Cement cased well cementing quality detection method based on bimodal SH guided waves

Abstract

The invention provides a cement cased well cementation quality detection method based on bimodal SH guided waves, and belongs to the technical field of electromagnetic ultrasonic non-destructive detection.The method comprises the following steps that a cement cemented casing simulation test piece is manufactured, an excitation transducer and two receiving transducers are arranged on the same horizontal plane in the cement cemented casing simulation test piece, and the excitation transducer and the two receiving transducers are arranged on the same horizontal plane in the cement cemented casing simulation test piece; attenuation values generated by propagation of the SH0 and SH1 modal guided waves between the two receiving transducers are obtained, and attenuation curves of the cement curing time and the attenuation values of the SH0 and SH1 modal guided waves are established respectively; obtaining an attenuation threshold value for judging the cement bonding quality according to the attenuation curve of the SH0 and SH1 modal guided waves; according to the operation, the exciting transducer and the receiving transducers are arranged in the test piece to be tested, an attenuation value generated by propagation of the SH0 and SH1 modal guided waves between the two receiving transducers is obtained, the attenuation value is compared with an attenuation threshold value, detection of the well cementation quality of the cement cased well is achieved, and the problem of well cementation quality detection of low-density cement is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of nondestructive testing, and in particular to a cement casing well cementing quality detection method based on dual-mode SH guided waves. Background Art

[0002] After drilling, oil and gas wells need to be cemented by injecting cement into the casing annulus. The quality of cementing is directly related to the life of the oil and gas wells, production capacity and the overall benefits of exploration and development. If the cementing quality meets the requirements, the oil and gas exploration and development will be efficient and effective; if the cementing quality is poor, it will lead to interlayer fluid channeling, a significant increase in development costs, and even damage to the casing of regional oil and water wells, causing great economic losses to the oil field. With the deepening of oil exploration and development, more and more low-pressure formations and weak formations are encountered. In order to prevent cementing fluid loss and effectively protect the oil and gas layers, low-density cement casing well cementing is usually used in the cementing process. The low-density cement slurry system is gradually developing and improving with the handling of complex underground conditions. It has now become the main technology for one-time return cementing of deep wells and ultra-deep wells. Cementing quality detection is a very important application field of acoustic logging in the process of oil field development. Quasi-Lamb waves in the casing are usually used to evaluate the bonding quality of cement. However, lightening agents are usually added to low-density cement, and the density is less than 1.75g / cm 3 . Usually 1.30g / cm 3 The acoustic impedance of cement stone is about 1.90g / cm 3 The acoustic impedance of cement stone is 1 / 2, which makes the acoustic coupling between low-density cement sheath and casing worse than that of conventional density cement, resulting in deviation and even wrong evaluation when evaluating it using the conventional density cement casing well cementing quality evaluation standard. Summary of the invention

[0003] In order to solve the problems existing in the prior art, the present invention provides a cement casing well cementing quality detection method based on dual-mode SH waveguide, which relies on the sound wave energy loss between the casing and the cement bonded to the pipe to evaluate the bonding quality of the cement and casing, thereby solving the problem that the acoustic impedance method is difficult to detect the cementing quality of low-density cement with a similar acoustic impedance to the mud.

[0004] To achieve the above object, the present invention provides the following technical solution: a cement casing well cementing quality detection method based on dual-mode SH guided wave, the specific steps are as follows:

[0005] S1 makes a cement bonded casing simulation specimen, arranges an excitation transducer and two receiving transducers on the same horizontal plane in the cement bonded casing simulation specimen, obtains the attenuation value Att generated by the propagation of SH0 and SH1 mode guided waves between the two receiving transducers, and establishes the attenuation curves of cement curing time and SH0 and SH1 mode guided wave attenuation values ​​respectively;

[0006] S2 obtains the attenuation threshold for judging the quality of cement bonding based on the attenuation curves of SH0 and SH1 mode guided waves;

[0007] S3 arranges the excitation transducer and the receiving transducer in the test piece according to S1, obtains the attenuation value Att generated by the propagation of the SH0 and SH1 mode guided waves between the two receiving transducers, compares the attenuation value with the attenuation threshold, and realizes the detection of cementing quality of cement casing wells.

[0008] Furthermore, in S1, a receiving transducer and an exciting transducer capable of exciting SH0 and SH1 modal guided waves are designed according to the size parameters of the test piece.

[0009] Furthermore, in S1, the excitation transducer and the receiving transducer are both composed of a PPM array and a racetrack coil, wherein the wire diameter of the racetrack coil of the excitation transducer is 0.2 mm and the number of turns is 80 turns; the wire diameter of the racetrack coil of the receiving transducer is 0.14 mm and the number of turns is 110 turns, and the PPM array is composed of 2 rows and 2 columns of magnet units with a width of 15 mm.

[0010] Furthermore, in S1, the excitation transducer and the receiving transducer are circumferentially arranged on the same horizontal plane inside the cement-bonded casing simulation specimen, and the angles between the two receiving transducers and the excitation transducer are 60° and 120° respectively.

[0011] Further, in S1, the cement-bonded casing consists of a casing and a clamp and cement poured in the annulus between the casing and the clamp.

[0012] Furthermore, in S1, the calculation formula of the attenuation value Att is:

[0013]

[0014]

[0015] In the formula, A n and A f are respectively the envelope peak values ​​of the forward direct waves of the signals obtained by the two receiving transducers; L is the propagation distance between the 60° and 120° receiving points; D1 and D2 are respectively the outer diameter and inner diameter of the casing; rad is the radian difference between the 60° and 120° receiving points.

[0016] Furthermore, in S2, the cement curing time is divided into a slurry cement time period, a cement gradual curing time period and a cement complete curing time period, which correspond to three conditions of cement bonding quality: no bonding, weak bonding and good bonding.

[0017] Furthermore, in S2, the attenuation value ranges of SH0 and SH1 modal guided waves corresponding to the slurry cement time period, the cement gradual solidification time period and the cement complete solidification time period are obtained according to the attenuation curve, that is, the attenuation thresholds corresponding to the cement bonding quality are obtained.

[0018] Furthermore, in S2, 0-3.5h is the time period of slurry cement, and SH0 or SH1 mode guided wave is used for detection; 4.5h-8.5h is the time period of gradual solidification of cement, and SH1 mode guided wave is used for detection; after 16h is the time period of complete solidification of cement, and SH0 mode guided wave is used for detection.

[0019] Furthermore, in S3, the excitation transducer and the receiving transducer arranged in the test piece are moved to detect the attenuation value Att generated by the propagation of the SH0 and SH1 modal guided waves at different positions in the test piece between the two receiving transducers, and the attenuation value is compared with the attenuation threshold to realize the detection of the cementing quality of the entire cement casing well.

[0020] Compared with the prior art, the present invention has at least the following beneficial effects:

[0021] The present invention provides a cement casing well cementing quality detection method based on dual-mode SH guided wave, which is used for cementing quality detection of low-density cement casing wells and has the following advantages:

[0022] 1. By setting the excitation transducer and the receiving transducer in the casing, the SH0 and SH1 mode guided waves can be excited and received directly inside the casing, solving the problem of large attenuation of the sound wave in the drilling fluid in the pulse echo detection method;

[0023] 2. By calculating the acoustic wave attenuation caused by the radiation of energy from the SH0 and SH1 mode guided waves propagating in the casing to the cement, the attenuation curve of cement curing time and the attenuation value of SH0 and SH1 mode guided waves is established. The cementing quality detection is realized based on the correlation between cement curing time and cement bonding quality, which solves the problem that conventional acoustic impedance detection methods are difficult to detect the cementing quality of low-density cement casing wells;

[0024] 3. The present invention flexibly uses SH0 and SH1 dual-mode guided waves to judge the quality of cement bonding, which can ensure the accuracy and sensitivity of detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the structure of the electromagnetic ultrasonic transducer of the present invention;

[0026] Figure 2 It is a schematic diagram of a cement-bonded casing simulation specimen according to the present invention;

[0027] Figure 3It is a schematic diagram of the arrangement scheme of the transducer according to the present invention;

[0028] Figure 4 It is a schematic diagram of the electromagnetic ultrasonic detection system of the present invention;

[0029] Figure 5 It is the wave train diagram of the SHO modal waveguide signal received at different times at the 60° position according to the present invention;

[0030] Figure 6 It is the wave train diagram of the SHO modal waveguide signal received at different times at the 120° position according to the present invention;

[0031] Figure 7 It is the wave train diagram of the SH1 modal waveguide signal received at different times at the 60° position described in the present invention;

[0032] Figure 8 It is the wave train diagram of the SH1 modal waveguide signal received at different times at the 120° position described in the present invention;

[0033] Fig. 9 is a graph showing the attenuation of the SHO modal waveguide signal over time according to the present invention;

[0034] Fig.10 is an attenuation curve diagram of the SH1 mode guided wave signal according to the present invention changing with time;

[0035] Fig.11 This is a flow chart of a cement casing well cementing quality detection method based on dual-mode SH guided wave of the present invention;

[0036] In the figure: 1-PPM array, 2-racetrack coil, 3-fixture, 4-cement, 5-casing, 6-receiving transducer, 7-exciting transducer, 8-computer, 9-oscilloscope, 10-high power pulse transmitter / receiver, 11-impedance matching network, 12-test piece. DETAILED DESCRIPTION

[0037] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0038] like Fig.11 As shown, the present invention provides a cement casing well cementing quality detection method based on dual-mode SH guided wave, which mainly includes the following steps:

[0039] Step 1: Design and manufacture an electromagnetic ultrasonic transducer capable of exciting SH0 and SH1 modal guided waves according to the size parameters of the test piece 12 .

[0040] The electromagnetic ultrasonic transducer is mainly composed of a PPM array 1 and a racetrack-shaped coil 2, wherein the wire diameter of the excitation transducer coil is 0.2 mm, and the number of turns is 80; the wire diameter of the receiving transducer coil is 0.14 mm, and the number of turns is 110; the PPM array 1 is a periodic permanent magnet array, which consists of 2 rows and 2 columns of magnet units with a width of 15 mm.

[0041] In addition, it also includes accessories such as RF connectors, SMA to BNC interfaces, RF connecting cables, and aluminum alloy packaging shells.

[0042] Step 2: low-density cement is configured in proportion and a cement-bonded casing simulation specimen is made, which is mainly composed of a casing 5 and a fixture 3, and then the configured cement 4 is slowly poured into the annulus between the casing 5 and the fixture 3 to form a cement ring.

[0043] Step 3: Arrange the excitation and receiving transducers.

[0044] The electromagnetic ultrasonic transducer used includes an excitation transducer 7 and two receiving transducers 6, forming a one-transmitter-two-receiver configuration, and the excitation transducer 7 and the receiving transducer 6 are circumferentially arranged on the same horizontal plane inside the casing, wherein the two receiving transducers 6 are arranged along one side of the excitation transducer 7, and the angles between the two receiving transducers 6 and the excitation transducer 7 are 60° and 120° respectively.

[0045] Step 4: Conduct a curing monitoring experiment on low-density cement and measure the attenuation values ​​of the SH0 and SH1 modes.

[0046] First, a high-power pulse transmitter / receiver 10 is used to generate and amplify a 4-cycle sinusoidal pulse signal with a center frequency of 100 kHz and 230 kHz, and transmitted to the excitation transducer 7 via the excitation end impedance matching network 11 to excite the SH0 and SH1 mode guided waves respectively;

[0047] Afterwards, the waveguide signal propagating along the casing wall is received by two receiving transducers 6 in succession, amplified by the internal amplifier of the high-power pulse transmitter / receiver 10 after passing through the receiving end impedance matching network 11, and further transmitted to the oscilloscope 9 and the computer 8 to complete data collection;

[0048] Finally, the envelope peaks of the forward direct wave signals received by the two receiving transducers 6 are extracted respectively, and the attenuation value Att generated when the SH waves of different modes propagate between the two receiving transducers 6 is calculated using the following formula.

[0049]

[0050]

[0051] In the formula, A nand A f are respectively the envelope peak values ​​of the forward direct waves of the signals received by the two receiving transducers 6; L is the propagation distance between the 60° and 120° receiving points; D1 and D2 are respectively the outer diameter and inner diameter of the casing; rad is the radian difference between the 60° and 120° receiving points.

[0052] In terms of cementing quality inspection in low-density cement casing wells, the attenuation dynamic range of the SH1 mode guided wave is larger than that of the SH0 mode, so more detailed judgments can be made when using the SH1 mode guided wave to inspect cementing quality. However, due to the large attenuation of the SH1 mode, the signal-to-noise ratio may be too low to be used during the inspection process; in comparison, although the SH0 mode has a smaller attenuation dynamic range, the signal direct wave packet can be clearly observed during the inspection process. In addition, the SH0 mode has almost no dispersion, which can reduce the difficulty of signal analysis. Therefore, in practice, the above two modes of SH guided waves should be considered comprehensively for inspection.

[0053] Step 5: Monitor the curing process of low-density cement in the cement-bonded casing simulation specimen and draw different modal SH guided wave attenuation curves to determine the curing state of the cement.

[0054] Repeat step 4 at certain intervals until the cement is completely cured. Finally, the attenuation curve of the cement curing time-different modal SH guided wave attenuation values ​​can be fitted. The curing state of the cement in different time periods can be determined by analyzing the changing trend of the attenuation curve.

[0055] Since cement will experience a process of shear modulus changing from zero to something and from small to large during its solidification process, and SH guided waves only propagate in media with shear modulus, the change in the shear modulus of low-density cement in the casing can be directly reflected by analyzing the change in the leakage attenuation value of SH guided waves in the casing, thereby judging the solidification state of the cement.

[0056] Generally, the solidification process of cement can be divided into three stages: slurry cement, gradual solidification of cement and complete solidification of cement. The change trend of the SH guided wave attenuation curve corresponding to each stage is as follows:

[0057] (1) The first stage (slurry cement): During this period, the cement is mainly in a slurry state and has no shear modulus. Therefore, the energy of the SH guided wave does not leak into the cement. Its attenuation is mainly the natural attenuation of the guided wave propagating in the casing. During this period, the attenuation value of the SH guided wave is small and in a stable state.

[0058] (2) The second stage (cement gradually solidifies): During this period, the shear modulus of cement increases from zero to a certain value, which can support the propagation of SH guided waves in cement. At the same time, the acoustic impedance difference between cement and casing gradually decreases. Therefore, the energy of SH guided waves leaking into cement in the received signal gradually increases, and the attenuation values ​​of SH guided waves of different modes are all in a trend of gradually increasing.

[0059] (3) The third stage (complete solidification of cement): During this period, the shear modulus of cement basically reaches its maximum value, and the acoustic impedance difference between cement and casing is the smallest. Therefore, the energy leaked from SH guided waves into cement is the largest at this time, and the attenuation values ​​of SH guided waves of different modes basically reach their maximum values ​​and tend to be stable again.

[0060] Step 6: Determine the attenuation threshold for judging the quality of cement bonding.

[0061] The bonding quality between the cement ring and the outer wall of the casing can generally be measured by three conditions: no bonding, weak bonding, and good bonding. From the cement curing process described in step 5, it can be seen that the change in cement properties during the slurry state-gradual solidification-complete solidification process of cement is equivalent to the process in which the bonding quality between cement and casing gradually improves. Therefore, the range of different modal SH guided wave attenuation values ​​corresponding to the three solidification states of cement determined in step 5 can be used to respectively define the threshold range of whether low-density cement is no bonding, weak bonding, or good bonding.

[0062] Step 7: Perform cementing quality inspection on low-density cement casing wells. According to steps 1, 3 and 4, measure the attenuation value of SH waveguide, and compare the thresholds corresponding to different cementing conditions determined in step 6 to determine the cementing quality of the casing at that position, and then change the position of the transducer for scanning to complete the inspection of cementing quality of low-density cement casing wells.

[0063] The present invention generates horizontal shear (SH) guided waves of SH0 mode and SH1 mode propagating along the circumferential direction of the pipeline in the casing by exciting the transducer 7. The SH guided waves radiate energy to the cement outside the casing during the circumferential propagation and the amplitude is attenuated. The attenuated signal is received by the transducer, sampled and recorded in the computer by the oscilloscope, the attenuation of the signal amplitude is calculated, the depth position of the transducer is changed to continue the detection, and finally the bonding condition of the cement outside the casing is evaluated by the attenuation values ​​at different depths.

[0064] SH0 and SH1 dual-mode guided waves are used to ensure detection accuracy and sensitivity; electromagnetic ultrasound is used instead of traditional piezoelectric methods to excite ultrasonic guided waves in the casing, which can avoid the use of coupling agents and make detection more flexible.

[0065] Preferably, the high-power pulse transmitter / receiver 10 can generate a pulse signal, and the width, frequency and energy of the pulse signal are controllable. The center frequency of the pulse signal is 100kHz and 230kHz, corresponding to the SH0 mode and SH1 mode respectively, and the high-power pulse transmitter / receiver can filter and amplify the echo signal.

[0066] In order to clearly illustrate the technical features of this solution, this solution is described below through a specific implementation method.

[0067] Example 1

[0068] The experimental casing used is made of J55 steel, 800mm long, 220mm outer diameter, and 200mm inner diameter. The specific application process is as follows:

[0069] Step 1: Design and manufacture an electromagnetic ultrasonic transducer that can excite SH0 and SH1 modal guided waves according to the size parameters of the casing to be tested. It is mainly composed of a racetrack coil and a periodic permanent magnet array, such as Figure 1 As shown. The wire diameter of the exciting transducer coil is 0.2 mm, and the number of turns is 80; the wire diameter of the receiving transducer coil is 0.14 mm, and the number of turns is 110. The periodic permanent magnet array consists of 2 rows and 2 columns of magnet units with a width of 15 mm.

[0070] Step 2: Prepare low-density cement in proportion and make a cement-bonded casing simulation specimen. The specimen is mainly composed of casing and fixture. Low-density cement slurry (density 1.3g / cm 3 ), then slowly pour the prepared cement slurry into the annulus between the casing and the fixture. During filling, slowly stir the slurry to remove the large amount of air remaining in the gap. The prepared simulation specimen is as follows Figure 2 shown.

[0071] Step 3: Arrange the excitation and receiving transducers. Use three electromagnetic ultrasonic transducers (T, R1, R2) to form a one-transmitter and two-receiver configuration, and arrange the probes circumferentially on the same horizontal plane inside the casing. The two receiving probes (R1, R2) are arranged along one side of the excitation probe (T), and the angles between them and the excitation probe (T) are 60° and 120° respectively. Figure 3 shown.

[0072] Step 4: Conduct a low-density cement curing monitoring experiment and measure the attenuation values ​​of the SH0 and SH1 modes. First, a high-power pulse transmitter / receiver is used to generate and amplify a 4-cycle sinusoidal pulse signal with a center frequency of 100kHz and 230kHz, which is transmitted to the excitation transducer (T) through the excitation end impedance matching network to excite the SH0 and SH1 mode waveguides respectively; then, the waveguide signal propagating along the casing wall is successively received by R1 and R2, and after passing through the receiving end impedance matching network, it will be amplified by the internal amplifier of the high-power pulse transmitter / receiver, and further transmitted to the oscilloscope and computer to complete data acquisition. The schematic diagram of the test system is shown in the figure. Figure 4 As shown; Finally, extract the envelope peaks of the forward direct wave signals received by R1 and R2 respectively, and use the following formula to calculate the attenuation A generated when different modes of SH waves propagate between R1 and R2: tt .

[0073] Step 5: Monitor the curing process of low-density cement in the cement-bonded casing simulation specimen and draw different modal SH guided wave attenuation curves to determine the curing state of the cement. Figure 5-Figure 8 The guided wave signals of the two modes SH0 and SH1 at the 60° and 120° positions in the cement-bonded steel pipe at different times during the experiment. Figure 5 The SH0 mode guided wave signals received at different times at the 60° position are: Figure 6 The SH0 mode guided wave signals received at the 120° position at different times. Affected by cement bonding, the signal amplitude received by the receiving transducer is relatively strong from 0 to 8.5 hours; after 16 hours, the signal amplitude is significantly reduced compared to before, and only the positive guided wave signal can be clearly observed.

[0074] Figure 7 The SH1 modal waveguide signal received at different times at the 60° position is: Figure 8 The SH1 mode waveguide signals received at the 120° position at different times. Similar to the SH0 mode, the attenuation of the SH1 mode signal amplitude is small from 0 to 8.5 hours, but after 16 hours, the signal amplitude attenuates sharply, and it is difficult to observe a clear SH1 waveguide signal at the 120° position, the signal-to-noise ratio is poor, and the signal amplitude remains basically unchanged afterwards.

[0075] The attenuation curves of the SH0 and SH1 modes of the steel pipe during the bonding process are shown in Fig. 9 , Fig.10 As shown in the figure, the whole process can be divided into three stages according to the changing trend of the attenuation curve:

[0076] (1) Within 0-3.5h, the signal amplitudes of SH0 and SH1 modal guided waves are large, the attenuation values ​​are small, and they are both in a relatively stable state, indicating that the attenuation characteristics of SH0 and SH1 modal guided waves are relatively consistent during this period, so they can both be used to judge the cement curing state;

[0077] (2) From 4.5h, the attenuation curve begins to show an increasing trend, and the attenuation value increases sharply during 4.5h-8.5h. The dynamic range of attenuation produced by the SH1 mode is larger than that of the SH0 mode, indicating that the SH1 mode guided wave is more sensitive to the change of cement shear modulus, which is conducive to making a more detailed judgment on the bonding quality of low-density cement. Therefore, the SH1 mode is mainly used to judge the cement curing state during this period;

[0078] (3) After 16 hours, the attenuation value basically reaches the maximum and the curve stabilizes again. The SH1 mode will cause the problem of difficulty in obtaining signals due to excessive attenuation, and additional signal processing methods are required to increase the signal-to-noise ratio, which increases the difficulty of signal analysis; for the SH0 mode waveguide, although its attenuation value is small, the direct wave packet of the SH0 mode signal can still be clearly observed, and the SH0 mode is almost non-dispersive, which can reduce the difficulty of signal analysis. Therefore, during this period, the SH0 mode is mainly used to judge the cement curing state.

[0079] Through the above analysis process, the attenuation characteristics of SH0 and SH1 mode guided waves can be comprehensively considered to reflect the changes in characteristic parameters during cement curing and thus determine its curing state. Corresponding to the above different time periods, the curing process of cement in the monitoring experiment can be divided into the following three stages:

[0080] (1) The first stage (slurry cement): within 0-3.5h, the energy of SH0 or SH1 mode guided waves does not leak into the cement. Their respective attenuation is mainly the natural attenuation of guided waves propagating in the steel pipe. At this time, the cement is mainly in a slurry state and there is no shear modulus.

[0081] (2) The second stage (beginning of solidification - gradual solidification of cement): At 4.5 h, the cement begins to solidify and bond with the pipe, and the solid frame begins to connect, thus supporting the propagation of SH waves in the cement. Between 4.5 h and 8.5 h, the cement gradually solidifies, the shear modulus gradually increases, and the SH1 mode waveguide leakage energy gradually increases, resulting in a gradual decrease in the signal amplitude and a gradual increase in attenuation.

[0082] (3) The third stage (complete curing): After 16 h, the amplitude of the SH0 mode guided wave drops to the minimum, and its attenuation value basically reaches the maximum value and tends to be stable again, indicating that the energy leaked from the SH0 mode guided wave into the cement no longer increases and the cement is completely cured.

[0083] Step 6: Determine the attenuation threshold for judging the quality of cementing. The bonding quality between the cement ring and the outer wall of the casing can generally be measured by three main conditions: no bonding, weak bonding, and good bonding. From the cement curing process described in step 5, it can be seen that the change in cement properties during the slurry state-gradual solidification-complete solidification process of cement is equivalent to the process in which the bonding quality between cement and casing gradually improves. Therefore, the range of different modal SH guided wave attenuation values ​​corresponding to the three solidification states of cement determined in step 5 can be used to respectively define the threshold range of whether low-density cement is no bonding, weak bonding, or good bonding. The range of different modal SH guided wave attenuation values ​​corresponding to different bonding qualities is shown in Table 1.

[0084] Table 1 SH guided wave attenuation range corresponding to different cementation qualities

[0085]

[0086] As shown in Table 1, in the actual process of low-density cement casing cementing quality inspection, SH0 mode guided wave can be used to detect and calculate its attenuation value at each inspection position. According to the distribution range of the attenuation value, the following three situations can be corresponded:

[0087] (1) If the attenuation value of the SH0 mode is ≤100dB / m, it can be determined that the cement here is not bonded;

[0088] (2) If the attenuation value of the SH0 mode is ≥200 dB / m, it can be determined that the cement bonding here is good;

[0089] (3) If the attenuation value of the SH0 mode is 100dB / m-200dB / m, it is necessary to use the SH1 mode for further testing and make further judgments on the type of weak cement bonding.

[0090] Technical features not described in the present invention can be achieved through or by adopting existing technologies and will not be described in detail here. Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by ordinary technicians in this technical field within the essential scope of the present invention should also fall within the scope of protection of the present invention.

Claims

1. A cement casing well cementing quality detection method based on dual-mode SH guided wave, characterized in that: The specific steps are as follows: S1 makes a cement bonded casing simulation specimen, arranges an excitation transducer (7) and two receiving transducers (6) on the same horizontal plane in the cement bonded casing simulation specimen, obtains the attenuation value Att generated by the propagation of SH0 and SH1 mode guided waves between the two receiving transducers (6), and respectively establishes attenuation curves of cement curing time and attenuation values ​​of SH0 and SH1 mode guided waves; S2 obtains the attenuation threshold for judging the quality of cement bonding based on the attenuation curves of SH0 and SH1 mode guided waves; S3 arranges an excitation transducer (7) and a receiving transducer (6) in the test piece (12) according to S1, obtains an attenuation value Att generated by the propagation of SH0 and SH1 mode guided waves between the two receiving transducers (6), compares the attenuation value with an attenuation threshold, and realizes the detection of cementing quality of cement casing wells.

2. A cement casing well cementing quality detection method based on dual-mode SH waveguide according to claim 1, characterized in that: In S1, a receiving transducer (6) and an excitation transducer (7) capable of exciting SH0 and SH1 modal guided waves are designed according to the size parameters of the test piece (12).

3. The cement casing well cementing quality detection method based on dual-mode SH guided wave according to claim 1 is characterized in that: In S1, the excitation transducer (7) and the receiving transducer (6) are both composed of a PPM array (1) and a racetrack coil (2), wherein the wire diameter of the racetrack coil (2) of the excitation transducer (7) is 0.2 mm, and the number of turns is 80; the wire diameter of the racetrack coil (2) of the receiving transducer (6) is 0.14 mm, and the number of turns is 110; the PPM array (1) is composed of 2 rows and 2 columns of magnet units with a width of 15 mm.

4. The cement casing well cementing quality detection method based on dual-mode SH guided wave according to claim 1 is characterized in that: In S1, the excitation transducer (7) and the receiving transducer (6) are circumferentially arranged on the same horizontal plane inside the cement-bonded casing simulation specimen, and the angles between the two receiving transducers (6) and the excitation transducer (7) are 60° and 120° respectively.

5. The cement casing well cementing quality detection method based on dual-mode SH guided wave according to claim 1 is characterized in that: In S1, the cement-bonded casing consists of a casing (5), a clamp (3), and cement (4) poured in the annulus between the casing (5) and the clamp (3).

6. The cement casing well cementing quality detection method based on dual-mode SH waveguide according to claim 1 is characterized in that: In S1, the calculation formula of the attenuation value Att is: In the formula, A n and A f are respectively the envelope peak values ​​of the forward direct waves of the signals obtained by the two receiving transducers (6); L is the propagation distance between the 60° and 120° receiving points; D1 and D2 are respectively the outer diameter and the inner diameter of the casing; rad is the radian difference between the 60° and 120° receiving points.

7. The cement casing well cementing quality detection method based on dual-mode SH waveguide according to claim 1 is characterized in that: In S2, the cement curing time is divided into the slurry cement time period, the cement gradual curing time period and the cement complete curing time period, which correspond to the three conditions of cement bonding quality: no bonding, weak bonding and good bonding.

8. The cement casing well cementing quality detection method based on dual-mode SH waveguide according to claim 7 is characterized in that: In S2, the attenuation value ranges of SH0 and SH1 modal guided waves corresponding to the slurry cement time period, the cement gradual solidification time period and the cement complete solidification time period are obtained according to the attenuation curve, that is, the attenuation thresholds corresponding to the cement bonding quality are obtained.

9. The cement casing well cementing quality detection method based on dual-mode SH waveguide according to claim 7, characterized in that: In S2, 0-3.5h is the time period of slurry cement, and SH0 or SH1 mode guided wave is used for detection; 4.5h-8.5h is the time period of gradual solidification of cement, and SH1 mode guided wave is used for detection; after 16h is the time period of complete solidification of cement, and SH0 mode guided wave is used for detection.

10. The cement casing well cementing quality detection method based on dual-mode SH guided wave according to claim 1, characterized in that: In S3, the excitation transducer (7) and the receiving transducer (6) arranged in the test piece (12) are moved to detect the attenuation value Att generated by the propagation of the SH0 and SH1 mode guided waves at different positions in the test piece between the two receiving transducers (6), and the attenuation value is compared with the attenuation threshold to achieve the detection of the cementing quality of the entire cement casing well.

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