阅读说明：本技术 一种随钻声波固井质量评价方法及处理装置 (While-drilling acoustic well cementation quality evaluation method and processing device ) 是由 李盛清 张广栋 张淼鹤 苏远大 唐晓明 于 2021-09-06 设计创作，主要内容包括：本发明公开了一种随钻声波固井质量评价方法及处理装置,包括：步骤一、对随钻数据进行预处理,获取阵列声波的全波列数据；步骤二、消除首波中钻铤波的影响；步骤三、计算首波能量,根据窗长计算窗内套管波能量；步骤四、计算首波阵列衰减因子,根据得到的首波能量计算相应的阵列衰减因子；步骤五、计算胶结指数,根据该区块衰减因子与CBL的拟合公式,利用胶结指数计算公式计算胶结指数；步骤六、利用胶结指数曲线进行固井质量综合评价；步骤七、判断是否处理完所有深度点,若是则结束处理,若否则重复上述步骤,直至处理完所有深度点。本发明可以解决电缆测井在大斜度井、水平井进行固井质量评价时耗时长、成本高的难题。(The invention discloses a method for evaluating the well cementation quality by acoustic wave while drilling and a processing device, comprising the following steps: the method comprises the following steps of firstly, preprocessing while-drilling data to obtain full-wave column data of array sound waves; eliminating the influence of drill collar waves in the head wave; step three, calculating head wave energy, and calculating the sleeve wave energy in the window according to the window length; step four, calculating head wave array attenuation factors, and calculating corresponding array attenuation factors according to the obtained head wave energy; calculating a cementation index, and calculating the cementation index by using a cementation index calculation formula according to a fitting formula of the block attenuation factor and the CBL; sixthly, comprehensively evaluating the cementing quality by using a cementing index curve; and step seven, judging whether all the depth points are processed or not, if so, finishing the processing, and otherwise, repeating the steps until all the depth points are processed. The invention can solve the problems of long time consumption and high cost when the cable logging is used for well cementation quality evaluation in a highly deviated well and a horizontal well.)

1. A method for evaluating the well cementation quality by acoustic wave while drilling comprises the following steps:

the method comprises the following steps of firstly, preprocessing while-drilling data, restoring a waveform curve, acquiring full-wave column data of array sound waves, and filtering according to requirements, namely removing low-frequency and high-frequency logging noises in the wave column;

filtering according to the inherent stop band of the while-drilling instrument to eliminate the influence of the drill collar wave in the head wave;

calculating head wave energy, and calculating the propagation time from the transmitter to each receiver, namely the arrival of the casing wave, according to the slowness of the casing wave and the source distance of the array receivers; determining the arrival time of the casing wave by using the arrival time, and calculating the casing wave energy in the window according to the window length;

step four, calculating head wave array attenuation factors, and calculating corresponding array attenuation factors according to the obtained head wave energy;

calculating a cementation index, and calculating the cementation index by using a cementation index calculation formula according to a fitting formula of the block attenuation factor and the CBL;

sixthly, evaluating the well cementation quality, namely performing comprehensive evaluation on the well cementation quality by using a cementation index curve according to the evaluation standard of the well cementation quality of the oil field;

and step seven, judging whether all the depth points are processed or not, if so, finishing the processing, otherwise, repeating the steps from two to six until all the depth points are processed.

2. The acoustic wave while drilling cementing quality evaluation method according to claim 1, wherein the second step specifically comprises: and filtering treatment is carried out according to the inherent drill collar wave sound insulation stop band of the while-drilling instrument sound insulator, the drill collar wave in the head wave is filtered to the maximum extent, and the casing wave is reserved so as to obtain the subsequent casing wave amplitude and attenuation.

3. The acoustic wave while drilling cementing quality evaluation method according to claim 1, the third step specifically being: extracting a casing wave time difference curve in a waveform while drilling by using a time-slowness correlation (STC) method, obtaining a head wave time difference (S) from the casing wave time difference curve, and determining the arrival time (T) of the casing wave according to a formula 1:

T＝S×D (1)

where D represents the distance between each receiver and the transmitter.

Determining a corresponding head wave time window in the full wave train according to the determined arrival time of the casing wave, wherein the window length is 2-3 periods of the head wave, and calculating the amplitude (or average energy) A of the head wave in the m receivers by using a formula 2_m：

Where AMP is the received waveform data and N is the number of sample points in the time window.

4. The acoustic wave while drilling cementing quality evaluation method according to claim 1, wherein the fourth step is specifically:

assuming that the amplitude spectrum of the waveform received by the receiver at depth z satisfies equation 3

Wherein S (w) and R (w) represent the amplitude spectra of the source and receiver, respectively; g (w, z) is a Green's function that controls the geometric dispersion of sound waves from the source to the receiver; t is the wave propagation time; q is a quality factor.

For different depths z₁、z₂The upper frequency spectrum ratio satisfies formula 4

Where f is the frequency and V is the wave velocity, it is generally assumed that the geometric diffusion G is frequency independent, so the last term in equation 4 is a constant that is frequency independent. Then at the same frequency there is a linear relationship between the natural logarithm of the spectral ratio and the distance between the two receivers, between which a linear fit can be made.

Therefore, we define the attenuation factor α ═ pi f/QV, and for the acoustic logging while drilling instrument, since there are multiple receivers, there is a linear relationship between any two receivers, taking the first receiver as an example, and equation 5 is satisfied

WhereinThe array attenuation coefficient received by the array receiver can be numerically calculated by a least square linear fitting method, thereby representing the attenuation factor between any two receivers.

5. The acoustic wave cementing while drilling quality evaluation method according to claim 1, wherein the fifth step is specifically:

counting attenuation factors (ATTN) in five to twenty wells in the block, intersecting the attenuation factors (ATTN) with a conventional well cementation quality evaluation method (CBL), fitting a functional relation between the ATTN and acoustic amplitude logging, and calculating a cementation index according to a formula 6:

wherein CBL_FPRepresenting the magnitude of the head wave at the free casing, CBL_MNRepresenting the head wave amplitude at full cementation. Therefore, the well cementation quality evaluation can be carried out according to the well cementation quality evaluation standards of different oil fields.

6. The device for evaluating the cementing quality with acoustic waves while drilling according to the evaluation method of claim 1, which is characterized by comprising a processor, a data processing unit and a data processing unit, wherein the processor is suitable for realizing various instructions; and a storage device adapted to store a plurality of instructions, the instructions adapted to be loaded and executed by a processor;

waveform preprocessing and band-pass filtering; specifically, a digital signal processor can be used for filtering the acquired array waveform to eliminate low-frequency and high-frequency logging noise, and then the inherent sound insulation stop band of the while-drilling instrument is used for band-pass filtering to eliminate the interference of the drill collar wave in the first wave;

calculating the energy of the head wave; presetting a casing wave slowness, calculating the arrival of the casing wave slowness, windowing and calculating waveform energy to obtain first wave energy on a plurality of receivers;

calculating an attenuation factor; performing linear fitting according to the head wave energy obtained by the plurality of receivers to obtain head wave attenuation factors in the array span;

calculating a cementation index; according to the relation formula obtained by fitting the attenuation factor and the CBL and the cementation index calculation formula, the cementation index can be calculated by directly utilizing the attenuation factor.

Technical Field

The invention belongs to the field of geophysical acoustic logging, and particularly relates to a method and a processing device for evaluating well cementation quality by using acoustic logging while drilling.

Background

The quality of well cementation directly influences the service life of the well and whether the whole injection and extraction process can be smoothly carried out. The conventional cable instruments face some challenges to develop well cementation quality evaluation: firstly, data are difficult to acquire by a conventional cable instrument in a highly deviated well/horizontal well; secondly, due to the influence of gravity, the cable instrument is small in size and cannot be well centered, and the data quality is seriously influenced; thirdly, the conventional cable instrument is difficult to operate in high-temperature high-pressure high-risk wells, and in addition, the cable logging consumes long time and has low efficiency, so that the operation cost is greatly increased. These conflicts appear more pronounced at sea.

Acoustic logging while drilling techniques are currently widely used for velocity measurements of formations under complex well conditions. During drilling, the while drilling tool may measure the cased hole during the lifting and lowering of the slick hole. The method for measuring the sliding hole greatly shortens the logging time while ensuring the data quality and the acquisition speed, plays a role in cost reduction and efficiency improvement, and is particularly suitable for deep water and deep layer logging environments. In addition, the characteristic of the logging-while-drilling instrument is utilized to replace a cable crawler, the logging-while-drilling instrument is large in size, the centering effect of the logging-while-drilling instrument in a large-size casing can be guaranteed to be good, and the measured sound wave information can accurately and comprehensively evaluate the well cementation quality. The special advantages of the acoustic logging while drilling make the well cementation quality evaluation while drilling have wide development prospect.

Disclosure of Invention

The invention aims to provide a method and a device for evaluating the well cementation quality by using sound waves while drilling, which are used for evaluating the well cementation quality by using casing waves of a monopole sound source according to the principle that sound waves while drilling have an acoustic isolation band so as to solve the problems of long time consumption and high cost when cable logging is used for evaluating the well cementation quality in a highly deviated well and a horizontal well.

In order to realize the method, the invention adopts the following processing scheme:

a method for evaluating the well cementation quality by acoustic wave while drilling,

the method comprises the following steps of firstly, preprocessing while-drilling data, restoring a waveform curve, acquiring full-wave column data of array sound waves, and filtering according to requirements, namely removing low-frequency and high-frequency logging noises in the wave column;

filtering according to the inherent stop band of the while-drilling instrument to eliminate the influence of the drill collar wave in the head wave;

calculating head wave energy, and calculating the propagation time from the transmitter to each receiver, namely the arrival time of the casing wave, according to the slowness of the casing wave and the source distance of the array receivers; determining the arrival time of the casing wave by using the arrival time, and calculating the casing wave energy in the window according to the window length;

step four, calculating head wave array attenuation factors, and calculating corresponding array attenuation factors according to the obtained head wave energy;

calculating a cementation index, and calculating the cementation index by using a cementation index calculation formula according to the fitting formula of the block attenuation factor and the CBL;

sixthly, evaluating the well cementation quality, namely performing comprehensive evaluation on the well cementation quality by using a cementation index curve according to the evaluation standard of the well cementation quality of the oil field;

and step seven, judging whether all the depth points are processed or not, if so, finishing the processing, otherwise, repeating the steps from two to six until all the depth points are processed.

The second step is specifically as follows: and filtering according to a drill collar wave sound insulation stop band inherent to a sound insulator of the while-drilling instrument, filtering the drill collar wave in the head wave to the maximum extent, and reserving the casing wave so as to obtain the subsequent casing wave amplitude and attenuation.

The third step is specifically as follows: extracting a casing wave time difference curve in a waveform while drilling by using a time-slowness correlation (STC) method, obtaining a head wave time difference (S) from the casing wave time difference curve, and determining the arrival time (T) of the casing wave according to a formula 1:

T＝S×D (1)

where D represents the distance between each receiver and the transmitter.

According to the determined sleeveWhen the tube wave arrives, determining a corresponding head wave time window in the full wave train, wherein the window length is 2-3 periods of the head wave, and calculating the amplitude (or average energy) A of the head wave in m receivers by using a formula 2_m：

Where AMP is the received waveform data and N is the number of sample points in the time window.

The fourth step is specifically as follows:

assuming that the amplitude spectrum of the waveform received by the receiver at depth z satisfies equation 3

Wherein S (w) and R (w) represent the amplitude spectra of the source and receiver, respectively; g (w, z) is a Green's function that controls the geometric dispersion of sound waves from the source to the receiver; t is the wave propagation time; q is a quality factor.

For different depths z₁、z₂The upper frequency spectrum ratio satisfies formula 4

Where f is the frequency and V is the wave velocity, it is generally assumed that the geometric diffusion G is frequency independent, so the last term in equation 4 is a constant that is frequency independent. Then at the same frequency there is a linear relationship between the natural logarithm of the spectral ratio and the distance between the two receivers, between which a linear fit can be made.

Therefore, we define the attenuation factor α ═ pi f/QV, and for the acoustic logging while drilling instrument, since there are multiple receivers, there is a linear relationship between any two receivers, taking the first receiver as an example, and equation 5 is satisfied

WhereinThe array attenuation coefficient received by the array receiver can be numerically calculated by a least square linear fitting method, thereby representing the attenuation factor between any two receivers.

The fifth step is specifically as follows:

counting attenuation factors (ATTN) in five to twenty wells in the block, intersecting the attenuation factors (ATTN) with a conventional well cementation quality evaluation method (CBL), fitting a functional relation between the ATTN and acoustic amplitude logging, and calculating a cementation index according to a formula 6:

wherein CBL_FPRepresenting the magnitude of the head wave at the free casing, CBL_MNRepresenting the head wave amplitude at full cementation. Therefore, the well cementation quality evaluation can be carried out according to the well cementation quality evaluation standards of different oil fields.

The invention also provides a processing device for carrying out well cementation quality evaluation by the acoustic wave while drilling, which comprises the following steps:

comprises a processor, which is suitable for realizing various instructions; and a storage device adapted to store a plurality of instructions, the instructions adapted to be loaded and executed by a processor;

waveform preprocessing and band-pass filtering; specifically, a digital signal processor can be used for filtering the acquired array waveform to eliminate low-frequency and high-frequency logging noise, and then the inherent sound insulation stop band of the while-drilling instrument is used for band-pass filtering to eliminate the interference of the drill collar wave in the first wave;

calculating the energy of the head wave; presetting a casing wave slowness, calculating the arrival of the casing wave slowness, windowing and calculating waveform energy to obtain first wave energy on a plurality of receivers;

calculating an attenuation factor; performing linear fitting according to the head wave energy obtained by the plurality of receivers to obtain head wave attenuation factors in the array span;

calculating a cementation index; according to the relation formula obtained by fitting the attenuation factor and the CBL and the cementation index calculation formula, the cementation index can be calculated by directly utilizing the attenuation factor.

The invention has the following advantages and positive effects:

the invention considers the field practical application, and in the drilling process, the drilling instrument can measure the last opened well cementation quality in the process of lifting and lowering the sliding hole. The method for measuring the sliding hole greatly shortens the logging time while ensuring the data quality and the acquisition speed, has the effects of reducing cost and improving efficiency, and is particularly suitable for deep water and deep layer logging environments. In addition, the characteristics of the logging-while-drilling instrument are utilized to replace a cable crawler, the centering effect of the logging instrument in a large-size casing pipe can be ensured to be good, and the measured sound wave information can accurately and comprehensively evaluate the well cementation quality.

Drawings

FIG. 1 is a schematic diagram of an acoustic logging while drilling model and apparatus according to the present invention.

FIG. 2 is a processing flow of the method for evaluating the well cementation quality by using acoustic logging while drilling data according to the present invention.

FIG. 3 is a structural diagram of the apparatus for evaluating cementing quality by acoustic logging while drilling provided by the present invention.

FIG. 4-a is a spectrum diagram of a while drilling apparatus; fig. 4-b is a comparison of waveforms before and after filtering with an acoustic stop band.

FIG. 5 is a cross plot of attenuation factors ATTN and CBL for the case of cables;

FIG. 6 is a diagram of treatment results of acoustic cementing while drilling.

Numbering in the figures: 1. mud, 2, a drill collar, 3, a casing, 4, a stratum, 5, a cement sheath, 6, a waveform diagram before filtration of a sound insulation stop band, 7 and an inherent stop band of a while-drilling instrument, and a waveform diagram after filtration of 8 and the inherent stop band.

The specific implementation mode is as follows:

as shown in figures 1 and 2, the invention provides a method for evaluating the cementing quality by sound waves while drilling, which comprises the following working procedures:

the method comprises the following steps of firstly, preprocessing while-drilling data, restoring a waveform curve, acquiring full-wave column data of acoustic waves while drilling, and filtering according to requirements, namely removing low-frequency and high-frequency logging noises in a wave column;

secondly, according to the inherent stopband of the while-drilling instrument, for example, FIG. 4-a is the inherent stopband of a certain logging-while-drilling instrument, band-pass filtering processing is carried out by utilizing the frequency range, and FIG. 4-b is a waveform diagram before and after band-pass filtering in sequence from top to bottom, so that the drill collar wave in the first wave after filtering is suppressed, and the rest is mainly casing wave;

calculating head wave energy, and calculating the propagation time from the transmitter to each receiver, namely the arrival time of the casing wave, according to the slowness of the casing wave and the source distance of the array receivers; determining the arrival time of the casing wave by using the arrival time, and calculating the energy of the first wave in the window according to the window length;

calculating array attenuation, performing least square linear fitting under a natural logarithmic coordinate system according to the obtained casing wave energy, wherein the slope obtained by fitting is the solved array attenuation factor;

and fifthly, calculating the cementation index, intersecting the attenuation factor obtained by logging with the same cable logging instrument under the same well hole condition of the block with acoustic amplitude logging (CBL), fitting to obtain a relational expression (shown in figure 5), and calculating the cementation index BI under the condition of drilling according to a calculation formula for calculating the cementation index by using the CBL.

Sixthly, evaluating the well cementation quality, namely performing comprehensive evaluation on the well cementation quality by using a cementation index curve according to different oil field well cementation quality evaluation standards;

and step seven, judging whether all the depth points are processed or not, if so, finishing the processing, otherwise, repeating the steps from two to six until all the depth points are processed.

The second step is specifically as follows: and filtering treatment is carried out according to the inherent drill collar wave sound insulation stop band of the while-drilling instrument, the drill collar wave in the head wave is filtered to the maximum extent, and the casing wave is reserved so as to obtain the subsequent casing wave amplitude and attenuation.

The third step is specifically as follows: extracting a casing wave time difference curve in a waveform while drilling by using a time-slowness correlation (STC) method, obtaining a head wave time difference (S) from the casing wave time difference curve, and determining the arrival time (T) of the casing wave according to a formula 1:

T＝S×D (1)

where D represents the distance between each receiver and the transmitter.

Determining a corresponding head wave time window in the full wave train according to the determined arrival time of the casing wave, wherein the window length is 2-3 periods of the head wave, and calculating the amplitude (or average energy) A of the head wave in the m receivers by using a formula 2_m：

Where AMP is the received waveform data and N is the number of sample points in the time window.

The fourth step is specifically as follows: performing least-squares linear fitting (formula 3) under a natural logarithmic coordinate by using the head wave amplitude of each receiver obtained in the steps,

whereinThe array attenuation coefficient received by the array receiver can be numerically calculated by a least square linear fitting method, thereby representing the attenuation factor between any two receivers.

The fifth step is specifically as follows: solving the sound amplitude curve of the well by using the formed attenuation factor and the CBL fitting formula in the block, and calculating the cementation index of the well by using a formula 4:

based on the same inventive concept, the embodiment of the invention also provides a device for evaluating and processing the cementing quality by using the acoustic wave while drilling, which is described in the following embodiment. Because the principle of solving the problems by the device is similar to the method for evaluating and treating the cementing quality by the sound wave while drilling, the implementation of the device can refer to the implementation of the method for evaluating and treating the cementing quality by the sound wave while drilling, and repeated parts are not repeated. As used hereinafter, the term "module" may include a combination of software and/or hardware that implements a predetermined function. Although the apparatus described in the following examples is preferably implemented in software, an implementation in hardware, or a combination of software and hardware is also possible. Please refer to fig. 3, which is a structural diagram of a device for evaluating the cementing quality by acoustic waves while drilling according to an embodiment of the present application, wherein the device includes a processor, and is adapted to implement various instructions; and a storage device adapted to store a plurality of instructions, the instructions adapted to be loaded and executed by a processor;

waveform preprocessing and band-pass filtering, specifically, a digital signal processor can be used for filtering the acquired array waveform to eliminate low-frequency and high-frequency logging noise, and then the inherent sound insulation stop band of the while-drilling instrument is used for band-pass filtering to eliminate the interference of the drill collar wave in the first wave;

calculating the head wave energy, specifically calculating the arrival of the preset sleeve wave slowness, windowing and calculating the waveform energy to obtain the head wave energy on a plurality of receivers;

calculating attenuation factors, specifically performing linear fitting according to head wave energy obtained by a plurality of receivers to obtain head wave attenuation factors in the array span;

and (4) calculating the cementation index, wherein the cementation index can be directly calculated by using the attenuation factor according to a relational expression obtained by fitting the attenuation factor and the CBL and a cementation index calculation formula.

The application effect of the method for evaluating the well cementation quality by acoustic logging while drilling is further explained below by combining specific example processing results.

FIG. 6 shows the result of long-source-distance while-drilling array acoustic cementing treatment. The first trace in the graph is a natural gamma curve; the second path is a monopole full wave train waveform; the third path is waveform data obtained by filtering the full wave train waveform between 9kHz and 13 kHz; the fourth path is a time difference curve of casing waves and longitudinal waves after filtering of 9kHz-13kHz and a coherence map thereof; the fifth path is waveform data of the drill collar waves obtained by filtering the full wave train waveform between 2kHz and 4 kHz; the sixth time difference curve and coherence map of drill collar wave and longitudinal wave after 2kHz-4kHz filtering; the seventh step is to extract the windowing time of the third waveform data; the eighth line is a sleeve wave amplitude curve extracted by the seventh wave form; the ninth path is the contrast of the CBL curve and the amplitude of the casing wave received by the first receiver with long source distance; the tenth is the array attenuation curve; the eleventh step is respectively calculating the cementing index by utilizing CBL and array attenuation; the twelfth step is a cementation index obtained by utilizing the wave amplitude of the long-source-distance casing; the thirteenth is an acoustic impedance curve; the fourteenth path is an acoustic impedance imaging graph; the fifteenth is the amplitude of the drill collar wave extracted by utilizing the fifth wave; the sixteenth is the array attenuation of the drill collar waves.

As can be seen from the result diagram, the amplitude and the attenuation curve calculated by the method for evaluating the well cementation quality by using the acoustic wave while drilling have better display on the well cementation quality. However, the time of acoustic logging while drilling and ultrasonic impedance (MUIL) logging is later than that of conventional well cementation quality logging (CBL), and a series of operations such as strengthening well fluid, fracturing and the like exist between the acoustic logging while drilling and the ultrasonic impedance (MUIL), so that a certain deviation exists before two well cementation conclusions. The cementing quality of the upper well section (630-745m) is poor, the head wave amplitude is low, and the attenuation factor is small; the cementing quality of the middle well section (745-945m) becomes good, the amplitudes of the CBL and the head part become small, the attenuation factor value becomes large, and the well sections are matched with the results of conventional well cementation quality evaluation and acoustic impedance well cementation quality evaluation. Therefore, the method can evaluate the well cementation quality accurately. The feasibility of the method and the wide application prospect are proved by the good coincidence and the good correspondence shown by the field application example.