CN115628040A - Acoustic system structure and logging method of a large-scale borehole acoustic logging tool - Google Patents

Abstract

The invention discloses a large-size borehole acoustic logging instrument acoustic system structure and a logging method, which relate to the field of acoustic logging and comprise a slotted shell and an acoustic system core arranged in the slotted shell, wherein a transmitting probe, a first receiving probe, a second receiving probe, a third receiving probe, a fourth receiving probe, a fifth receiving probe and a sixth receiving probe are arranged in the acoustic system core from far to near; the transmitting probes are matched with the receiving probes to realize large-size cased well acoustic amplitude variable density logging or open hole acoustic velocity logging. The invention can not only carry out acoustic amplitude variable density well logging in a large-size cased well (13.625 inches-20 inches) and provide cement bond quality information, but also measure depth-lapse borehole compensation high resolution time difference and common interval acoustic time difference in open hole acoustic velocity well logging.

Description

Acoustic system structure and logging method of a large-scale borehole acoustic logging tool

technical field

The invention relates to the field of acoustic logging, in particular to an acoustic system structure of a large-scale borehole acoustic logging tool and a logging method.

Background technique

At present, in the process of geophysics and oil and gas exploration and development, acoustic logging is one of the main methods, using the different acoustic properties of acoustic waves in different rocks, such as propagation speed, amplitude and frequency changes, to study the drilling geological profile and judge the cementing quality . During the sound wave propagation, the sound power attenuates in proportion to the square of the propagation distance. In addition, due to friction, viscosity, heat conduction and other reasons in the medium, part of the sound wave energy is converted into other forms of energy (mainly heat energy), which also attenuates. The absorption coefficient of viscosity and heat conduction is proportional to the square of the frequency of the sound wave. Therefore, when logging, as the borehole size increases, the attenuation of the acoustic signal generated by the transmitting probe increases sharply. Logging requirements for sized boreholes.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies in the prior art, and provide an acoustic system structure and logging method of a large-scale borehole acoustic logging tool, which can perform acoustic logging in large-scale cased wells (13.625 inches to 20 inches). Amplitude-variable density logging can provide cement cement quality information, and can also measure depth-shifting wellbore compensation high-resolution time difference and ordinary spacing sound wave time difference in open hole sound velocity logging.

The object of the present invention is achieved through the following technical solutions: the acoustic system structure of this large-scale borehole acoustic logging instrument includes a grooved casing and an acoustic core installed in the grooved casing, and the acoustic system core is installed in the grooved casing. Set the transmitting probe and the first receiving probe, the second receiving probe, the third receiving probe, the fourth receiving probe, the fifth receiving probe and the sixth receiving probe arranged in order from far to near with the transmitting probe; The receiving probes are selectively matched to realize the acoustic amplitude variable density logging of large-scale cased holes or the sound velocity logging of open-hole wells.

As a further technical solution, the front end of the acoustic system core is provided with an upper joint, the rear end of the acoustic system core is provided with a transmitting probe and a lower joint, and the front end of the transmitting probe is provided with a transmitting upper joint, and the upper joint and the transmitting upper joint are connected and sealed by a capsule ; The rear end of the launch probe is provided with a launch lower connector for connecting the lower connector.

As a further technical solution, a front socket assembly is arranged in the upper joint, and the front socket assembly is connected to the upper sound insulation assembly through the upper adapter, and five groups of receiving transducer assemblies are connected in sequence behind the upper sound insulation assembly, and the adjacent receiving transducer assemblies The sound insulation components are connected between the five sets of receiving transducer components; the rear of the five sets of receiving transducer components is connected with a set of receiving transducer components through a set of long sound insulation rubber components, and the rear of the single set of receiving transducer components is passed through several groups of short The sound insulation rubber component is connected to the lower sound insulation component, and the lower sound insulation component is connected to the launch upper joint through the lower adapter.

As a further technical solution, the front socket assembly includes a 31-core adapter sleeve, a 37-core pressure plate and a 37-core socket, the 37-core pressure plate is fixed in the upper joint with a retaining ring, and the front end of the 37-core pressure plate Connect the 31-core adapter sleeve, the rear end of the 37-core pressure plate is connected to the 37-core socket, the 37-core socket is fixed on the upper adapter with screws, and the upper sound insulation component is fixed on the upper adapter with screws; the long spacer The acoustic rubber assembly includes a long connecting shaft and a long sound-insulating rubber rod set on the long connecting shaft, and sound-insulating assemblies are arranged at both ends of the long sound-insulating rubber assembly; the short sound-insulating rubber assembly includes a short connecting shaft and a There are three sets of short sound-insulating rubber rods on the short connecting shaft and short sound-insulating rubber components, and the adjacent short sound-insulating rubber components are connected in sequence through the sound-insulating components.

As a further technical solution, the rear end of the upper launch joint is fixed on the lower launch joint by screws, and a sound insulation sheet is provided at the joint between the two, and the middle part of the launch upper joint is covered with an intermediate insulating seat, and the two sides of the middle insulating seat Each launch transducer is installed, and the outer side of each launch transducer is sealed and installed on an insulating seat through a sealing ring A and a sealing ring B.

As a further technical solution, the insulating seat close to the launch upper joint is pressed against the inner wall of the launch upper joint through the sound insulation rubber sheet A, and the insulating seat close to the launch lower joint is axially locked by the sound insulation rubber sheet B and the lock nut On the launch upper joint; a sound-permeable cover is installed between the outer wall of the launch upper joint and the outer wall of the launch lower joint, and a transformer assembly is fixed on the launch lower joint through threads, and the outer cover of the transformer assembly is provided with a transformer shell, which is connected to the Launch between the lower connector and the lower connector.

As a further technical solution, the lower joint is fixed on the rear end of the grooved shell through the positioning screw B and the threaded ring A, one end of the lower shell is fixed on the lower joint through the threaded ring B, and the other end of the lower shell is equipped with a protective Plug; the rear end of the lower connector is installed with a 32-core socket through a bushing, and the 32-core socket is used to connect and fix the 32-core pressure plate in the lower shell; the lower launch connector is fixed and positioned on the grooved shell by fixing screws.

As a further technical solution, the upper joint is fixed and positioned at the front end of the grooved shell by a positioning screw A, and a protective cap is set on the front end of the upper joint, and the protective cap is fixed on the upper joint by an open ring pad, an open ring and a threaded ring C On the outer wall of the shell, the threaded ring C is pressed on the front port of the grooved shell through the end fixing ring and the left and right end rings.

As a further technical solution, the distance between the first receiving probe and the transmitting probe is 7 feet, the distance between the second receiving probe and the transmitting probe is 6.5 feet, the distance between the third receiving probe and the transmitting probe is 6 feet, and the fourth receiving probe The distance between the probe and the transmitting probe is 5.5 feet, the distance between the fifth receiving probe and the transmitting probe is 5 feet, and the distance between the sixth receiving probe and the transmitting probe is 3 feet.

The logging method using the above-mentioned acoustic system structure of the large-scale borehole acoustic logging tool includes the following steps:

1) Select the logging method according to the type of the wellbore to be measured. For the open hole, the sound velocity logging is used, and step 2) is performed; for the large-scale cased hole, the acoustic amplitude variable density logging is used, and the step 3) is executed;

2) Select the transmitting probe and the first receiving probe, the second receiving probe, the third receiving probe, the fourth receiving probe and the fifth receiving probe to form a single sending and five receiving mode. Ordinary spacing acoustic compressional wave time difference, and then through the compressional wave time difference to invert the porosity of the formation;

3) Judging the borehole size of a large-sized cased well, when the borehole size is 13.625 inches to 16 inches, perform step 4), when the borehole size is 16 inches to 18 inches, perform step 5), when the borehole size When it is 18 inches to 20 inches, perform step 6);

4) Use the transmitting probe, the sixth receiving probe, and the fifth receiving probe to form a single-send and double-receive mode, and respectively detect the sound amplitude CBL and variable density VDL signals of the corresponding wellbore;

5) Use the transmitting probe, the sixth receiving probe, and the third receiving probe to form a single-send and double-receive mode, and respectively detect the sound amplitude CBL and variable density VDL signals of the corresponding wellbore;

6) Use the transmitting probe, the sixth receiving probe, and the first receiving probe to form a single-sending and double-receiving mode, and detect the sound amplitude CBL and variable density VDL signals of the corresponding wellbore respectively.

The beneficial effects of the present invention are:

1. Five groups of long source distance receiving probes, one group of short source distance receiving probes and transmitting probes arranged at equal intervals form a single-shot and six-receiving mode. Through different combinations of receiving probes and transmitting probes, it can Acoustic amplitude variable density logging in the borehole range, and sound velocity logging can be taken into account at the same time. The depth measured in the open hole can be compensated for high-resolution time difference and ordinary interval acoustic time difference, which solves the problem that existing instruments cannot log wells in large-scale boreholes. deficiency;

2. The sound system core is sealed and installed with a capsule, which has good sealing and pressure resistance performance. The maximum outer diameter of the sound system is Φ118mm, and it can work in the environment of 150°C high temperature and 110MPa underground.

Description of drawings

Fig. 1 is a structural schematic diagram of the present invention.

Fig. 2 is a structural sectional view of the present invention.

FIG. 3 is a partially enlarged schematic diagram of area A in FIG. 2 .

FIG. 4 is a partially enlarged schematic diagram of area B in FIG. 2 .

Fig. 5 is a schematic diagram of the structure of the acoustic core in the present invention.

Fig. 6 is a partially enlarged schematic view of the upper joint part in Fig. 5 .

FIG. 7 is a partially enlarged schematic diagram of five sets of receiving transducer assemblies in FIG. 5 .

Fig. 8 is a partially enlarged schematic diagram of the long sound-insulating rubber assembly and the single receiving transducer assembly in Fig. 5 .

Fig. 9 is a partially enlarged schematic diagram of the short sound-insulating rubber component in Fig. 5 .

FIG. 10 is a partially enlarged schematic view of the lower joint in FIG. 5 .

Explanation of reference numerals: first receiving probe R0, second receiving probe R1, third receiving probe R2, fourth receiving probe R3, fifth receiving probe R4, sixth receiving probe R5, transmitting probe T, upper connector 1, 31 Core adapter sleeve 2, 37-core pressure plate 3, 37-core socket 4, upper adapter 5, upper sound insulation component 6, screw 7, receiving transducer component 8, sound insulation component 9, capsule 10, long spacer Acoustic rubber rod 11, long connecting shaft 12, short sound-insulating rubber 13, short connecting shaft 14, lower sound-insulating component 15, launching upper joint 16, sound-insulating rubber sheet A17, insulating seat 18, sealing ring A19, sealing ring B20, Transmitting transducer 21, intermediate insulating seat 22, sound-insulating rubber sheet B23, lock nut 24, sound-insulating sheet 25, launching lower joint 26, transformer shell 27, transformer assembly 28, lower joint 29, threaded ring A30, screw thread Ring B31, bushing 32, 32-core socket 33, sound-transmitting cover 34, protective cap 35, open-ring gasket 36, open-ring 37, threaded ring C38, end fixing ring 39, left and right end rings 40, set screw A41, sound system Core 42, grooved shell 43, fixing screw 44, positioning screw B45, lower shell 46, 32-core pressure plate 47, protective plug 48, lower adapter 49.

Detailed ways

The present invention will be described in detail below in conjunction with accompanying drawing:

Embodiment: As shown in accompanying drawings 1-10, the acoustic system structure of this large-scale borehole acoustic logging tool includes a first receiving probe R0, a second receiving probe R1, a third receiving probe R2, and a fourth receiving probe R3 , The fifth receiving probe R4, the sixth receiving probe R5, the transmitting probe T, the upper connector 1, the 31-pin adapter sleeve 2, the 37-pin pressure plate 3, the 37-pin socket 4, the upper adapter 5, and the upper sound insulation component 6. Screw 7, receiving transducer assembly 8, sound insulation assembly 9, capsule 10, long sound insulation rubber rod 11, long connection shaft 12, short sound insulation rubber 13, short connection shaft 14, lower sound insulation assembly 15, transmitter Upper joint 16, sound insulation rubber sheet A17, insulating seat 18, sealing ring A19, sealing ring B20, transmitting transducer 21, intermediate insulating seat 22, sound insulating rubber sheet B23, lock nut 24, sound insulating sheet 25, transmitting Lower joint 26, transformer shell 27, transformer assembly 28, lower joint 29, threaded ring A30, threaded ring B31, bushing 32, 32-core socket 33, sound-permeable cover 34, protective cap 35, open-ring pad 36, open-ring 37. Threaded ring C38, end fixing ring 39, left and right end rings 40, positioning screw A41, acoustic core 42, grooved shell 43, fixing screw 44, positioning screw B45, lower shell 46, 32-core pressure plate 47, Protective plug 48 and lower adapter 49.

Referring to accompanying drawings 2, 3, and 4, the grooved shell 43 is built into the acoustic core 42, and the transmitting probe T and the first receiving probe R0, the first receiving probe R0, and the first receiving probe T are arranged in sequence from far to near with the transmitting probe T in the acoustic core 42. The second receiving probe R1, the third receiving probe R2, the fourth receiving probe R3, the fifth receiving probe R4 and the sixth receiving probe R5. Preferably, the distance between the first receiving probe R0 and the transmitting probe T is 7 feet, the distance between the second receiving probe R1 and the transmitting probe T is 6.5 feet, and the distance between the third receiving probe R2 and the transmitting probe T is 6 feet, The distance between the fourth receiving probe R3 and the transmitting probe T is 5.5 feet, the distance between the fifth receiving probe R4 and the transmitting probe T is 5 feet, and the distance between the sixth receiving probe R5 and the transmitting probe T is 3 feet.

Further, the upper joint 1 is set at the front end of the sound system core 42, the rear end of the sound system core 42 is provided with a transmitting probe T and a lower joint 29, and the front end of the transmitting probe T is provided with an upper joint 16 for launching, and the connection between the upper joint 1 and the upper joint 16 for launching The space is connected and sealed by the capsule 10 to ensure the performance of sealing and pressure resistance. The rear end of the transmitting probe T is provided with a lower launching joint 26 , and the lower launching joint 26 and the lower joint 29 are connected through a transformer shell 27 .

As shown in Figures 5 and 6, the upper joint 1 is provided with a front socket assembly, which includes a 31-pin adapter sleeve 2, a 37-pin pressure plate 3, and a 37-pin socket 4, and a retaining ring for the 37-pin pressure plate 3 Fixed in the upper joint 1, the 31-pin adapter sleeve 2 is connected to the front end of the 37-pin pressure plate 3, the 37-pin socket 4 is connected to the rear end of the 37-pin pressure plate 3, and the 37-pin socket 4 is threaded on the upper turn The front end of the joint 5 and the rear end of the upper adapter 5 are installed with the upper sound insulation assembly 6 through the screw 7 .

Referring to accompanying drawing 7, five sets of receiving transducer assemblies 8 are arranged at equal intervals at the rear end of the upper sound insulation assembly 6, respectively corresponding to the first receiving probe R0, the second receiving probe R1, the third receiving probe R2, and the fourth receiving probe. The distance between adjacent receiving transducer assemblies 8 of the probe R3 and the fifth receiving probe R4 is 0.5 feet, and are connected to each other through a sound insulation assembly 9 . As shown in Figure 8, after the rear ends of the five groups of receiving transducer assemblies 8 are sound-insulated by a group of long sound-insulating rubber assemblies, a group of receiving transducer assemblies 8 (corresponding to the sixth receiving probe) are connected through the sound-insulating assembly 9 R5), with reference to accompanying drawing 9, at the rear of the receiving transducer assembly 8 (the sixth receiving probe R5) of this single group, the lower sound insulation assembly 15 is connected by three groups of short sound insulation rubber assemblies, and the lower sound insulation assembly 15 is connected by turning down Connector 49 is connected to launch upper connector 16 . Further, as shown in Figures 8 and 9, the long sound-insulating rubber assembly includes a long connecting shaft 12 and a long sound-insulating rubber rod 11 sleeved on the long connecting shaft 12, and both ends of the long sound-insulating rubber assembly are set Sound insulation assembly 9; the short sound insulation rubber assembly includes a short connection shaft 14 and a short sound insulation rubber rod 13 sleeved on the short connection shaft 14. There are three groups of short sound insulation rubber assemblies, and the adjacent short sound insulation rubber assemblies They are connected in turn by sound insulation components 9 .

With reference to accompanying drawing 10, the rear end of described launching upper joint 16 is fixed on the launching lower joint 26 by screw, and the sound insulation sheet 25 is arranged at the junction of the two, and the middle part of launching the upper joint 16 is set with intermediate insulating seat 22, and the middle insulation A transmitting transducer 21 is respectively installed on both sides of the seat 22, and the outer side of each transmitting transducer 21 is sealed and mounted on an insulating seat 18 through a sealing ring A19 and a sealing ring B20 to form a transmitting probe T. Further, the insulating seat 18 (that is, the left insulating seat 18 in FIG. 10 ) close to the launch upper joint 16 is pressed against the inner wall of the launch upper joint 16 by the sound insulation rubber sheet A17, and the insulating seat 18 near the launch lower joint 26 ( That is, the insulating seat 18 on the right side in FIG. 10 is axially locked on the launching joint 16 through the sound-insulating rubber sheet B23 and the locking nut 24 . A sound-permeable cover 34 is installed between the outer wall of the upper launch joint 16 and the outer wall of the lower launch joint 26, and a transformer assembly 28 is fixedly installed on the launch lower joint 26. The outer cover of the transformer assembly 28 is provided with a transformer shell 27, and the transformer shell 27 is connected between the lower launching joint 26 and the lower joint 29, and the transformer assembly 28 is sealed and protected.

As shown in Figures 2, 4, and 10, the lower joint 29 is fixed on the rear end of the grooved shell 43 through the positioning screw B45 and the threaded ring A30, and the left end of the lower tube shell 46 is fixed on the lower joint 29 through the threaded ring B31. The right end of 46 is equipped with protective plug 48, and the whole logging instrument is sealed and protected. A 32-core pressure plate 47 is fixedly installed in the lower shell 46, and a 32-core socket 33 is installed at the rear end of the lower joint 29 through a bush 32, and the 32-core socket 33 is used to connect the 32-core pressure plate 47. The lower launch sub 26 is fixed and positioned on the notched housing 43 by means of set screws 44 .

With reference to accompanying drawing 3, described upper joint 1 is fixed by positioning screw A41, and is positioned at the front end of grooved housing 43, and the front end of upper joint 1 is covered with protective cap 35, and protective cap 35 passes through open-ring pad 36, open-ring 37 and screw thread The ring C38 is fixed on the outer wall of the upper joint 1 , and the threaded ring C38 is pressed against the front port of the notched shell 43 through the end fixing ring 39 and the left and right end rings 40 .

The logging method using the above-mentioned acoustic system structure of the large-scale borehole acoustic logging tool includes the following steps:

1) Select the logging method according to the type of the wellbore to be measured. For the open hole, the sound velocity logging is used, and step 2) is performed; for the large-scale cased hole, the acoustic amplitude variable density logging is used, and the step 3) is executed;

2) Select the transmitting probe T and the first receiving probe R0, the second receiving probe R1, the third receiving probe R2, the fourth receiving probe R3 and the fifth receiving probe R4 to form a single-transmission and five-reception mode, and the measured depth-shifting borehole compensation High-resolution compressional wave time difference and ordinary spacing acoustic wave time difference, and then use the compressional wave time difference to invert the porosity of the formation;

3) Judging the borehole size of a large-sized cased well, when the borehole size is 13.625 inches to 16 inches, perform step 4), when the borehole size is 16 inches to 18 inches, perform step 5), when the borehole size When it is 18 inches to 20 inches, perform step 6);

4) Use the transmitting probe T, the sixth receiving probe R5, and the fifth receiving probe R4 to form a single-send and double-receive mode, and respectively detect the sound amplitude CBL and variable density VDL signals of the corresponding wellbore (CBL is the first signal that reflects the casing at the first interface). The curve of wave amplitude changing with depth. After the first wave amplitude is calibrated in the free casing, the attenuation rate of the first wave amplitude measured in the cement bonded casing is calculated to obtain the cementation index of the first interface; VDL is Stone Libo's strength curve, which can be qualitatively analyzed to reflect the quality of the second interface cementation);

5) Use the transmitting probe T, the sixth receiving probe R5, and the third receiving probe R2 to form a single-send and double-receive mode, and respectively detect the sound amplitude CBL and variable density VDL signals of the corresponding wellbore;

6) Use the transmitting probe T, the sixth receiving probe R5, and the first receiving probe R0 to form a single-send and double-receive mode to detect the sound amplitude CBL and variable density VDL signals of the corresponding wellbore respectively.

Working principle of the present invention:

The sonic logging instrument is used to check the bonding of cement and casing after cementing. The conventional sonic logging instrument generally adopts the working mode of single emission and double reception, and the short source distance acoustic wave receiving signal is used for sound amplitude measurement. Quantitative analysis of the cement bonding quality of the second interface is carried out; the long source distance acoustic wave receiving signal is used for variable density measurement, and the cement bonding quality of the second interface is quantitatively analyzed. However, conventional acoustic logging tools have only two receiving probes, which adapt to a relatively small borehole size. The present invention adopts the probe combination of single transmission and six receivers, by adjusting the combination of receiving probes and changing the source distance, it can adapt to the borehole of 13.625 inches to 20 inches. At the same time, it is also possible to use receiving probes and transmitting probes 5 feet, 5.5 feet, 6 feet, 6.5 feet, and 7 feet away from the transmitting probe to form a single-shot and five-receive array, and measure the depth-shifting wellbore to compensate for high-resolution time difference and ordinary spacing. time difference, and then invert the porosity of the formation through the P-wave time difference. Realize the sound velocity logging of open hole.

It can be understood that, for those skilled in the art, equivalent replacements or changes to the technical solutions and inventive concept of the present invention shall fall within the protection scope of the appended claims of the present invention.

Claims (10)

1. A jumbo size borehole acoustic logger acoustic system structure which characterized in that: the acoustic system comprises a groove shell (43) and an acoustic system core (42) installed in the groove shell (43), wherein a transmitting probe (T) and a first receiving probe (R0), a second receiving probe (R1), a third receiving probe (R2), a fourth receiving probe (R3), a fifth receiving probe (R4) and a sixth receiving probe (R5) which are sequentially arranged from far to near with the transmitting probe (T) are arranged in the acoustic system core (42); the transmitting probe (T) is selectively matched with each receiving probe to realize large-size cased well acoustic amplitude variable density logging or open hole acoustic velocity logging.

2. The large-scale borehole acoustic tool acoustic structure of claim 1, wherein: the front end of the acoustic system core (42) is provided with an upper joint (1), the rear end of the acoustic system core (42) is provided with a transmitting probe (T) and a lower joint (29), the front end of the transmitting probe (T) is provided with a transmitting upper joint (16), and the upper joint (1) and the transmitting upper joint (16) are connected and sealed through a capsule (10); the rear end of the emission probe (T) is provided with an emission lower joint (26) which is used for connecting a lower joint (29).

3. The large-scale borehole acoustic tool acoustic structure of claim 2, wherein: a front socket assembly is arranged in the upper connector (1), the front socket assembly is connected with an upper sound insulation assembly (6) through an upper connector (5), five groups of receiving transducer assemblies (8) are sequentially connected behind the upper sound insulation assembly (6), and adjacent receiving transducer assemblies (8) are connected through a sound insulation assembly (9); the rear parts of the five groups of receiving transducer assemblies (8) are connected with one group of receiving transducer assemblies (8) through one group of long sound insulation rubber assembly, the rear parts of the single group of receiving transducer assemblies (8) are connected with the lower sound insulation assembly (15) through a plurality of groups of short sound insulation rubber assemblies, and the lower sound insulation assembly (15) is connected to the upper transmitting joint (16) through the lower connecting joint (49).

4. The large-scale acoustic tool architecture of claim 3, wherein: the front socket assembly comprises a 31-core adapter sleeve (2), a 37-core bearing disc (3) and a 37-core socket (4), the 37-core bearing disc (3) is fixed in the upper connector (1) through a check ring, the front end of the 37-core bearing disc (3) is connected with the 31-core adapter sleeve (2), the rear end of the 37-core bearing disc (3) is connected with the 37-core socket (4), the 37-core socket (4) is fixed on the upper connector (5), and the upper sound insulation assembly (6) is fixed on the upper connector (5); the long sound insulation rubber component comprises a long connecting shaft (12) and a long sound insulation rubber rod (11) sleeved on the long connecting shaft (12), and sound insulation components (9) are arranged at two ends of the long sound insulation rubber component; the short sound-proof rubber components comprise three groups of short connecting shafts (14) and short sound-proof rubber rods (13) sleeved on the short connecting shafts (14), and adjacent short sound-proof rubber components are sequentially connected through sound-proof components (9).

5. The large-scale borehole acoustic tool acoustic structure of claim 4, wherein: the rear end of the transmitting upper joint (16) is fixed on the transmitting lower joint (26), a sound insulation sheet (25) is arranged at the joint of the transmitting upper joint and the transmitting lower joint, a middle insulation seat (22) is sleeved at the middle part of the transmitting upper joint (16), two transmitting transducers (21) are respectively arranged on two sides of the middle insulation seat (22), and the outer side of each transmitting transducer (21) is hermetically arranged on one insulation seat (18).

6. The large-scale borehole acoustic tool acoustic structure of claim 4, wherein: an insulating seat (18) close to the launching upper joint (16) is pressed on the inner wall of the launching upper joint (16) through a sound insulation rubber sheet A (17), and the insulating seat (18) close to the launching lower joint (26) is axially locked on the launching upper joint (16) through a sound insulation rubber sheet B (23) and a locking nut (24); a sound-transmitting cover (34) is installed between the outer wall of the launching upper connector (16) and the outer wall of the launching lower connector (26), a transformer assembly (28) is fixed on the launching lower connector (26), a transformer tube shell (27) is arranged outside the transformer assembly (28), and the transformer tube shell (27) is connected between the launching lower connector (26) and the lower connector (29).

7. The large-scale acoustic tool architecture of claim 6, wherein: the lower joint (29) is fixed at the rear end of the engraved outer shell (43), one end of the lower pipe shell (46) is fixed on the lower joint (29), and the other end of the lower pipe shell (46) is provided with a protective plug (48); the rear end of the lower joint (29) is provided with a 32-core socket (33) through a bushing (32), and the 32-core socket (33) is used for connecting a 32-core pressure bearing disc (47) fixed in the lower pipe shell (46); the lower emission joint (26) is fixed and positioned on the engraved shell (43).

8. The large-scale borehole acoustic tool acoustic structure of claim 7, wherein: the upper joint (1) is fixed and positioned at the front end of the grooved shell (43), the front end of the upper joint (1) is sleeved with a protective cap (35), and the protective cap (35) is fixed on the outer wall of the upper joint (1).

9. The large-scale borehole acoustic tool acoustic structure of claim 8, wherein: the distance between the first receiving probe (R0) and the transmitting probe (T) is 7 feet, the distance between the second receiving probe (R1) and the transmitting probe (T) is 6.5 feet, the distance between the third receiving probe (R2) and the transmitting probe (T) is 6 feet, the distance between the fourth receiving probe (R3) and the transmitting probe (T) is 5.5 feet, the distance between the fifth receiving probe (R4) and the transmitting probe (T) is 5 feet, and the distance between the sixth receiving probe (R5) and the transmitting probe (T) is 3 feet.

10. A logging method using the acoustic system structure of the large-size borehole acoustic tool according to any of claims 1 to 9, characterized in that: the method comprises the following steps:

1) selecting a logging mode according to the type of a borehole to be tested, carrying out step 2) for open hole logging by adopting sound velocity, carrying out step 3) for large-size cased hole logging by adopting sound amplitude variable density;

2) Selecting a transmitting probe (T), a first receiving probe (R0), a second receiving probe (R1), a third receiving probe (R2), a fourth receiving probe (R3) and a fifth receiving probe (R4) to form a single-transmitting five-receiving mode, measuring depth-lapse borehole compensation high-resolution longitudinal wave time difference and common interval acoustic wave longitudinal wave time difference, and inverting the porosity of the stratum through the longitudinal wave time difference;

3) Judging the borehole size of a large-size cased well, and executing the step 4) when the borehole size is between 13.625 inches and 16 inches, executing the step 5) when the borehole size is between 16 inches and 18 inches, and executing the step 6) when the borehole size is between 18 inches and 20 inches;

4) A transmitting probe (T), a sixth receiving probe (R5) and a fifth receiving probe (R4) are adopted to form a single-transmitting and double-receiving mode, and acoustic amplitude CBL and variable density VDL signals of corresponding boreholes are respectively detected;

5) A transmitting probe (T), a sixth receiving probe (R5) and a third receiving probe (R2) are adopted to form a single-transmitting and double-receiving mode, and acoustic amplitude CBL and variable density VDL signals of corresponding boreholes are respectively detected;

6) A single-transmitting double-receiving mode is formed by the transmitting probe (T), the sixth receiving probe (R5) and the first receiving probe (R0), and the sound amplitude CBL and the variable density VDL signals of the corresponding well bores are detected respectively.

Images