Denoising system and method for drilling fluid pulse signal

Abstract

The invention discloses a denoising system and method for drilling fluid pulse signals, and the system comprises a plurality of pressure sensors which are sequentially installed on the outer surface of a vertical pressure pipeline in the axial direction, and are used for collecting the drilling fluid pulse signals which are carried by drilling fluid and contain underground measurement data information in the drilling fluid circulation process, the vertical pressure pipeline is used for conveying drilling fluid which is pumped by the drilling pump and flows back to the ground to a wellhead from the drilling pump; the data processing device is used for determining signal propagation time delay between a master sensor and slave sensors except the master sensor in the plurality of pressure sensors, so that time delay compensation is carried out on drilling fluid pulse signals collected by the slave sensors, and the drilling fluid pulse signals subjected to time delay compensation are used for outputting the drilling fluid pulse signals. And noise signals in the drilling fluid pulse signals are removed. Noise signals in drilling fluid pulse signals are effectively removed, and accurate underground measurement data information can be obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas exploration and development drilling engineering, and in particular relates to a denoising system and method for drilling fluid pulse signals. Background Art

[0002] Drilling fluid pulse transmission is currently the most widely used data transmission method while drilling. Its basic principle is to change the mud pressure in the drill pipe through the downhole pulse generator to form a pressure wave, thereby transmitting the measurement data to the ground in the form of pulses. This transmission method has the advantages of low requirements for equipment and operation, strong adaptability to wellbores and formations, etc. However, when the pulse signal propagates in the drilling fluid, it will inevitably be interfered by various noise sources such as well site voltage, ground mud pumps, bottom hole power machinery, bubbles in the drilling fluid, and moving drill tools. It is usually impossible to directly identify useful coded pulse signals from the waveform received on the ground.

[0003] At present, conventional drilling fluid pulse denoising algorithms are all based on single / dual pressure sensors, mainly including median filtering, FIR digital filtering, wavelet transform, modal decomposition, coherent averaging, adaptive filtering, etc. However, in drilling environments such as ultra-deep layers, small boreholes or high-speed pulse transmission, the coded pulse signal is very weak, and the coded pulse frequency band may overlap with the noise frequency band, resulting in poor denoising effect and poor adaptability of conventional drilling fluid pulse denoising algorithms, making it difficult to provide reliable data for subsequent signal recognition and processing, and unable to meet the measurement while drilling requirements of exploration and development projects. Summary of the invention

[0004] In order to solve the above problems, an embodiment of the present invention provides a denoising system for drilling fluid pulse signals, comprising: a plurality of pressure sensors, which are axially installed in sequence on the outer surface of a riser pressure pipeline, and are used to collect drilling fluid pulse signals containing downhole measurement data information carried by the drilling fluid during the circulation of the drilling fluid, wherein the riser pressure pipeline is used to transport the drilling fluid drawn by the drilling pump and returned to the ground from the drilling pump to the wellhead; a data processing device, which is used to determine the signal propagation delay between a main sensor among the plurality of pressure sensors and a slave sensor other than the main sensor, thereby performing delay compensation on the drilling fluid pulse signal collected by the slave sensor, so as to use the drilling fluid pulse signal after delay compensation to remove the noise signal in the drilling fluid pulse signal.

[0005] Preferably, the data processing device is further used to determine the signal propagation delay according to the positional relationship between each slave sensor and the master sensor, and the propagation speed of the drilling fluid pulse signal in the drilling fluid channel.

[0006] Preferably, the signal propagation delay is expressed using the following expression:

[0007]

[0008] Among them, τ m represents the signal propagation delay between the mth slave sensor and the master sensor, L m represents the length of the standing pressure pipeline between the mth slave sensor and the drilling pump, L * represents the length of the standing pressure pipeline between the main sensor and the drilling pump, and c represents the propagation speed of the drilling fluid pulse signal in the drilling fluid channel.

[0009] Preferably, the noise signal includes: pump noise and random noise, the pump noise includes pump impulse harmonic noise and low-frequency baseline noise, and the drilling fluid pulse signal is expressed by the following expression:

[0010]

[0011] Among them, s n (t) represents the drilling fluid pulse signal collected by the nth sensor, sig represents the coded pulse signal, pum represents the pump noise, t represents the acquisition time of the drilling fluid pulse signal, and a n and b n They represent the amplitude coefficients of the coded pulse signal and the pump noise respectively, L represents the distance from the generating position of the drilling fluid pulse signal to the drilling pump, and L′ n It represents the distance from the drilling fluid pulse signal generation position to the nth sensor, g n (t) represents the random noise in the drilling fluid pulse signal collected by the nth sensor, and c represents the propagation speed of the drilling fluid pulse signal in the drilling fluid channel.

[0012] Preferably, the following expression is used to perform time delay compensation on the drilling fluid pulse signal collected by each slave sensor:

[0013]

[0014] Among them, s cn (t) represents the drilling fluid pulse signal of the nth sensor after time delay compensation, τ n Represents the signal propagation delay between the nth sensor and the main sensor.

[0015] Preferably, the data processing device is also used to perform denoising processing on the drilling fluid pulse signal that has been time-delay compensated for multiple times in a row, so as to remove the pump noise through the first denoising processing, and after the first denoising processing is completed, remove the random noise in the current drilling fluid pulse signal through the second denoising processing, wherein each denoising processing includes a noise identification step and a denoising step for the current identification result.

[0016] Preferably, the noise identification method in the first denoising process is selected from one of multi-channel median filtering, multi-channel mean filtering and multi-channel singular value decomposition; the noise identification method in the second denoising process is selected from one of bandpass filtering, wavelet transform and modal decomposition.

[0017] Preferably, the number of the plurality of pressure sensors is an odd number, and the main sensor is a sensor located in the middle of the plurality of pressure sensors.

[0018] Preferably, the denoising system further comprises: a ground interface box, which is connected to the plurality of pressure sensors respectively and is used for simultaneously performing multi-channel collection of the drilling fluid pulse signal collected by each pressure sensor.

[0019] In addition, the present invention also proposes a denoising method for drilling fluid pulse signals, wherein the denoising method utilizes the denoising system described in the present invention to realize denoising of drilling fluid pulse signals, wherein the denoising method comprises: utilizing a plurality of pressure sensors installed axially in sequence on the outer surface of a riser pressure pipeline to collect drilling fluid pulse signals containing downhole measurement data information carried by the drilling fluid during the circulation of the drilling fluid, wherein the riser pressure pipeline is used to transport the drilling fluid drawn by the drilling pump and returned to the ground from the drilling pump to the wellhead; determining the signal propagation delay between a main sensor among the plurality of pressure sensors and a slave sensor other than the main sensor through a data processing device, thereby performing time delay compensation on the drilling fluid pulse signal collected by the slave sensor, so as to utilize the drilling fluid pulse signal after time delay compensation to remove the noise signal in the drilling fluid pulse signal.

[0020] Compared with the prior art, one or more embodiments of the above scheme may have the following advantages or beneficial effects:

[0021] The present invention proposes a denoising system and method for drilling fluid pulse signals. In the system, a vertical pressure pipeline, a drilling pump, a drilling fluid pool, a drilling fluid diversion pipeline and a wellbore constitute a circulation channel for the drilling fluid, wherein the vertical pressure pipeline connects the drilling pump and the wellbore, and is used to transport the drilling fluid drawn from the drilling fluid pool by the drilling pump and returned to the ground from the drilling pump to the wellhead, and the drilling fluid diversion pipeline connects the drilling fluid pool and the wellbore for storing the drilling fluid returned to the ground. Based on the aforementioned circulation channel, a plurality of pressure sensors are arranged axially on the outer surface of the vertical pressure pipeline, and the plurality of pressure sensors are used to collect the drilling fluid pulse signals containing downhole measurement data information carried by the drilling fluid during the circulation of the drilling fluid. The data processing device is used to perform time delay compensation on the drilling fluid pulse signals collected by the aforementioned plurality of pressure sensors, so as to obtain a time-delay compensated drilling fluid pulse signal that is convenient for removing noise signals. The present invention obtains more drilling fluid pulse signals and utilizes the time delay characteristics of multi-channel drilling fluid pulse signals to quickly and effectively remove interference noise in the drilling fluid pulse signals under complex well conditions, thereby reducing the complexity of on-site operations and improving the decoding success rate of the drilling fluid pulse signals. This meets the measurement while drilling requirements of exploration and development projects and can obtain accurate downhole measurement data information.

[0022] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0024] Figure 1 This is a schematic diagram of the overall structure of a denoising system for drilling fluid pulse signals according to an embodiment of the present application.

[0025] Figure 2 This is a schematic diagram of the specific structure of a denoising system for drilling fluid pulse signals according to an embodiment of the present application.

[0026] Figure 3 A schematic diagram of a multi-channel drilling fluid pulse signal of a drilling fluid pulse signal denoising system according to an embodiment of the present application.

[0027] Figure 4 A schematic diagram of a multi-channel drilling fluid pulse signal after delay compensation in a denoising system for drilling fluid pulse signals according to an embodiment of the present application.

[0028] Figure 5A schematic diagram of pump noise in a multi-channel drilling fluid pulse signal of a drilling fluid pulse signal denoising system according to an embodiment of the present application.

[0029] Figure 6 This is a schematic diagram of the first denoising process result of the denoising system for drilling fluid pulse signals according to an embodiment of the present application.

[0030] Figure 7 This is a schematic diagram of the second denoising process result of the denoising system for drilling fluid pulse signals according to an embodiment of the present application.

[0031] Figure 8 This is a step diagram of a method for denoising a drilling fluid pulse signal according to an embodiment of the present application.

[0032] In the present application, all drawings are schematic drawings, which are only used to illustrate the principles of the present invention and are not drawn according to the actual scale.

[0033] The reference numerals are listed as follows:

[0034] 10: Vertical pressure pipeline

[0035] 20: Pressure sensor group

[0036] 30: Ground interface box

[0037] 40: Ground Computer

[0038] 50: Drilling pump

[0039] 60: Drilling fluid pool

[0040] 70: Drilling fluid diversion pipeline DETAILED DESCRIPTION

[0041] The following will describe the implementation methods of the present invention in detail with reference to the accompanying drawings and embodiments, so that the implementation process of how the present invention applies technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly. It should be noted that as long as there is no conflict, the various embodiments of the present invention and the various features in the embodiments can be combined with each other, and the technical solutions formed are all within the protection scope of the present invention.

[0042] In addition, the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be performed in an order different from that shown here.

[0043] Drilling fluid pulse transmission is currently the most widely used data transmission method while drilling. Its basic principle is to change the mud pressure in the drill pipe through the downhole pulse generator to form a pressure wave, thereby transmitting the measurement data to the ground in the form of pulses. This transmission method has the advantages of low requirements for equipment and operation, strong adaptability to wellbores and formations, etc. However, when the pulse signal propagates in the drilling fluid, it will inevitably be interfered by various noise sources such as well site voltage, ground mud pumps, bottom hole power machinery, bubbles in the drilling fluid, and moving drill tools. It is usually impossible to directly identify useful coded pulse signals from the waveform received on the ground.

[0044] At present, conventional drilling fluid pulse denoising algorithms are all based on single / dual pressure sensors, mainly including median filtering, FIR digital filtering, wavelet transform, modal decomposition, coherent averaging, adaptive filtering, etc. However, in drilling environments such as ultra-deep layers, small boreholes or high-speed pulse transmission, the coded pulse signal is very weak, and the coded pulse frequency band may overlap with the noise frequency band, resulting in poor denoising effect and poor adaptability of conventional drilling fluid pulse denoising algorithms, making it difficult to provide reliable data for subsequent signal recognition and processing, and unable to meet the measurement while drilling requirements of exploration and development projects.

[0045] Therefore, in order to solve the above problems, the present invention proposes a denoising system and method for drilling fluid pulse signals. In the system, a vertical pressure pipeline, a drilling pump, a drilling fluid pool, a drilling fluid diversion pipeline and a wellbore constitute a circulation channel for drilling fluid, wherein the vertical pressure pipeline connects the drilling pump and the wellbore, and is used to transport the drilling fluid drawn from the drilling fluid pool by the drilling pump and returned to the ground from the drilling pump to the wellhead, and the drilling fluid diversion pipeline connects the drilling fluid pool and the wellbore for storing the drilling fluid returned to the ground. Based on the aforementioned circulation channel, a plurality of pressure sensors are arranged axially on the outer surface of the vertical pressure pipeline, and the plurality of pressure sensors are used to collect the drilling fluid pulse signals containing downhole measurement data information carried by the drilling fluid during the circulation of the drilling fluid. The data processing device is used to perform time delay compensation on the drilling fluid pulse signals collected by the aforementioned plurality of pressure sensors, so as to obtain a time-delay compensated drilling fluid pulse signal that is convenient for removing noise signals. The present invention obtains more drilling fluid pulse signals and utilizes the time delay characteristics of multi-channel drilling fluid pulse signals to quickly and effectively remove interference noise in the drilling fluid pulse signals under complex well conditions, thereby reducing the complexity of on-site operations and improving the decoding success rate of the drilling fluid pulse signals. This meets the measurement while drilling requirements of exploration and development projects and can obtain accurate downhole measurement data information.

[0046] Embodiment 1

[0047] The denoising system for drilling fluid pulse signals in this embodiment at least includes: a plurality of pressure sensors 11 and a data processing device 12. The plurality of pressure sensors 11 are sequentially installed on the outer surface of the vertical pressure pipeline 10 along the axial direction, and are used to collect the drilling fluid pulse signals (i.e., pressure wave signals) containing downhole measurement data information carried by the drilling fluid during the circulation of the drilling fluid, wherein the vertical pressure pipeline 10 is used to transport the drilling fluid drawn by the drilling pump 50 and returned to the ground from the drilling pump 50 to the wellhead. The data processing device 12 is used to determine the signal propagation delay between the main sensor among the plurality of pressure sensors 11 and the slave sensors other than the main sensor, so as to perform delay compensation on the drilling fluid pulse signals collected by the slave sensors, so as to remove the noise signals in the drilling fluid pulse signals by using the drilling fluid pulse signals after delay compensation. In the embodiment of the present application, the data processing device 12 is built into the ground computer 40 to realize the corresponding functions.

[0048] Figure 1 This is a schematic diagram of the overall structure of a denoising system for drilling fluid pulse signals according to an embodiment of the present application. Figure 2 The specific structural diagram of the denoising system for drilling fluid pulse signals according to the embodiment of the present application is shown below. Figure 1 and Figure 2 The structure of the denoising system for drilling fluid pulse signals according to the present invention is described in detail.

[0049] In practical applications, multiple pressure sensors 11 are arranged on the flow channel of the drilling fluid to collect the drilling fluid pulse signal, which can realize multiple acquisitions of the same pulse signal propagated to different positions, and then through the integration and analysis of all the collected drilling fluid pulse signals, comprehensive and accurate downhole measurement data information can be obtained. Therefore, the present invention forms a denoising system for removing noise in the drilling fluid pulse signal by arranging corresponding equipment on the well to be measured, so as to directly denoise the drilling fluid pulse signal containing downhole measurement data information carried by the drilling fluid during the logging process using the denoising system to obtain comprehensive and accurate downhole measurement data information.

[0050] The present invention realizes the circulation of drilling fluid by constructing a drilling fluid circulation channel between a vertical pressure pipeline 10, a drilling pump 50, a drilling fluid pool 60, a drilling fluid diversion pipeline 70 and a wellbore, so that the drilling fluid is discharged from the underground to the ground and enters the underground again from the wellhead, thereby realizing the collection of drilling fluid pulse signals containing downhole measurement data information carried by the drilling fluid. Specifically, the drilling fluid pool 60 is used to collect and store the drilling fluid discharged back to the ground on the ground, and the drilling pump 50 is used to extract the drilling fluid in the drilling fluid pool 60, so that the extracted drilling fluid re-enters the underground from the wellbore. The drilling fluid diversion pipeline 70 is used for diversion of drilling fluid, and provides a flow channel for the drilling fluid discharged back to the ground to enter the drilling fluid pool 60 from the underground. The standing pressure pipeline 10 is used to transport the drilling fluid (i.e., the drilling fluid in the drilling fluid pool 60) drawn by the drilling pump 50 and returned to the ground from the drilling pump 50 to the wellhead, so as to achieve the purpose of allowing the drawn drilling fluid to re-enter the well from the wellbore.

[0051] Based on the constructed drilling fluid circulation channel, the present invention sequentially installs a plurality of pressure sensors 11 axially on the outer surface of the vertical pressure pipeline 10, so as to collect the drilling fluid pulse signal containing downhole measurement data information carried by the drilling fluid during the circulation of the drilling fluid. In the embodiment of the present application, a plurality of pressure sensors 11 are axially arranged on the outer surface of the vertical pressure pipeline 10, so as to form a pressure sensor group 20 on the ground, and each pressure sensor in the pressure sensor group 20 collects the drilling fluid pulse signal containing downhole measurement data information carried by the drilling fluid on a partial flow section during the entire flow process of the drilling fluid in the circulation channel, that is, each pressure sensor senses the drilling fluid pulse signal separately, so as to achieve the purpose of sensing the drilling fluid pulse signal. The present invention uses a plurality of pressure sensors 11 to collect drilling fluid pulse signals along the transmission of the drilling fluid, and obtains corresponding multi-channel drilling fluid pulse signals, and the more channels of the drilling fluid pulse signals, the easier it is to eliminate the interference of noise.

[0052] In the embodiment of the present application, the number of the plurality of pressure sensors 11 is an odd number, and the main sensor hereinafter is a sensor located in the middle of the plurality of pressure sensors 11. That is, the number of the plurality of pressure sensors 11 is greater than or equal to three.

[0053] The denoising system of the present invention further includes a ground interface box 30. The ground interface box 30 is connected to the plurality of pressure sensors 11 respectively, and is used to simultaneously perform multi-channel collection of the drilling fluid pulse signals collected by each pressure sensor. In the embodiment of the present application, the ground interface box 30 is based on the connection mode of being respectively connected to the plurality of pressure sensors 11, and simultaneously performs multi-channel collection of the drilling fluid pulse signals collected by different pressure sensors, and obtains the following Figure 3 The multi-channel drilling fluid pulse signal shown in FIG. 1 is transmitted to the data processing device 12, which effectively improves the signal transmission efficiency ( Figure 3 Schematic diagram of a multi-channel drilling fluid pulse signal of a denoising system for drilling fluid pulse signals according to an embodiment of the present application).

[0054] Furthermore, the data processing device 12 is used to determine the signal propagation delay between the main sensor among the multiple pressure sensors 11 and the slave sensors other than the main sensor, so as to perform delay compensation on the drilling fluid pulse signal collected by the slave sensor, so as to use the drilling fluid pulse signal after delay compensation to remove the noise signal in the drilling fluid pulse signal. The data processing device 12 of this embodiment is used to process the drilling fluid pulse signal containing downhole measurement data information carried by the drilling fluid collected by the multiple pressure sensors 11, so as to restore the downhole measurement data information from the collected signal. Before performing data processing, this embodiment first determines the main sensor among the multiple pressure sensors 11, so as to determine the signal propagation delay between the main sensor and the slave sensors other than the main sensor based on the main sensor. In a specific embodiment of the present application, the main sensor is a pressure sensor in the middle position. The data processing device 12 performs delay compensation on the drilling fluid pulse signal collected by the slave sensor based on the calculation result of the signal propagation delay, and obtains the following Figure 4 The multi-channel drilling fluid pulse signal after delay compensation is shown in Figure 4 Schematic diagram of a multi-channel drilling fluid pulse signal after delay compensation for a denoising system for drilling fluid pulse signals in an embodiment of the present application). By utilizing the delay characteristics of the drilling fluid pulse signal after delay compensation, it is possible to quickly and effectively distinguish interference signals such as interference noise in the drilling fluid pulse signal under complex well conditions and useful signals other than interference noise. Accordingly, based on the delay characteristics of the drilling fluid pulse signal after delay compensation and the comprehensiveness of the collected drilling fluid pulse signal, the present invention effectively removes interference noise under complex well conditions, reduces the complexity of on-site operations, and improves the decoding success rate of the drilling fluid pulse signal.

[0055] Next, the data processing device 12 is also used to determine the signal propagation delay according to the positional relationship between each slave sensor and the master sensor, and the propagation speed of the drilling fluid pulse signal in the drilling fluid channel. In the embodiment of the present application, the data processing device 12 calculates the signal propagation delay between each slave sensor and the master sensor according to the positional relationship between each slave sensor and the master sensor, combined with the propagation speed of the current drilling fluid pulse signal in the drilling fluid channel.

[0056] Furthermore, since the propagation speed of the drilling fluid pulse signal in the drilling fluid channel is related to the drilling fluid, the drill pipe, and the pressure wave signal parameters, the present embodiment uses the following expression to calculate the propagation speed of the drilling fluid pulse signal in the drilling fluid channel:

[0057]

[0058] Where c represents the propagation speed of the drilling fluid pulse signal in the drilling fluid channel, R f represents the average hydraulic friction coefficient, ω represents the signal transmission angular frequency, ρ represents the drilling fluid density, K p represents the bulk elastic modulus of the drill string, K l represents the bulk elastic modulus of the liquid phase, α g represents the volume content of gas phase fluid, α s Indicates the volume content of solid phase fluid.

[0059] Next, first, calculate the drilling fluid density using the following expression:

[0060] ρ=(1-α g -α s )ρl+α g ρ g +α s ρ s (2)

[0061] Among them, ρ l Represents the density of liquid drilling fluid, ρ g Represents the density of gas-phase drilling fluid, ρ s Indicates the density of solid drilling fluid.

[0062] Next, the bulk modulus is calculated using the following expression:

[0063]

[0064]

[0065]

[0066]

[0067] Among them, K g represents the gas phase bulk elastic modulus, △P represents the pressure difference, V g Represents the gas phase volume, △V g Represents the gas phase volume difference, V l Indicates the volume of the liquid phase, △V l represents the liquid phase volume difference, K s represents the solid phase bulk elastic modulus, V s Represents the solid phase volume, △V s represents the solid phase volume difference, V p Indicates the volume of the drill string, △V p Indicates the volume difference of the drill string.

[0068] Finally, the average hydraulic friction coefficient is calculated using the following expression:

[0069]

[0070] Where, v represents the average flow rate of drilling fluid, D represents the outer diameter of drill pipe, η p represents the plastic viscosity of the drilling fluid, and τ0 represents the yield stress of the drilling fluid.

[0071] In the embodiment of the present application, the signal propagation delay is expressed by the following expression:

[0072]

[0073] Among them, τ m represents the signal propagation delay between the mth slave sensor and the master sensor, L m represents the length of the standing pressure pipeline between the mth slave sensor and the drilling pump, L * Indicates the length of the standing pressure line between the main sensor and the drilling pump.

[0074] In the embodiment of the present application, when the number of the plurality of pressure sensors 11 is an odd number, the length of the standing pressure pipeline 10 between the main sensor and the drilling pump 50 is calculated using the following expression:

[0075] L * =L( n+1 ) / 2 (9

[0076] The drilling fluid pulse signals collected by the multiple pressure sensors 11 mainly include coded pulse signals (useful signals), pump harmonic noise (interference signals), low-frequency baseline noise (interference signals) and random noise (interference signals). Among them, the coded pulse signal is generated by the drilling fluid pulse generator and propagates from the bottom of the well to the ground along the drilling fluid channel; the pump harmonic noise and low-frequency baseline noise are generated by the drilling pump 50 and propagate from the ground to the bottom of the well along the drilling fluid channel, while the random noise always exists. This embodiment uses the pump harmonic noise and the low-frequency baseline noise as Figure 5 The pump noise shown ( Figure 5 Schematic diagram of pump noise in a multi-channel drilling fluid pulse signal of a drilling fluid pulse signal denoising system according to an embodiment of the present application). Figure 3 and Figure 5 It can be seen that the purpose of noise suppression can be achieved by utilizing the different propagation directions of useful signals and interference signals. Based on the above analysis, it can be seen that the noise signals in the drilling fluid pulse signal include pump harmonic noise, low-frequency baseline noise, and random noise, among which pump harmonic noise and low-frequency baseline noise both belong to pump noise, that is, the noise signal includes pump noise and random noise.

[0077] In the embodiment of the present application, the location where the drilling fluid pulse signal is generated is the location where the drilling fluid pulse generator is located, and the drilling fluid pulse signal is represented by the following expression:

[0078]

[0079] Among them, s n (t) represents the drilling fluid pulse signal collected by the nth sensor, sig represents the coded pulse signal, pum represents the pump noise, t represents the acquisition time of the drilling fluid pulse signal, and a n and b n They represent the amplitude coefficients of the coded pulse signal and the pump noise respectively, L represents the distance from the generating position of the drilling fluid pulse signal to the drilling pump, and L′ n It represents the distance from the drilling fluid pulse signal generation position to the nth sensor, g n (t) represents the random noise in the drilling fluid pulse signal collected by the nth sensor.

[0080] The longer the propagation distance of the drilling fluid pulse signal, the greater the signal attenuation and the smaller the signal amplitude. In other words, if L1 <L2<……<L n , then a1 <a2<……<a n and b1>b2>...>b n .

[0081] After determining the signal propagation delay of each pressure sensor, the drilling fluid pulse signals s1, s2, ..., s n Perform time delay compensation to obtain the drilling fluid pulse signal s after time delay compensation c1 、s c2 ,……,s cn The following expression is used to perform time delay compensation on the drilling fluid pulse signal collected by each slave sensor:

[0082]

[0083] Among them, s cn (t) represents the drilling fluid pulse signal of the nth sensor after time delay compensation, τ n Represents the signal propagation delay between the nth sensor and the main sensor.

[0084] In the embodiment of the present application, when the number of the plurality of pressure sensors 11 is an odd number n, the drilling fluid pulse signal after delay compensation is expressed by the following expression:

[0085]

[0086] Continue to refer to Figure 4It can be seen that after time delay compensation, the pump noise phase in the drilling fluid pulse signal collected by each pressure sensor is consistent, only the amplitude is different, and the phase difference between the coded pulses is further increased.

[0087] Furthermore, the data processing device 12 is also used to perform denoising processing on the drilling fluid pulse signal after delay compensation for multiple times, so as to remove the pump noise through the first denoising processing, and after the first denoising processing is completed, remove the random noise in the current drilling fluid pulse signal through the second denoising processing. Specifically, the data processing device 12 performs denoising processing on the drilling fluid pulse signal s after delay compensation. c1 、s c2 ,……,s cn The denoising process is performed multiple times continuously, so that the noise signal ss of the first noise identification is obtained in the first denoising process, thereby removing the pump noise. The noise signal s' of the second noise identification is obtained in the second denoising process, thereby removing the random noise in the current drilling fluid pulse signal. In the embodiment of the present application, each denoising process includes a noise identification step and a denoising step for the current identification result.

[0088] The noise identification method in the first denoising process is selected from one of multi-channel median filtering, multi-channel mean filtering and multi-channel singular value decomposition.

[0089] In a specific embodiment of the present application, the drilling fluid pulse signal is subjected to multi-channel median filtering, and the noise signal of the first noise identification is represented by the following expression, and the following is obtained: Figure 6 The first denoising result is shown in Figure 6 This is a schematic diagram of the first denoising process result of the denoising system for drilling fluid pulse signals according to an embodiment of the present application):

[0090]

[0091] Among them, median represents the median function, ss(t) represents the noise signal of the first noise recognition, A represents the overall contribution of the coded pulse, and G represents the overall contribution of the random noise.

[0092] In practical applications, since pump noise is usually much larger than coded pulses and random noise, A and G can generally be ignored. That is to say, the drilling fluid pulse signal obtained after multi-channel median filtering is approximately equal to the pump noise in the drilling fluid pulse signal collected by the pressure sensor at the middle position. Therefore, in this embodiment, the drilling fluid pulse signal collected by the pressure sensor at the middle position is subtracted from the noise signal ss of the first noise identification to obtain the drilling fluid pulse signal s' after the first denoising, wherein the drilling fluid pulse signal after the first denoising is expressed by the following expression:

[0093]

[0094] Reference Figure 6 It can be seen that after the first denoising process, the pump noise in the drilling fluid pulse signal is basically eliminated, and the random noise signal is not significantly suppressed.

[0095] Next, the drilling fluid pulse signal s' after the first denoising is subjected to a second denoising process to obtain the coded pulse signal s in the drilling fluid pulse signal d , further to the coded pulse signal s d The corresponding downhole measurement data information can be obtained by decoding.

[0096] The noise identification method in the second denoising process is selected from one of bandpass filtering, wavelet transform and modal decomposition.

[0097] In a specific embodiment of the present application, the frequency of the coded pulse signal in the drilling fluid pulse signal is 24 Hz, so the passband of the bandpass filter is set to 22-26 Hz. The drilling fluid pulse signal is subjected to bandpass filtering by the bandpass filter, and the following is obtained: Figure 7 The second denoising result is shown in Figure 7 Schematic diagram of the second denoising process result of the denoising system for drilling fluid pulse signals according to an embodiment of the present application).

[0098] Reference Figure 7 It can be seen that the second denoising process can further suppress the noise, and the coded pulse signal in the drilling fluid pulse signal can be highlighted.

[0099] After completing the second denoising process, the data processing device 12 also decodes the current drilling fluid pulse signal (at this time, only the encoded pulse signal remains in the drilling fluid pulse signal), and after the decoding is completed, stores the decoded current drilling fluid pulse signal as the original drilling fluid pulse signal.

[0100] Embodiment 2

[0101] On the other hand, based on the denoising system for drilling fluid pulse signals described in the aforementioned embodiment 1, an embodiment of the present invention also proposes a denoising method for drilling fluid pulse signals. The method utilizes the above-mentioned denoising system for drilling fluid pulse signals to effectively remove noise from drilling fluid pulse signals. Figure 8 FIG. 1 is a step diagram of a method for denoising a drilling fluid pulse signal according to an embodiment of the present application. Figure 8As shown, the denoising method for drilling fluid pulse signals of the present invention comprises the following steps: step S810 utilizes a plurality of pressure sensors 11 sequentially installed along the axial direction on the outer surface of a riser pressure pipeline 10 to collect drilling fluid pulse signals containing downhole measurement data information carried by the drilling fluid during the circulation of the drilling fluid, wherein the riser pressure pipeline 10 is used to transport the drilling fluid drawn by the drilling pump 50 and returned to the ground from the drilling pump 50 to the wellhead; step S820 determines the signal propagation delay between a main sensor among the plurality of pressure sensors 11 in step S810 and a slave sensor other than the main sensor through a data processing device 12, thereby performing delay compensation on the drilling fluid pulse signal collected by the slave sensor, so as to utilize the drilling fluid pulse signal after delay compensation to remove the noise signal in the drilling fluid pulse signal.

[0102] The present invention proposes a denoising system and method for drilling fluid pulse signals. In the system, a vertical pressure pipeline, a drilling pump, a drilling fluid pool, a drilling fluid diversion pipeline and a wellbore constitute a circulation channel for the drilling fluid, wherein the vertical pressure pipeline connects the drilling pump and the wellbore, and is used to transport the drilling fluid drawn from the drilling fluid pool by the drilling pump and returned to the ground from the drilling pump to the wellhead, and the drilling fluid diversion pipeline connects the drilling fluid pool and the wellbore for storing the drilling fluid returned to the ground. Based on the aforementioned circulation channel, a plurality of pressure sensors are arranged axially on the outer surface of the vertical pressure pipeline, and the plurality of pressure sensors are used to collect the drilling fluid pulse signals containing downhole measurement data information carried by the drilling fluid during the circulation of the drilling fluid. The data processing device is used to perform time delay compensation on the drilling fluid pulse signals collected by the aforementioned plurality of pressure sensors, so as to obtain a time-delay compensated drilling fluid pulse signal that is convenient for removing noise signals. The present invention obtains more drilling fluid pulse signals and utilizes the time delay characteristics of multi-channel drilling fluid pulse signals to quickly and effectively remove interference noise in the drilling fluid pulse signals under complex well conditions, thereby reducing the complexity of on-site operations and improving the decoding success rate of the drilling fluid pulse signals. This meets the measurement while drilling requirements of exploration and development projects and can obtain accurate downhole measurement data information.

[0103] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any person familiar with the technology within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

[0104] It should be understood that the embodiments disclosed in the present invention are not limited to the specific structures, processing steps or materials disclosed herein, but should be extended to equivalent substitutions of these features understood by ordinary technicians in the relevant field. It should also be understood that the terms used herein are only used for the purpose of describing specific embodiments and are not meant to be limiting.

[0105] The "one embodiment" or "embodiment" mentioned in the specification means that the specific features, structures or characteristics described in conjunction with the embodiment are included in at least one embodiment of the present invention. Therefore, the phrases "one embodiment" or "embodiment" appearing in various places throughout the specification do not necessarily refer to the same embodiment.

[0106] Although the embodiments disclosed in the present invention are as above, the contents described are only embodiments adopted for facilitating the understanding of the present invention and are not intended to limit the present invention. Any technician in the technical field to which the present invention belongs can make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in the present invention, but the patent protection scope of the present invention shall still be subject to the scope defined in the attached claims.

Claims

1. A denoising system for drilling fluid pulse signals, characterized in that: include: A plurality of pressure sensors are sequentially installed on the outer surface of the riser line in the axial direction, and are used to collect drilling fluid pulse signals containing downhole measurement data information carried by the drilling fluid during the circulation of the drilling fluid, wherein the riser line is used to transport the drilling fluid drawn by the drilling pump and returned to the ground from the drilling pump to the wellhead; A data processing device is used to determine the signal propagation delay between a main sensor among the multiple pressure sensors and a slave sensor other than the main sensor, so as to perform delay compensation on the drilling fluid pulse signal collected by the slave sensor, so as to use the drilling fluid pulse signal after delay compensation to remove the noise signal in the drilling fluid pulse signal.

2. The denoising system according to claim 1, characterized in that: The data processing device is further used to determine the signal propagation delay according to the positional relationship between each slave sensor and the master sensor, and the propagation speed of the drilling fluid pulse signal in the drilling fluid channel.

3. The denoising system according to claim 2, characterized in that: The signal propagation delay is expressed by the following expression: Among them, τ m represents the signal propagation delay between the mth slave sensor and the master sensor, L m represents the length of the standing pressure pipeline between the mth slave sensor and the drilling pump, L * represents the length of the standing pressure pipeline between the main sensor and the drilling pump, and c represents the propagation speed of the drilling fluid pulse signal in the drilling fluid channel.

4. The denoising system according to any one of claims 1 to 3, characterized in that: The noise signal includes: pump noise and random noise. The pump noise includes pump impulse harmonic noise and low-frequency baseline noise. The drilling fluid pulse signal is expressed by the following expression: Among them, s n (t) represents the drilling fluid pulse signal collected by the nth sensor, sig represents the coded pulse signal, pum represents the pump noise, t represents the acquisition time of the drilling fluid pulse signal, and a n and b n represent the amplitude coefficients of the coded pulse signal and pump noise respectively, L represents the distance from the generating position of the drilling fluid pulse signal to the drilling pump, and L ′ n It represents the distance from the drilling fluid pulse signal generation position to the nth sensor, g n (t) represents the random noise in the drilling fluid pulse signal collected by the nth sensor, and c represents the propagation speed of the drilling fluid pulse signal in the drilling fluid channel.

5. The denoising system according to claim 4, characterized in that: The following expression is used to perform time delay compensation on the drilling fluid pulse signal collected by each slave sensor: Among them, s cn (t) represents the drilling fluid pulse signal of the nth sensor after time delay compensation, τ n Represents the signal propagation delay between the nth sensor and the main sensor.

6. The denoising system according to claim 4 or 5, characterized in that: The data processing device is also used to perform denoising processing on the drilling fluid pulse signal that has undergone time delay compensation for multiple times in a row, so as to remove the pump noise through the first denoising processing, and after the first denoising processing is completed, remove the random noise in the current drilling fluid pulse signal through the second denoising processing, wherein each denoising processing includes a noise identification step and a denoising step for the current identification result.

7. The denoising system according to claim 6, characterized in that: The noise identification method in the first denoising process is selected from one of multi-channel median filtering, multi-channel mean filtering and multi-channel singular value decomposition; The noise identification method in the second denoising process is selected from one of bandpass filtering, wavelet transform and modal decomposition.

8. The denoising system according to any one of claims 1 to 7, characterized in that: The number of the plurality of pressure sensors is an odd number, and the main sensor is a sensor located in the middle of the plurality of pressure sensors.

9. The denoising system according to any one of claims 1 to 8, characterized in that: The denoising system further comprises: The ground interface box is connected to the plurality of pressure sensors respectively and is used for simultaneously performing multi-channel collection of the drilling fluid pulse signal collected by each pressure sensor.

10. A method for denoising a drilling fluid pulse signal, characterized in that: The denoising method is implemented by using the denoising system according to any one of claims 1 to 9, wherein the denoising method comprises: A plurality of pressure sensors are sequentially installed on the outer surface of a riser pressure pipeline along the axial direction to collect a drilling fluid pulse signal containing downhole measurement data information carried by the drilling fluid during the circulation of the drilling fluid, wherein the riser pressure pipeline is used to transport the drilling fluid drawn by the drilling pump and returned to the ground from the drilling pump to the wellhead; The signal propagation delay between a main sensor among the multiple pressure sensors and slave sensors other than the main sensor is determined by a data processing device, so as to perform delay compensation on the drilling fluid pulse signal collected by the slave sensor, so as to use the drilling fluid pulse signal after delay compensation to remove the noise signal in the drilling fluid pulse signal.

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