7-core cable, while the energy is replenished for the downhole capacitor short section. The ground system sends the encoded control signal to the downhole receiving and collecting control electronic circuit in the receiving probe through the 7-core cable. The downhole receiving and collecting control electronic circuit decodes the control signal, forms an acoustic wave emission control signal and sends it to the emission control electronic circuit, and forms a push control signal. The push control signal drives the servo mechanism to open its legs, so that the receiving transducer in the receiving acoustic system is close to the well wall. The acoustic wave emission control signal is driven by the emission control electronic circuit to control the multi-frequency and multi-mode transducer in the emission acoustic system to emit regular acoustic wave signals into the formation to reach the abnormal reflector outside the well. The energy during the acoustic wave emission is completed by the ground panel through the 7-core cable and the downhole capacitor short section to ensure stable energy supply.

[0029] After the acoustic wave is transmitted, the receiving transducer in the transmitting probe receives and collects the direct wave mainly from the instrument housing. At the same time, the high-precision receiving transducer located in the receiving acoustic system attached to the well wall is mainly used to receive and collect the acoustic waves reflected by the abnormal body and interface from the formation and the mode waves excited in some wellbores. The various signals collected are encoded downhole and uploaded to the ground system via a 7-core cable. The measurement process, that is, the process of transmitting and collecting acoustic wave signals, is as follows: the capacitor short section is charged, the capacitor discharge circuit is opened, and the transmitting acoustic system transmits the acoustic wave signal under the control of the transmitting control electronic circuit, and then the capacitor short section charging circuit is turned off and the acoustic wave signal is collected at the same time. After the acoustic wave signal is collected, the charging circuit is connected to charge the capacitor short section, and this is repeated continuously until the measurement of the target well section is completed.

Claims

1. A method for using a multi-frequency multi-mode reflection wave logging instrument, characterized in that: Using a multi-frequency multi-mode reflection wave logging instrument, the instrument includes an acoustic wave transmitting probe and an acoustic wave receiving probe; The acoustic wave transmitting probe is composed of a downhole capacitor short section, a downhole transmitting control electronic circuit, and a downhole transmitting acoustic system, wherein the downhole transmitting acoustic system is composed of a plurality of multi-frequency multi-mode transmitting transducers and receiving transducers; The acoustic wave receiving probe is composed of a downhole acquisition control electronic circuit and a downhole acoustic receiving system; The downhole capacitor short section, downhole acquisition control electronic circuit, downhole receiving acoustic system, downhole transmitting acoustic system, and downhole transmitting control electronic circuit are sequentially connected from top to bottom to form an instrument string, wherein the downhole capacitor short section is electrically connected to the downhole transmitting acoustic system; The downhole receiving sound system includes a well wall measuring sound system and a sound wave pushing device, wherein the well wall measuring sound system is arranged on the sound wave pushing device. Wherein, the method of use includes: The winch uses the cable to place the instrument consisting of a downhole capacitor short section, a downhole acquisition control electronic circuit, a downhole receiving acoustic system, a downhole transmitting acoustic system, and a downhole transmitting control electronic circuit to the target depth; Power the reflection wave logging instrument through the cable and replenish energy for the downhole capacitor sub; The ground system sends the coded control signal to the downhole acquisition control electronic circuit in the receiving probe through the cable. The downhole acquisition control electronic circuit decodes the control signal, forms an acoustic wave emission control signal and sends it to the downhole emission control electronic circuit, and forms a push control signal. The push control signal drives the servo mechanism to open its legs, so that the receiving transducer in the downhole receiving acoustic system is close to the well wall. The acoustic wave emission control signal is driven by the downhole emission control electronic circuit to control the multi-frequency and multi-mode emission transducer in the downhole emission acoustic system to emit regular multi-frequency and multi-mode acoustic wave signals into the formation to reach the abnormal reflector outside the well. The energy during the acoustic wave emission is completed by the ground system through the cable and the downhole capacitor short section. Among them, the downhole capacitor short section is responsible for providing sufficient energy to the downhole emission acoustic system under the control of the downhole emission control electronic circuit to meet the emission of high-power acoustic wave signals into the formation to reach the reflector outside the well. Among them, the downhole acquisition control electronic circuit is responsible for collecting and controlling the sound signals from the downhole receiving acoustic system, and forming an emission logic signal to send to the downhole emission control electronic circuit in the emission probe, and the downhole emission control electronic circuit decodes the emission logic signal from the receiving probe and generates various frequency or broadband emission signals by the DDS circuit. After the emission signal is driven, the downhole emission acoustic system is controlled to emit multi-mode waves with multiple frequencies and multiple modes into the formation; After the sound wave is transmitted, the receiving transducer in the sound wave transmitting probe receives and collects the direct wave mainly from the instrument shell. At the same time, the high-precision receiving transducer located in the downhole receiving sound system attached to the well wall receives and collects the sound waves reflected by the abnormal body and interface from the formation and the mode waves excited in some wellbores. The various signals collected are encoded downhole and uploaded to the ground system via cables. The downhole receiving acoustic system coordinates with the downhole transmitting control electronic circuit to collect acoustic signals under the control of the downhole acquisition control electronic circuit. The acoustic signal collection and transmission process is as follows: the downhole capacitor short section is charged, the capacitor discharge circuit is opened, and the downhole transmitting acoustic system transmits multi-frequency and multi-mode acoustic signals under the control of the downhole transmission control electronic circuit, and then the capacitor short section charging circuit is turned off and the acoustic signal is collected at the same time. After the acoustic signal collection is completed, the charging circuit is connected to charge the downhole capacitor short section, and this is repeated continuously.

2. The method for using the multi-frequency multi-mode reflection wave logging instrument according to claim 1, characterized in that: The acoustic wave pushing device comprises a plurality of pushing arms which are arranged circumferentially around the instrument string.

3. The method for using the multi-frequency multi-mode reflection wave logging instrument according to claim 2, characterized in that: The number of the pushing arms is 3 to 6.

4. The method for using the multi-frequency multi-mode reflection wave logging instrument according to claim 3, characterized in that: The pushing arms are symmetrically distributed in the circumferential direction.

5. A method for using a multi-frequency multi-mode reflection wave logging instrument according to any one of claims 2 to 4, characterized in that: The receiving transducer in the acoustic system for measuring against the well wall is arranged on the pushing arm.

6. The method for using the multi-frequency multi-mode reflection wave logging instrument according to claim 5, characterized in that: The number of receiving transducers in the well wall measurement acoustic system is 6-12.

7. The method for using the multi-frequency multi-mode reflection wave logging instrument according to claim 6, characterized in that: The transmitting frequency bands of the multi-frequency multi-mode transmitting transducer and the receiving transducer in the well wall measurement acoustic system cover the frequency bands of 100Hz-1.5kHz, 1.5kHz-3kHz, 3kHz-5kHz, 5kHz-10kHz, and 10kHz-20kHz, and the frequency band resolution is 100Hz.

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