A method and device for inversion of casing wave attenuation in acoustic logging while drilling

Abstract

The present invention discloses a method and device for inversion of casing wave attenuation in acoustic logging while drilling. According to the technical solution provided by the present invention, an inversion objective function of acoustic casing wave attenuation while drilling is constructed according to the signal amplitude relationship between each receiving transducer in the receiving transducer array; monopole acoustic logging while drilling in cased wells is performed at multiple detection positions within the logging depth interval to obtain an array waveform signal corresponding to each detection position; for each detection position, the energy value of the first wave signal of each receiving transducer corresponding to the detection position is determined according to the array waveform signal corresponding to the detection position, the energy value of the first wave signal of each receiving transducer is substituted into the inversion objective function and calculated using an optimization algorithm to obtain the casing wave attenuation rate corresponding to the detection position; based on the casing wave attenuation rates corresponding to multiple detection positions, a casing wave attenuation rate curve corresponding to the logging depth interval is obtained. The present invention can conveniently obtain a casing wave attenuation rate curve.

Description

Technical Field

[0001] The invention relates to the field of sonic surveying, and in particular to a casing wave attenuation inversion method and device for sonic logging while drilling. Background Art

[0002] With the development of oil drilling technology, in the process of oil and gas field development, if the cementing quality is not good, it will lead to interlayer fluid cross-channeling, increasing the cost of exploration and development. Therefore, it is necessary to inject cement between the casing and the formation to ensure the quality of cementing, and further ensure the safe development and environmental protection of the oil and gas field. After injecting cement between the casing and the formation, it is necessary to understand the bonding condition of cement and formation through cementing quality evaluation methods.

[0003] In the prior art, the traditional cable acoustic cementing quality evaluation instrument is not applicable to horizontal wells or high-angle wells, and the acoustic cementing quality evaluation instrument while drilling is needed to solve this problem. However, when the acoustic cementing quality evaluation instrument while drilling uses a monopole mode (i.e., a monopole sound source) to measure cementing quality in a cased well, the drill collar wave and the casing wave arrive almost at the same time, so the drill collar wave signal will overlap with the casing wave signal, and it is impossible to directly use the amplitude of the casing wave signal to evaluate cementing quality. Summary of the invention

[0004] In view of the above problems, the present invention is proposed to provide a method for inverting casing waves of acoustic logging while drilling and a corresponding device for inverting casing waves of acoustic logging while drilling that overcome the above problems or at least partially solve the above problems.

[0005] According to one aspect of the present invention, a method for casing wave attenuation inversion of acoustic logging while drilling is provided, comprising:

[0006] According to the signal amplitude relationship between each receiving transducer in the receiving transducer array, the inversion objective function of the while-drilling acoustic casing wave attenuation is constructed;

[0007] Perform cased well monopole acoustic logging while drilling at multiple detection positions within the logging depth interval to obtain an array waveform signal corresponding to each detection position;

[0008] For each detection position, the energy value of the first wave signal of each receiving transducer corresponding to the detection position is determined according to the array waveform signal corresponding to the detection position, the energy value of the first wave signal of each receiving transducer is brought into the inversion objective function and calculated using the optimization algorithm to obtain the casing wave attenuation rate corresponding to the detection position;

[0009] According to the casing wave attenuation rates corresponding to the plurality of detection positions, a casing wave attenuation rate curve corresponding to the logging depth interval is obtained.

[0010] In the above scheme, the inversion objective function includes the signal amplitude ratio between the drill collar wave signal and the casing wave signal corresponding to the first receiving transducer in the receiving transducer array and the casing wave attenuation rate of the receiving transducer array.

[0011] In the above scheme, constructing the inversion objective function of the attenuation of the acoustic casing wave while drilling according to the signal amplitude relationship between each receiving transducer in the receiving transducer array further includes:

[0012] constructing a signal amplitude ratio function between two receiving transducers at different positions in the receiving transducer array according to the position relationship and signal amplitude relationship between the first receiving transducer and other receiving transducers in the receiving transducer array;

[0013] According to the signal amplitude ratio function between two receiving transducers at different positions, the measurement error and the combination mode of the signals of each receiving transducer in the receiving transducer array, the inversion objective function of the while drilling acoustic casing wave attenuation is constructed.

[0014] In the above scheme, for each detection position, determining the energy value of the first wave signal of each receiving transducer corresponding to the detection position according to the array waveform signal corresponding to the detection position further includes:

[0015] For each detection position, performing a Hilbert transform on the array waveform signal corresponding to the detection position, and calculating an envelope curve of the array waveform signal;

[0016] According to the envelope curve, the signal energy value of each receiving transducer within the preset time window is calculated as the energy value of the first wave signal of each receiving transducer.

[0017] In the above scheme, the energy value of the first wave signal is calculated using the following formula:

[0018]

[0019] Among them, E n is the energy value of the first wave signal received by the nth receiving transducer; T n is the starting time of the preset time window corresponding to the nth receiving transducer; T w is the window length of the preset time window; S n (t) is the envelope curve.

[0020] In the above solution, the first wave signal includes: a drill collar wave signal and a casing wave signal.

[0021] In the above scheme, constructing a signal amplitude ratio function between two receiving transducers at different positions in the receiving transducer array according to the position relationship and signal amplitude relationship between the first receiving transducer and other receiving transducers in the receiving transducer array further includes:

[0022] The signal of the second receiving transducer at a distance x+Δ1 from the transmitting transducer is:

[0023]

[0024] The signal of the third receiving transducer at a distance x+Δ2 from the transmitting transducer is:

[0025]

[0026] Wherein, Amp is the receiving signal received by the receiving transducer; AmpCol(TR1) is the drill collar wave signal received by the first receiving transducer; AmpCas(TR1) is the casing wave signal received by the first receiving transducer; TR1 is the distance between the first receiving transducer and the transmitting transducer in the receiving transducer array; x+Δ1 is the distance between the second receiving transducer and the transmitting transducer; x+ Δ2 is the distance between the third receiving transducer and the transmitting transducer; x is the distance between the receiving transducer used as a reference in the receiving transducer array and the transmitting transducer; the first receiving transducer is the first receiving transducer from the bottom to the top in the receiving transducer array; the second receiving transducer and the third receiving transducer are two receiving transducers at different positions in the receiving transducer array; ATTCRE is the drill collar wave attenuation rate of the receiving transducer array; ATTNRE is the casing wave attenuation rate of the receiving transducer array;

[0027] The signal amplitude ratio function between two receiving transducers at different positions in the receiving transducer array is:

[0028]

[0029] Wherein, R is the signal amplitude ratio between the drill collar wave signal and the casing wave signal received by the first receiving transducer,

[0030] In the above scheme, the inversion objective function of the attenuation of the acoustic casing wave while drilling is constructed based on the signal amplitude ratio function between two receiving transducers at different positions, the measurement error and the combination mode of the signals of each receiving transducer in the receiving transducer array, further comprising:

[0031] A signal amplitude ratio function including a measurement error is obtained according to the signal amplitude ratio function between two receiving transducers at different positions in the receiving transducer array and the measurement error:

[0032]

[0033] Wherein, δ(x, Δ1, Δ2) is the measurement error of the receiving transducer array;

[0034] The number of combinations of signals of each receiving transducer in the receiving transducer array is determined according to the number of receiving transducers in the receiving transducer array, and the inversion objective function of the while drilling acoustic casing wave attenuation is obtained; wherein the inversion objective function Ω(ATTNRE, R) is:

[0035]

[0036] Wherein, n is the number of combinations of signals of each receiving transducer in the receiving transducer array.

[0037] In the above scheme, the step of substituting the energy value of the first wave signal of each receiving transducer into the inversion objective function and performing calculation using an optimization algorithm to obtain the casing wave attenuation rate corresponding to the detection position further includes:

[0038] An optimization algorithm is used for the inversion objective function to search for the signal amplitude ratio between the drill collar wave signal and the casing wave signal received by the first receiving transducer corresponding to the global minimum value of the inversion objective function and the casing wave attenuation rate of the receiving transducer array corresponding to the detection position.

[0039] According to another aspect of the present invention, a casing wave attenuation inversion device for acoustic logging while drilling is provided, comprising: a construction module, a detection module, a calculation module and a determination module; wherein:

[0040] The construction module is used to construct an inversion objective function of the attenuation of the acoustic casing wave while drilling according to the signal amplitude relationship between each receiving transducer in the receiving transducer array;

[0041] The detection module is used to perform monopole acoustic logging while drilling in a cased well at multiple detection positions within the logging depth interval, and obtain an array waveform signal corresponding to each detection position;

[0042] The operation module is used to determine, for each detection position, the energy value of the first wave signal of each receiving transducer corresponding to the detection position according to the array waveform signal corresponding to the detection position, substitute the energy value of the first wave signal of each receiving transducer into the inversion objective function and perform operation using the optimization algorithm to obtain the casing wave attenuation rate corresponding to the detection position;

[0043] The determination module is used to obtain the casing wave attenuation rate curve corresponding to the logging depth interval according to the casing wave attenuation rates corresponding to multiple detection positions.

[0044] According to the technical solution provided by the present invention, an inversion objective function of casing wave attenuation while drilling acoustic wave is constructed according to the signal amplitude relationship between each receiving transducer in the receiving transducer array; monopole acoustic logging while drilling of casing well is performed at multiple detection positions within the logging depth interval to obtain the array waveform signal corresponding to each detection position; for each detection position, the energy value of the first wave signal of each receiving transducer corresponding to the detection position is determined according to the array waveform signal corresponding to the detection position, the energy value of the first wave signal of each receiving transducer is brought into the inversion objective function and calculated using the optimization algorithm to obtain the casing wave attenuation rate corresponding to the detection position; according to the casing wave attenuation rates corresponding to multiple detection positions, the casing wave attenuation rate curve corresponding to the logging depth interval is obtained. This solves the problem in the prior art that the casing wave signal and the drill collar wave signal overlap in the existing cementing quality evaluation instrument of the while drilling acoustic logging, and the amplitude of the casing wave signal cannot be directly used for cementing quality evaluation to truly reflect the cement and formation bonding conditions.

[0045] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0047] Figure 1 A schematic flow chart of a method for casing wave attenuation inversion of acoustic logging while drilling according to an embodiment of the present invention is shown;

[0048] Figure 2 The figure shows an envelope curve of a while drilling acoustic wave signal and a schematic diagram of energy calculation according to an embodiment of the present invention;

[0049] Figure 3 A schematic diagram of a process for determining a casing wave attenuation rate curve in a logging depth interval according to an embodiment of the present invention is shown;

[0050] Figure 4A schematic diagram of the structure of a while-drilling sonic instrument in a cased well according to an embodiment of the present invention is shown;

[0051] Figure 5 shows a target function curve diagram based on different ATTNRE and R according to one embodiment of the present invention;

[0052] Figure 6 A signal energy curve diagram of each receiving transducer at different positions according to an embodiment of the present invention is shown;

[0053] Figure 7 A schematic diagram showing the calculation of casing wave attenuation rate of monopolar acoustic wave signal while drilling according to an embodiment of the present invention is shown;

[0054] Figure 8 A schematic diagram of a casing wave attenuation inversion device for acoustic logging while drilling according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0055] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0056] Figure 1 FIG. 4 is a flow chart showing a method for inverting casing wave attenuation in acoustic logging while drilling according to an embodiment of the present invention. Figure 1 As shown, the method comprises the following steps:

[0057] Step S101: construct an inversion objective function of while-drilling acoustic casing wave attenuation according to the signal amplitude relationship between each receiving transducer in the receiving transducer array.

[0058] Specifically, the inversion objective function includes a signal amplitude ratio between a drill collar wave signal and a casing wave signal corresponding to a first receiving transducer in the receiving transducer array and a casing wave attenuation rate of the receiving transducer array.

[0059] Specifically, according to the positional relationship and signal amplitude relationship between the first receiving transducer and other receiving transducers in the receiving transducer array, a signal amplitude ratio function between two receiving transducers at different positions in the receiving transducer array is constructed; according to the signal amplitude ratio function between two receiving transducers at different positions, the measurement error and the combination mode of the signals of each receiving transducer in the receiving transducer array, an inversion objective function of the attenuation of acoustic casing waves while drilling is constructed.

[0060] Step S102 , performing cased well while drilling monopole acoustic logging at multiple detection positions within the logging depth interval, and obtaining an array waveform signal corresponding to each detection position.

[0061] Preferably, after acquiring the array waveform signal corresponding to the detection position, it is determined whether the acquisition of the array waveform signals corresponding to all the detection positions in the logging depth interval is completed, and if completed, step S103 is continued.

[0062] Step S103, for each detection position, determine the energy value of the first wave signal of each receiving transducer corresponding to the detection position according to the array waveform signal corresponding to the detection position, substitute the energy value of the first wave signal of each receiving transducer into the inversion objective function and calculate it using the optimization algorithm to obtain the casing wave attenuation rate corresponding to the detection position.

[0063] Specifically, for each detection position, a Hilbert transform is performed on the array waveform signal corresponding to the detection position, and an envelope curve of the array waveform signal is calculated; based on the envelope curve, the signal energy value of each receiving transducer within a preset time window is calculated as the energy value of the first wave signal of each receiving transducer.

[0064] Preferably, the energy value of the first wave signal is calculated using the following formula:

[0065]

[0066] Among them, E n is the energy value of the first wave signal received by the nth receiving transducer; T n is the starting time of the preset time window corresponding to the nth receiving transducer; T w is the window length of the preset time window; S n (t) is the envelope curve. Figure 2 As shown, Figure 2 The figure shows an envelope curve of a while drilling acoustic wave signal and a schematic diagram of energy calculation according to an embodiment of the present invention; wherein:

[0067] The solid line is the array waveform signal at different detection positions, and the dotted line is the envelope curve of the array waveform signal at different detection positions; the width of the dotted line frame is the window length T of the preset time window. w , the curve contained in the dotted box is the first wave signal curve received by each receiving transducer.

[0068] Optionally, the maximum value of the signal energy of each receiving transducer within a preset time window may also be obtained according to the envelope curve as the energy value of the first wave signal of each receiving transducer.

[0069] Specifically, an optimization algorithm is used for the inversion objective function to search for the signal amplitude ratio between the drill collar wave signal and the casing wave signal received by the first receiving transducer corresponding to the global minimum value of the inversion objective function and the casing wave attenuation rate of the receiving transducer array corresponding to the detection position.

[0070] Step S104, obtaining a casing wave attenuation rate curve corresponding to the logging depth interval according to the casing wave attenuation rates corresponding to the plurality of detection positions.

[0071] Figure 3 FIG. 4 is a schematic diagram showing a flow chart of determining a casing wave attenuation rate curve in a logging depth interval according to an embodiment of the present invention. Figure 3 As shown, the method comprises the following steps:

[0072] Step S301 : constructing a signal amplitude ratio function between two receiving transducers at different positions in the receiving transducer array according to the position relationship and signal amplitude relationship between the first receiving transducer and other receiving transducers in the receiving transducer array.

[0073] Specifically, the relationship between the signal amplitudes of a receiving transducer at a distance x from the transmitting transducer and a receiving transducer at a distance x+Δ from the transmitting transducer is as follows:

[0074]

[0075] Therefore, the apparent attenuation of the two receiver signals is:

[0076]

[0077] Figure 4 FIG. 2 shows a schematic diagram of a while-drilling acoustic wave instrument in a cased well according to an embodiment of the present invention. Figure 4 As shown, the distance between the transmitting transducer and the first receiving transducer is TR1, and the first receiving transducer is the first receiving transducer from the bottom to the top in the receiving transducer array; the distance between the transmitting transducer and any other receiving transducer is TRX; ATTCRE is the drill collar wave attenuation rate of the receiving transducer array; ATTNRE is the casing wave attenuation rate of the receiving transducer array; ATTCTR1 is the drill collar wave attenuation rate of the drill collar part between the transmitting transducer and the first receiving transducer; ATTNTR1 is the casing wave attenuation rate of the drill collar part between the transmitting transducer and the first receiving transducer.

[0078] Preferably, the receiving signal of the first receiving transducer is the sum of the drill collar wave signal and the casing wave signal:

[0079] Amp(TR1)=AmpCol(TR1)+AmpCas(TR1) Formula 4

[0080] Among them, Amp is the receiving signal received by the receiving transducer; AmpCol (TR1) is the drill collar wave signal received by the first receiving transducer; AmpCas (TR1) is the casing wave signal received by the first receiving transducer.

[0081] Then the signal of the receiving transducer at a distance x from the transmitting transducer can be expressed as:

[0082]

[0083] Wherein, x is the distance between a certain receiving transducer and the transmitting transducer; Amp(x) is the receiving signal received by the receiving transducer; TR1 is the distance between the first receiving transducer and the transmitting transducer; and x-TR1 is the distance between the receiving transducer and the first receiving transducer.

[0084] The signal of the receiving transducer at a distance x+Δ from the transmitting transducer can be expressed as:

[0085]

[0086] Wherein, x+Δ is the distance between another receiving transducer and the transmitting transducer; Amp(x+Δ) is the receiving signal received by the receiving transducer; and x-TR1+Δ is the distance between the receiving transducer and the first receiving transducer.

[0087] Preferably, two receiving transducers at different positions in the receiving transducer array are respectively referred to as a second receiving transducer and a third receiving transducer;

[0088] Then the signal of the second receiving transducer at a distance x+Δ1 from the transmitting transducer can be expressed as:

[0089]

[0090] The signal of the third receiving transducer at a distance x+Δ2 from the transmitting transducer can be expressed as:

[0091]

[0092] Wherein, x+Δ1 is the distance between the second receiving transducer and the transmitting transducer; x+Δ2 is the distance between the third receiving transducer and the transmitting transducer; x is the distance between the receiving transducer used as a reference in the receiving transducer array and the transmitting transducer;

[0093] Preferably, since the second receiving transducer and the third receiving transducer are any two receiving transducers in the receiving transducer array, the second receiving transducer or the third receiving transducer may also be specifically the first receiving transducer.

[0094] Based on the signals of the second receiving transducer and the third receiving transducer in Formula 7 and Formula 8, the signal amplitude ratio function between two receiving transducers at different positions in the receiving transducer array is:

[0095]

[0096] The above formula can be converted to:

[0097]

[0098] The above formula can eliminate the excitation energy A0 of the transducer and the percentage α of the emission energy entering the drill collar energy, and further convert it into:

[0099]

[0100] Wherein, R is the signal amplitude ratio between the drill collar wave signal and the casing wave signal received by the first receiving transducer,

[0101]

[0102] Formula 11 is a function of the signal amplitude ratio between two receiving transducers at different positions in the receiving transducer array.

[0103] Step S302: construct an inversion objective function of while-drilling acoustic casing wave attenuation.

[0104] Specifically, an inversion objective function of acoustic casing wave attenuation while drilling is constructed according to a signal amplitude ratio function between two receiving transducers at different positions, a measurement error, and a combination of signals of each receiving transducer in the receiving transducer array.

[0105] Preferably, when the drill collar wave attenuation rate ATTCRE is known, Formula 11 can be further converted to:

[0106]

[0107] Preferably, there are two unknown parameters in formula 13, namely, the casing wave attenuation rate ATTNRE of the receiver array and the signal amplitude ratio R between the drill collar wave signal and the casing wave signal received by the first receiving transducer. In actual measurement, the measurement signal will be affected by noise, resulting in measurement error, and the error value can be recorded as δ(x, Δ1, Δ2). Therefore, according to the signal amplitude ratio function between two receiving transducers at different positions in the receiving transducer array and the measurement error, the signal amplitude ratio function containing the measurement error is obtained:

[0108]

[0109] Wherein, δ(x, Δ1, Δ2) is the measurement error of the receiving transducer array.

[0110] Specifically, the number of combinations of signals of each receiving transducer in the receiving transducer array is determined according to the number of receiving transducers in the receiving transducer array, and the inversion objective function of the while drilling acoustic casing wave attenuation is obtained; wherein the inversion objective function Ω(ATTNRE, R) is:

[0111]

[0112] Wherein, n is the number of combinations of signals of each receiving transducer in the receiving transducer array. Assuming that the receiving transducer array includes 8 receiving transducers, the number of combinations is 56.

[0113] Figure 5 FIG. 4 shows an objective function curve diagram based on different ATTNRE and R according to an embodiment of the present invention.

[0114] Step S303, performing cased well acoustic logging while drilling in the logging depth interval, and determining the energy value of the first wave signal of each receiving transducer corresponding to the detection position.

[0115] Specifically, for each detection position, a Hilbert transform is performed on the array waveform signal corresponding to the detection position, and an envelope curve of the array waveform signal is calculated; based on the envelope curve, the signal energy value of each receiving transducer within a preset time window is calculated as the energy value of the first wave signal of each receiving transducer.

[0116] Figure 6 The signal energy curve diagram of each receiving transducer at different positions according to an embodiment of the present invention is shown.

[0117] The source distance on the horizontal axis is the distance between the receiving transducer and the transmitting transducer at different positions in the receiving transducer array; the vertical axis is the signal amplitude of each receiving transducer at different positions, and the signal energy is reflected by the signal amplitude.

[0118] Step S304: obtaining the casing wave attenuation rate corresponding to each detection position according to the energy value of the first wave signal of each receiving transducer.

[0119] Specifically, the energy value of the first wave signal of each receiving transducer is substituted into the inversion objective function, and an optimization algorithm is used for the inversion objective function to search for the signal amplitude ratio between the drill collar wave signal and the casing wave signal received by the first receiving transducer corresponding to the global minimum value of the inversion objective function and the casing wave attenuation rate of the receiving transducer array corresponding to the detection position.

[0120] by Figure 5 The objective function curve in Figure 6 Taking the energy value of the first wave signal of each receiving transducer as an example, it can be known that when the distance between the first receiving transducer and the transmitting transducer is TR1=7ft, the distance between two adjacent receiving transducers is RR=0.5ft, the excitation energy A0 of the transducer and the percentage of the transmitting energy entering the drill collar energy α=20%, the drill collar wave attenuation rate ATTCTR1=5dB / ft of the drill collar part between the transmitting transducer and the first receiving transducer, the drill collar wave attenuation rate ATTCRE=0.5dB / ft of the receiving transducer array, the casing wave attenuation rate ATTNTR1=5dB / ft of the drill collar part between the transmitting transducer and the first receiving transducer, and the casing wave attenuation rate ATTNRE=3dB / ft, the signal amplitude ratio R1=0.1179 between the drill collar wave signal and the casing wave signal received by the first receiving transducer can be calculated by the above parameters. The minimum value Ω of the objective function is calculated by the optimization algorithm min , Ω min The corresponding R2 = 0.12, ATTNRE2 = 2.98. It can be seen that compared with the parameters of the theoretical model of the present invention, the calculation error of R is 1.7%, and the calculation error of ATTNRE is 0.7%.

[0121] Step S305, determining whether the casing wave attenuation rates of all detection positions in the logging depth interval are obtained.

[0122] Specifically, the specific method of determining whether the casing wave attenuation rate of all detection positions in the logging depth interval is obtained is not limited by the present invention;

[0123] If it is determined that the casing wave attenuation rates of all detection positions in the logging depth interval have been obtained, step S306 is executed; if it is determined that the casing wave attenuation rates of all detection positions in the logging depth interval have not been obtained, step S303 is executed again until the casing wave attenuation rates of all detection positions are obtained.

[0124] Step S306: obtaining a casing wave attenuation rate curve corresponding to the logging depth interval according to the casing wave attenuation rates corresponding to the plurality of detection positions.

[0125] Specifically, the cementing quality evaluation of the logging depth interval is completed through the casing wave attenuation rate curves corresponding to all the logging depth intervals.

[0126] Figure 7 The schematic diagram of calculating the casing wave attenuation rate of the monopole acoustic signal while drilling according to an embodiment of the present invention is shown, wherein the first track is the original monopole variable density curve of the first receiving transducer while drilling, and the signal includes the drill collar wave signal and the casing wave signal; the second track is the energy curve of the corresponding first wave signal calculated; and the third track is the real casing wave attenuation curve inverted by the present invention. As shown in the figure, the casing wave attenuation rate inverted in the 900-960m well section is about 2dB / ft, which is a free casing response; the casing wave attenuation rate inverted in the 960-1850m well section is about 4-6dB / ft, that is, the cement bonding of this well section is at a medium level; the casing wave attenuation rate inverted in the 1850-1890m well section is about 7dB / ft, that is, the cement bonding of this well section is at a good level.

[0127] According to the inversion method for casing wave attenuation of acoustic logging while drilling provided by this embodiment, an inversion objective function of acoustic casing wave attenuation while drilling is constructed according to the signal amplitude relationship between each receiving transducer in the receiving transducer array; monopole acoustic logging while drilling of the casing well is performed at multiple detection positions within the logging depth interval to obtain the array waveform signal corresponding to each detection position; for each detection position, the energy value of the first wave signal of each receiving transducer corresponding to the detection position is determined according to the array waveform signal corresponding to the detection position, and the energy value of the first wave signal of each receiving transducer is substituted into the inversion objective function and calculated using the optimization algorithm to obtain the casing wave attenuation rate corresponding to the detection position; according to the casing wave attenuation rates corresponding to multiple detection positions, the casing wave attenuation rate curve corresponding to the logging depth interval is obtained. Using the technical solution provided by the present invention, by constructing the inversion objective function, the signal received by the receiving transducer array is substituted into the inversion objective function and calculated using the optimization algorithm, the influence of the drill collar wave signal on the casing wave signal is eliminated, and the casing wave attenuation rate curve obtained is used to complete the cementing quality evaluation of the logging depth interval. This solution effectively solves the problem that existing cementing quality evaluation instruments cannot directly perform cementing quality evaluation to quickly obtain the bonding condition of cement and formation. While fully ensuring the accuracy of cementing quality evaluation, it greatly improves the efficiency of cementing quality measurement and evaluation and effectively improves the convenience of logging.

[0128] Figure 8FIG. 4 shows a schematic diagram of a casing wave attenuation inversion device for acoustic logging while drilling according to an embodiment of the present invention. Figure 8 As shown, the device includes: a construction module 801, a detection module 802, a calculation module 803 and a determination module 804; wherein,

[0129] The construction module 801 is used to construct an inversion objective function of the attenuation of the acoustic casing wave while drilling according to the signal amplitude relationship between each receiving transducer in the receiving transducer array;

[0130] Specifically, the inversion objective function includes a signal amplitude ratio between a drill collar wave signal and a casing wave signal corresponding to a first receiving transducer in the receiving transducer array and a casing wave attenuation rate of the receiving transducer array.

[0131] Specifically, according to the positional relationship and signal amplitude relationship between the first receiving transducer and other receiving transducers in the receiving transducer array, a signal amplitude ratio function between two receiving transducers at different positions in the receiving transducer array is constructed.

[0132] Preferably, the signal of the second receiving transducer at a distance x+Δ1 from the transmitting transducer is:

[0133]

[0134] The signal of the third receiving transducer at a distance x+Δ2 from the transmitting transducer is:

[0135]

[0136] Wherein, Amp is the receiving signal received by the receiving transducer; AmpCol(TR1) is the drill collar wave signal received by the first receiving transducer; AmpCas(TR1) is the casing wave signal received by the first receiving transducer; TR1 is the distance between the first receiving transducer and the transmitting transducer in the receiving transducer array; x+Δ1 is the distance between the second receiving transducer and the transmitting transducer; x+ Δ2 is the distance between the third receiving transducer and the transmitting transducer; x is the distance between the receiving transducer used as a reference in the receiving transducer array and the transmitting transducer; the first receiving transducer is the first receiving transducer from the bottom to the top in the receiving transducer array; the second receiving transducer and the third receiving transducer are two receiving transducers at different positions in the receiving transducer array; ATTCRE is the drill collar wave attenuation rate of the receiving transducer array; ATTNRE is the casing wave attenuation rate of the receiving transducer array;

[0137] The signal amplitude ratio function between two receiving transducers at different positions in the receiving transducer array is:

[0138]

[0139] Wherein, R is the signal amplitude ratio between the drill collar wave signal and the casing wave signal received by the first receiving transducer,

[0140]

[0141] Specifically, an inversion objective function of acoustic casing wave attenuation while drilling is constructed according to a signal amplitude ratio function between two receiving transducers at different positions, a measurement error, and a combination of signals of each receiving transducer in the receiving transducer array.

[0142] Preferably, a signal amplitude ratio function including the measurement error is obtained according to the signal amplitude ratio function between two receiving transducers at different positions in the receiving transducer array and the measurement error:

[0143]

[0144] Wherein, δ(x, Δ1, Δ2) is the measurement error of the receiving transducer array;

[0145] The number of combinations of signals of each receiving transducer in the receiving transducer array is determined according to the number of receiving transducers in the receiving transducer array, and the inversion objective function of the while drilling acoustic casing wave attenuation is obtained; wherein the inversion objective function Ω(ATTNRE, R) is:

[0146]

[0147] Wherein, n is the number of combinations of signals of each receiving transducer in the receiving transducer array.

[0148] The detection module 802 is used to perform cased well while drilling monopole acoustic logging at multiple detection positions within the logging depth interval, and obtain an array waveform signal corresponding to each detection position;

[0149] The operation module 803 is used to determine, for each detection position, the energy value of the first wave signal of each receiving transducer corresponding to the detection position according to the array waveform signal corresponding to the detection position, substitute the energy value of the first wave signal of each receiving transducer into the inversion objective function and perform operation using the optimization algorithm to obtain the casing wave attenuation rate corresponding to the detection position;

[0150] Specifically, for each detection position, a Hilbert transform is performed on the array waveform signal corresponding to the detection position to calculate an envelope curve of the array waveform signal;

[0151] According to the envelope curve, the signal energy value of each receiving transducer within the preset time window is calculated as the energy value of the first wave signal of each receiving transducer.

[0152] Specifically, the energy value of the first wave signal is calculated using the following formula:

[0153]

[0154] Among them, E n is the energy value of the first wave signal received by the nth receiving transducer; T n is the starting time of the preset time window corresponding to the nth receiving transducer; T w is the window length of the preset time window; S n (t) is the envelope curve.

[0155] Specifically, the first wave signal includes: a drill collar wave signal and a casing wave signal.

[0156] Specifically, an optimization algorithm is used for the inversion objective function to search for the signal amplitude ratio between the drill collar wave signal and the casing wave signal received by the first receiving transducer corresponding to the global minimum value of the inversion objective function and the casing wave attenuation rate of the receiving transducer array corresponding to the detection position.

[0157] The determination module 804 is used to obtain a casing wave attenuation rate curve corresponding to the logging depth interval according to the casing wave attenuation rates corresponding to multiple detection positions.

[0158] According to the casing wave attenuation inversion device for acoustic logging while drilling provided by this embodiment, an inversion objective function of acoustic casing wave attenuation while drilling is constructed according to the signal amplitude relationship between each receiving transducer in the receiving transducer array; monopole acoustic logging while drilling of the casing well is performed at multiple detection positions within the logging depth interval to obtain the array waveform signal corresponding to each detection position; for each detection position, the energy value of the first wave signal of each receiving transducer corresponding to the detection position is determined according to the array waveform signal corresponding to the detection position, the energy value of the first wave signal of each receiving transducer is substituted into the inversion objective function and calculated using the optimization algorithm to obtain the casing wave attenuation rate corresponding to the detection position; according to the casing wave attenuation rates corresponding to multiple detection positions, the casing wave attenuation rate curve corresponding to the logging depth interval is obtained. Using the technical device provided by the present invention, by constructing the inversion objective function, the signal received by the receiving transducer array is substituted into the inversion objective function and calculated using the optimization algorithm, the influence of the drill collar wave signal on the casing wave signal is eliminated, and the casing wave attenuation rate curve obtained is used to complete the cementing quality evaluation of the logging depth interval. This solution effectively solves the problem that existing cementing quality evaluation instruments cannot directly perform cementing quality evaluation to quickly obtain the bonding condition of cement and formation. While fully ensuring the accuracy of cementing quality evaluation, it greatly improves the efficiency of cementing quality measurement and evaluation and effectively improves the convenience of logging.

[0159] In the description provided herein, a large number of specific details are described. However, it is understood that embodiments of the present invention can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.

[0160] Similarly, it should be understood that in order to streamline the present disclosure and aid in understanding one or more of the various inventive aspects, in the above description of exemplary embodiments of the present invention, various features of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof. However, this disclosed method should not be interpreted as reflecting the intention that the claimed invention requires more features than those explicitly recited in each claim. Rather, as reflected in the claims, inventive aspects lie in less than all of the features of the individual embodiments disclosed above. Therefore, the claims that follow the detailed description are hereby expressly incorporated into the detailed description, with each claim itself serving as a separate embodiment of the present invention.

[0161] Those skilled in the art will appreciate that the modules in the devices in the embodiments may be adaptively changed and arranged in one or more devices different from the embodiments. The modules or units or components in the embodiments may be combined into one module or unit or component, and in addition they may be divided into a plurality of submodules or subunits or subcomponents. Except that at least some of such features and / or processes or units are mutually exclusive, all features disclosed in this specification (including the accompanying claims, abstracts and drawings) and all processes or units of any method or device disclosed in this manner may be combined in any combination. Unless otherwise expressly stated, each feature disclosed in this specification (including the accompanying claims, abstracts and drawings) may be replaced by an alternative feature providing the same, equivalent or similar purpose.

[0162] In addition, those skilled in the art will appreciate that, although some embodiments described herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present invention and form different embodiments. For example, in the claims, any one of the claimed embodiments may be used in any combination.

[0163] The various component embodiments of the present invention can be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof. It should be understood by those skilled in the art that a microprocessor or digital signal processor (DSP) can be used in practice to implement some or all of the functions of some or all of the components in the embodiments of the present invention. The present invention can also be implemented as a device or apparatus program (e.g., computer program and computer program product) for executing part or all of the methods described herein. Such a program implementing the present invention can be stored on a computer-readable medium, or can have the form of one or more signals. Such a signal can be downloaded from an Internet website, or provided on a carrier signal, or provided in any other form.

[0164] It should be noted that the above embodiments illustrate the present invention rather than limit it, and that those skilled in the art may design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference symbol between brackets should not be constructed as a limitation to the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "one" or "an" preceding an element does not exclude the presence of multiple such elements. The present invention may be implemented by means of hardware including several different elements and by means of appropriately programmed computers. In a unit claim that lists several devices, several of these devices may be embodied by the same hardware item. The use of the words first, second, and third, etc. does not indicate any order. These words may be interpreted as names.

Claims

1. A casing wave attenuation inversion method for acoustic logging while drilling, comprising: According to the signal amplitude relationship between each receiving transducer in the receiving transducer array, the inversion objective function of the while-drilling acoustic casing wave attenuation is constructed; Perform cased well monopole acoustic logging while drilling at multiple detection positions within the logging depth interval to obtain an array waveform signal corresponding to each detection position; For each detection position, the energy value of the first wave signal of each receiving transducer corresponding to the detection position is determined according to the array waveform signal corresponding to the detection position, the energy value of the first wave signal of each receiving transducer is substituted into the inversion objective function and calculated using the optimization algorithm to obtain the casing wave attenuation rate corresponding to the detection position; According to the casing wave attenuation rates corresponding to the plurality of detection positions, a casing wave attenuation rate curve corresponding to the logging depth interval is obtained; Wherein, constructing the inversion objective function of the attenuation of the acoustic casing wave while drilling according to the signal amplitude relationship between each receiving transducer in the receiving transducer array further comprises: Constructing a signal amplitude ratio function between two receiving transducers at different positions in the receiving transducer array according to the position relationship and signal amplitude relationship between the first receiving transducer and other receiving transducers in the receiving transducer array; According to the signal amplitude ratio function between two receiving transducers at different positions, the measurement error and the combination mode of the signals of each receiving transducer in the receiving transducer array, the inversion objective function of the while drilling acoustic casing wave attenuation is constructed.

2. The method according to claim 1, wherein: The inversion objective function includes a signal amplitude ratio between a drill collar wave signal and a casing wave signal corresponding to a first receiving transducer in the receiving transducer array and a casing wave attenuation rate of the receiving transducer array.

3. The method according to claim 1, wherein: The step of determining, for each detection position, the energy value of the first wave signal of each receiving transducer corresponding to the detection position according to the array waveform signal corresponding to the detection position further includes: For each detection position, performing a Hilbert transform on the array waveform signal corresponding to the detection position, and calculating an envelope curve of the array waveform signal; According to the envelope curve, the signal energy value of each receiving transducer within the preset time window is calculated as the energy value of the first wave signal of each receiving transducer.

4. The method according to claim 3, wherein: The energy value of the first wave signal is calculated using the following formula: Among them, E n is the energy value of the first wave signal received by the nth receiving transducer; T n is the starting time of the preset time window corresponding to the nth receiving transducer; T w is the window length of the preset time window; S n (t) is the envelope curve.

5. The method according to claim 1, wherein: The first wave signal includes: a drill collar wave signal and a casing wave signal.

6. The method according to claim 1, wherein: The step of constructing a signal amplitude ratio function between two receiving transducers at different positions in the receiving transducer array according to the position relationship and signal amplitude relationship between the first receiving transducer and other receiving transducers in the receiving transducer array further comprises: The signal of the second receiving transducer at a distance x+Δ1 from the transmitting transducer is: The signal of the third receiving transducer at a distance x+Δ2 from the transmitting transducer is: Wherein, Amp is the receiving signal received by the receiving transducer; AmpCol(TR1) is the drill collar wave signal received by the first receiving transducer; AmpCas(TR1) is the casing wave signal received by the first receiving transducer; TR1 is the distance between the first receiving transducer and the transmitting transducer in the receiving transducer array; x+Δ1 is the distance between the second receiving transducer and the transmitting transducer; x+Δ2 is the distance between the third receiving transducer and the transmitting transducer; x is the distance between the receiving transducer used as a reference in the receiving transducer array and the transmitting transducer; the first receiving transducer is the first receiving transducer from bottom to top in the receiving transducer array; the second receiving transducer and the third receiving transducer are two receiving transducers at different positions in the receiving transducer array; ATTCRE is the drill collar wave attenuation rate of the receiving transducer array; ATTNRE is the casing wave attenuation rate of the receiving transducer array; The signal amplitude ratio function between two receiving transducers at different positions in the receiving transducer array is: Wherein, R is the signal amplitude ratio between the drill collar wave signal and the casing wave signal received by the first receiving transducer, 7. The method according to claim 6, wherein: The inversion objective function of the attenuation of the acoustic casing wave while drilling is constructed based on the signal amplitude ratio function between two receiving transducers at different positions, the measurement error and the combination mode of the signals of each receiving transducer in the receiving transducer array further comprises: A signal amplitude ratio function including a measurement error is obtained according to the signal amplitude ratio function between two receiving transducers at different positions in the receiving transducer array and the measurement error: Wherein, δ(x, Δ1, Δ2) is the measurement error of the receiving transducer array; The number of combinations of signals of each receiving transducer in the receiving transducer array is determined according to the number of receiving transducers in the receiving transducer array, and the inversion objective function of the while drilling acoustic casing wave attenuation is obtained; wherein the inversion objective function Ω(ATTNRE, R) is: Wherein, n is the number of combinations of signals of each receiving transducer in the receiving transducer array.

8. The method according to any one of claims 1 to 7, wherein: Substituting the energy value of the first wave signal of each receiving transducer into the inversion objective function and performing calculation using an optimization algorithm to obtain the casing wave attenuation rate corresponding to the detection position further includes: An optimization algorithm is used for the inversion objective function to search for the signal amplitude ratio between the drill collar wave signal and the casing wave signal received by the first receiving transducer corresponding to the global minimum value of the inversion objective function and the casing wave attenuation rate of the receiving transducer array corresponding to the detection position.

9. A casing wave attenuation inversion device for acoustic logging while drilling, comprising: A construction module, a detection module, a calculation module and a determination module; wherein, The construction module is used to construct an inversion objective function of the attenuation of the acoustic casing wave while drilling according to the signal amplitude relationship between each receiving transducer in the receiving transducer array; The detection module is used to perform monopole acoustic logging while drilling in a cased well at multiple detection positions within the logging depth interval, and obtain an array waveform signal corresponding to each detection position; The operation module is used to determine, for each detection position, the energy value of the first wave signal of each receiving transducer corresponding to the detection position according to the array waveform signal corresponding to the detection position, substitute the energy value of the first wave signal of each receiving transducer into the inversion objective function and perform operation using the optimization algorithm to obtain the casing wave attenuation rate corresponding to the detection position; The determination module is used to obtain a casing wave attenuation rate curve corresponding to the logging depth interval according to the casing wave attenuation rates corresponding to the multiple detection positions; Wherein, the construction module is further used for: Constructing a signal amplitude ratio function between two receiving transducers at different positions in the receiving transducer array according to the position relationship and signal amplitude relationship between the first receiving transducer and other receiving transducers in the receiving transducer array; According to the signal amplitude ratio function between two receiving transducers at different positions, the measurement error and the combination mode of the signals of each receiving transducer in the receiving transducer array, the inversion objective function of the while drilling acoustic casing wave attenuation is constructed.

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