A near-bit array ultrasonic velocity imaging logging device and method

Abstract

The application discloses a near-bit array ultrasonic velocity imaging logging device and method, relates to the technical field of logging, and comprises a drill collar sub, a logging acoustic system and a booster plate. The logging acoustic system comprises a focused transmitting probe and an array receiver. A sound insulation groove is arranged on the drill collar sub between the focused transmitting probe and the array receiver. Ultrasonic waves excited by the focused ultrasonic probe are refracted in the stratum at the well wall to generate sliding longitudinal and transverse waves through the fluid in the well, and are received by the array receiver through the fluid in the well. The first wave received by the array receiver is the sliding longitudinal wave of the stratum. The application can measure the stratum velocity near the drill bit in real time, accurately determine the position of the drill bit, timely adjust the well trajectory, reduce the risk of out-of-zone, and increase the reservoir drilling rate.

Description

Technical Field

[0001] This invention relates to the field of well logging technology, and in particular to a near-bit drilling array ultrasonic velocity imaging well logging device and method. Background Technology

[0002] In recent years, logging-while-drilling (LOD) technology has developed rapidly, especially in horizontal and highly deviated wells, and has become an essential technology for deep-sea and deep-earth drilling. As a key aspect of this technology, sonic logging-while-drilling can determine the P-wave and S-wave velocities of the formation during drilling, which can then be used to determine the location of formation interfaces in real time, estimate formation pore pressure, and evaluate wellbore stability. This provides crucial information for the exploration and development of oil and gas fields.

[0003] However, current array acoustic logging tools operate at frequencies below 20 kHz, with acoustic system dimensions of 3-4 feet, and are installed at a distance of more than 10 meters from the drill bit. Consequently, existing acoustic logging tools cannot provide real-time information about the vicinity of the drill bit, and low-frequency, long-spacing instruments lack azimuth resolution and have limited axial resolution. The unknown and complex underground rock formations, the lag in measurement points, and insufficient measurement resolution hinder accurate determination of the drill bit's position on-site, preventing timely adjustments to the wellbore trajectory and increasing the risk of encountering formations.

[0004] Therefore, there is an urgent need to provide a near-bit drilling array ultrasonic velocity imaging logging device or method that can measure the formation velocity near the drill bit in real time, accurately determine the drill bit position, adjust the wellbore trajectory in a timely manner, reduce the risk of encountering formations, and increase the reservoir encounter rate. Summary of the Invention

[0005] The purpose of this invention is to provide a near-bit drilling array ultrasonic velocity imaging logging device and method, which can measure the formation velocity near the drill bit in real time, accurately determine the drill bit position, adjust the wellbore trajectory in a timely manner, reduce the risk of encountering formations, and increase the reservoir encounter rate.

[0006] To achieve the above objectives, the present invention provides the following solution: A near-bit drilling array ultrasonic velocity imaging logging device, the device comprising: a drill collar sub, several sets of logging acoustic systems and booster plates; the drill collar sub is located above the drill bit; the logging acoustic systems and the booster plates are installed at uniform circumferential intervals along the drill collar sub; The logging acoustic system includes: a focused ultrasonic transmitter and an array receiver; the focused ultrasonic transmitter is located below the array receiver and is on the same vertical line, parallel to the axis of the drill collar sub; the focused ultrasonic transmitter is obliquely incident on the well wall at a set angle to the well axis; the array receiver is parallel to the axis of the drill collar sub; the upward angle of the focused ultrasonic transmitter in each logging acoustic system is different; The drill collar section between the focused ultrasonic transmitter and the array receiver is provided with a sound-insulating groove; the width of the sound-insulating groove is greater than or equal to the diameter of the focused ultrasonic transmitter and the width of the array receiver; the thickness of the sound-insulating groove is greater than the wavelength of the ultrasonic waves excited by the focused ultrasonic transmitter propagating in the drill collar. The ultrasonic waves excited by the focused ultrasonic transmitting probe are refracted by the fluid in the well and generated as sliding longitudinal and transverse waves in the formation at the well wall. These waves are then received by the array receiver after passing through the fluid in the well. The first wave received by the array receiver is the formation sliding longitudinal wave.

[0007] Optionally, the wall thickness of the drill collar sub is H1; the embedding depth of the focused ultrasonic transmitter and the array receiver is H2; H2≤H1 / 3.

[0008] Optionally, the distance between the focused ultrasonic transmitter and the array receiver, which are on the same vertical line, is 10 cm.

[0009] Optionally, a matching layer is provided at the end of the focused ultrasonic transmitting probe; the surface of the matching layer is arc-shaped; an absorbing backing for the focused ultrasonic transmitting probe is provided at the bottom; and a piezoelectric ceramic is provided in the middle of the focused ultrasonic transmitting probe.

[0010] Optionally, the top of the array receiver is provided with a flat array receiver matching layer; the bottom of the array receiver is provided with an array receiver backing; and the middle of the array receiver is provided with piezoelectric ceramic.

[0011] Optionally, the center frequency range of the focused ultrasonic transmitting probe is 100KHz~300KHz; the operating frequency range of the array receiver is 100KHz~300KHz.

[0012] A near-bit drilling array ultrasonic velocity imaging logging method, applied to the aforementioned near-bit drilling array ultrasonic velocity imaging logging device; the method includes: As the drill collar rotates and advances, the drill collar sub section drives the logging acoustic system into the wellbore; Multiple sets of focusing ultrasonic transmitting probes with different oblique incident angles located below the array receiver excite high-frequency ultrasonic waves, which are then received by the array receiver; and the ultrasonic waves are filtered by a high-pass filter before being received by the array receiver. Based on the received ultrasonic waves, the slowness of the P-waves and S-waves of the formation measured at different incident angles is extracted using the time-slowness coherence method, and the formation velocity is determined. The formation velocity is processed by wellbore formation wave velocity imaging; and the booster plate is adjusted accordingly based on the imaging results to bring the drill bit closer to the reservoir.

[0013] Optionally, the wellbore formation wave velocity imaging processing of the formation velocity specifically includes: A 2D color-filled contour map was used to perform well-circumferential formation velocity imaging.

[0014] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects: This invention provides a near-bit drilling array ultrasonic velocity imaging logging device and method, comprising a drill collar sub with a logging acoustic system and a booster plate mounted on it; the logging acoustic system includes a focusing ultrasonic transmitting probe and an array receiver; the focusing ultrasonic transmitting probe is located below the array receiver and maintained on the same vertical line; using multiple logging acoustic systems for measurement facilitates the selection of P-waves and S-waves with strong time slowness and coherence during data processing, improving data quality; simultaneously, data from each logging acoustic system can be compared and compensated, improving both logging accuracy and logging timeliness. This invention can overcome the technical problems of traditional drilling acoustic logging such as measurement point lag and insufficient measurement resolution, thereby enabling real-time measurement of formation velocity near the drill bit, accurate determination of drill bit position, timely adjustment of wellbore trajectory, reduction of formation encounter risk, and increase reservoir encounter rate. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the overall structure of Embodiment 1 provided by the present invention; Figure 2 This is a schematic diagram of the application structure of Embodiment 1 provided by the present invention; Figure 3 This is a schematic diagram of the drill collar sub section in Embodiment 1 provided by the present invention; Figure 4 This is a cross-sectional view of the drill collar sub section in Embodiment 1 provided by the present invention; Figure 5 This is a schematic diagram of the focused ultrasonic transmitting probe structure in Embodiment 1 provided by the present invention; Figure 6 This is a cross-sectional view of the focused ultrasonic transmitting probe in Embodiment 1 of the present invention. Figure 7 This is a schematic diagram of the array receiver structure in Embodiment 1 provided by the present invention. Figure 8 This is a schematic diagram of the specific structure of the array receiver in Embodiment 2 provided by the present invention; Figure 9 This is a schematic diagram of the measurement results at the horizontal well interface in Embodiment 2 provided by the present invention; Figure 10 This is a schematic diagram of the imaging results of the well section in Embodiment 2 provided by the present invention.

[0017] Explanation of reference numerals in the attached figures: 1. Drill collar sub; 2. Booster plate; 3. Drill bit; 4. Logging acoustic system; 5. Array receiver; 6. Focused ultrasonic transmitter probe; 7. Sound insulation groove; 8. Focused ultrasonic transmitter probe absorbing backing; 9. Piezoelectric ceramic; 10. Array receiver matching layer; 11. Array receiver backing. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] The purpose of this invention is to provide a near-bit drilling array ultrasonic velocity imaging logging device and method, which can measure the formation velocity near the drill bit 3 in real time, accurately determine the position of the drill bit 3, adjust the wellbore trajectory in a timely manner, reduce the risk of encountering formations, and increase the reservoir encounter rate.

[0020] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] Example 1 like Figures 1-4 As shown, the present invention provides a near-bit drilling array ultrasonic velocity imaging logging device, the device comprising: a drill collar sub 1, a logging acoustic system 4, and a booster plate 2; the drill collar sub 1 is located above the drill bit 3; the logging acoustic system 4 and the booster plate 2 are uniformly spaced circumferentially along the drill collar sub 1; the drill collar sub 1 is cylindrical and can be integrally formed with the drill collar, enabling the drill collar to drive the logging device to move, and can easily enter horizontal wells or highly deviated wells; the logging acoustic system 4 includes: a focusing ultrasonic transmitting probe 6 and an array receiver 5; the focusing ultrasonic transmitting probe 6 is located below the array receiver 5 and is on the same vertical line, and parallel to the axis of the drill collar sub 1; the focusing ultrasonic transmitting probe is obliquely incident on the well wall at a set angle with the well axis; the array receiver 5 is parallel to the axis of the drill collar sub 1; the set angle ranges from 0° to 90°.

[0022] A sound-insulating groove 7 is provided on the drill collar section 1 between the focused ultrasonic transmitting probe 6 and the array receiver 5; the width of the sound-insulating groove 7 is greater than or equal to the diameter of the focused ultrasonic transmitting probe 6 and the width of the array receiver 5; the thickness of the sound-insulating groove 7 is greater than the wavelength of the ultrasonic waves excited by the focused ultrasonic transmitting probe 6 that propagate in the drill collar; the sound-insulating groove 7 is filled with drilling fluid or other sound-absorbing materials.

[0023] The ultrasonic waves excited by the focused ultrasonic transmitter are refracted by the fluid in the well and generated as sliding longitudinal and transverse waves in the formation. These waves are then received by the array receiver 5 through the fluid in the well. The first wave received by the array receiver 5 is the formation sliding longitudinal wave.

[0024] In each group of logging acoustic systems 4, the focused ultrasonic transmitting probes 6 have different upward angles. The device provided by this invention can measure while rotating with the drill collar without the need for an additional motor, which not only simplifies the structural design of the logging device, but also enables logging operations on horizontal wells and highly deviated wells.

[0025] Setting up a multi-angle logging acoustic system 4 for simultaneous measurement improves data quality and enhances the fault tolerance of slow extraction.

[0026] The wall thickness of the drill collar section 1 is H1; the embedding depth of the focused ultrasonic transmitter probe and the array receiver 5 is H2; H2≤H1 / 3.

[0027] The distance between the focused ultrasonic transmitter and the array receiver 5, which are on the same vertical line, is 10 cm.

[0028] like Figure 5 and Figure 6 As shown, a matching layer is provided at the end of the focused ultrasonic transmitting probe; the surface of the matching layer is arc-shaped; a focused ultrasonic transmitting probe absorbing backing 8 is provided at the bottom of the focused ultrasonic transmitting probe; and a piezoelectric ceramic 9 is provided in the middle of the focused ultrasonic transmitting probe.

[0029] like Figure 7 As shown, the array receiver 5 has a flat array receiver matching layer 10 on top; the array receiver 5 has an array receiver backing 11 on the bottom; and the array receiver 5 has a piezoelectric ceramic 9 in the middle.

[0030] The center frequency range of the focused ultrasonic transmitting probe is 100KHz~300KHz; the operating frequency range of the array receiver 5 is 100KHz~300KHz.

[0031] Example 2 According to the apparatus provided in the embodiments of the present invention, a near-bit drilling array ultrasonic velocity imaging logging method is provided, the method comprising: S101, during the rotation and forward movement of the drill collar, the drill collar sub 1 drives the logging acoustic system 4 into the wellbore; S102, multiple sets of focusing ultrasonic transmitting probes with different oblique incident angles located below the array receiver 5 excite high-frequency ultrasonic waves, which are then received by the array receiver 5; and, before being received by the array receiver 5, the ultrasonic waves are filtered by a high-pass filter. When a sound wave is incident at the first critical angle of the formation into another medium, the refracted P-wave energy reaches its maximum; when it is incident at the second critical angle, the refracted S-wave energy reaches its maximum. The critical angle of the formation and the P-wave and S-wave velocities of the formation are related to the fluid velocity in the well. Since the formation properties ahead are unknown during drilling, sound waves are emitted at various angles to approach the critical angle of the formation in order to increase the energy of the received P-wave and S-wave.

[0032] Multiple sets of focusing probes with different oblique incidence angles excite high-frequency ultrasonic waves, which are critically refracted at the well wall into gliding waves that propagate a certain distance in the formation, and then refracted again at the well wall, passing through the fluid in the well to reach the array receiver 5.

[0033] A high-pass filter is set in the receiving circuit to filter low-frequency irrelevant noise from the mechanical vibration of drill bit 3 and drill rod, thereby improving the signal-to-noise ratio in the array waveform; the high-pass filter is a fourth-order Butterworth high-pass filter.

[0034] S103. Based on the received ultrasonic waves, the formation P-wave and S-wave slowness measured at different incident angles is extracted using the time-slowness coherence method, and the formation velocity is determined. The formation velocity determination process is as follows: compare the time-slowness coherence processing results of acoustic systems with different emission angles at the same azimuth around the well, and select the slowness value with the strongest correlation as the formation velocity corresponding to that azimuth.

[0035] The time-slowness coherence method uses a two-dimensional grid (one dimension for time, the other for slowness) search to find the arrival time and slowness of the wave at the extreme values ​​of the correlation function of the array waveform. Waveform coherence is defined for a given time window. Regarding waveform data, the relevant functions for waveform similarity (Semblance) are defined as follows: ; In the formula, It is the m-th receiving transducer in an array of N receiving transducers, with a spacing of d between the transducers. The related functions above are in fractional form. Given a time window... Location The calculation process of the correlation function for a certain slowness value s in the slowness interval is as follows: (1) In the molecule part, the waveform data on each receiver The waveform is propagated backward in time, or in other words, forward s(m-1)d along the time axis to the position of the first receiver. Next, the N data points (the data received by the first transducer plus N-1 time-shifted waveform data points) are summed. Then, the absolute value of this sum is calculated, squared, and its position within the time window is calculated. The points on the scale.

[0036] (2) In the denominator, the operation of the waveform propagating backward in time remains unchanged. However, in this case, we first take the square of the absolute value of each point of the waveform, then superimpose the squared data, and calculate its value at the 1000-1000 ohm. Integral over the interval. Repeat the above operations on the numerator and denominator for all s values ​​in the slow interval.

[0037] (3) Next, let the time window Location Change. Time variable. It is a time window At the midpoint, the above processing is repeated on the waveform within a given time period using this time window at a certain time step (in actual operation, It typically includes 2 to 3 cycles of the waveform, and the time step is generally taken as... Half of it.

[0038] Calculate the two-dimensional correlation function using the correlation function formula for the entire waveform, a specific time period within the waveform, and a given slowness interval, and find the value that maximizes the correlation function. and s value, This allows us to determine the slowness of a specific phase (such as a P-wave). At each time window position, the slope of the straight line across the array that the time window crosses is the slowness value s used for time-shift calculations. By varying this slope from small to large to cover the entire slowness range—that is, by having the time window scan the array with a slope—and then stepping along the waveform on the time axis, repeating the array slope scan at each step, we obtain a two-dimensional correlation function or surface with time and slowness as variables, called a correlation plot. The peak value of the correlation function gives the arrival time and slowness of each mode in the acoustic waveform, and the reciprocal of the slowness gives the velocity of each mode. Due to the increased computing speed of modern computers, this can be used to process acoustic array data quickly and efficiently.

[0039] S104, perform wellbore formation velocity imaging; and adjust the booster plate 2 accordingly based on the imaging results to bring the drill bit 3 closer to the reservoir. Specifically, a 2D color-filled contour map (one dimension is the wellbore azimuth, and the other dimension is the depth, with the color intensity representing the velocity) is used for wellbore formation velocity imaging.

[0040] Figure 8The source-to-receiver distance is 4 inches, and the array receiver span is 2 inches. The time-slow coherence processing method assumes that the formation acoustic characteristics at this distance are constant; therefore, the effective vertical resolution of the array acoustic logging instrument is consistent with the length of the array receiver used for processing. Traditional multipole array acoustic logging uses a source-to-receiver distance of approximately 10 feet and an array receiver span of typically 3-4 feet. The acoustic span in ultrasonic logging while drilling is much smaller than that of conventional logging while drilling, providing higher resolution data along the axial direction. Furthermore, traditional multipole array acoustic logging typically uses omnidirectional sound sources, which cannot measure the slowness at different azimuths around the well, instead averaging the slowness variation with azimuth to the final result. In vertical wells or wells with a formation dip of 90 degrees, this effect can be ignored due to the small distance across the formation boundary. However, in highly deviated wells, several feet of formation boundary are required to cross the entire range of the receiver array, making this effect non-negligible.

[0041] like Figure 9 As shown, Figure 9 In the diagram, U represents above, D represents below, L represents left, and R represents right. When the drill collar enters Formation 2 below, the azimuth imaging clearly shows an increase in slowness and a decrease in velocity at the corresponding azimuth. If Formation 2 is the target reservoir, due to the small size and high resolution of the ultrasonic velocity imaging logging while drilling array, the imaging position only reflects the position very close to the drill bit 3. Therefore, the booster plate 2 can be adjusted in time to control the drill bit 3 to drill downwards.

[0042] exist Figure 10 In the image, from left to right, the first channel is the ultrasonic velocity imaging result of the drilling array, the second channel is the depth channel, and the third channel is the conventional array acoustic velocity imaging. It is clear from the image that the ultrasonic velocity imaging results not only have higher axial resolution but also azimuth information. The specific location of fractures and vulnerabilities can be determined from the velocity changes around the wellbore, guiding the drilling direction.

[0043] The logging device provided by this invention is approximately 1 foot in length. This small-sized device can be installed between two booster plates 2 with minimal damage to mechanical strength, allowing for timely identification and adjustment of the drill bit 3's position in the formation, achieving precise geological guidance. Furthermore, utilizing multiple logging acoustic systems 4 for measurement facilitates the selection of time-slowing, highly coherent P-waves and S-waves during data processing, improving data quality. Simultaneously, the data from each logging acoustic system 4 can be compared and compensated, improving both logging accuracy and timeliness.

[0044] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0045] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A near-bit drilling array ultrasonic velocity imaging logging device, characterized in that, The device includes: a drill collar sub, several sets of logging acoustic systems and booster plates; the drill collar sub is located above the drill bit; the logging acoustic systems and the booster plates are installed at even circumferential intervals along the drill collar sub; The logging acoustic system includes: a focused ultrasonic transmitter and an array receiver; the focused ultrasonic transmitter is located below the array receiver and is on the same vertical line, parallel to the axis of the drill collar sub; the focused ultrasonic transmitter is obliquely incident on the well wall at a set angle to the well axis; the array receiver is parallel to the axis of the drill collar sub; the upward angle of the focused ultrasonic transmitter in each logging acoustic system is different; The drill collar section between the focused ultrasonic transmitter and the array receiver is provided with a sound-insulating groove; the width of the sound-insulating groove is greater than or equal to the diameter of the focused ultrasonic transmitter and the width of the array receiver; the thickness of the sound-insulating groove is greater than the wavelength of the ultrasonic waves excited by the focused ultrasonic transmitter propagating in the drill collar. The ultrasonic waves excited by the focused ultrasonic transmitting probe are refracted by the fluid in the well and generated as sliding longitudinal and transverse waves in the formation at the well wall. These waves are then received by the array receiver after passing through the fluid in the well. The first wave received by the array receiver is the formation sliding longitudinal wave.

2. The near-bit drilling array ultrasonic velocity imaging logging device according to claim 1, characterized in that, The wall thickness of the drill collar section is H1; the embedding depth of the focused ultrasonic transmitter and array receiver is H2; H2≤H1 / 3.

3. The near-bit drilling array ultrasonic velocity imaging logging device according to claim 1, characterized in that, The distance between the focused ultrasonic transmitter and the array receiver, which are on the same vertical line, is 10 cm.

4. The near-bit drilling array ultrasonic velocity imaging logging device according to claim 1, characterized in that, The focused ultrasonic transmitter has a matching layer at its end; the surface of the matching layer is arc-shaped; the bottom of the focused ultrasonic transmitter has an absorbing backing; and a piezoelectric ceramic is disposed in the middle of the focused ultrasonic transmitter.

5. The near-bit drilling array ultrasonic velocity imaging logging device according to claim 1, characterized in that, The array receiver has a flat matching layer on top; an array receiver backing is provided at the bottom; and a piezoelectric ceramic is provided in the middle of the array receiver.

6. The near-bit drilling array ultrasonic velocity imaging logging device according to claim 1, characterized in that, The center frequency range of the focused ultrasonic transmitting probe is 100KHz~300KHz; the operating frequency range of the array receiver is 100KHz~300KHz.

7. A near-bit drilling array ultrasonic velocity imaging logging method, applied to the near-bit drilling array ultrasonic velocity imaging logging device described in any one of claims 1-6; characterized in that, The method includes: As the drill collar rotates and advances, the drill collar sub section drives the logging acoustic system into the wellbore; Multiple sets of focusing ultrasonic transmitting probes with different oblique incident angles located below the array receiver excite high-frequency ultrasonic waves, which are then received by the array receiver; and the ultrasonic waves are filtered by a high-pass filter before being received by the array receiver. Based on the received ultrasonic waves, the slowness of the P-waves and S-waves of the formation measured at different incident angles is extracted using the time-slowness coherence method, and the formation velocity is determined. The formation velocity is processed by wellbore formation wave velocity imaging; and the booster plate is adjusted accordingly based on the imaging results to bring the drill bit closer to the reservoir.

8. The near-bit drilling array ultrasonic velocity imaging logging method according to claim 7, characterized in that, The wellbore formation wave velocity imaging processing specifically includes: A 2D color-filled contour map was used to perform well-circumferential formation velocity imaging.

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