Downhole drilling depth measuring method and system based on time domain reflection

Abstract

The invention discloses an underground drilling depth measurement method and system based on time domain reflection, and belongs to the technical field of drilling measurement, and the technical scheme comprises the steps: injecting a first pulse signal at the head end of a to-be-measured cable, and receiving a second pulse signal which is a reflection signal of the first pulse signal at the tail end of the to-be-measured cable, the to-be-tested cable is located in a to-be-tested well, and the head end of the to-be-tested cable is located at the wellhead of the to-be-tested well; the injection time of the first pulse signal and the receiving time of the second pulse signal are recorded, and the time difference between the injection time and the receiving time is obtained; obtaining the depth of the to-be-measured well according to the time difference and the pulse wave velocity; measurement is carried out based on the time domain reflection principle, the principle is simple and easy to understand, the actual operation difficulty is small, the sensitivity is high, the problem of inaccurate measurement caused by cable tension and cable elastic deformation in the prior art is solved, and meanwhile, the signal processing and waveform correction algorithm is adopted, so that the measurement accuracy is further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of drilling measurement, and more particularly to a downhole drilling depth measurement method and system based on time domain reflection. Background Art

[0002] At present, the drilling depth is usually measured by measuring the cable length. By measuring the lowering length of the cable of the logging instrument and the tension of the cable, the actual cable length in the well can be calculated. The lowering length of the cable is calculated by the encoder driven by the cable.

[0003] For example, the Chinese utility model patent with the authorization announcement CN207879317U provides a bracket for a drilling depth measurement component, which controls the rotation of the cable drum by a switch to release or reel in the cable, and measures the drilling depth through the length of the lowered cable.

[0004] However, in actual applications, measuring the drilling depth by lowering the cable length will affect the accuracy of the drilling depth measurement, so the existing technology has shortcomings. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a downhole drilling depth measurement method and system based on time domain reflection. Based on the principle of time domain reflection, the drilling depth is obtained by measuring the propagation time and wave velocity of the pulse signal in the cable, thereby avoiding the problem of inaccurate measurement caused by cable tension and elastic deformation of the cable.

[0006] To achieve the above object, the present invention provides the following technical solutions: In one aspect, the present invention provides a downhole drilling depth measurement method based on time domain reflection, comprising: A first pulse signal is injected into the head end of the cable to be tested, and a second pulse signal is received, wherein the second pulse signal is a reflection signal of the first pulse signal at the end of the cable to be tested, the cable to be tested is located in the well to be tested, and the head end of the cable to be tested is an end located at the wellhead of the well to be tested; Recording the injection time of the first pulse signal and the reception time of the second pulse signal to obtain a time difference between the injection time and the reception time; The depth of the well to be measured is obtained according to the time difference and the pulse wave velocity.

[0007] As a further improvement of the present invention, obtaining the depth of the well to be measured according to the time difference and the pulse wave velocity includes: Performing shaping processing on the second pulse signal to obtain a target pulse signal; Update the time difference according to the target pulse signal to obtain an actual time difference; The depth of the well to be measured is obtained according to the actual time difference and the pulse wave velocity.

[0008] As a further improvement of the present invention, the step of performing shaping processing on the second pulse signal to obtain a target pulse signal includes: Performing filtering on the second pulse signal to obtain a restored pulse signal; The restored pulse signal is subjected to waveform distortion correction to obtain the target pulse signal.

[0009] As a further improvement of the present invention, the filtering process on the second pulse signal to obtain a restored pulse signal includes: Set the preset weight value; Perform an iterative operation, the iterative operation comprising: calculating an actual output signal according to the second pulse signal and the preset weight value, calculating an error value between the actual output signal and the preset signal, calculating a step factor of the filter according to the error value, and updating the preset weight value according to the step factor to obtain an actual weight value, determining whether a preset termination condition is met, if not, repeating the above steps until the preset termination condition is met, outputting the actual output signal, and obtaining the restored pulse signal, wherein the preset signal is an expected signal that does not require filtering and noise reduction processing.

[0010] As a further improvement of the present invention, the step factor It is constructed based on the hyperbolic tangent function curve, where the step factor , is a control factor used to control the value range of the hyperbolic tangent function curve, is a first shape factor, used to control the shape of the hyperbolic tangent function curve, is the second shape factor, used to control the shape of the bottom of the hyperbolic tangent function curve, is the error value, represents the number of iterations, Represents an exponential function with base e.

[0011] As a further improvement of the present invention, the actual weight value ,in is the preset weight value, is the step size factor, is the error value, represents the number of iterations, is the wavelet transform form of the second pulse signal, is the scale factor, is the translation factor.

[0012] As a further improvement of the present invention, the waveform distortion correction of the restored pulse signal to obtain the target pulse signal includes: Constructing a convolution expression according to the response characteristics of the restored pulse signal and the pulse signal, and converting the convolution expression into a circular convolution matrix form; The circular convolution matrix form is solved according to discrete Fourier transform and inverse discrete Fourier transform to obtain the target pulse signal.

[0013] As a further improvement of the present invention, the step of updating the time difference according to the target pulse signal to obtain the actual time difference includes: Respectively acquiring the time intervals when the target pulse signal and the second pulse signal change from a low level to a high level; The time difference is updated according to the two time intervals to obtain the actual time difference.

[0014] As a further improvement of the present invention, the depth of the well to be measured ,in is the actual time difference, the pulse wave speed , ,in is the frequency of the cable under test, is the complex phase shift constant, , , and are respectively the inductance, capacitance, resistance and conductance of the cable to be tested per unit length.

[0015] In another aspect, the present invention provides a downhole drilling depth measurement system based on time domain reflectometry, comprising: A pulse coupler, the pulse coupler comprising a pulse generator and a pulse timer, the pulse generator being used to generate a first pulse signal, the pulse timer being used to record an injection time of the first pulse signal and a reception time of a second pulse signal, and obtaining a time difference between the injection time and the reception time, the second pulse signal being a reflection signal of the first pulse signal at the end of a cable to be tested, the cable to be tested being located in a well to be tested, and the end of the cable to be tested being an end located at the bottom of the well to be tested; A cable to be tested, used for transmitting the first pulse signal and the second pulse signal; A host computer, the host computer comprising: A calculation module, used for performing shaping processing on the second pulse signal to obtain a target pulse signal, and updating the time difference according to the target pulse signal to obtain an actual time difference; A measuring module, used for obtaining the depth of the well to be measured according to the actual time difference and the pulse wave velocity; The server is communicatively connected with the host computer and is used to output adjustment information of subsequent drilling operations according to the depth of the well to be measured.

[0016] The present invention realizes the measurement of drilling depth through the principle of time domain reflection, avoiding the measurement errors caused by factors such as cable elastic deformation, slippage and drilling friction in traditional methods. At the same time, through signal filtering and waveform correction technology, it effectively compensates for the attenuation and waveform distortion problems of pulse signals in the transmission process, obtains accurate target pulse signals, and updates the measurement time error according to the target pulse signal to obtain the actual time difference, thereby further improving the accuracy of drilling depth measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the prior art; Figure 2 A flowchart of the steps of the method of the present invention; Figure 3 Schematic diagram of the error in measuring time; Figure 4 It is a schematic diagram of an actual measurement scenario of the present invention.

[0018] Figure numerals: 1. encoder; 2. cable to be tested; 3. logging equipment; 4. drilling; 5. pulse coupler; 6. first pulse signal; 7. second pulse signal; 8. waveform of the first pulse signal; 9. waveform of the second pulse signal; 10. waveform of the target pulse signal. DETAILED DESCRIPTION

[0019] The technical solution of the present invention is described in detail below through the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical solution of the present invention, rather than limitations of the technical solution of the present invention.

[0020] The term "and / or" in the following text is only a description of the association relationship between the associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " generally indicates that the associated objects before and after are in an "or" relationship.

[0021] The same components are denoted by the same reference numerals hereinafter. It should be noted that the words "front", "rear", "left", "right", "upper" and "lower" used in the following description refer to directions in the drawings, and the words "bottom" and "top", "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively.

[0022] like Figure 1As shown, when measuring underground rock formations, current oil logging instruments mainly infer the depth by measuring the length of the downhole cable. Specifically, the cable length is measured by an encoder and the cable length is calculated in combination with the cable tension, thereby obtaining the drilling depth.

[0023] The present application finds that the method of estimating depth by measuring the length of the downhole cable in the prior art is inaccurate because the elastic deformation of the cable downhole, as well as inaccurate cable tension caused by slippage and drilling friction, result in large errors in depth measurement.

[0024] In order to solve the problems existing in the existing technology and improve the accuracy of drilling measurement, such as Figure 2 As shown, an embodiment of the present application provides a downhole drilling depth measurement method based on time domain reflection, the method comprising: A first pulse signal is injected into the head end of the cable to be tested, and a second pulse signal is received, wherein the second pulse signal is a reflection signal of the first pulse signal at the end of the cable to be tested, wherein the cable to be tested is located in the well to be tested, and the head end of the cable to be tested is an end located at the wellhead of the well to be tested; Recording the injection time of the first pulse signal and the reception time of the second pulse signal to obtain the time difference between the injection time and the reception time; The depth of the well to be tested is obtained based on the time difference and the pulse wave velocity.

[0025] The method provided in this embodiment measures the drilling depth based on the time domain reflection principle. First, the cable to be tested is lowered into the well to be tested, and a pulse signal is injected at one end of the cable to be tested. Then, the pulse signal reflected from the end of the cable is received at the injected pulse point. By measuring the time difference between the two pulse signals and the propagation speed of the pulse, the distance between the end of the cable and the injection pulse signal point can be calculated, that is, the depth of the well to be tested is obtained. Compared with the prior art, the method provided in this embodiment is not affected by cable deformation and has higher measurement accuracy.

[0026] Furthermore, this embodiment provides a step of obtaining the depth of the well to be measured according to the time difference and the pulse wave velocity, including: Performing shaping processing on the second pulse signal to obtain a target pulse signal; Update the time difference according to the target pulse signal to obtain the actual time difference; The depth of the well to be tested is obtained based on the actual time difference and the pulse wave velocity.

[0027] The steps provided in this embodiment can obtain a waveform that is closer to the target pulse signal by shaping the second pulse signal, thereby reducing the impact of waveform distortion caused by noise, signal attenuation and cable quality problems on the measurement results. At the same time, the time difference is updated according to the target pulse signal to obtain the actual time difference, which can more accurately reflect the propagation time of the pulse signal in the cable, and help to improve the accuracy of drilling depth measurement.

[0028] Furthermore, in order to solve the problem of pulse signal attenuation and noise interference, this embodiment provides a step of filtering the second pulse signal to obtain a restored pulse signal, which step includes: Set the preset weight value; Perform an iterative operation, the iterative operation includes: calculating the actual output signal according to the second pulse signal and the preset weight value, calculating the error value between the actual output signal and the preset signal, calculating the step factor of the filter according to the error value, and updating the preset weight value according to the step factor to obtain the actual weight value, judging whether the preset termination condition is met, if not, repeating the above steps until the preset termination condition is met, outputting the actual output signal, and obtaining the restored pulse signal, the preset signal is the expected signal that does not require filtering and noise reduction processing.

[0029] Specifically, the second pulse signal is expressed as , for dimensional column vector, is the order of the filter, and the preset weight value is recorded as ,express The weight coefficient of the filter is The filter The weight coefficients can be obtained: ; ; in is the actual output signal, For the preset signal, is the error value.

[0030] Then calculate the step size factor of the filter based on the error value , the step size factor based on the hyperbolic tangent function in the prior art for: ; This embodiment provides a step size factor based on a hyperbolic tangent function and logarithmic variation. Compared with the step size factor using the above-mentioned prior art, the initial step size of the step size factor provided by this embodiment is larger, which leads to a faster convergence speed.

[0031] First, separate the above In , restore the hyperbolic tangent function, and get and The step size adjustment formula controlled by two parameters: ; Then perform logarithmic operation on the above formula, and combine the monotonic characteristics of the logarithmic function, negate the fraction part and flip the function to obtain: ; At this time, the step factor It can meet the principle of using a larger step size in the initial stage and a smaller step size when close to convergence. However, according to the step size adjustment principle, the error value As it approaches zero, the step factor It should also approach zero, and taking the limit of the above formula gives: ; Then adjust the above formula to shift the curve upward and add the previously separated , the final step factor is: ;

[0032] in is the control factor, which is used to control the value range of the hyperbolic tangent function curve. is the first shape factor, used to control the shape of the hyperbolic tangent function curve, is the second shape factor, which is used to control the shape of the bottom of the hyperbolic tangent function curve. is the error value, Indicates the number of iterations.

[0033] The step size factor provided in this embodiment complies with the step size adjustment principle, that is, a larger step size is used in the initial stage to obtain a faster convergence speed, and a smaller step size is used when close to convergence to obtain a smaller steady-state error, thereby solving the problems existing in the prior art.

[0034] Then update the preset weight value according to the step factor to get the actual weight value. ,in is the preset weight value, is the step size factor, is the error value, represents the number of iterations, is the wavelet transform form of the second pulse signal, is the scale factor, is the translation factor.

[0035] Specifically, The calculation formula is: ; in represents the wavelet function, express The elements, express The interval between two adjacent elements in .

[0036] This embodiment adjusts the weight according to the wavelet transform form of the second pulse signal. Compared with the prior art that directly uses the second pulse signal for adjustment, the wavelet transform can capture the local details and overall trend of the pulse signal at the same time, and is more suitable for non-stationary signals such as pulse signals. At the same time, the wavelet transform can also play a role in removing noise. After combining the wavelet transform with the above-mentioned filtering operation, accurate noise suppression can be achieved, and it has good stability. It can maintain a high signal processing quality even in a complex noise environment, which can further improve the filtering effect and obtain a more accurate signal, thereby improving the accuracy of drilling measurements.

[0037] Then, it is determined whether the preset termination condition is met, where the preset termination condition can be determined based on the error value, the actual weight value, and the number of iterations. For example, a preset error value can be set. When the error is less than the preset error value, the actual output signal calculated is considered to be approximate to the preset signal. A weight change value can also be set. When the variation range of the actual weight values ​​of two adjacent iterative operations is less than the weight change value, the algorithm is considered to have converged and the iteration can be terminated. A preset number of iterations can also be set. When When the number of iterations is equal to the preset number, the iteration is terminated.

[0038] This embodiment adjusts the second pulse signal based on adaptive weights and wavelet transform, thereby alleviating the noise impact and signal attenuation caused by factors such as transmission medium loss, signal dispersion effect and external interference, which helps to more accurately calculate the actual time difference, thereby obtaining a more accurate drilling depth. Further, in response to the problem of waveform distortion, this embodiment provides a step of performing waveform distortion correction on the restored pulse signal to obtain a target pulse signal, which includes: Construct a convolution expression according to the response characteristics of the restored pulse signal and the pulse signal, and convert the convolution expression into a circular convolution matrix form; The circular convolution matrix is ​​solved according to discrete Fourier transform and inverse discrete Fourier transform to obtain the target pulse signal.

[0039] Specifically, the waveform of the target pulse signal is represented as a sequence , The sequence length is , using the impulse response sequence Represents the response characteristics of the pulse signal, The sequence length is , we can get the convolution expression as: ; in Represents the waveform sequence of the restored pulse signal, Indicates the first elements, the length of the waveform sequence , express The elements, express Middle elements.

[0040] In order to convert it into matrix form, and sequence Perform zero padding to extend the length of the input sequence and keep the lengths of the two sequences consistent. Finally, get and for: ; ; Then according to and Convert the convolution expression into circular convolution form: ; in, express The elements, Indicates taking right The remainder.

[0041] Then the circular convolution form is converted into a circular convolution matrix form, expressed as: ; in, , and They are respectively , and The matrix formed by The inverse matrix , we can find the waveform of the target pulse signal. Matrix and Inverse Matrix They are all circular convolution matrices and have the same properties, so we can analyze Any row or column of a matrix or its inverse matrix can be used to obtain information about the entire matrix. Assume by sequence Composition, we can get: ; in is the unit pulse function.

[0042] At the same time, the discrete Fourier transform of both sides is obtained:

[0043] in, and They are respectively and The matrix formed after discrete Fourier transform is sorted out to get: ; At the same time, the inverse discrete Fourier transform is obtained on both sides: ; according to You can get the inverse matrix sequence , the waveform of the target pulse signal can be obtained when the waveform sequence of the restored pulse signal is known, and then the target pulse signal is obtained according to the waveform to achieve the purpose of waveform correction.

[0044] This embodiment restores the waveform of the target pulse signal by measuring the pulse response characteristics of the instrument and recovering the pulse signal, thereby achieving the purpose of waveform correction, solving the problem of waveform distortion during signal propagation, and improving measurement accuracy.

[0045] Furthermore, the above-mentioned waveform correction method can restore the shape of the target pulse wave, but it is difficult to adjust the amplitude of the target pulse wave. Due to the limitations of downhole operating conditions, high-frequency pulse equipment is prone to cause safety problems. This embodiment usually uses low-frequency pulse equipment, but the amplitude of the low-frequency pulse signal is low, which is easy to affect the timing accuracy. Therefore, this embodiment provides a method for compensating the amplitude of the target pulse signal.

[0046] ; in is the transmission loss, The transmission distance can be roughly estimated by the drilling speed and drilling time of the drill bit. is the frequency of the pulse signal. Represents the power ratio, which is used to measure the proportional relationship between two power values. The formula is as follows: ; in is the power of the target pulse signal before compensation, is the power of the target pulse signal after compensation. Since the relationship between signal power and signal amplitude is ,in is the amplitude, is the resistance of the cable to be tested, so it can be calculated based on and The proportional relationship of the signal amplitude is obtained as follows: ; in The amplitude of the target pulse signal before compensation can be determined using the amplitude of the second pulse signal. is the amplitude of the target pulse signal after compensation. According to the above relationship, the amplitude of the target pulse signal can be compensated.

[0047] This embodiment provides a method for compensating the signal amplitude according to the transmission loss of the pulse signal in the cable to be tested, which solves the impact of the limitation of drilling operation conditions on the signal amplitude, and the method can be applied to pulse devices of various frequencies.

[0048] Furthermore, this embodiment provides a step of updating the time difference according to the target pulse signal to obtain the actual time difference, which step includes: Respectively obtain the time intervals when the target pulse signal and the second pulse signal change from a low level to a high level; The time difference is updated according to the two time intervals to obtain the actual time difference.

[0049] Specifically, Figure 3 As shown in the figure, during the propagation of pulse signals, problems such as noise, signal attenuation and cable quality may cause distortion of the signal waveform, and the longer the cable length, the greater the amplitude of signal attenuation and the greater the degree of waveform distortion. According to the principle of pulse timing, the pulse timer measures the time based on the sudden change of the monitoring pulse from low level to high level, that is, the rising edge. The rising and falling edges of the undistorted signal are very steep, which means that they complete the state transition in a very short time. This large-scale sudden change in a short time enables the pulse timer to measure more accurately, while the rising and falling edges of the distorted pulse signal are relatively gentle, which can easily affect the accuracy of the measurement.

[0050] For example, Figure 3 Point P in the figure is the mutation point where the second pulse signal changes from low level to high level. is the mutation point where the target pulse signal changes from a low level to a high level. It can be seen that due to the relatively gentle rising edge of the distorted pulse signal, the level transition time is relatively long, which makes the measurement time difference Greater than the actual time difference Therefore, it is necessary to obtain the point P and point Between and Points With point The time interval between the two signals, that is, the time interval between the two signals changing from low level to high level, and the time difference is updated according to the two time intervals to obtain the actual time difference .

[0051] This embodiment updates the measured time difference through the sudden change time of the pulse signal from low level to high level, thereby compensating for the measurement error caused by waveform distortion and improving the accuracy of drilling measurement.

[0052] Furthermore, the formula for calculating the depth of the well to be tested provided in this embodiment is: ; in is the depth of the well to be tested, is the actual time difference, is the pulse velocity.

[0053] Specifically, the calculation formula of pulse wave velocity is: ; ; in is the frequency of the cable to be tested, is the complex phase shift constant, , , and They are the inductance, capacitance, resistance and conductance of the cable under test per unit length.

[0054] Compared with the prior art method of selecting a constant reference wave speed as the actual wave speed calculation method, the pulse wave speed calculation method provided in this embodiment takes into account the influence of multiple variables such as the cable structure itself and has higher accuracy.

[0055] The embodiment of the present application provides a downhole drilling depth measurement method based on time domain reflection, which accurately measures the downhole drilling depth through the principle of time domain reflection, and solves the problem of inaccurate measurement caused by slippage and drilling friction in the prior art. At the same time, based on precise signal processing and waveform distortion correction algorithms, the accuracy of the reflected signal is further improved, and the attenuation and waveform distortion problems in the pulse signal transmission process are solved.

[0056] Furthermore, an embodiment of the present application provides a downhole drilling depth measurement system based on time domain reflection, the system comprising: A pulse coupler, the pulse coupler comprises a pulse generator and a pulse timer, the pulse generator is used to generate a first pulse signal, the pulse timer is used to record the injection time of the first pulse signal and the reception time of the second pulse signal, and obtain the time difference between the injection time and the reception time, the second pulse signal is a reflection signal of the first pulse signal at the end of the cable to be tested, the cable to be tested is located in the well to be tested, and the end of the cable to be tested is an end located at the bottom of the well to be tested; The cable to be tested is used to transmit a first pulse signal and a second pulse signal; Host computer, the host computer includes: A calculation module, used for performing shaping processing on the second pulse signal to obtain a target pulse signal, and updating the time difference according to the target pulse signal to obtain an actual time difference; A measuring module is used to obtain the depth of the well to be measured according to the actual time difference and the pulse wave velocity; The server is communicatively connected with the host computer and is used to output adjustment information of subsequent drilling operations according to the depth of the well to be measured.

[0057] Specifically, Figure 4 The scenario of using the system provided in this embodiment to perform drilling measurement is demonstrated, wherein the logging device 3 includes a drill bit and is connected to a cable. The depth of the well to be measured is the length of drilling by the drill bit. When the logging device is located at the bottom of the well, the end of the cable to be measured is also located at the bottom of the well. At this time, the depth of the well to be measured can be obtained by measuring the signal reflected at the end of the cable to be measured.

[0058] The adjustment information for subsequent drilling operations is output according to the depth of the well to be tested, including: by measuring the drilling depth, the position and thickness of different strata can be accurately determined to prevent drilling accidents caused by misjudgment of strata position, such as well wall collapse, blowout, etc. It can also help drillers to adjust subsequent drilling parameters in time to avoid drilling through the target strata or missing important geological landmark layers.

[0059] The embodiment of the present application provides a downhole drilling depth measurement method and system based on time domain reflection. Through the time domain reflection principle, signal processing algorithm and waveform correction algorithm, the drilling depth can be accurately measured, and the influence of cable elastic deformation, slippage and drilling friction on the depth measurement can be eliminated. The problems of signal attenuation and interference of the cable in the complex downhole environment can be overcome, and the stability and accuracy of the measurement signal can be ensured. At the same time, the present application provides a complete drilling measurement system, through which the drilling depth measurement can be effectively completed.

[0060] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0061] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0062] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0063] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0064] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A downhole drilling depth measurement method based on time domain reflection, characterized in that: include: A first pulse signal is injected into the head end of the cable to be tested, and a second pulse signal is received, wherein the second pulse signal is a reflection signal of the first pulse signal at the end of the cable to be tested, the cable to be tested is located in the well to be tested, and the head end of the cable to be tested is an end located at the wellhead of the well to be tested; Recording the injection time of the first pulse signal and the reception time of the second pulse signal to obtain a time difference between the injection time and the reception time; The depth of the well to be measured is obtained according to the time difference and the pulse wave velocity.

2. A downhole drilling depth measurement method based on time domain reflection according to claim 1, characterized in that: The step of obtaining the depth of the well to be measured according to the time difference and the pulse wave velocity comprises: Performing shaping processing on the second pulse signal to obtain a target pulse signal; Update the time difference according to the target pulse signal to obtain an actual time difference; The depth of the well to be measured is obtained according to the actual time difference and the pulse wave velocity.

3. A downhole drilling depth measurement method based on time domain reflection according to claim 2, characterized in that: The step of performing shaping processing on the second pulse signal to obtain a target pulse signal includes: Performing filtering on the second pulse signal to obtain a restored pulse signal; The restored pulse signal is subjected to waveform distortion correction to obtain the target pulse signal.

4. A downhole drilling depth measurement method based on time domain reflection according to claim 3, characterized in that: The filtering the second pulse signal to obtain a restored pulse signal includes: Set the preset weight value; Perform an iterative operation, the iterative operation comprising: calculating an actual output signal according to the second pulse signal and the preset weight value, calculating an error value between the actual output signal and the preset signal, calculating a step factor of the filter according to the error value, and updating the preset weight value according to the step factor to obtain an actual weight value, determining whether a preset termination condition is met, if not, repeating the above steps until the preset termination condition is met, outputting the actual output signal, and obtaining the restored pulse signal, wherein the preset signal is an expected signal that does not require filtering and noise reduction processing.

5. A downhole drilling depth measurement method based on time domain reflection according to claim 4, characterized in that: The step factor It is constructed based on the hyperbolic tangent function curve, where the step factor , is a control factor used to control the value range of the hyperbolic tangent function curve, is a first shape factor, used to control the shape of the hyperbolic tangent function curve, is the second shape factor, used to control the shape of the bottom of the hyperbolic tangent function curve, is the error value, represents the number of iterations, Represents an exponential function with base e.

6. A downhole drilling depth measurement method based on time domain reflection according to claim 4, characterized in that: The actual weight value ,in is the preset weight value, is the step size factor, is the error value, represents the number of iterations, is the wavelet transform form of the second pulse signal, is the scale factor, is the translation factor.

7. The downhole drilling depth measurement method based on time domain reflection according to claim 3 is characterized in that: The step of performing waveform distortion correction on the restored pulse signal to obtain the target pulse signal includes: Constructing a convolution expression according to the response characteristics of the restored pulse signal and the pulse signal, and converting the convolution expression into a circular convolution matrix form; The circular convolution matrix form is solved according to discrete Fourier transform and inverse discrete Fourier transform to obtain the target pulse signal.

8. The downhole drilling depth measurement method based on time domain reflection according to claim 2 is characterized in that: The updating of the time difference according to the target pulse signal to obtain the actual time difference comprises: Respectively acquiring the time intervals when the target pulse signal and the second pulse signal change from a low level to a high level; The time difference is updated according to the two time intervals to obtain the actual time difference.

9. The downhole drilling depth measurement method based on time domain reflection according to claim 2 is characterized in that: The depth of the well to be tested ,in is the actual time difference, the pulse wave speed , ,in is the frequency of the cable under test, is the complex phase shift constant, , , and are respectively the inductance, capacitance, resistance and conductance of the cable to be tested per unit length.

10. A downhole drilling depth measurement system based on time domain reflection, used to implement a downhole drilling depth measurement method based on time domain reflection as claimed in any one of claims 1 to 9, characterized in that: include: A pulse coupler, the pulse coupler comprising a pulse generator and a pulse timer, the pulse generator being used to generate a first pulse signal, the pulse timer being used to record an injection time of the first pulse signal and a reception time of a second pulse signal, and obtaining a time difference between the injection time and the reception time, the second pulse signal being a reflection signal of the first pulse signal at the end of a cable to be tested, the cable to be tested being located in a well to be tested, and the end of the cable to be tested being an end located at the bottom of the well to be tested; The cable to be tested is used to transmit the first pulse signal and the second pulse signal; A host computer, the host computer comprising: A calculation module, used for performing shaping processing on the second pulse signal to obtain a target pulse signal, and updating the time difference according to the target pulse signal to obtain an actual time difference; A measuring module, used for obtaining the depth of the well to be measured according to the actual time difference and the pulse wave velocity; The server is communicatively connected with the host computer and is used to output adjustment information of subsequent drilling operations according to the depth of the well to be measured.

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