A through-drilling tool acoustic logging system

Abstract

The present invention provides a through-hole tool acoustic logging system, comprising an acoustic system, an electronic circuit stub arranged at one end of the acoustic system, and centralizers arranged at both ends of the acoustic system for centralizing the acoustic system. The acoustic system includes an acoustic wave transmitter, an instrument sound insulator, and a receiving array composed of multiple receiving transducers. The system can reduce the impact of scraping noise caused by the through-hole tool acoustic logging instrument scraping against the well wall on useful signals, and can obtain accurate formation time difference and logging data with a high signal-to-noise ratio.

Description

Technical Field

[0001] The invention belongs to the technical field of well logging, and in particular to a through-drilling tool sonic logging system. Background Art

[0002] With the continuous advancement of drilling technology and the increasing technical difficulty of oil and gas exploration and development, horizontal wells have become a crucial technical support for efficient oil and gas development. Horizontal wells have been highly successful in increasing oilfield production capacity, boosting reserves, and improving overall cost efficiency. Consequently, many operators are integrating horizontal wells into their reservoir management strategies. As the application and scope of horizontal wells continue to expand and their number increases, the challenges associated with horizontal well logging are becoming increasingly prominent. Horizontal wells used in unconventional oil and gas operations are characterized by deep wells, long horizontal sections, large vertical-to-vertical ratios, and relatively harsh wellbore conditions. Traditional horizontal well logging techniques pose significant operational risks and may even render production impossible. Through-drill tool storage logging systems offer a simple and reliable construction process. By pumping the instrument downhole via a wireline and then pulling the drill tool up for logging, they shorten logging time, reduce safety risks, and minimize costs. They are capable of performing logging operations under complex wellbore conditions, such as wellbore collapse and shale expansion. They offer unique advantages in horizontal well construction and have become a key logging technology for horizontal wells, with increasing application.

[0003] The through-drill tool storage type logging device is composed of a set of ultra-small diameter downhole instruments and a set of special tools for through-drill tool waterhole operations. During logging, the logging instrument is placed in a protective sleeve and transmitted to the measurement formation by the drill pipe. The drill pipe is pulled up to drive the instrument up for logging, and the collected data is stored in the instrument's memory. After the instrument is raised from the wellhead, the logging data in the instrument's memory is read on the ground, and the time, depth, and measurement data are matched in combination with the actual depth data. Finally, the ground system processes the data to obtain various logging data that change with depth. The outer diameters of common through-drill tool storage system instruments are usually 54mm, 55mm, 57mm, and 60mm. The smaller the rigid outer diameter of the instrument, the better the instrument's passability and adaptability when going through the drill tool waterhole downhole.

[0004] Acoustic logging utilizes the varying acoustic properties of sound waves, such as velocity and amplitude, in different rock types to analyze the geological profile of a well and assess cementing quality. It not only determines rock mechanical parameters and fracture orientation, but can also, when combined with well inclination and azimuth instruments, pinpoint microcracks and the direction of geostress, providing azimuthal anisotropy analysis. Acoustic transit time is a key method for determining formation porosity and is a common measurement in horizontal wells. Through-hole storage acoustic logging tools have also achieved significant success in reservoir evaluation and engineering applications.

[0005] Acoustic logging tools typically consist of an electronic subsection and an acoustic subsection. The acoustic subsection consists of one or more transmitting transducers and a receiving array consisting of multiple equally spaced receiving transducers. The mechanical structures between the transmitting transducer and the nearest receiving transducer, as well as between adjacent receivers, serve as sound insulators.

[0006] Part of the energy emitted by the transmitting transducer is transferred through the mud into the formation and then back into the wellbore to be received by the receiver. Part of the energy is transmitted through the instrument body. The main function of the sound insulator is to attenuate and delay the sound waves propagating through the instrument body, reducing their interference with the sound signals from the formation. The sound insulator of the instrument is usually designed with grooves or reduced diameters to attenuate and delay the sound waves propagating through the instrument. The sound insulator is usually located on the outer shell and inner shaft between the transmitter and receiver, and between adjacent receivers.

[0007] However, the special process of drilling sonic logging instruments through the drilling water hole to the bottom of the well for logging requires a small outer diameter of the instrument. In addition, the sonic instrument requires a special structure of sound insulation, which causes the drilling sonic instrument to bend and collapse when it is supported at both ends and placed horizontally. Figure 2 shown. Summary of the Invention

[0008] In order to solve the problems existing in the prior art, the present invention provides a through-hole acoustic logging system, which enables a through-hole acoustic logging instrument to obtain accurate formation time difference and logging data with a high signal-to-noise ratio.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a through-drilling tool acoustic logging system, comprising an acoustic system, an electronic circuit stub arranged at one end of the acoustic system, and centralizers arranged at both ends of the acoustic system for centralizing the acoustic system, wherein the acoustic system includes an acoustic wave transmitter, an instrument sound insulator, and a receiving array composed of multiple receiving transducers.

[0010] Furthermore, centralizers are provided at both ends of the acoustic system, one end of the centralizer is connected to the electronic circuit short section. When the acoustic system and the electronic short section must be directly connected, a centralizer is provided at one end of the acoustic system, the other end of the acoustic system is connected to one end of the electronic circuit short section, and the other end of the electronic circuit short section is connected to another centralizer.

[0011] Furthermore, it also includes a sound insulation and centralizing integrated short section, which is composed of an instrument sound insulation body and a centralizing short section integrated on the instrument sound insulation body, and the sound insulation and centralizing integrated short section is arranged between the sound wave transmitter and the receiving array.

[0012] Furthermore, the righting sub comprises four groups of lantern-shaped righting bow springs, and instrument sound insulation bodies are provided on both sides of the four groups of lantern-shaped righting bow springs.

[0013] Furthermore, it also includes a counterweight short section arranged at both ends of the sound system, the counterweight short section includes an outer shell, a line sealing pressure-bearing joint arranged at both ends of the outer shell, a wiring groove arranged in the outer shell, and a universal upper joint and a universal lower joint arranged at both ends of the outer shell for connection. The main material of the counterweight short section is 17-4 stainless steel.

[0014] Furthermore, the counterweight sub is connected to the end of the centralizer away from the acoustic system through a universal upper joint, and the length of the counterweight sub is determined according to the lengths of the acoustic system, the centralizer and the electronic circuit sub.

[0015] Furthermore, it also includes a flexible short section, which is arranged between the counterweight short section and the instrument string, and the bending angle of the flexible short section is 0°~10°.

[0016] Furthermore, one end of the centralizer away from the acoustic system is connected to one end of the electronic circuit short section.

[0017] Furthermore, the centralizer is a lantern-type bow spring centralizer, the main structure of which is made of 17-4 stainless steel, and the bow spring is made of spring steel.

[0018] Compared with the prior art, the present invention has at least the following beneficial effects:

[0019] The through-drilling tool sonic logging system of the present invention uses a centralizer as a part of the sonic logging instrument. Adding centralizers at both ends of the acoustic system maximizes the centering effect of the sonic logging instrument, ensures that the logging device is parallel to the well wall, and thus improves the accuracy of time difference measurement.

[0020] The present invention shortens the distance between two adjacent centralizers or adds a sound-insulating integrated centralizer short section, thereby ensuring that the logging device is parallel to the well wall during horizontal well logging, thereby ensuring the measurement accuracy of the time difference of the logging device and reducing the impact of the scraping noise caused by the logging device and the well wall on the useful signal.

[0021] The present invention realizes that for instruments that cannot integrate the centralizer into the two ends of the acoustic system, a solution of adding a centralizer, a counterweight short section and a flexible short section to improve the centering effect of the instrument is proposed. By adding the counterweight short section and the centralizer at both ends of the acoustic logging instrument, in horizontal well logging, not only the bending of the acoustic system of the logging device and the time difference measurement error can be reduced, but also the scratching noise of the logging device can be reduced, the signal-to-noise ratio of the data can be improved, the time difference curve jump caused by the scratching noise can be reduced, the labor intensity of engineers in data processing can be reduced, and the work efficiency can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, without making any creative efforts, the rest of the relevant information of the present invention obtained from the drawings shall fall within the scope of protection of the present invention. In the drawings:

[0023] Figure 1 It is a schematic diagram of the principle of the sonic logging method of the present invention;

[0024] Figure 2 This is a diagram showing a state in which the through-drilling tool sonic instrument of the present invention is supported at both ends and placed horizontally.

[0025] Figure 3 This is the first integrated design solution of the long-source-distance through-drilling tool sonic logging instrument and the centralizer described in the present invention.

[0026] Figure 4 This is the second integrated design solution of the short-source-distance through-drilling tool sonic logging instrument and the centralizer described in the present invention.

[0027] Figure 5 This is a diagram showing the through-drilling tool sonic instrument of the present invention in a horizontally placed state after centralizers and counterweight short sections are added to both ends.

[0028] Figure 6 It is a schematic diagram of the integrated short section of the sound insulation centralizer of the present invention.

[0029] Figure 7 It is a schematic diagram of the counterweight short section of the present invention.

[0030] Figure 8 The present invention provides a logging result in a horizontal well after adding a centralizer, a counterweight sub and flexibility to both ends of the through-drilling tool monopole digital acoustic instrument.

[0031] Among them: 11 electronic circuit short section; 12 acoustic wave transmitter; 13 instrument sound insulation; 14 acoustic wave receiver; 15 mud in the well; 16 well wall; 17 centralizer; 18 integrated sound insulation and centralizing short section; 19 counterweight short section; 20 pressure-bearing joint; 21 casing; 22 wiring trough. DETAILED DESCRIPTION

[0032] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0033] like Figure 1The following figure illustrates the principle of acoustic logging to measure formation time difference information. Figure 1 As shown, the acoustic logging instrument is centered in the wellbore. Part of the energy emitted by the transmitting transducer is transmitted into the formation through the mud and then returns to the wellbore to be received by the receiver. The energy received by different receivers propagates different distances in the formation and therefore arrives at different times. The time difference of different mode waves in the formation can be obtained by the difference in the arrival times of the received waveform array.

[0034] The acoustic logging instrument specifically includes an electronic circuit sub 11, an acoustic transmitter 12, an instrument sound insulator 13, and a receiving array composed of multiple receiving transducers 14. In this invention, the unit consisting of transmitter 12, instrument sound insulator 13, and receiving array is referred to as an acoustic system. In other words, the electronic circuit sub 11 and the acoustic system constitute the acoustic logging instrument.

[0035] When the acoustic logging instrument is working, it is placed in the wellbore formed by the mud 15 and the well wall 16 in the well.

[0036] The electronic circuit short section 11 is used to control the transmission of the sound wave transmitter 12, the reception of the receiving array, and the collection and storage of signals. The electronic circuit short section 11 can be set on either side of the acoustic system. The receiving array is composed of multiple sound wave receivers 14. The sound wave transmitter 12 can be set at both ends or on either side of the receiving array.

[0037] During the sonic logging process, the electronic circuit sub 11 controls the sonic transmitter 12 to radiate energy in all directions. According to the SNELL principle, a portion of this sonic energy propagates through the mud to the wellbore wall 16 and along it, continuously radiating energy into the mud and being received by each receiver in the receiving array. The waveform received by receiver 14 carries formation information. A portion of the energy emitted by the sonic transmitter 12 propagates through the instrument body, undergoes attenuation and delay through the sound insulator 13, and is received by each receiver in the receiving array. A portion of the energy emitted by the sonic transmitter 12 propagates through the mud 15 and is received by each receiver in the receiving array. Only the energy radiated in all directions by the sonic transmitter 12 that is received by a receiver in the receiving array can affect the measurement results.

[0038] like Figure 2 As shown, the design of the instrument sound insulator 13 causes the acoustic logging instrument to be more easily deformed, especially when the through-hole tool system requires the outer diameter of the acoustic logging instrument to be reduced.

[0039] In order to improve the measurement accuracy of through-hole acoustic wave instruments in horizontal wells, the present invention proposes the following Figure 3 、 Figure 4The integrated design scheme of the acoustic logging instrument and the centralizer is proposed. Taking into account the specific conditions of different acoustic instruments, it is proposed to use a design scheme combining counterweight and independent centralizer when the integrated design cannot be achieved, such as Figure 5 shown.

[0040] The present invention provides a through-drilling tool acoustic logging system, comprising an acoustic system consisting of an acoustic transmitter 12, an instrument sound insulator 13 and a receiving array, with two centralizers 17 provided at both ends of the acoustic system;

[0041] 1) If Figure 3 As shown, when the source distance from the acoustic wave transmitter 12 to the receiving array is large, the instrument sound insulator 13 and the straightening short section are integrated to obtain a sound insulation and straightening integrated short section 18, and the sound insulation and straightening integrated short section 18 is set between the acoustic wave transmitter 12 and the receiving array. The sound insulation and straightening integrated short section 18 and the two straightening devices 17 together ensure the centering of the acoustic logging instrument.

[0042] Preferably, Figure 6 As shown, the sound isolation centralizer integrated sub 18 features four sets of lantern-shaped centralizing springs, flanked by instrument sound insulators 13. The sub 18 is rigidly connected between the acoustic transmitter 12 and the receiving array via its universal upper and lower connectors, attenuating and delaying the direct wave signal from the transmitting to the receiving system. The main material is 17-4 stainless steel.

[0043] Preferably, the electronic circuit sub 11 is arranged between the acoustic system and the centralizer 17 or on the outside of the centralizer 17, but the electronic circuit sub 11 has a better effect when it is arranged on the outside of the centralizer 17. This design is particularly suitable for instruments with a large source distance and a long acoustic system, such as the through-hole cross-dipole array acoustic logging instrument.

[0044] Preferably, the centralizer 17 is a lantern-type bow spring centralizer, which is mainly used for logging in vertical wells and small-angle wells. The width of the lantern-type bow spring centralizer is adjustable to meet the needs of centralizing different well diameters.

[0045] When the sound insulation centralizer integrated short section 18 is used together with the centralizer 17, the lantern body centralizing bow spring used is of the same model, the purpose of which is to keep the instrument parallel to the well wall.

[0046] 2) If Figure 4As shown in the figure, when the source distance between the acoustic wave transmitter 12 and the receiving array is small, the electronic circuit short section 11 is placed outside the two centralizers 17. By shortening the distance between the two centralizers 17, the centering effect is improved. This design is suitable for acoustic logging instruments with a small source distance. For example, the source distance between the transmitter and the receiver of a monopole digital acoustic logging instrument is usually 3 feet, which makes it impossible to realize the integrated design of the instrument sound insulation body 13 and the sound insulation and centralization integrated short section 18. Therefore, the following is adopted. Figure 4 The solution shown is the most suitable. The principle of selecting the centralizer bow spring is to ensure the smooth passage of the instrument and to support the instrument to the maximum extent in the horizontal well.

[0047] 3) If Figure 5 As shown, a counterweight sub 19 is installed outside the centralizer 17. This sub is used to increase axial tension, thereby centering the acoustic logging instrument. The centralizer bow spring is selected to maximize support for the instrument in horizontal wells while ensuring smooth instrument movement. Together with the counterweight sub 19, it maintains parallelism between the instrument and the wellbore wall.

[0048] Preferably, the length of the counterweight sub 19 is adjusted according to the sonic logging instrument and the connected instrument string, and the counterweight sub 19 is such that the sonic logging instrument is parallel to the ground when the instrument string is placed horizontally.

[0049] Preferably, Figure 7 As shown, the counterweight sub 19 comprises a housing 20, a wire hole 21 provided therein, a threaded ring 22 mounted on the housing, an O-ring 23 mounted on the housing, threads 24 on the housing, a sealing surface 25 on the housing, an upper connector 26, and a lower connector 27. The counterweight's primary weight rests on the housing 20, which is made of corrosion-resistant metal. The threaded ring 22 connects to the acoustic instrument, while the threads 24 connect to other instruments at the lower end. The O-ring 23 and sealing surface 25, together with the connected instruments, provide a pressure-bearing seal. The upper and lower connectors 26 and 27, when connected to the instruments at the upper and lower ends, provide electrical and signal communication. The upper and lower connectors 26 and 27 are connected by a cable, which passes through the wire hole 21. The main material of the counterweight sub 19 is 17-4 stainless steel.

[0050] Based on the principle that deflection decreases with increasing axial tension, adding high-strength centralizers 17 at both ends of the acoustic logging instrument or the instrument's acoustic system pup joint and then adding a counterweight pup joint 19 on the outside of the centralizing pup joint can straighten the acoustic instrument, achieving the effect of making the acoustic instrument parallel to the well wall in horizontal wells and improving measurement accuracy.

[0051] Deflection represents the linear displacement of the cross-section centroid perpendicular to the axis of a rod when subjected to stress or non-uniform temperature changes. Maximum deflection is inversely proportional to the section moment of inertia. The following formula calculates the section moment of inertia for a cylindrical shell.

[0052]

[0053] Where I is the moment of inertia of the cross section, D is the outer diameter of the cylinder, and d is the inner diameter of the cylinder. This equation shows that the moment of inertia of the cylindrical housing of the instrument in the through-hole system is primarily influenced by D and d. D is determined by the through-hole system, and d has limited room for variation.

[0054] Preferably, when the entire instrument string is long or other logging instruments have an impact on the effect of adding the counterweight sub 19, a flexible sub can be added at the connection between the counterweight sub 19 and the instrument string to reduce the impact of other instruments in the instrument string on the effect of the centralizer 17 + counterweight sub 19 in straightening the sonic instrument.

[0055] Preferably, the flexible sub acts like a joint, increasing the flexibility of the instrument when installed in the instrument string, helping it to reach the bottomhole smoothly along a challenging wellbore trajectory. Used at the top of the instrument string, it reduces the lateral force exerted by the drill pipe on the instrument string. Used at different locations in the instrument string, it alleviates lateral loads on the instrument, preventing damage from excessive bending.

[0056] Preferably, the flexible sub includes an upper joint component, a balancing cylinder component, a flexible component, and a lower joint component, which are connected in sequence. The balancing cylinder component and the flexible component constitute the instrument body, and pressure-bearing devices are installed at the upper and lower ends of the instrument body. The balancing cylinder component is used to ensure pressure balance between the inside and outside of the instrument, and the flexible component is used to enable the instrument body to bend freely between 0° and 10°.

[0057] Preferably, the flexible short section main body is made of 17-4 stainless steel, and the flexible component joint structure is made of beryllium bronze. It is connected to other instruments through the upper joint component and the lower joint component.

[0058] Preferably, the centralizer 17, the integrated sound-isolating and centralizing sub 18, and the counterweight sub 19 should all be strong enough to support the acoustic instrument within the instrument string. When the instrument string is fully connected and placed horizontally, the acoustic instrument's receiving array should be parallel to the ground, with the lowest point of the instrument not touching the ground and at a sufficient height above it. This prevents noise from scratches during instrument operation and improves the signal-to-noise ratio. This enhances the stability and accuracy of acoustic measurement results, reduces the difficulty for engineers to process the results, and improves processing efficiency.

[0059] In vertical wells or wells with low deviation, a centralizer 17 with sufficient strength to adapt to the wellbore size is also a necessary condition for the stable measurement of the acoustic wave instrument.

[0060] The aforementioned sonic logging instrument design and the combined sonic logging instrument and associated equipment can be used independently or in combination, with effectiveness determined by the specific instrument and its serial connection. The ultimate goal is to achieve the centered measurement required by the sonic instrument's measurement principle and reduce the time-of-day measurement error caused by the receiving array being non-parallel to the wellbore wall during horizontal well logging.

[0061] According to the invention, the effect of adding a centralizer at both ends of the through-drilling tool monopole digital sonic instrument and placing a counterweight short section horizontally on the outside is as follows: Figure 5 In the figure below, the middle of the two centralizer short sections is the through-drilling tool monopole digital sonic instrument, and the outer side of the centralizer is the counterweight short section. The instrument is placed horizontally before the centralizer and counterweight short section are attached as shown in the attached figure. Figure 2 As shown in the figure, the support provided by the centralizer and the tension provided by the counterweight sub keep the instrument parallel to the ground when placed horizontally. This ensures that the instrument remains parallel to the wellbore wall during horizontal well logging, thereby ensuring the accuracy of time difference measurements and reducing the impact of scraping noise caused by the tool rubbing against the wellbore wall on the useful signal.

[0062] The above-mentioned through-hole acoustic logging instrument and its associated equipment were used to perform a well logging operation scheme, and the logging results were compared after logging in horizontal wells. Experiments in multiple wells showed that using this scheme significantly reduced the error in time difference measurement. Figure 8 The results are shown in the horizontal well logging test after adding centralizers, counterweight subs and flexible subs to both ends of the through-hole monopole digital acoustic logging instrument. Figure 8 As shown in the fourth track, the time difference curve obtained by removing R1 or R5 in the horizontal section has no overall offset phenomenon compared with the time difference curve obtained by calculating with all R1-R5 involved, and the time difference measurement error is significantly reduced. Figure 8 Track 5 shows the difference between the time difference curve calculated using all R1-R5 components, the curves obtained using R1-R4, and the curves obtained using R2-R5. The two difference curves show no significant positive or negative bias. Well testing has verified the effectiveness of the acoustic logging tool installation scheme, which incorporates centralizers and counterweight subs at both ends. Adding counterweight subs and centralizers to both ends of the acoustic logging tool not only reduces tool acoustic system bending and time difference measurement errors during horizontal well logging, but also reduces tool scratch noise, improves the signal-to-noise ratio, and reduces time difference curve jumps caused by scratch noise. This reduces the data processing workload for engineers and improves work efficiency.

Claims

1. A through-drilling tool acoustic logging system, characterized in that: The invention comprises an acoustic system, an electronic circuit short section (11) arranged at one end of the acoustic system, and a centralizer (17) arranged at both ends of the acoustic system for centralizing the acoustic system, wherein the acoustic system comprises an acoustic wave transmitter (12), an instrument sound insulator (13), and a receiving array composed of a plurality of receiving transducers (14); A centralizer (17) is provided at one end of the acoustic system, the other end of the acoustic system is connected to one end of an electronic circuit short section (11), and the other end of the electronic circuit short section (11) is connected to another centralizer (17); The device further comprises a counterweight short section (19) provided at both ends of the acoustic system, wherein the counterweight short section (19) comprises a housing (21), line sealing pressure-bearing joints (20) provided at both ends of the housing (21), a wiring groove (22) provided in the housing (21), and a universal upper joint and a universal lower joint provided at both ends of the housing (21) for connection, wherein the main material of the counterweight short section (19) is 17-4 stainless steel; The counterweight short section (19) is connected to the end of the centralizer (17) away from the acoustic system through a universal upper joint, and the length of the counterweight short section (19) is determined according to the length of the acoustic system, the centralizer (17) and the electronic circuit short section (11); It also includes a flexible short section, which is arranged between the counterweight short section (19) and the instrument string, and the bending angle of the flexible short section is 0°~10°.

2. The through-hole acoustic logging system according to claim 1, characterized in that: It also includes a sound insulation and centralizing integrated short section (18), which is composed of an instrument sound insulation body (13) and a centralizing short section integrally arranged on the instrument sound insulation body (13). The sound insulation and centralizing integrated short section (18) is arranged between the sound wave transmitter (12) and the receiving array.

3. The through-hole acoustic logging system according to claim 2, characterized in that: The straightening short section comprises four groups of lantern body straightening bow springs, and instrument sound insulation bodies (13) are provided on both sides of the four groups of lantern body straightening bow springs.

4. The through-hole acoustic logging system according to claim 1, characterized in that: One end of the centralizer (17) away from the acoustic system is connected to one end of the electronic circuit short section (11).

5. The through-hole acoustic logging system according to claim 1, characterized in that: The centralizer (17) is a lantern-type bow spring centralizer, wherein the main structure of the lantern-type bow spring centralizer is made of 17-4 stainless steel, and the bow spring is made of spring steel.

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