Oil well annulus liquid level opening measuring method and system

Abstract

The invention belongs to the technical field of oil well drilling and mining, and particularly relates to an oil well annulus liquid level opening measuring method and system.The method comprises the steps that a Y-shaped tee joint and a manual flat valve above the Y-shaped tee joint are installed at a kill manifold valve, and underground liquid level detection equipment is connected; annulus sound wave signals are collected in the well opening state; sequentially carrying out wavelet threshold noise reduction and self-adaptive notch filtering on the signal; an echo period T is determined through fusion of autocorrelation analysis and spectral analysis, sliding window template matching is carried out according to the period, and liquid level echo signals are extracted and enhanced; finally, the liquid level depth is calculated, dynamic verification is conducted, and then a result is output. Through collaborative innovation of a mechanical structure and a signal processing algorithm, real-time, automatic and high-precision measurement of the annulus liquid level without well shut-in is achieved, the defect that well shut-in operation is needed in a traditional method is overcome, and production continuity and operation safety are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oil well drilling and production, and particularly relates to an oil well annular space liquid level opening measurement method and system. BACKGROUND

[0002] In oil well drilling and production operations, real-time and accurate monitoring of the downhole liquid level of the oil well is a key link to ensure operation safety and improve production efficiency. Currently, downhole liquid level detection mainly focuses on the water eye and the annular space. Among them, the measurement method at the water eye position is simple in structure, convenient to operate, and the echo signal collected by the downhole liquid level detection equipment is clear and stable, so that the downhole liquid level depth can be easily and accurately read automatically.

[0003] However, due to the complex pipeline structure at the annular space position, the existing measurement technology has obvious defects. The conventional method needs to be in the closed well state to enable the downhole liquid level detection equipment to collect a relatively obvious liquid level echo signal, and after detection, the well is re-opened. This operation method not only seriously affects the continuity of the field drilling operation, brings many inconveniences to the actual production, but also greatly reduces the real-time performance of liquid level measurement, cannot timely reflect the dynamic changes of the downhole liquid level, and is difficult to meet the real-time monitoring needs of modern oil well operations. Therefore, developing a method capable of automatically and accurately measuring the annular space liquid level under the open well condition has become an urgent need to solve the current technical bottleneck. SUMMARY

[0004] To solve the problems raised in the background art, the present application provides an oil well annular space liquid level opening measurement method and system, which cooperates the innovative Y-shaped tee structure with a special weak signal processing algorithm to accurately measure the annular space liquid level without the need to close the well and affect the normal drilling and production operation. This completely overcomes the fundamental defect of the traditional method that must be closed to measure, avoids the operation interruption, time delay and production loss caused by closing the well, ensures the continuity and efficiency of oilfield production operations, and meets the development trend of modern intelligent and continuous oilfield operations.

[0005] The technical scheme adopted by the present application to solve its technical problems is to provide an oil well annular space liquid level opening measurement method, comprising the following steps:

[0006] S1, mechanical structure building: installing a Y-shaped tee at the valve of the oil well blowout manifold, installing a manual flat valve above the Y-shaped tee, and connecting a downhole liquid level detection equipment to a special interface of the Y-shaped tee;

[0007] S2, signal acquisition: under the open well condition, collecting the original sound wave signal of the annular space area by the downhole liquid level detection equipment;

[0008] S3. Signal preprocessing: The original acoustic signal is sequentially subjected to wavelet threshold noise reduction and adaptive notch filtering to obtain a preprocessed signal;

[0009] S4. Period detection and signal extraction: Based on the preprocessed signal, the period T of the liquid surface echo signal is determined by autocorrelation analysis and spectrum analysis, and the enhanced liquid surface echo signal is extracted by template matching based on the period T.

[0010] S5. Depth Calculation and Verification: Calculate the liquid surface depth based on the enhanced liquid surface echo signal, perform dynamic verification, and output the final measurement result.

[0011] Furthermore, the wavelet thresholding denoising in step S3 specifically includes:

[0012] The original signal was decomposed into three levels of wavelet using the db6 wavelet basis.

[0013] The optimal threshold λ for wavelet coefficients at each level is determined using the maximum likelihood estimation method.

[0014] The low-frequency wavelet coefficients are processed using a soft thresholding function y=sign(x)·max(|x|-λ,0), where x is the wavelet coefficient and λ is the optimal threshold.

[0015] The wavelet coefficients are reconstructed to obtain the denoised signal.

[0016] Furthermore, the method for determining the period T1 through autocorrelation analysis in step S4 is as follows:

[0017] Calculate the autocorrelation function of the preprocessed signal. ,

[0018] Where N is the signal length, Let x(n) be the delay time, and x(n) be the signal value at the nth sampling point. (delay) The signal value after each sampling point is obtained by finding the position of the first peak of the autocorrelation function. Preliminary determination of the candidate periodic value T1= × ;in, The sampling frequency.

[0019] Furthermore, step S4 also includes determining the period T2 through spectrum analysis:

[0020] Perform a Fast Fourier Transform on the preprocessed signal to find the frequency f corresponding to the spectral peak. p ,

[0021] Calculate the candidate value of the period T2=1 / f p ;

[0022] If |T1-T2|≤0.01T1, then take the average value. The final cycle T is used; otherwise, the detection is repeated until the accuracy requirement is met.

[0023] Further, the extraction of the liquid surface echo signal based on the period T through template matching in step S4 includes:

[0024] A sliding window is set with a period T as the window length and a step size of T / 10 to extract candidate signal segments from the preprocessed signal;

[0025] The average value of the signal segments within the first three windows is selected as the standard template S. ref ;

[0026] Calculate the relationship between each candidate signal segment s and the standard template S ref Cross-correlation coefficient r:

[0027]

[0028] Where M is the number of data points within the window, s i Let be the sampled value of the i-th candidate signal segment. s is the average value of the candidate signal segment. ref,i Let i be the i-th sampled value of the template signal. The average value of the template signal is r; when r ≥ 0.85, it is determined to be a valid echo segment.

[0029] The enhanced liquid surface echo signal S is obtained by superimposing and averaging all valid echo segments. echo .

[0030] Furthermore, the depth calculation and verification described in step S5 includes:

[0031] Calculate the liquid surface depth based on the propagation time t of the liquid surface echo signal and the propagation speed v of the sound wave in the medium. ;

[0032] If the current measurement value H and the previous measurement value H satisfy the condition... Then, the second measurement is initiated to obtain H verification;

[0033] like Then the average depth value will be output. ;

[0034] Otherwise, an error message will be displayed.

[0035] The present invention also provides an oil well annulus fluid level opening measurement system for implementing the above method, comprising:

[0036] Y-type tee, installed at the well kill manifold valve, is used to change the propagation path of sound waves and enhance echo reception;

[0037] A manual flat valve, installed below the Y-type tee, is used to isolate mud.

[0038] The downhole fluid level detection equipment is connected to the Y-type three-way interface and is used to transmit and receive acoustic signals;

[0039] The signal processing unit is used to execute the wavelet denoising, period detection, template matching and depth calculation algorithms.

[0040] Furthermore, the signal processing unit includes:

[0041] The preprocessing module is used to perform wavelet thresholding and adaptive notch filtering;

[0042] The period detection module is used to perform autocorrelation analysis and spectrum analysis to determine the signal period;

[0043] The signal extraction module is used to extract liquid surface echoes based on period T and template matching;

[0044] The verification output module is used to calculate the depth and output the results after performing consistency verification.

[0045] A storage medium storing a computer program, characterized in that, when the computer program is executed by a processor, it implements the above-described method for measuring the opening of the annulus fluid level in an oil well.

[0046] An electronic device is characterized by comprising a processor and a memory, wherein the memory stores a computer program, and the processor executes the computer program to implement the above-described method for measuring the opening of the annulus fluid level in an oil well.

[0047] Compared with the prior art, the beneficial effects of the present invention are:

[0048] (1) This invention, through the innovative Y-type three-way structure and the collaborative operation of a dedicated weak signal processing algorithm, achieves accurate measurement of the annular fluid level for the first time without shutting in the well or affecting normal drilling and production operations. This completely overcomes the fundamental defect of traditional methods that require well shut-in for measurement, avoids operation interruptions, time delays and production losses caused by well shut-in, ensures the continuity and efficiency of oilfield production operations, and conforms to the development trend of intelligent and continuous operations in modern oilfields.

[0049] (2) The Y-shaped three-way structure optimizes the sound wave propagation and reception path from a physical perspective, effectively enhancing the strength of the effective echo signal. Combined with the "wavelet denoising-adaptive notch filtering" preprocessing technology and the "multi-dimensional periodic detection-template matching" extraction algorithm, it can accurately lock the weak periodic liquid surface echo signal in a strong noise background, ensuring the reliability of the data from the source.

[0050] (3) Through field measurements under various complex working conditions, the measurement error of the method of the present invention can be stably controlled within ±0.3m, and the correlation coefficient with the well shut-in measurement results is as high as 0.996, which proves that it can still provide high-precision data comparable to well shut-in measurement in the well-open state, providing a reliable basis for downhole safety monitoring and process adjustment.

[0051] (4) This invention introduces a "dynamic verification and optimization" mechanism, which can intelligently distinguish between real dynamic changes in the liquid level and measurement errors caused by accidental strong interference by making consistency judgments on continuous measurement results. This mechanism can automatically trigger retesting, make logical judgments, and provide prompts when an anomaly is confirmed, effectively avoiding false alarms and enhancing the robustness of the system in complex field environments and the reliability of the output results.

[0052] (5) From signal acquisition, intelligent processing, depth calculation to result verification and output, the entire process is completed automatically by the system, with a single measurement cycle of ≤5 seconds. This not only frees workers from tedious and dangerous well shut-in operations and manual signal interpretation, but also achieves near real-time liquid level depth monitoring, enabling timely capture of rapid changes in downhole liquid levels, saving valuable time for early warning and rapid decision-making, and significantly improving the timeliness of well control safety and production management. Attached Figure Description

[0053] Figure 1 This is a flowchart of a method for measuring the fluid level opening in the annulus of an oil well according to the present invention;

[0054] Figure 2 This is another flowchart of a method for measuring the fluid level opening in the annulus of an oil well according to the present invention;

[0055] Figure 3 This is a structural diagram of an oil well annulus fluid level opening measurement system according to the present invention;

[0056] Figure 4 This is a structural diagram of a measuring device for an oil well annular fluid level opening measurement system according to the present invention;

[0057] The attached diagram is labeled as follows: 1. Downhole measuring equipment; 2. Y-type tee; 3. Manual flat valve. Detailed Implementation

[0058] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0059] Example 1:

[0060] This embodiment provides a method for measuring the opening of the annulus fluid level in an oil well, such as... Figure 1 and Figure 2 The flowchart shown illustrates the method, which includes the following steps:

[0061] Step S101: Mechanical structure construction. (e.g.) Figure 4 As shown, a matching Y-type tee 2 component is machined and customized according to the actual dimensions of the well kill manifold. The Y-type tee 2 is securely installed at the designated valve position on the well kill manifold, ensuring interface sealing and structural stability. A manual flat valve 3 is installed below the Y-type tee 2, and the valve is tested to ensure flexible opening and closing, effectively isolating mud and other impurities, and protecting subsequent measurement equipment. Finally, the downhole fluid level detection device 1 (such as an acoustic gun) is connected to the dedicated interface reserved on the Y-type tee 2, and the installation angle is adjusted to optimize echo signal reception.

[0062] Step S102: Signal Acquisition. While the oil well remains open, the downhole fluid level detection device installed in step S101 actively transmits acoustic signals and receives reflected signals from the annulus. The device converts the acquired raw analog acoustic signals, including fluid surface echoes and various noises, into digital signals via an analog-to-digital converter at a sampling frequency of 4096Hz, and transmits them to the signal processing unit.

[0063] Step S103: Signal Preprocessing. The acquired raw digital signal undergoes noise reduction preprocessing to improve the signal-to-noise ratio. The preprocessing uses a combination of wavelet thresholding and adaptive notch filtering.

[0064] Wavelet thresholding for noise reduction: The signal is decomposed into three levels using the db6 wavelet basis. The optimal threshold λ for each level of decomposition coefficients is determined using maximum likelihood estimation. A soft thresholding function y=sign(x)·max(|x|-λ,0) is used to process the low-frequency approximation coefficients (where x is the wavelet coefficient), effectively suppressing random noise while preserving the main characteristics of the signal. After processing, the wavelet coefficients are reconstructed to obtain the preliminary denoised signal.

[0065] Adaptive notch filtering: Power spectral density analysis is performed on the pre-denoised signal to identify fixed-frequency interference components introduced by drilling operations, motor operation, etc. A digital notch filter with an adjustable center frequency and adaptive bandwidth within the range of 0.5Hz to 2Hz is designed to accurately filter out these fixed-frequency interferences and avoid excessive attenuation of the useful echo signal. After this step, the output signal-to-noise ratio is improved to a pre-processed signal of 10-15dB.

[0066] Step S104: Periodic detection and signal extraction. Based on the preprocessed signal, weak periodic liquid surface echo signals are extracted.

[0067] Multi-dimensional periodic detection:

[0068] First, calculate the autocorrelation function of the preprocessed signal. Where N is the signal length, τ is the delay time, and x(n) is the signal value. Find the position τ1 of the first significant peak of the autocorrelation function, and calculate the initial candidate period value T1 = × f s The sampling frequency is 4096Hz.

[0069] Next, a Fast Fourier Transform (FFT) is performed on the preprocessed signal to obtain its frequency spectrum. The frequency f corresponding to the main peak is then located in the spectrum. p Calculate another candidate value for the period T2 = 1 / f p .

[0070] Finally, the Welch method is used to estimate the signal power spectrum to enhance resolution, and T1 and T2 are verified. If |T1−T2|≤0.01T1, the periodic detection is considered consistent, and the value is taken as... Use the final period T of the liquid surface echo signal as the reference value; otherwise, adjust the delay time range of the autocorrelation analysis (e.g., 5-50ms) and repeat the above process until the consistency requirements are met.

[0071] Signal extraction based on period matching:

[0072] With a defined period T as the window length, a sliding window is set on the preprocessed signal, with a window movement step of T / 10. Signal segments within each window are sequentially extracted as candidate echo segments.

[0073] The standard template S is constructed by selecting the average value of signal segments within three consecutive initial windows. ref .

[0074] Calculate the relationship between each subsequent candidate signal segment s and the standard template S ref Cross-correlation coefficient r:

[0075] ;

[0076] Where M is the number of data points within the window, s i For the i-th sample value of the candidate segment, It is its average value; s ref,i For the i-th sampled value of the standard template, Its average value.

[0077] A threshold of 0.85 is set. When r ≥ 0.85, the candidate segment is determined to be a valid liquid surface echo segment.

[0078] All valid echo segments are superimposed and averaged to obtain the liquid surface echo signal S with a further enhanced signal-to-noise ratio. echo .

[0079] Step S105: Depth calculation and verification.

[0080] Based on the extracted enhanced echo signal S echo Calculate the liquid level depth and verify its reliability.

[0081] Depth computing: in S echo The peak position of the echo pulse is identified in the signal, and the propagation time t of the sound wave from transmission to reception is calculated. Combined with the sound wave propagation speed v in the current annular medium (such as drilling fluid) obtained from on-site calibration, the formula is used... The current liquid level depth H is calculated. 当前 .

[0082] Dynamic consistency verification: The measured value H... 当前 Compared with the last valid measurement value H stored in the system 前次 Compare them.

[0083] If the current measured value H 当前 Compared with the previous measurement value H 前次 satisfy Then, the second measurement is initiated to obtain H. 验证 ;

[0084] like If the two measurements are consistent, the average depth value will be output. As the final depth result;

[0085] If the relative deviation is greater than 2%, it is considered that there may be a large error or interference in the measurement. The system will not output the depth value, but will generate an abnormal prompt message on the human-machine interface to remind the on-site staff to check the equipment or working conditions.

[0086] Step S106: Output the result.

[0087] The finalized and verified annular fluid level depth value is displayed in real time on the monitoring interface of the on-site terminal equipment (such as an industrial PC or explosion-proof tablet). Simultaneously, the measurement data is transmitted synchronously to the logging room monitoring system, remote data center, etc., via data interface or network, enabling real-time data sharing and comprehensive monitoring.

[0088] To verify the effectiveness of the method of the present invention, field tests were conducted at oil well sites under various typical working conditions.

[0089] Test environment: including conventional drilling wells, high-pressure gas drive wells, and complex wells with high sand content.

[0090] Testing Procedure: During well opening operations, the annular fluid level was continuously monitored using the method and system described in this invention. Simultaneously, under safe conditions, traditional shut-in measurement methods were intermittently used as a comparison benchmark.

[0091] Test results:

[0092] Measurement accuracy: The single measurement error of the method of the present invention is stable within ±0.3 meters under the well opening state, which is better than the design target (±0.5 meters).

[0093] Signal processing performance: After algorithm processing, the signal-to-noise ratio of the liquid surface echo signal is improved to 25-30dB; the recognition accuracy of period T reaches 99.2%.

[0094] Consistency: When compared with the well shut-in measurement results, the two measurement data showed a high degree of consistency, with a determination coefficient R² of 0.996.

[0095] Real-time performance: A single complete measurement (from signal acquisition to result output) takes no more than 5 seconds, which can meet the needs of real-time on-site monitoring.

[0096] Practicality: No well shut-in is required throughout the entire process, ensuring continuous operation and making on-site operation simple.

[0097] Example 2: This example provides an oil well annulus fluid level opening measurement system for implementing the method described in Example 1, such as... Figure 3 The system structure diagram shown includes:

[0098] Mechanical structural unit: includes a custom-made Y-tee, which is installed at the well kill manifold valve to optimize the acoustic propagation path and enhance echo reception efficiency; and a manual flat valve installed below the Y-tee to isolate downhole fluids and protect measurement equipment when necessary.

[0099] Signal sensing unit: also known as downhole fluid level detection equipment, which includes an acoustic wave transmitting and receiving transducer (gun body) connected to a Y-type three-way interface, responsible for transmitting acoustic waves into the annulus and receiving reflected signals when the well is open.

[0100] Signal processing unit: Receives digital signals from the sensing unit and executes the algorithm in Example 1. This unit can be further divided into:

[0101] Preprocessing module: Used to perform wavelet thresholding and adaptive notch filtering algorithms.

[0102] Period detection module: used to perform autocorrelation analysis, FFT spectrum analysis and period verification algorithm.

[0103] Signal extraction module: Used to execute periodic signal extraction algorithms based on sliding window and template matching.

[0104] Verification output module: used to calculate depth and execute dynamic consistency verification logic, and finally output the result.

[0105] These modules can be implemented using software programs in dedicated digital signal processors (DSPs), field-programmable gate arrays (FPGAs), or high-performance industrial computers.

[0106] Example 3: An electronic device and a storage medium

[0107] This embodiment provides an electronic device, including at least one processor and a memory. The memory stores a computer program, which, when executed by the processor, causes the electronic device to perform all or part of the steps of the oil well annulus fluid level opening measurement method as described in Embodiment 1.

[0108] This embodiment also provides a computer-readable storage medium (such as a USB flash drive, hard disk, optical disk, server storage space, etc.) storing a computer program. When the computer program is executed by a processor, it implements all or part of the steps of the oil well annulus fluid level opening measurement method as described in Embodiment 1.

[0109] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method of measuring an oil well annulus fluid level opening, characterized by, The method comprises the following steps: S1, mechanical structure building: installing a Y-shaped tee at the valve of the well killing manifold, installing a manual flat valve above the Y-shaped tee, and connecting a downhole liquid level detection device to a special interface of the Y-shaped tee; S2, signal acquisition: in the open well state, acquiring the original acoustic signal of the annular region by the downhole liquid level detection device; S3, signal preprocessing: sequentially performing wavelet threshold denoising and adaptive notch filtering on the original acoustic signal to obtain a preprocessed signal; S4, cycle detection and signal extraction: based on the preprocessed signal, determining the cycle T of the liquid level echo signal through autocorrelation analysis and spectrum analysis, and extracting the enhanced liquid level echo signal through template matching based on the cycle T; S5, depth calculation and verification: calculating the liquid level depth according to the enhanced liquid level echo signal, and outputting the final measurement result after dynamic verification.

2. The method of claim 1, wherein, The wavelet threshold denoising in step S3 specifically comprises: Performing 3-layer wavelet decomposition on the original signal using a db6 wavelet basis; Using the maximum likelihood estimation method to determine the optimal threshold λ of the wavelet coefficients of each layer; Using a soft threshold function y=sign(x)·max(|x|-λ,0) to process the low-frequency wavelet coefficients, where x is the wavelet coefficient and λ is the optimal threshold; Reconstructing the wavelet coefficients to obtain the denoised signal.

3. The method of claim 1, wherein, The method for determining the cycle T1 through autocorrelation analysis in step S4 is: Computing an autocorrelation function of a preprocessed signal , where N is the signal length, is the delay time, x(n) is the signal value at the nth sample point, x(n- ) is the signal value after a delay of x(n- ) samples, the period candidate value T1= is preliminarily determined by finding the first peak position of the autocorrelation function; and is the sampling frequency.​​ 4. The method of claim 3, wherein, Step S4 also includes determining the cycle T2 through spectrum analysis: A fast Fourier transform is performed on the preprocessed signal to obtain a frequency spectrum, and a frequency f corresponding to a frequency spectrum peak is searched p , Computing the period candidate value T2 = 1 / f p ; If |T1-T2|≤0.01T1, then take the average As the final period T, else repeat the detection until the accuracy requirement is met.

5. The method of claim 1, wherein, The extraction of the liquid level echo signal based on the cycle T through template matching in step S4 comprises: Setting a sliding window with a window length of T and a step length of T / 10, and cutting a candidate signal segment from the preprocessed signal; The average value of the signal segments in the first three windows is selected as the standard template S ref ; The cross-correlation coefficient r of each candidate signal segment s with the standard template S is calculated: ref r = s · S / (s · s · S · S) ； where M is the number of data points in the window, s i is the sample value of the i-th candidate signal segment, is the average value of the candidate signal segment, s ref,i is the i-th sample value of the template signal, is the average value of the template signal; when r≥0.85, it is determined as a valid echo segment; The enhanced liquid surface echo signal S is obtained by stacking and averaging all valid echo segments echo .

6. The method of claim 1, wherein, The depth calculation and verification in step S5 comprise: According to the liquid surface echo signal propagation time t and the sound wave propagation speed v in the medium, the liquid surface depth is calculated ; If the current measured value H 当前 Compared with the previous measurement value H 前次 satisfy Then, the second measurement is initiated to obtain H. 验证 ; If , then output the average depth value ; Otherwise, output an abnormal prompt.

7. An oil well annulus fluid level opening measurement system for implementing the method of any one of claims 1 to 6, characterized by Comprise: The Y-shaped tee is installed at the valve of the well killing manifold to change the sound wave propagation path and enhance the echo reception; The manual flat valve is installed below the Y-shaped tee to isolate the mud; The downhole liquid level detection device is connected to the interface of the Y-shaped tee to transmit and receive acoustic signals; The signal processing unit is used to execute the wavelet denoising, cycle detection, template matching, and depth calculation algorithms.

8. The oil well annular fluid level opening measurement system of claim 7, wherein, The signal processing unit comprises: A preprocessing module for performing wavelet threshold denoising and adaptive notch filtering; A cycle detection module for performing autocorrelation analysis and spectrum analysis to determine the signal cycle; A signal extraction module for extracting the liquid level echo based on the cycle T and template matching; A verification output module for calculating the depth and performing consistency verification to output the result.

9. A storage medium storing a computer program, characterized by comprising: The computer program, when executed by the processor, implements the oil well annular liquid level opening measurement method of any one of claims 1 to 6.

10. An electronic device, comprising: The computer program, when executed by the processor, implements the oil well annular liquid level opening measurement method of any one of claims 1 to 6. The computer program, when executed by the processor, implements the oil well annular liquid level opening measurement method of any one of claims 1 to 6.

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