A method for correcting cement bond logging data in eight sectors

Abstract

The present invention discloses an eight-sector cement bonding logging data correction method, comprising: S1, calculating the distance of the eight-sector acoustic wave receiving probes from the casing wall relative to the center; S2, correcting the sector acoustic wave according to the size of the change in the corresponding distance of each sector. This scheme eliminates the influence of the instrument eccentricity on the measurement results of the eight sectors without changing the existing instrument structure, thereby improving the accuracy of the measurement results. At the same time, it reduces the requirements for the well conditions and instrument centralizers during logging construction, thereby improving the timeliness of logging.

Description

Technical Field

[0001] The invention relates to the technical field of cementing quality measurement, and in particular to an eight-sector cement bonding logging data correction method. Background Art

[0002] At present, when oil and gas fields are conducting cementing quality logging, eight-sector cement bonding logging is a commonly used method and plays a very important role in cementing quality detection. In addition to outputting traditional acoustic amplitude logging curves CBL and variable density VDL to evaluate the cementing quality around the well as a whole, it also has 8 acoustic wave receiving probes evenly distributed on the central axis of the instrument, which divides the 360° of the casing into 8 45° areas, and measures the amplitude of the acoustic wave signal after the sound wave passes through these 8 areas, and obtains 8 sector evaluation curves of the casing cement bonding conditions of the partitions, thereby achieving a detailed evaluation of the cementing quality around the well. However, in order to obtain accurate measurement results for the eight-sector cement bonding logging, the premise is that during the logging construction, it must be ensured that the instrument is always in the center of the wellbore during the measurement construction process.

[0003] In order to keep the instrument centered during the construction of cement bonded logging in the eighth sector, a centralizer is added. However, with the development of oilfield exploration technology, there are more and more high-angle wells, and the power of the centralizer used to keep the instrument centered is limited. On the one hand, the power of the centralizer is too large, making it difficult to move the instrument up and down during logging, and the centralizer is severely worn during the up and down movement of logging. On the other hand, the supporting force of the centralizer is too small to ensure that the instrument is centered. This poses a challenge to cement bonded logging in the eighth sector, and it is difficult to ensure a good centralizing effect during logging construction.

[0004] Experiments show that whether the instrument is centered has a great influence on the measurement results. When the instrument is eccentric, the cementing quality of a sector close to the casing wall is generally low, and a white band appears on the black-and-white graph of the sector cementation logging. The cementing quality of a sector far from the casing wall is generally high, and a black band appears on the black-and-white graph of the sector cementation logging, resulting in inaccurate evaluation of cementing quality. Summary of the invention

[0005] In view of this, the present invention provides an eight-sector cement bonding logging data correction method, which can eliminate the influence of instrument eccentricity on the measurement results of the eight sectors without changing the existing instrument structure, and improve the accuracy of the measurement results. At the same time, it reduces the requirements for well conditions and instrument centralizers during logging construction, and improves the timeliness of logging.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] An eight-sector cement bonding logging data correction method comprises:

[0008] S1. Calculate the distances of the eight sector acoustic wave receiving probes from the casing wall relative to the center;

[0009] S2. Correct the sector sound wave according to the change in the distance corresponding to each sector.

[0010] Preferably, before step S1, the method further includes:

[0011] S0. By using the transmission time of the sound wave from the transmitting probe to the 8-sector sound wave receiving probe, CBL receiving probe, and VDL receiving probe, and the speed of the sound wave in water, the change in the 8-sector transmission time relative to when the instrument is centered is calculated.

[0012] Preferably, the step S0 includes:

[0013] S01, calculate the gain coefficients Gs[I], Gc of 8 sectors and the sound amplitude CBL;

[0014] S02, calculate the eccentricity correction coefficients Xn[J], Xf[J] corresponding to the eight sectors, and the eccentricity correction coefficient Xc[J] of the sound amplitude CBL;

[0015] S03, record the transmission time TTc[I] of the sound wave from the transmitting probe to the 8 receiving sectors, the transmission time TT3c of the sound amplitude CBL, and the transmission time TT5c of the variable density VDL;

[0016] S04. Calculate the propagation speed Vt of the sound wave in the casing;

[0017] S05. Calculate the change in the transmission time of the eight sectors relative to when the instrument is centered.

[0018] Preferably, in the step S01, the gain coefficients Gs[I], Gc of the eight sectors and the sound amplitude CBL are calculated, including:

[0019] The 8 sectors and the sound amplitude CBL are calibrated to obtain the gain coefficients Gs[I] and Gc of the 8 sectors and the sound amplitude CBL respectively:

[0020] Gs[I]=100 / Rs[I]

[0021] Gc=P / Rc

[0022] Where Rs[] and Rc are the original signals of the 8 sectors and the sound amplitude CBL respectively; P is the CBL standard value of the scale sleeve, and the range of I is 1 to 8.

[0023] Preferably, in the step S02, the eccentricity correction coefficients Xn[J], Xf[J] corresponding to the eight sectors and the eccentricity correction coefficient Xc[J] of the sound amplitude CBL are calculated, including:

[0024] The actual data after the calibration coefficient calculation in step S01 is measured in the calibration sleeve at different eccentricity states, and the eccentricity correction coefficients Xn[J], Xf[J] corresponding to the eight sectors and the eccentricity correction coefficient Xc[J] of the sound amplitude CBL are calculated;

[0025] Wherein, J is the change in distance from the casing relative to the center, in mm; Xn[J] is the sector correction coefficient that is J mm closer to the casing wall than when it is centered; Xf[J] is the sector correction coefficient that is J mm farther from the casing wall than when it is centered; and Xc[J] is the correction coefficient of the sound amplitude CBL when it is eccentric by J mm.

[0026] Preferably, in step S04, calculating the propagation speed Vt of the sound wave in the casing includes:

[0027] The transmission time of the sound wave from the transmitting probe to the CBL receiving probe and the VDL receiving probe is used to calculate the propagation speed of the sound wave along the casing, that is, the casing sound velocity Vt, in mm / us:

[0028] Vt=(2*12*2.54*100) / (TT5c-TT3c) (7).

[0029] Preferably, in step S05, calculating the change DTs[I] of the 8-sector transmission time relative to when the instrument is centered includes:

[0030] According to the transmission time TTs[I] of the actual sound wave in the well from the transmitting probe to the 8-sector sound wave receiving probe, the change DTs[I] of the transmission time of the 8 sectors relative to the time when the instrument is centered is calculated:

[0031] DTs[I]=TTs[I]-TTc[I] (8).

[0032] Preferably, in step S1, calculating the distances of the eight sector acoustic wave receiving probes from the casing wall relative to the center includes:

[0033] According to the change in the transmission time of the eight sectors DTs[I], the distance D[I] that the acoustic wave receiving probe of each sector deviates from the casing wall is calculated:

[0034] When DTs[I]=0, D[I]=0;

[0035] When DTs[I]>0, the distance between the corresponding sector and the casing wall increases compared to the center, unit: mm:

[0036] D[I]=(Vs*2 / cos(Φ)-Vt*2*tan(Φ)) / DTs[I] (13)

[0037] When DTs[I]<0, the distance between the corresponding sector and the casing wall is smaller than that when it is centered, in mm:

[0038] D[I]=(Vt*2*tan(Φ)-Vs*2 / cos(Φ)) / |DTs[I]| (14)

[0039] Where Φ is the incident angle of the acoustic wave from the clear water into the casing to generate the sliding wave, |DTs[I]| is the absolute value of D[I];

[0040] Calculate the eccentric distance Dc of the sound amplitude CBL, in mm

[0041] Dc=(DTMAX+DTMIN) / 2 (15)

[0042] Where DTMAX is the maximum value of D[I], DTMIN is the absolute value of the minimum value of D[I], and I ranges from 1 to 8.

[0043] Preferably, in step S2, the sector sound wave is corrected according to the size of the change in the distance corresponding to each sector, including:

[0044] According to the distance D[I] of the acoustic wave receiving probe of each sector away from the casing wall, the eccentric distance Dc of the sound amplitude CBL and the eccentricity correction coefficient in step S02, the eccentricity correction coefficient Zs[I] of each sector and the eccentricity correction coefficient Zc of the sound amplitude CBL are calculated:

[0045] Zs[I]=Xf[K]*(1-|D[I]|+K)+Xf[K+1]*(|D[I]|-K),D[I]>0 (16)

[0046] Zs[I]=Xn[K]*(1-|D[I]|+K)+Xn[K+1]*(|D[I]|-K),D[I]<0 (17)

[0047] Where K is the integer part of |D[I]|;

[0048] Zc=Xc[N]*(1-Dc+N)+Xc[N+1]*(Dc-N) (18)

[0049] Wherein, N is the integer part of Dc.

[0050] Preferably, after step S2, the method further comprises:

[0051] After correcting the sector acoustic wave according to the size of the distance change corresponding to each sector, an output result is obtained, and the calculation is looped back to step S05 until the logging is completed.

[0052] It can be seen from the above technical solutions that the eight-sector cement bond logging data correction method provided by the present invention has the following beneficial effects:

[0053] Without changing the existing instrument structure, the influence of instrument eccentricity on the measurement results of the 8 sectors is eliminated, and the accuracy of the measurement results is improved. At the same time, the requirements for well conditions and instrument centralizers during logging construction are reduced, and the timeliness of logging is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0055] Figure 1 A data processing flow chart of an eight-sector cement bonding logging data correction method provided by an embodiment of the present invention;

[0056] Figure 2 A schematic diagram of the eccentric scale position of the sector sound wave provided in an embodiment of the present invention;

[0057] Figure 3 A schematic diagram of calculating the sector acoustic wave eccentricity provided by an embodiment of the present invention;

[0058] Figure 4 A comparison chart of sector cement bonding treatment provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0059] The purpose of the present invention is to overcome the measurement error caused by the eccentricity of the instrument during the above-mentioned eight-sector cement bonding logging, and to provide a method for effectively performing real-time correction using the logging data of the existing logging instrument. It uses the transmission time of the sound wave from the transmitting probe to the eight-sector sound wave receiving probe, the CBL receiving probe, and the VDL receiving probe, and the speed of the sound wave in the water, so as to calculate the distance of the eight-sector sound wave receiving probe from the casing wall relative to the center, and corrects the sector sound wave according to the size of the change in the corresponding distance of each sector, eliminating the influence of eccentricity on the measurement results of the eight-sector sound waves. The present invention eliminates the measurement error of the eight-sector cement bonding logging data under the condition of instrument eccentricity through a new calculation method without changing the existing instrument hardware on the market, and at the same time reduces the requirements for well conditions and instrument centralizers during logging construction.

[0060] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0061] The eight-sector cement bonding logging data correction method provided by the embodiment of the present invention comprises:

[0062] S1. Calculate the distances of the eight sector acoustic wave receiving probes from the casing wall relative to the center;

[0063] S2. Correct the sector sound wave according to the change in the distance corresponding to each sector.

[0064] It can be seen from the above technical solutions that the eight-sector cement bond logging data correction method provided by the embodiment of the present invention has the following beneficial effects:

[0065] Without changing the existing instrument structure, the influence of instrument eccentricity on the measurement results of the 8 sectors is eliminated, and the accuracy of the measurement results is improved. At the same time, the requirements for well conditions and instrument centralizers during logging construction are reduced, and the timeliness of logging is improved.

[0066] Furthermore, before step S1 of this solution, it also includes: by using the transmission time of the sound wave from the transmitting probe to the 8-sector sound wave receiving probe, CBL2-5 receiving probe, and VDL2-6 receiving probe, and the speed of the sound wave in water, the change of the 8-sector transmission time relative to when the instrument is centered is calculated. Among them, the distribution of the CBL2-5 receiving probe and the VDL2-6 receiving probe is as follows: Figure 3 Step S0 of this solution is designed so that the distance of the 8-sector acoustic wave receiving probes from the casing wall relative to the center can be further calculated by the change in the 8-sector transmission time relative to the center. Specifically:

[0067] 1) In step S01 of this solution, the instrument is centered in the calibration casing and calibrates 8 sectors and the acoustic amplitude CBL, and obtains the gain coefficients Gs[I] and Gc of the 8 sectors and the acoustic amplitude CBL, respectively, where I ranges from 1 to 8. This step is the common operation process before the current sector acoustic logging. Specifically:

[0068] Place the instrument in the calibration casing, keep the instrument centered in the casing, fill it with water and pressurize it above 3MPa to simulate the condition of free casing, i.e., there is no cement outside the casing, calibrate the 8 sectors and the sound amplitude CBL, and obtain the gain coefficients Gs[I] and Gc of the 8 sectors and the sound amplitude CBL respectively:

[0069] Gs[I]=100 / Rs[I]

[0070] Gc=P / Rc

[0071] Where Rs[] and Rc are the original signals of the 8 sectors and the sound amplitude CBL respectively; P is the CBL standard value of the scale sleeve, and the range of I is 1 to 8.

[0072] 2) In step S02 of this solution, the actual data after the calibration coefficient calculation in step S01 is measured in the scale sleeve at different eccentric states, so as to calculate the corresponding eccentricity correction coefficients Xn[J], Xf[J], and Xc[J]; wherein J is the change in the distance from the sleeve relative to the center, and the unit is mm; Xn[J] is the sector correction coefficient that is Jmm closer to the sleeve wall than when it is centered, Xf[J] is the sector correction coefficient that is Jmm farther from the sleeve wall than when it is centered, and Xc[J] is the correction coefficient of the sound amplitude CBL when the eccentricity is Jmm. Specifically:

[0073] The location of the acoustic wave receiving probe of sector 8 of the instrument in casing 1-9 is as follows: Figure 2 As shown, 1-10 is the instrument housing, 1-1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8 are 8 acoustic wave receiving probes of 8 sectors respectively. Since the sector acoustic wave receiving probe 1-1 and probe 1-5 of the instrument are in axially symmetrical positions, the center connecting line of the sector acoustic wave receiving probe 1-1 and probe 1-5 is ensured to be on the center O of the casing when the scale is eccentric. The position of the instrument is adjusted along the AA′ direction so that it is eccentric in the casing 1-9, so that the distance between the sector acoustic wave receiving probe 1-1 and probe 1-5 and the casing wall 1-9 changes, one becomes smaller and the other becomes larger, and the corresponding received signals become larger and smaller.

[0074] Starting from the position when the instrument is centered, move the instrument along the AA′ direction to adjust the position, each time adjusting the moving distance by 1mm, move 20 times, and simulate the state of maximum eccentricity of 20mm. If a larger eccentricity is simulated, adjust the moving distance of the instrument.

[0075] First, the collected original signal is standardized by the scale factor of step S01:

[0076] Ps[J]=Rs[1]*Gs[1] (1)

[0077] Pl[J]=Rs[5]*Gs[1] (2)

[0078] Pc[J]=Rc*Gc (3)

[0079] Wherein, J ranges from 1 to 20, Ps[J], Pl[J], and Pc[J] are the standardized values ​​of the sector sound wave receiving probe 1-1, probe 1-5, and sound amplitude CBL after the scale coefficient is calculated when the eccentric movement is J.

[0080] Calculation of correction coefficient under eccentricity:

[0081] The eccentricity correction coefficient of the sector acoustic wave receiving probe 1-1, that is, the sector correction coefficient that is J mm closer to the casing wall than when it is centered:

[0082] Xn[J]=100 / Ps[J] (4)

[0083] The eccentricity correction coefficient of the sector acoustic wave receiving probe 1-5, that is, the sector correction coefficient that is J mm farther from the casing wall than when centered:

[0084] Xf[J]=100 / Pl[J] (5)

[0085] Correction coefficient of sound amplitude CBL at eccentricity Jmm:

[0086] Xc[J]=P / Pc[J] (6)

[0087] Because the characteristics of each sector are consistent, after scale standardization, this correction factor is applicable to the correction of eccentricity of all sectors of the instrument.

[0088] 3) In step S03 of this solution, during actual well logging, the transmission time TTc[I] of the signal received by 8 sectors in the vertical well section recording instrument centered in the casing, the transmission time TT3c of the sound amplitude CBL, and the transmission time TT5c of the variable density VDL are recorded in units of us.

[0089] 4) In step S04 of this solution, the transmission time of the sound wave from the transmitting probe to the CBL2-5 receiving probe and the VDL2-6 receiving probe is used to calculate the propagation speed of the sound wave along the casing, that is, the casing sound speed Vt, in units of mm / us:

[0090] Vt=(2*12*2.54*100) / (TT5c-TT3c) (7).

[0091] 5) In step S05 of this solution, the transmission time TTs[I] of the actual sound wave in the well from the transmitting probe to the 8-sector sound wave receiving probe is calculated, and then the change DTs[I] of the 8-sector transmission time relative to the instrument being centered is calculated based on this:

[0092] DTs[I]=TTs[I]-TTc[I] (8).

[0093] 6) In step S1 and step S2 of this scheme, according to the change in the transmission time DTs[I] of the eight sectors, combined with the water acoustic velocity Vs and the casing sound velocity Vt, the distance D[I] of the acoustic wave receiving probe of each sector deviating from the casing wall is calculated, and eccentricity correction is performed; wherein, according to the distance D[I] of the acoustic wave receiving probe of each sector deviating from the casing wall, the eccentric distance Dc of the sound amplitude CBL and the eccentricity correction coefficient in step S02, the eccentricity correction coefficient Zs[I] of each sector and the eccentricity correction coefficient Zc of the sound amplitude CBL are calculated. Specifically:

[0094] ① When DTs[I] = 0, the instrument is in the centered state and no eccentricity correction is required;

[0095] ② When DTs[I]>0, the distance between the corresponding sector and the casing wall increases compared to when it is centered, such as Figure 3 As shown. In the figure, 2-1 is the actual position of the casing, and the dotted line 2-2 is the position of the casing when the instrument is centered, and the casing is filled with clean water. When centered, the transmission path of the sound wave is from the transmitting crystal 2-3, through A, E, to the 8-sector receiving crystal 2-4. When eccentric, the transmission path of the sound wave is from the transmitting crystal 2-3, through A, B, C, D, E points in the figure in turn, to the 8-sector receiving crystal 2-4. From this, we can get:

[0096] DTs[I]=AC*Vs*2-BC*Vt*2 (9)

[0097] AC=D[I] / cos(Φ) (10)

[0098] BC=D[I]*tan(Φ) (11)

[0099] sin(Φ)=Vs / Vt (12)

[0100] Among them, Vs is the speed of water sound, and Φ is the incident angle of the sound wave from the clear water into the casing to generate the sliding wave. Based on the above formula, the change distance D[I] of sector I can be calculated:

[0101] D[I]=(Vs*2 / cos(Φ)-Vt*2*tan(Φ)) / DTs[I] (13)

[0102] At this time, D[I] is greater than 0, indicating that the distance between the Ith sector and the casing is larger than when the instrument is centered, in mm.

[0103] ③ When DTs[I]<0, the distance between the corresponding sector and the casing wall is smaller than when it is centered. The dotted line 2-2 is the actual casing position, and 2-1 is the casing position when the instrument is centered. The casing is filled with water. When centered, the transmission path of the sound wave is from the transmitting crystal 2-3, through A, B, C, D, E in sequence, to the 8-sector receiving crystal 2-4. When eccentric, the transmission path of the sound wave is from the transmitting crystal 2-3, through A, E, to the 8-sector receiving crystal 2-4, from which we can get:

[0104] D[I]=(Vt*2*tan(Φ)-Vs*2 / cos(Φ)) / |DTs[I]| (14)

[0105] At this time, D[I] is less than 0, indicating that the distance between the Ith sector and the casing is smaller than when the instrument is centered. The unit is mm, and |DTs[I]| is the absolute value of D[I].

[0106] ④ Figure 3 Calculation of eccentric distance of medium sound amplitude CBL2-5:

[0107] Dc=(DTMAX+DTMIN) / 2 (15)

[0108] Wherein, DTMAX is the maximum value of D[I], DTMIN is the absolute value of the minimum value of D[I], I ranges from 1 to 8, and Dc is the eccentric distance of the sound amplitude CBL, in mm.

[0109] ⑤Calculate real-time correction coefficient:

[0110] The sector time-real correction coefficient is calculated using the interpolation method:

[0111] Zs[I]=Xf[K]*(1-|D[I]|+K)+Xf[K+1]*(|D[I]|-K), D[I]>0 (16)

[0112] Zs[I]=Xn[K]*(1-|D[I]|+K)+Xn[K+1]*(|D[I]|-K), D[I]<0 (17)

[0113] Wherein, K is the integer part of |D[I]|, and Zs[I] is the correction coefficient of sector I.

[0114] Calculation of real correction coefficient for sound amplitude CBL:

[0115] Zc=Xc[N]*(1-Dc+N)+Xc[N+1]*(Dc-N) (18)

[0116] Wherein, N is the integer part of Dc, and Zc is the sound amplitude CBL correction coefficient.

[0117] Furthermore, if Figure 1 As shown, after step S2 of this solution, it also includes: after correcting the sector acoustic wave according to the size of the distance change corresponding to each sector, an output result is obtained, and the calculation is returned to step S05 in a loop until the logging is completed.

[0118] The present invention is further described below in conjunction with specific embodiments:

[0119] The flow chart of the well logging data correction of this scheme is as follows Figure 1 As shown:

[0120] When performing actual eight-sector cement bond logging, a lot of cement used in cementing is currently returned from the bottom of the well to the wellhead, and it is impossible to find the free casing scale on site. Therefore, firstly, the instrument is operated in steps S01 and S02 in the laboratory to obtain the calibration coefficients Gs[], Gc, and the correction coefficients Xf[], Xn[], and Xc[]. Among them, for the same instrument and calibration casing, the correction coefficient only needs to be performed once in step S02. This is the standard coefficient under different eccentricity distances, and there is no need to calibrate the standard system every time you go up the well.

[0121] Steps S03 and S04 need to be performed at the logging construction site. After the instrument is lowered into the well, in the upper vertical well section of the well, the instrument is in the centered state. The transmission time TTc[] of the signal received by the 8 sectors when the instrument is centered in the casing is recorded, and the propagation speed Vt of the sound wave in the casing is calculated. During the logging construction process, the actual eccentricity correction coefficients Zs[] and Zc of the 8 sectors and the sound amplitude CBL are calculated through steps S05 and S06. After the collected original data of the sectors and the sound amplitude CBL are corrected for scale and eccentricity, the output result is obtained:

[0122] 8 sector output = Rs[I]*Gs[I]*Zs[I]

[0123] Amplitude CBL = Rc*Gc*Zc

[0124] Among them, Rs[] and Rc are the original signals of 8 sectors and acoustic amplitude CBL collected during real-time logging.

[0125] In addition, the method provided in this solution was applied at the well logging construction site and compared with the situation without correction. Figure 4 This is a comparison chart of cement bonding logging in 8 sectors of a well section. The completion logging of the well shows that the well inclination in this section has increased to 42 degrees. Figure 4 The left side of the middle is the cement bonding diagram without eccentricity correction. It can be seen that due to the influence of eccentricity, two obvious black and white strips appear from top to bottom in the figure. This is precisely the influence of the sector moving away from and close to the casing wall on the measurement results when the instrument is eccentric. Figure 4The right side of the middle is the 8-sector cement bonding logging diagram obtained by using this method for eccentricity correction. It can be seen that the black and white stripes caused by eccentricity are basically eliminated in the diagram, which is more in line with the actual cement bonding condition, making the cementing quality evaluation more rigorous and the results more accurate.

[0126] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0127] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An eight-sector cement bond logging data correction method, characterized in that: include: S0. By using the transmission time of the sound wave from the transmitting probe to the 8-sector sound wave receiving probe, CBL receiving probe, and VDL receiving probe, and the speed of the sound wave in the water, calculate the change in the 8-sector transmission time relative to when the instrument is centered; including: S01, calculate the gain coefficients Gs[I], Gc of 8 sectors and the sound amplitude CBL; S02, calculate the eccentricity correction coefficients Xn[J], Xf[J] corresponding to the eight sectors, and the eccentricity correction coefficient Xc[J] of the sound amplitude CBL; S03, record the transmission time TTc[I] of the sound wave from the transmitting probe to the 8 receiving sectors, the transmission time TT3c of the sound amplitude CBL, and the transmission time TT5c of the variable density VDL; S04. Calculate the propagation speed Vt of the sound wave in the casing; S05, calculating the change DTs[I] of the transmission time of the 8 sectors relative to when the instrument is centered; S1. Calculate the distances of the eight sector acoustic wave receiving probes from the casing wall relative to the center; S2. Correcting the sector sound wave according to the change in the distance corresponding to each sector; including: According to the distance D[I] of the acoustic wave receiving probe of each sector away from the casing wall, the eccentric distance Dc of the sound amplitude CBL and the eccentricity correction coefficient in step S02, the eccentricity correction coefficient Zs[I] of each sector and the eccentricity correction coefficient Zc of the sound amplitude CBL are calculated: Zs[I]=Xf[K]*(1-|D[I]|+K)+Xf[K+1]*(|D[I]|-K), D[I] >0 Zs[I]=Xn[K]*(1-|D[I]|+K)+Xn[K+1]*(|D[I]|-K), D[I] <0 Where K is the integer part of |D[I]|; Zc=Xc[N]* (1- Dc +N)+Xc[N+1]* (Dc-N) Wherein, N is the integer part of Dc.

2. The eight-sector cement bond logging data correction method according to claim 1 is characterized in that: In the step S01, the gain coefficients Gs[I] and Gc of the eight sectors and the sound amplitude CBL are calculated, including: The 8 sectors and the sound amplitude CBL are calibrated to obtain the gain coefficients Gs[I] and Gc of the 8 sectors and the sound amplitude CBL respectively: Gs[I]=100 / Rs[I] Gc=P / Rc Where Rs[] and Rc are the original signals of the 8 sectors and the sound amplitude CBL respectively; P is the CBL standard value of the scale sleeve, and the range of I is 1 to 8.

3. The eight-sector cement bond logging data correction method according to claim 1, characterized in that: In step S02, the eccentricity correction coefficients Xn[J], Xf[J] corresponding to the eight sectors and the eccentricity correction coefficient Xc[J] of the sound amplitude CBL are calculated, including: The actual data after the calibration coefficient calculation in step S01 is measured in the calibration sleeve at different eccentricity states, and the eccentricity correction coefficients Xn[J], Xf[J] corresponding to the eight sectors and the eccentricity correction coefficient Xc[J] of the sound amplitude CBL are calculated; Wherein, J is the change in distance from the casing relative to the center, in mm; Xn[J] is the sector correction coefficient that is J mm closer to the casing wall than when it is centered; Xf[J] is the sector correction coefficient that is J mm farther from the casing wall than when it is centered; and Xc[J] is the correction coefficient of the sound amplitude CBL when it is eccentric by J mm.

4. The eight-sector cement bond logging data correction method according to claim 1, characterized in that: In the step S04, calculating the propagation speed Vt of the sound wave in the casing includes: The transmission time of the sound wave from the transmitting probe to the CBL receiving probe and the VDL receiving probe is used to calculate the propagation speed of the sound wave along the casing, that is, the casing sound velocity Vt, in mm / us: Vt= (2*12*2.54*100) / (TT5c-TT3c).

5. The eight-sector cement bond logging data correction method according to claim 1, characterized in that: In step S05, the change DTs[I] of the transmission time of 8 sectors relative to when the instrument is centered is calculated, including: According to the transmission time TTs[I] of the actual sound wave in the well from the transmitting probe to the 8-sector sound wave receiving probe, the change DTs[I] of the transmission time of the 8 sectors relative to the time when the instrument is centered is calculated: DTs[I]=TTs[I]-TTc[I].

6. The eight-sector cement bond logging data correction method according to claim 5 is characterized in that: In step S1, calculating the distances of the eight sector acoustic wave receiving probes from the casing wall relative to the center includes: According to the change in the transmission time of the eight sectors DTs[I], the distance D[I] that the acoustic wave receiving probe of each sector deviates from the casing wall is calculated: When DTs[I]=0, D[I]=0; When DTs[I]>0, the distance between the corresponding sector and the casing wall increases compared to the center, unit: mm: D[I]=(Vs*2 / cos(Φ)-Vt*2*tan(Φ)) / DTs[I] When DTs[I]<0, the distance between the corresponding sector and the casing wall is smaller than that when it is centered, in mm: D[I]=(Vt*2*tan(Φ)-Vs*2 / cos(Φ)) / |DTs[I]| Where Φ is the incident angle of the acoustic wave from the clear water into the casing to generate the sliding wave, |DTs[I]| is the absolute value of D[I]; Calculate the eccentric distance Dc of the sound amplitude CBL, in mm Dc=(DTMAX+DTMIN) / 2 Where DTMAX is the maximum value of D[I], DTMIN is the absolute value of the minimum value of D[I], and I ranges from 1 to 8.

7. The eight-sector cement bond logging data correction method according to claim 1, characterized in that: After step S2, the method further includes: After correcting the sector acoustic wave according to the size of the distance change corresponding to each sector, an output result is obtained, and the calculation is looped back to step S05 until the logging is completed.

Images