In-situ measuring device and method for core length entering into a barrel based on barrel wall sliding wave

Abstract

The application relates to the technical field of drilling coring, in particular to a device and method for measuring the length of a core entering a barrel in situ based on a barrel wall sliding wave, which comprises a coring barrel assembly, a rotary follow-up excitation assembly and a receiving assembly; the receiving assembly is provided with at least two receiving transducers. The method comprises the following steps: initially calibrating the propagation speed and clock deviation; drilling and coring, a coring bit cuts the stratum to make the core enter a coring inner barrel and push the core marker to move and rotate synchronously, the core marker drives the cam to rotate, the cam pushes the follow-up rod and the piezoelectric ceramic sheet to periodically approach the inner wall of the coring inner barrel, in the process, the coded acoustic wave signals carrying time stamps are emitted along the barrel wall to propagate in real time, the receiving assembly receives and extracts the first wave arrival time and the time stamp, the propagation speed is calibrated in real time, the real-time distance is calculated, and the length of the core entering the barrel is converted. The application can realize the downhole in-situ dynamic measurement of the length of the core entering the barrel by using the passive driving emission end of the core marker.

Description

Technical Field

[0001] This application relates to the field of drilling core technology, specifically to an in-situ measurement device and method for core length based on cylinder wall sliding waves. Background Technology

[0002] Core drilling is the most direct means of obtaining raw formation data. Real-time measurement of the length of the core entering the core barrel is crucial for determining whether core blockage or jamming has occurred downhole. If changes in core length cannot be detected in a timely manner during core drilling, early-stage blockage is difficult to identify, often leading to core wear or even core loss. In severe cases, it can damage the core drilling tools, resulting in reduced core recovery rates and significantly increased construction costs. Therefore, monitoring the core length during core drilling operations has significant engineering value.

[0003] Current methods for monitoring core length during coring operations primarily involve indirectly monitoring the core length by installing fixed sensors inside the coring barrel or by estimating the length using the drilling footage from the surface. For example, some methods use multiple resistive or capacitive contacts on the inner wall of the coring barrel; when the core passes through, the contact changes to determine the core's location. Other methods estimate the downhole core length by measuring the feed displacement of the surface drill string, or by using downhole radioactive sensors to determine the presence of the core.

[0004] However, the aforementioned methods for monitoring core length still have significant shortcomings in practical applications. Fixed sensors or transmitting elements, if in continuous contact with the core, increase frictional resistance and hinder smooth core entry. If a mud layer exists between the sensor and the borehole wall, the coupling state becomes unstable, leading to decreased reliability of the measurement signal. Surface drill pipe footage estimation methods are affected by drill string elastic deformation and friction, failing to accurately reflect the actual core length entered downhole. Furthermore, distance measurement schemes based on sound wave propagation time suffer from inconsistencies between the time references of the transmitting and receiving ends, and the difficulty in accurately obtaining the actual sound velocity propagating within the borehole wall in real time. Summary of the Invention

[0005] To address the technical problems of existing methods for monitoring core length during coring operations, such as the fixed transmitting element continuously pressing against the cylinder wall, obstructing core passage, unstable acoustic coupling, inaccurate ground drill pipe advance estimation, inconsistent transmission and reception time references, and difficulty in obtaining real-time sound velocity, this application provides an in-situ measurement device and method for core length measurement based on cylinder wall sliding waves. This method utilizes the core's own rotation to passively drive a piezoelectric ceramic plate to periodically adhere to the cylinder wall, emitting sliding waves. Combined with a receiving transducer array for real-time calibration of sound velocity and time synchronization, this achieves in-situ dynamic measurement of core length downhole, avoiding long-term obstruction and improving ranging accuracy.

[0006] In a first aspect, this application provides an in-situ measurement device for core length based on cylinder wall sliding wave, including a core cylinder assembly, which includes an inner core cylinder, an outer core cylinder, a front end shell, and a core drill bit. A core-taking outer cylinder is fitted outside the core-taking inner cylinder. The front end of the core-taking outer cylinder is fixedly connected to the front end shell, and the front end shell is fixedly connected to the core-taking drill bit. The core drill bit is used to cut the formation to form a rock core during the rotation of the core cylinder assembly and to allow the rock core to enter the inner core cylinder. The direction in which the core drill bit points to the formation is called the front, and the opposite direction is called the back. The inner cylinder of the core sampler is equipped with a rotary follower excitation assembly, which includes a core marker, a cam connecting rod, a cam, an excitation end sleeve, a follower rod, a piezoelectric ceramic plate, a spring, and a roller-driven centralizer. The core marker is placed inside the core sampling cylinder. The front end of the core marker is used to contact the core entering the core sampling cylinder. The core marker can move along the axial direction of the core sampling cylinder and rotate independently coaxially with the core sampling cylinder. The rear end of the core marker is connected to a cam connecting rod, and a cam is installed on the cam connecting rod. An excitation end sleeve is fitted over the cam connecting rod, and the excitation end sleeve is fixed axially relative to the cam connecting rod. A follower rod is slidably mounted on the excitation end sleeve. The follower rod is arranged radially, with its inner end in contact with the cam and its outer end fitted with a piezoelectric ceramic plate. A spring is configured to cooperate with the follower rod. The spring is used to keep the inner end of the follower rod in contact with the cam and drive the piezoelectric ceramic plate to reset away from the inner wall of the core-taking cylinder. A roller-loaded centralizer is installed on the outer periphery of the excitation end sleeve, and the roller-loaded centralizer makes rolling contact with the inner wall of the core extraction inner cylinder. The rear end of the core-taking inner cylinder is provided with a receiving component. The receiving component is used to receive the acoustic wave signal propagating along the wall of the core-taking inner cylinder. The receiving component includes at least two sets of receiving transducers. The axial distance between any two adjacent receiving transducers is equal, and the axial direction is the direction of the central axis of the core-taking inner cylinder. The core inner cylinder, core outer cylinder, front end shell, core drill bit, core marker, cam connecting rod, cam and excitation end sleeve are coaxially arranged.

[0007] It should be further noted that the inner wall of the core-taking cylinder is a smooth cylindrical surface.

[0008] It should be further noted that the core marker is a cylindrical component with a cavity inside. A transmitting circuit is installed inside the cavity and is electrically connected to the piezoelectric ceramic sheet. The transmitting circuit is used to provide an electrical excitation signal to the piezoelectric ceramic sheet.

[0009] It should be further explained that the acoustic signal emitted by the piezoelectric ceramic plate driven by the transmitting circuit towards the inner wall of the core sampler is an encoded acoustic signal carrying a transmission timestamp. The encoded acoustic signal consists of a coded segment and a blank segment. The main frequency sine wave signal that lasts for a certain period of time is a coded segment and corresponds to binary "1", while the blank time slot is a blank segment and corresponds to binary "0". The encoded information of the encoded acoustic signal includes a transmission timestamp, which is the timestamp of the current clock of the core marker in the rotating follower excitation component.

[0010] It should be further noted that a radially through groove is provided on the side wall of the excitation end sleeve, and the follower rod is slidably disposed in the groove. The groove guides and limits the radial movement of the follower rod. A sliding bearing is provided between the excitation end sleeve and the cam connecting rod, so that the cam connecting rod can rotate relative to the excitation end sleeve. The inner end of the follower rod is equipped with a pulley, which contacts the outer side of the cam.

[0011] It should be further noted that the spring is a helical tension spring; One end of the spring is connected to the inner wall of the excitation end sleeve, and the other end extends out of the excitation end sleeve and is connected to the inner side of the piezoelectric ceramic plate. The spring is always in a stretched state.

[0012] As can be seen from the above structure, the spring and the follower rod are designed to provide a restoring force to the follower rod after the cam leaves the working position at its highest point, so that the follower rod and the piezoelectric ceramic plate return to their original positions away from the inner wall of the core-taking cylinder, thereby realizing the periodic reciprocating motion of the piezoelectric ceramic plate.

[0013] Specifically, when the core drives the core marker to rotate, the cam rotates synchronously and drives the follower rod to move towards the inner wall of the core-taking cylinder via a pulley, thereby causing the piezoelectric ceramic plate to come close to the inner wall of the core-taking cylinder. When the cam's highest point leaves the working position, the spring provides a restoring force, causing the follower rod and the piezoelectric ceramic plate to return to their original position away from the inner wall of the core-taking cylinder. Thus, the piezoelectric ceramic plate can stay close to the cylinder wall during emission to improve acoustic coupling conditions, and detach from the cylinder wall during non-emission phases to avoid long-term pressure against the cylinder wall obstructing the passage of the core.

[0014] It should be further noted that the roller-mounted centralizer has a ring-shaped structure; The inner ring with roller stabilizer is fixedly fitted to the outer circumference of the excitation end sleeve. At least three rollers are evenly distributed along the circumference of the outer ring with roller stabilizer, and the rollers make rolling contact with the inner wall of the core extraction inner cylinder. The roller-driven centralizer is used to keep the excitation end sleeve centered inside the core-taking inner cylinder, allow the excitation end sleeve to move axially, and circumferentially limit the excitation end sleeve.

[0015] It should be further noted that the receiving component includes a transducer frame, at least two sets of receiving transducers, a back-end connector, and a receiving circuit. The transducer frame is fixedly installed on the inner wall of the rear end of the core-taking inner cylinder. At least two sets of receiving transducers are equally spaced along the axial direction on the transducer frame. The receiving transducers face the inner wall of the core-taking inner cylinder. A coupling layer is provided between the receiving transducers and the inner wall of the core-taking inner cylinder. The transducer frame is connected to the rear connector, which has a cable channel inside. The rear of the rear connector has a receiving circuit, which is electrically connected to each receiving transducer through the cable in the cable channel.

[0016] It should be further noted that the receiving transducers are arranged in four groups at equal intervals along the axial direction, and each group of receiving transducers is arranged in a circumferential array with multiple transducers.

[0017] It should be further explained that the assembly method of the above-mentioned in-situ core length measuring device is as follows: Receiver assembly: First, install each receiving transducer on the transducer frame according to the predetermined position. Set a coupling layer between the receiving transducer and the core sampling inner cylinder to improve the efficiency of the sound signal transmission from the inner cylinder wall to the receiving transducer. Then, fix the transducer frame to the rear connector and lead the lead wires of each receiving transducer out through the internal channel of the rear connector to connect to the receiving circuit. The receiving circuit is installed at the rear of the rear connector. The water distribution connector and the upper connector are further assembled at the rear to complete the pre-assembly of the receiving end. Preferably, multiple sets of receiving transducers are arranged at equal intervals along the axial direction, and multiple transducers are arranged in a circumferential array in each set. The transmitter assembly method is as follows: First, assemble the core marker and the transmitting circuit. Install the transmitting circuit inside the core marker and reserve the electrical connection lead with the piezoelectric ceramic sheet. Then, assemble the cam and the cam connecting rod. The cam and the cam connecting rod are fixedly connected. The other end of the cam connecting rod is connected to the core marker through threads and studs, so that the core marker can transmit the rotational motion to the cam. Further, assemble the sliding bearing between the cam connecting rod and the transmitter sleeve to ensure that the cam connecting rod can rotate relative to the transmitter sleeve, while the transmitter sleeve remains relatively stationary. Inside the transmitter sleeve, pulleys, follower rods, and piezoelectric ceramic plates are further assembled. The pulleys are in contact with the outer contour of the cam, the follower rods are connected to the pulleys, and the piezoelectric ceramic plates are installed at the end of the follower rods. This allows the follower rods and piezoelectric ceramic plates to reciprocate radially through the pulleys when the cam rotates. Then, a roller-equipped centralizer is assembled around the outer periphery of the transmitter sleeve. The roller-equipped centralizer is preferably fixed to the transmitter sleeve by a threaded connection to achieve centering and circumferential positioning of the transmitter. After completion, a pre-assembled transmitter component is formed. Overall assembly: First, fix the receiver assembly to the rear end of the core tube, keeping the receiver stationary relative to the core tube. Then, insert the transmitter assembly and the core marker into the inner core tube, allowing the core marker to move freely within the inner core tube, while the transmitter sleeve is held near the center of the inner core tube by the roller stabilizer. During assembly, position the piezoelectric ceramic plate close to the inner wall of the inner core tube and ensure that the follower rod can reciprocate freely along the slotted direction of the transmitter sleeve. Then, check the fit between the cam, pulley, follower rod, and piezoelectric ceramic plate to ensure that the rotation of the core marker can drive the cam to rotate, further driving the piezoelectric ceramic plate closer to or away from the inner wall of the inner core tube. After completing the mechanical assembly, connect the transmitter lead to the transmitter circuit, connect the receiver transducer lead to the receiver circuit, and complete the insulation, protection, and sealing of each electrical connection part; finally, assemble the water distribution connector and the upper connector to complete the assembly of the whole machine.

[0018] Secondly, this application provides an in-situ measurement method for core length based on cylinder wall sliding waves, using the aforementioned in-situ core length measurement device, the steps of which include: S1. Before drilling and coring, the in-situ measurement device for the core length of the inlet tube is lowered into the well and the coring drill bit is brought to the target coring position. The initial distance between the rotating follower excitation component and the receiving component is determined, the initial propagation speed is obtained by initial calibration of the propagation speed, and the initial clock deviation between the rotating follower excitation component and the receiving component is obtained by time synchronization. S2. Start drilling and coring. Drive the coring cylinder assembly to rotate around its axis. The coring drill bit rotates synchronously with the coring cylinder assembly and cuts the formation to form a core. The core enters the inner cylinder of the coring cylinder. The core pushes the core marker to move backward along the axis and drives the core marker to rotate synchronously with the core. The core marker drives the cam to rotate through the cam connecting rod. The cam pushes the follower rod and the piezoelectric ceramic plate to periodically approach the inner wall of the inner cylinder of the coring cylinder. During the drilling and coring process, the following steps S21 to S24 are executed in real time and cyclically: S21. The piezoelectric ceramic sheet emits an coded acoustic signal carrying an emission timestamp towards the inner wall of the core sampler, causing the coded acoustic signal to couple into the inner wall of the core sampler and slide along the wall to propagate. S22. Each receiving transducer in the receiving component synchronously receives the coded acoustic wave signal propagating along the inner wall of the core sampler, extracts the arrival time of the first wave corresponding to each receiving transducer, and decodes the received coded acoustic wave signal to obtain the transmission timestamp. S23. The receiving component calibrates the sound velocity of the sound wave in the inner wall of the core sample tube in real time based on the known spacing between each receiving transducer and the corresponding first wave arrival time difference, and calculates the current sound wave propagation time based on the initial clock deviation, the first wave arrival time, and the transmission timestamp. S24. The receiving component calculates the real-time distance between the rotating follower excitation component and the receiving component based on the current sound wave propagation time and the real-time calibrated propagation speed, and converts the current core length into the core length based on the correspondence between the real-time distance and the core length.

[0019] It should be further explained that, in step S1, determining the initial distance between the rotating follower excitation component and the receiving component is specifically as follows: Based on the assembly dimensions of the in-situ core length measurement device, the initial axial distance between the piezoelectric ceramic plate and the reference receiving transducer in the receiving assembly is determined, and this distance is used as the initial distance between the rotating servo excitation assembly and the receiving assembly. .

[0020] It should be further explained that step S1, which involves the initial calibration of the propagation speed of sound, specifically includes the following steps: S101. The piezoelectric ceramic plate in the rotating follower excitation assembly emits an initial acoustic signal toward the inner wall of the core-collecting cylinder, and each set of receiving transducers in the receiving assembly receives the initial acoustic signal propagating along the inner wall of the core-collecting cylinder. S102. Extract the initial first wave arrival time of the initial acoustic signal received by each receiving transducer. Based on the known axial distance between adjacent receiving transducers and the corresponding initial first wave arrival time difference, calculate the initial propagation velocity of sound. The calculation formula is as follows:

[0021] in, This represents the number of pairs of adjacent receiving transducers. For the first Axial distance between adjacent receiving transducers; For the first The initial first wave arrival time difference for adjacent receiving transducers.

[0022] It should be further explained that step S1, which involves completing time synchronization, specifically includes the following steps: S111. Calculate the initial propagation time based on the initial distance and the initial propagation speed of sound. The calculation formula is:

[0023] in, The initial distance between the rotating follower excitation component and the receiving component. The initial speed of sound propagation; S112. Record the initial arrival time of the first wave from the reference receiving transducer and calculate the transmission time corresponding to the receiving component's time base. The calculation formula is:

[0024] in, The initial arrival time of the first wave is recorded by the reference receiving transducer, which is a specific receiving transducer designated by the user. S113. The receiving component decodes the transmission timestamp from the received coded acoustic signal and calculates the clock offset between the rotating servo excitation component and the receiving component. The calculation formula is:

[0025] in, This is the transmission timestamp obtained from decoding.

[0026] It should be further noted that the reference receiving transducer is the set of receiving transducers closest to the front end of the core-taking inner cylinder among all the receiving transducers in the receiving assembly.

[0027] It should be further explained that in step S21, the encoded acoustic signal carrying the transmission timestamp consists of a coded segment and an empty coded segment. The main frequency sine wave signal that lasts for a period of time is a coded segment and corresponds to binary "1", while the blank time slot is an empty coded segment and corresponds to binary "0". The encoded information of the encoded acoustic signal includes the transmission timestamp, which is the timestamp of the current clock of the core marker in the rotating follower excitation component.

[0028] It should be further noted that the current clock of the core marker is the count value or absolute time value of the current clock of the internal transmitting circuit of the core marker.

[0029] It should be further noted that, in step S21, the timing of the piezoelectric ceramic sheet emitting the encoded acoustic signal carrying the emission timestamp towards the inner wall of the core sample tube is as follows: The cam pushes the follower rod to bring the piezoelectric ceramic plate close to the inner wall of the core-taking cylinder, and then it is launched.

[0030] It should be further explained that in step S22, each receiving transducer in the receiving assembly synchronously receives the coded acoustic wave signal propagating along the inner wall of the core sampler, and extracting the first wave arrival time corresponding to each receiving transducer specifically includes: Each set of receiving transducers in the receiving component starts collecting acoustic signals simultaneously, and each set of receiving transducers outputs an electrical signal independently. The receiving circuit of the receiving component amplifies, filters, and samples each electrical signal. Through threshold detection or waveform feature recognition, it determines the time corresponding to the first peak or the first zero crossing of the coded acoustic signal received by each receiving transducer, which is taken as the first wave arrival time of that receiving transducer.

[0031] It should be further explained that, in step S22, decoding the received coded acoustic signal to obtain the transmission timestamp specifically includes: The receiving circuit of the receiving component decodes the coded acoustic signal received by any receiving transducer, identifies the timing of code segments and empty code segments, resolves the main frequency sine wave signal into binary "1" and the blank time slot into binary "0", thereby restoring the binary sequence, and extracts the timestamp of the current clock of the core mark from the binary sequence.

[0032] It should be further noted that, in step S23, the formula for real-time calibration of the sound wave propagation speed in the inner wall of the core sample is:

[0033] in, The propagation speed of sound as determined in real time; This represents the number of pairs of adjacent receiving transducers. For the first Axial distance between adjacent receiving transducers; For the first The first wave arrival time difference for adjacent receiving transducers.

[0034] It should be further noted that in step S23, the formula for calculating the current sound wave propagation time t is:

[0035] in, The first wave arrival time is the reference receiving transducer, which is a specific receiving transducer designated by the user. The timestamp of the transmission obtained through decoding; This represents the initial clock offset.

[0036] It should be further noted that in step S24, the real-time distance between the rotating servo excitation component and the receiving component... The calculation formula is:

[0037] in, For the real-time calibrated speed of sound, This represents the current sound wave propagation time.

[0038] It should be further noted that in step S24, the formula for calculating the current core length of the infeed, based on the correspondence between the real-time distance and the core length of the infeed, is as follows:

[0039] in, The initial distance between the rotating follower excitation component and the receiving component; The real-time distance between the rotating follower excitation component and the receiving component; This is the fixed axial distance from the tip of the coring drill bit to the tip of the core marker.

[0040] As can be seen from the above technical solutions, this application has the following advantages: 1. The in-situ measurement device for core length based on sliding wave along the cylinder wall provided in this application, through the overall coordination of the core cylinder assembly, the rotating follower excitation assembly and the receiving assembly, utilizes the core drill bit to cut the formation to allow the core to enter the core inner cylinder, and then performs distance inversion by measuring the propagation time of the sliding wave along the cylinder wall. This solves the problems of increased frictional resistance, unstable acoustic coupling, and inaccurate reflection of the actual core length downhole by the continuous contact of existing fixed sensors or transmitting elements with the core. It directly utilizes the metal core inner cylinder wall as an excellent acoustic wave transmission channel, minimizing the attenuation of acoustic waves by multiphase mixed media such as drilling fluid, and the measurement range can reach the entire length of the core cylinder.

[0041] 2. This application solves the problems of fixed transmitting elements continuously pressing against the cylinder wall, hindering the passage of the core, and the instability of acoustic coupling caused by changes in the mud layer. By setting the core marker to move axially synchronously and rotate independently with the core, the cam, follower rod, and piezoelectric ceramic plate periodically approach the inner wall of the core sampling cylinder. The follower rod is reset by using a spring.

[0042] 3. This application solves the problems of increased measurement error caused by eccentric rotation of the transmitting end, large frictional resistance during core drilling, and inability to calibrate the propagation velocity online in a single acoustic channel by setting a roller-equipped centralizer on the outer periphery of the excitation end sleeve and making rolling contact with the inner wall of the core drilling cylinder, and fixing at least two axially equidistant receiving transducers in the receiving assembly. It achieves centralization, circumferential limiting, reduced frictional resistance, and real-time dynamic correction of the sound velocity using the arrival time difference of the first wave, eliminating the influence of temperature, pressure, and cylinder wall condition changes on measurement accuracy.

[0043] 4. The in-situ measurement method for core length based on barrel wall sliding waves provided in this application solves the problems of information lag and inability to identify core blockages caused by the reliance on indirect calculations based on ground parameters in traditional methods. This method organically combines barrel wall sliding wave propagation time measurement, online calibration of propagation sound velocity, and dynamic conversion of core length into in-situ measurement. It achieves large-range dynamic monitoring of core length in the wellbore, providing real-time core data for directional drilling engineers to reduce operational risks.

[0044] 5. This application obtains the clock deviation by back-calculating the transmission time based on the initial distance and initial propagation speed of sound during the initial calibration stage and comparing it with the decoded timestamp. During the normal measurement stage, it transmits the coded acoustic signal carrying the transmission timestamp in real time. This solves the problem of inaccurate propagation time measurement caused by inconsistent time references under the condition of separate transmitting and receiving ends. It uses a single signal channel to simultaneously obtain ranging acoustic waves and time synchronization information, eliminating the need for an additional time synchronization channel and simplifying the structure and communication complexity of the downhole measurement system. Attached Figure Description

[0045] To more clearly illustrate the technical solution of this application, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 This is a schematic diagram of the lateral cross-sectional structure of an in-situ core length measurement device based on the sliding wave of the cylinder wall in one embodiment of this application.

[0047] Figure 2 This is a schematic diagram of the axial cross-sectional structure of the in-situ core length measurement device based on the sliding wave of the cylinder wall at the follower rod in one embodiment of this application.

[0048] Figure 3 This is a flowchart of an embodiment of the in-situ measurement method of core length based on tube wall sliding wave in this application.

[0049] In the diagram, 11-coring inner cylinder, 12-coring outer cylinder, 13-front end shell, 14-coring drill bit, 21-core marker, 22-cam connecting rod, 23-cam, 24-excitation end sleeve, 25-follower rod, 26-piezoelectric ceramic plate, 27-pulley, 28-centerer with roller, 29-spring, 31-transducer frame, 32-receiving transducer, 33-receiving end circuit. Detailed Implementation

[0050] To make the purpose, features, and advantages of this application more apparent and understandable, specific embodiments and accompanying drawings will be used to clearly and completely describe the technical solutions protected by this application below. Obviously, the embodiments described below are only a part of the embodiments of this application, and not all of them. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. To enable those skilled in the art to better understand the technical solutions of this application, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort should be within the scope of protection of this application.

[0051] Example 1 An in-situ measurement device for core length based on cylinder wall sliding waves.

[0052] Figure 1 This is a schematic diagram of the lateral cross-sectional structure of the in-situ core length measurement device based on the sliding wave of the cylinder wall in Example 1. Figure 2 This is a schematic diagram of the axial cross-sectional structure of the in-situ core length measurement device based on the sliding wave of the cylinder wall in Example 1 at the follower rod.

[0053] like Figures 1-2 As shown, the core cylinder assembly of the in-situ measurement device for core length based on cylinder wall sliding wave includes an inner core cylinder 11, an outer core cylinder 12, a front end shell 13, and a core drill bit 14. The inner wall of the core-taking inner cylinder 11 is a smooth cylindrical surface, and the outer core-taking outer cylinder 12 is fitted on the outside. The front end of the outer core-taking outer cylinder 12 is fixedly connected to the front end shell 13, and the front end shell 13 is fixedly connected to the core-taking drill bit 14. The core drill bit 14 is used to cut the formation to form a rock core during the rotation of the core cylinder assembly and to allow the rock core to enter the inner core cylinder 11. The direction in which the core drill bit 14 points to the formation is called front, and the opposite direction is called back. The inner cylinder 11 of the core sampler is equipped with a rotary follower excitation assembly, which includes a core marker 21, a cam connecting rod 22, a cam 23, an excitation end sleeve 24, a follower rod 25, a piezoelectric ceramic plate 26, a spring 29, and a roller-equipped centralizer 28. The core marker 21 is installed inside the core extraction inner cylinder 11. The core marker 21 is a cylindrical component with a cavity inside. A transmitting circuit is installed inside the cavity. The transmitting circuit is electrically connected to the piezoelectric ceramic sheet 26. The transmitting circuit is used to provide an electrical excitation signal to the piezoelectric ceramic sheet 26. The front end of the core marker 21 is used to contact the core entering the core cylinder 11. The core marker 21 can move along the axial direction of the core cylinder 11 and rotate independently coaxially with the core cylinder 11. The rear end of the core marker 21 is connected to the cam connecting rod 22, and the cam 23 is installed on the cam connecting rod 22. An excitation end sleeve is fitted onto the outside of the cam connecting rod 22, and the excitation end sleeve 24 is fixed relative to the cam connecting rod 22 in the axial direction; A radially through groove is provided on the side wall of the excitation end sleeve 24. A follower rod 25 is slidably arranged in the groove. The follower rod 25 is arranged radially. The groove guides and limits the radial movement of the follower rod 25. The inner end of the follower rod 25 is provided with a pulley 27, which contacts the outer side of the cam 23. The outer end of the follower rod 25 is equipped with a piezoelectric ceramic plate 26. A spring 29 is configured to cooperate with the follower rod 25. The spring 29 is used to keep the inner end of the follower rod 25 in contact with the cam 23 and drive the piezoelectric ceramic plate 26 to reset away from the inner wall of the core-taking cylinder. Spring 29 is a helical tension spring; One end of the spring 29 is connected to the inner wall of the excitation end sleeve 24, and the other end extends out of the excitation end sleeve 24 and is connected to the inner side of the piezoelectric ceramic plate 26. Spring 29 is always in a stretched state; A sliding bearing is provided between the excitation end sleeve 24 and the cam connecting rod 22, so that the cam connecting rod 22 can rotate relative to the excitation end sleeve 24; A roller-driven centralizer 28 is installed on the outer periphery of the excitation end sleeve 24. The roller-driven centralizer 28 rolls in contact with the inner wall of the core-taking inner cylinder 11. The roller-driven centralizer 28 has a ring structure. The inner ring of the roller stabilizer 28 is fixedly fitted onto the outer ring of the excitation end sleeve 24. At least three rollers are evenly distributed circumferentially on the outer ring of the roller stabilizer 28, and the rollers make rolling contact with the inner wall of the core-taking inner cylinder 11. The roller-driven centralizer 28 is used to keep the excitation end sleeve 24 centered in the core inner cylinder 11, allow the excitation end sleeve 24 to move axially, and circumferentially limit the excitation end sleeve 24. The rear end of the core-taking inner cylinder 11 is provided with a receiving component. The receiving component is used to receive the acoustic wave signal propagating along the cylinder wall of the core-taking inner cylinder 11. The receiving component includes a transducer frame 31, four sets of receiving transducers 32, a rear end connector and a receiving end circuit 33. The transducer frame 31 is fixedly installed on the inner wall of the rear end of the core-taking inner cylinder 11. Four sets of receiving transducers 32 are equally spaced along the axial direction on the transducer frame 31. Each set of receiving transducers 32 has multiple transducers arranged in a circumferential array. The receiving transducers 32 face the inner wall of the core-taking inner cylinder 11, and a coupling layer is provided between the receiving transducers 32 and the inner wall of the core-taking inner cylinder 11. A rear connector is connected to the transducer frame 31. The rear connector has a cable channel inside. A receiver circuit 33 is set at the rear of the rear connector. The receiver circuit 33 is electrically connected to each receiver transducer 32 through the cable in the cable channel. Among them, the inner core cylinder 11, the outer core cylinder 12, the front end shell 13, the core drill bit 14, the core marker 21, the cam connecting rod 22, the cam 23 and the excitation end sleeve 24 are coaxially arranged; The acoustic signal emitted by the piezoelectric ceramic plate 26 driven by the transmitting circuit to the inner wall of the core cylinder 11 is an encoded acoustic signal carrying a transmission timestamp. The encoded acoustic signal consists of a coded segment and a blank segment. The main frequency sine wave signal that lasts for a period of time is a coded segment and corresponds to binary "1", while the blank time slot is a blank segment and corresponds to binary "0". The encoded information of the encoded acoustic signal contains a transmission timestamp, which is the timestamp of the current clock of the core marker in the rotating follower excitation component.

[0054] Example 2 A method for in-situ measurement of core length based on cylinder wall sliding wave, using the in-situ core length measurement device of Example 1.

[0055] Figure 3 This is a flowchart of the in-situ measurement method for core length based on cylinder wall sliding waves in this embodiment, as follows: Figure 3 As shown, this step includes: S1. Before drilling and coring, the in-situ measurement device for the core length of the inlet tube is lowered into the well and the coring drill bit 14 is brought to the target coring position. The initial distance between the rotating follower excitation component and the receiving component is determined, the initial propagation speed is obtained by initial calibration of the propagation speed, and the initial clock deviation between the rotating follower excitation component and the receiving component is obtained by time synchronization.

[0056] Specifically, the initial distance between the rotating follower excitation component and the receiving component is determined as follows: Based on the assembly dimensions of the in-situ core length measurement device, the initial axial distance between the piezoelectric ceramic plate 26 and the reference receiving transducer 32 in the receiving assembly is determined, and used as the initial distance between the rotating servo excitation assembly and the receiving assembly. .

[0057] The initial calibration of the propagation speed of sound includes the following steps: S101. The piezoelectric ceramic plate 26 in the rotating follower excitation assembly emits an initial acoustic signal to the wall of the core-taking inner cylinder 11, and each set of receiving transducers 32 in the receiving assembly receives the initial acoustic signal propagating along the wall of the core-taking inner cylinder 11. S102. Extract the initial first wave arrival time of the initial acoustic signal received by each receiving transducer 32. Based on the known axial distance between adjacent receiving transducers 32 and the corresponding initial first wave arrival time difference, calculate the initial propagation velocity of sound. The calculation formula is as follows:

[0058] in, The number of pairs of adjacent receiving transducers 32; For the first The axial distance between adjacent receiving transducers 32; For the first The initial first wave arrival time difference for adjacent receiving transducers 32.

[0059] The specific steps to complete time synchronization are as follows: S111. Calculate the initial propagation time based on the initial distance and the initial propagation speed of sound. The calculation formula is:

[0060] in, The initial distance between the rotating follower excitation component and the receiving component. The initial speed of sound propagation; S112. Record the initial arrival time of the first wave at the reference receiving transducer 32, and calculate the transmission time corresponding to the receiving component time base. The calculation formula is:

[0061] in, The initial arrival time of the first wave is recorded by the reference receiving transducer 32. The reference receiving transducer 32 is the set of receiving transducers 32 closest to the front end of the core inner cylinder 11 among all the receiving transducers 32 in the receiving assembly. S113. The receiving component decodes the transmission timestamp from the received coded acoustic signal and calculates the clock offset between the rotating servo excitation component and the receiving component. The calculation formula is:

[0062] in, This is the transmission timestamp obtained from decoding.

[0063] S2. Start drilling and coring, drive the coring cylinder assembly to rotate around its axis, the coring drill bit 14 rotates synchronously with the coring cylinder assembly and cuts the formation to form a core, so that the core enters the inner coring cylinder 11, the core pushes the core marker 21 to move backward along the axis and drives the core marker 21 to rotate synchronously with the core, the core marker 21 drives the cam 23 to rotate through the cam connecting rod 22, the cam 23 pushes the follower rod 25 and the piezoelectric ceramic plate 26 to periodically approach the inner wall of the inner coring cylinder 11.

[0064] During the drilling and coring process, the following steps S21 to S24 are executed in real time and cyclically: S21. The piezoelectric ceramic sheet 26 emits an encoded acoustic signal carrying an emission timestamp to the wall of the core-taking inner cylinder 11, so that the encoded acoustic signal is coupled into the wall of the core-taking inner cylinder 11 and slides along the wall to propagate. The encoded acoustic signal carrying the transmission timestamp consists of a coded segment and an empty coded segment. The main frequency sine wave signal that lasts for a period of time is a coded segment and corresponds to binary "1", while the blank time slot is an empty coded segment and corresponds to binary "0". The encoded information of the encoded acoustic signal includes the transmission timestamp, which is the timestamp of the current clock of the core marker in the rotating follower excitation component. The current clock of the core marker is the count value or absolute time value of the current clock of the transmission circuit inside the core marker 21. The timing for the piezoelectric ceramic sheet 26 to emit a coded acoustic signal carrying a transmission timestamp to the inner wall of the core-taking cylinder 11 is as follows: When the cam 23 pushes the follower rod 25 to bring the piezoelectric ceramic plate 26 close to the inner wall of the core-taking inner cylinder 11, it is launched.

[0065] S22. Each receiving transducer 32 in the receiving assembly synchronously receives the coded acoustic wave signal propagating along the wall of the inner cylinder 11, extracts the arrival time of the first wave corresponding to each receiving transducer 32, and decodes the received coded acoustic wave signal to obtain the transmission timestamp. Each receiving transducer 32 in the receiving assembly synchronously receives the coded acoustic wave signal propagating along the wall of the inner core cylinder 11. Extracting the arrival time of the first wave corresponding to each receiving transducer 32 specifically includes: Each set of receiving transducers 32 in the receiving component starts collecting acoustic signals simultaneously, and each set of receiving transducers 32 outputs an electrical signal independently. The receiving circuit 33 of the receiving component amplifies, filters and samples each electrical signal. Through threshold detection or waveform feature recognition, it determines the time corresponding to the first peak or the first zero crossing of the coded acoustic signal received by each group of receiving transducers 32, which is taken as the first wave arrival time of the receiving transducer 32. Decoding the received coded acoustic signal to obtain the transmission timestamp specifically includes: The receiving circuit 33 of the receiving component decodes the coded acoustic signal received by any receiving transducer 32, identifies the timing of code segments and empty code segments, resolves the main frequency sine wave signal as binary "1" and the blank time slot as binary "0", thereby restoring the binary sequence, and extracts the timestamp of the current clock of the core mark from the binary sequence.

[0066] S23. The receiving component calibrates the sound velocity of the sound wave in the inner wall of the core-taking cylinder 11 in real time based on the known spacing between each receiving transducer 32 and the corresponding first wave arrival time difference, and calculates the current sound wave propagation time based on the initial clock deviation, the first wave arrival time, and the transmission timestamp. The formula for real-time calibration of the sound velocity propagating in the inner wall of the core-taking cylinder 11 is:

[0067] in, The propagation speed of sound as determined in real time; The number of pairs of adjacent receiving transducers 32; For the first The axial distance between adjacent receiving transducers 32; For the first The first wave arrival time difference corresponding to adjacent receiving transducers 32; The formula for calculating the current sound wave propagation time t is:

[0068] in, The first wave arrival time of the reference receiving transducer 32 is used as the reference receiving transducer 32, which is a specific receiving transducer 32 that is manually designated. The timestamp of the transmission obtained through decoding; This represents the initial clock offset.

[0069] S24. The receiving component calculates the real-time distance between the rotating follower excitation component and the receiving component based on the current sound wave propagation time and the real-time calibrated propagation speed, and converts the current core length into the core length based on the correspondence between the real-time distance and the core length.

[0070] Real-time distance between the rotating servo excitation component and the receiving component The calculation formula is:

[0071] in, For the real-time calibrated speed of sound, This represents the current sound wave propagation time.

[0072] The calculation formula for the current infeed is derived from the correspondence between real-time distance and core length:

[0073] in, The initial distance between the rotating follower excitation component and the receiving component; The real-time distance between the rotating follower excitation component and the receiving component; This is the fixed axial distance from the front end of the core drill bit 14 to the front end of the core marker 21.

[0074] Although this application has been described in detail with reference to the accompanying drawings and preferred embodiments, it is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of this application by those skilled in the art without departing from the spirit and essence of this application, and such modifications or substitutions should all be within the scope of this application / any technology disclosed in this application by those skilled in the art.

Claims

1. A method for in-situ measurement of core length based on sliding waves along the cylinder wall, characterized in that, The in-situ core length measuring device is used, which includes a core tube assembly, which includes an inner core tube, an outer core tube, a front end shell, and a core drill bit. A core-taking outer cylinder is fitted outside the core-taking inner cylinder. The front end of the core-taking outer cylinder is fixedly connected to the front end shell, and the front end shell is fixedly connected to the core-taking drill bit. The core drill bit is used to cut the formation to form a rock core during the rotation of the core cylinder assembly and to allow the rock core to enter the inner core cylinder. The direction in which the core drill bit points to the formation is called the front, and the opposite direction is called the back. The inner cylinder of the core sampler is equipped with a rotary follower excitation assembly, which includes a core marker, a cam connecting rod, a cam, an excitation end sleeve, a follower rod, a piezoelectric ceramic plate, a spring, and a roller-driven centralizer. The core marker is placed inside the core sampling cylinder. The front end of the core marker is used to contact the core entering the core sampling cylinder. The core marker can move along the axial direction of the core sampling cylinder and rotate independently coaxially with the core sampling cylinder. The rear end of the core marker is connected to a cam connecting rod, and a cam is installed on the cam connecting rod. An excitation end sleeve is fitted over the cam connecting rod, and the excitation end sleeve is fixed axially relative to the cam connecting rod. A follower rod is slidably mounted on the excitation end sleeve. The follower rod is arranged radially, with its inner end in contact with the cam and its outer end fitted with a piezoelectric ceramic plate. A spring is configured to cooperate with the follower rod. The spring is used to keep the inner end of the follower rod in contact with the cam and drive the piezoelectric ceramic plate to reset away from the inner wall of the core-taking cylinder. A roller-loaded centralizer is installed on the outer periphery of the excitation end sleeve, and the roller-loaded centralizer makes rolling contact with the inner wall of the core extraction inner cylinder. The rear end of the core-taking inner cylinder is provided with a receiving component. The receiving component is used to receive the acoustic wave signal propagating along the wall of the core-taking inner cylinder. The receiving component includes at least two sets of receiving transducers. The axial distance between any two adjacent receiving transducers is equal, and the axial direction is the direction of the central axis of the core-taking inner cylinder. The core inner cylinder, core outer cylinder, front end shell, core drill bit, core marker, cam connecting rod, cam and excitation end sleeve are coaxially arranged. The steps of the in-situ measurement method for core length in the feed tube include: S1. Before drilling and coring, the in-situ measurement device for the core length of the inlet tube is lowered into the well and the coring drill bit is brought to the target coring position. The initial distance between the rotating follower excitation component and the receiving component is determined, the initial propagation speed is obtained by initial calibration of the propagation speed, and the initial clock deviation between the rotating follower excitation component and the receiving component is obtained by time synchronization. S2. Start drilling and coring. Drive the coring cylinder assembly to rotate around its axis. The coring drill bit rotates synchronously with the coring cylinder assembly and cuts the formation to form a core. The core enters the inner cylinder of the coring cylinder. The core pushes the core marker to move backward along the axis and drives the core marker to rotate synchronously with the core. The core marker drives the cam to rotate through the cam connecting rod. The cam pushes the follower rod and the piezoelectric ceramic plate to periodically approach the inner wall of the inner cylinder of the coring cylinder. During the drilling and coring process, the following steps S21 to S24 are executed in real time and cyclically: S21. The piezoelectric ceramic sheet emits an coded acoustic signal carrying a transmission timestamp towards the inner wall of the core sampler, causing the coded acoustic signal to couple into the inner wall of the core sampler and slide along the wall to propagate. S22. Each receiving transducer in the receiving component synchronously receives the coded acoustic wave signal propagating along the inner wall of the core sampler, extracts the arrival time of the first wave corresponding to each receiving transducer, and decodes the received coded acoustic wave signal to obtain the transmission timestamp. S23. The receiving component calibrates the sound velocity of the sound wave in the inner wall of the core sample tube in real time based on the known spacing between each receiving transducer and the corresponding first wave arrival time difference, and calculates the current sound wave propagation time based on the initial clock deviation, the first wave arrival time, and the transmission timestamp. S24. The receiving component calculates the real-time distance between the rotating follower excitation component and the receiving component based on the current sound wave propagation time and the real-time calibrated propagation speed, and converts the current core length into the core length based on the correspondence between the real-time distance and the core length.

2. The in-situ measurement method for core length in the feed tube as described in claim 1, characterized in that, The core marker is a cylindrical component with a cavity inside. A transmitting circuit is installed inside the cavity and is electrically connected to a piezoelectric ceramic sheet. The transmitting circuit is used to provide an electrical excitation signal to the piezoelectric ceramic sheet.

3. The in-situ measurement method for core length in the feed tube as described in claim 1, characterized in that, A radially through groove is provided on the side wall of the excitation end sleeve, and the follower rod is slidably disposed in the groove. The groove guides and limits the radial movement of the follower rod. A sliding bearing is provided between the excitation end sleeve and the cam connecting rod, so that the cam connecting rod can rotate relative to the excitation end sleeve. The inner end of the follower rod is equipped with a pulley, which contacts the outer side of the cam.

4. The in-situ measurement method for core length in the feed tube as described in claim 1, characterized in that, The receiving component includes a transducer frame, at least two sets of receiving transducers, a back-end connector, and receiving circuitry. The transducer frame is fixedly installed on the inner wall of the rear end of the core-taking inner cylinder. At least two sets of receiving transducers are equally spaced along the axial direction on the transducer frame. The receiving transducers face the inner wall of the core-taking inner cylinder. A coupling layer is provided between the receiving transducers and the inner wall of the core-taking inner cylinder. The transducer frame is connected to the rear connector, which has a cable channel inside. The rear of the rear connector has a receiving circuit, which is electrically connected to each receiving transducer through the cable in the cable channel.

5. The in-situ measurement method for core length in the feed tube as described in claim 4, characterized in that, The receiving transducers are arranged in four groups at equal intervals along the axial direction, and each group of receiving transducers is arranged in a circumferential array with multiple transducers.

6. The in-situ measurement method for core length in the feed tube as described in claim 1, characterized in that, Step S1, completing the initial calibration of the propagation speed of sound, specifically includes the following steps: S101. The piezoelectric ceramic plate in the rotating follower excitation assembly emits an initial acoustic signal toward the inner wall of the core-collecting cylinder, and each set of receiving transducers in the receiving assembly receives the initial acoustic signal propagating along the inner wall of the core-collecting cylinder. S102. Extract the initial first wave arrival time of the initial acoustic signal received by each receiving transducer. Based on the known axial distance between adjacent receiving transducers and the corresponding initial first wave arrival time difference, calculate the initial propagation velocity of sound. The calculation formula is as follows: in, This represents the number of pairs of adjacent receiving transducers. For the first Axial distance between adjacent receiving transducers; For the first The initial first wave arrival time difference for adjacent receiving transducers; The specific steps to complete time synchronization are as follows: S111. Calculate the initial propagation time based on the initial distance and the initial propagation speed of sound. The calculation formula is: in, The initial distance between the rotating follower excitation component and the receiving component. The initial speed of sound propagation; S112. Record the initial arrival time of the first wave from the reference receiving transducer and calculate the transmission time corresponding to the receiving component's time base. The calculation formula is: in, The initial arrival time of the first wave is recorded by the reference receiving transducer, which is a specific receiving transducer designated by the user. S113. The receiving component decodes the transmission timestamp from the received coded acoustic signal and calculates the initial clock offset between the rotating servo excitation component and the receiving component. The calculation formula is: in, This is the transmission timestamp obtained from decoding.

7. The in-situ measurement method for core length in the feed tube as described in claim 1, characterized in that, In step S23, the formula for real-time calibration of the sound wave propagation velocity in the inner wall of the core sample cylinder is: in, The propagation speed of sound as determined in real time; This represents the number of pairs of adjacent receiving transducers. For the first Axial distance between adjacent receiving transducers; For the first The time difference of arrival of the first wave for adjacent receiving transducers.

8. The in-situ measurement method for core length in the feed tube as described in claim 1, characterized in that, In step S23, the formula for calculating the current sound wave propagation time t is: in, The first wave arrival time is the reference receiving transducer, which is a specific receiving transducer designated by the user. The timestamp of the launch obtained through decoding; This represents the initial clock offset.

9. The in-situ measurement method for core length in the feed tube as described in claim 1, characterized in that, In step S24, the formula for calculating the current core length is obtained by converting the real-time distance into the core length of the inlet tube based on the correspondence between the real-time distance and the core length of the inlet tube: in, The initial distance between the rotating follower excitation component and the receiving component; The real-time distance between the rotating follower excitation component and the receiving component; This is the fixed axial distance from the tip of the coring drill bit to the tip of the core marker.

Images