Method for correcting positioning measurement error of well cementation rubber plug excited by shock tube

Abstract

The invention discloses a method for correcting the positioning measurement error of a well cementation rubber plug excited by a shock tube, which relates to the technical field of oil and gas well cementation and comprises the following steps of: generating a lower shock wave signal and an upper shock wave signal in an underground tubular column when the shock wave well cementation rubber plug moves for a preset stroke; detecting an upper shock wave signal and a lower shock wave signal; a drilling fluid propagation velocity initial value and a cement slurry propagation velocity initial value are preset, the position of the shock wave well cementation rubber plug in the underground pipe column is calculated, and a resolving position sequence is obtained; according to a preset stroke, combining with the resolving position sequence to obtain an error sequence; and performing propagation velocity correction according to the error sequence by adopting a mathematical optimization algorithm. According to the method, the error sequence is provided, the propagation velocity is corrected by adopting the mathematical optimization algorithm, the estimation error of the shock wave signal propagation velocity is reduced, and the accuracy of well cementation rubber plug positioning measurement is further improved.

Description

Technical Field

[0001] The present application relates to the technical field of oil and gas well cementing, and in particular to a method for correcting cementing plug positioning measurement errors by shock tube excitation. Background Art

[0002] Cementing operation is one of the important links in oil and gas well drilling engineering. Cementing plugs play the role of isolating cementing slurry and drilling fluid in cementing operation. During the slurry replacement process of cementing operation, the cementing plug is driven by the pressure of the drilling fluid on the upper side and moves to the bottom of the pipe string, driving the cement slurry under the cementing plug into the annulus between the pipe string and the well wall. During the slurry replacement process, if the cementing plug breaks and leaks or gets stuck in the pipe string, the annulus will be replaced or a cement plug will form at the bottom of the pipe string, resulting in cementing failure. Therefore, it is necessary to study the positioning and measurement of the cementing plug in the downhole pipe string.

[0003] In the prior art, Chinese patent CN108150131A discloses a pressure wave generator and cementing device for position positioning, the pressure wave generator includes: a base, a transmission device is provided in the base, a rolling wheel is provided on the base, and the rolling wheel is connected to the base through a mounting shaft; a pressure wave generating mechanism includes a support seat, a push rod, a reset spring, a connecting rod and a push wing plate; the rotation of the rolling wheel can drive the transmission device to periodically push the push rod to move upward along the axial direction of the support seat, thereby driving the connecting rod to move radially along the support seat and push the push wing plate out; the reset spring is used to restore the push rod to its initial position. The device is a purely mechanical structure with strong environmental adaptability, and can periodically generate pressure waves to effectively and accurately locate the actual position of the equipment.

[0004] In the actual cementing plug positioning measurement process, the propagation speed of the pressure wave (i.e., shock wave signal) is related to parameters such as the propagation medium, propagation channel and propagation temperature. There are many unknown quantities, which will cause estimation errors in the propagation speed of the shock wave signal, resulting in positioning measurement errors. However, the above-mentioned prior art has not studied or solved the above-mentioned problems, the estimation error of the propagation speed of the shock wave signal is large, and the accuracy of the cementing plug positioning measurement is poor. Summary of the invention

[0005] The present application provides a method for correcting cementing plug positioning measurement errors by shock tube excitation, which is used to solve the problems in the prior art of large estimation errors in shock wave signal propagation velocity and poor accuracy in cementing plug positioning measurement.

[0006] On the one hand, the present application provides a method for correcting cementing plug positioning measurement errors by shock tube excitation, comprising the following steps:

[0007] Step 1: Every time the shock wave cementing plug moves a preset distance, a lower shock wave signal and an upper shock wave signal are generated in the downhole tubing.

[0008] Step 2: Detect the upper shock wave signal at the wellhead pipe string, detect the lower shock wave signal at the wellhead annulus, and obtain the detection time difference between the upper shock wave signal and the lower shock wave signal.

[0009] Step three, preset the initial value of the drilling fluid propagation velocity and the initial value of the cement slurry propagation velocity, calculate the position of the shock wave cementing plug in the downhole tubing according to the initial value of the drilling fluid propagation velocity, the initial value of the cement slurry propagation velocity and the detection time difference, and obtain a solution position sequence; and obtain an error sequence according to the preset stroke combined with the solution position sequence.

[0010] Step 4: Using a mathematical optimization algorithm to correct the propagation velocity according to the error sequence, to obtain a corrected drilling fluid propagation velocity and a corrected cement slurry propagation velocity.

[0011] Step five: calculating the position of the shock wave cementing plug in the downhole tubing string according to the corrected drilling fluid propagation velocity, the corrected cement slurry propagation velocity and the detection time difference to obtain a corrected position sequence.

[0012] In a possible implementation, in step 3, the position sequence is calculated as follows:

[0013] {H1,H2,H3,...,H i ,H i+1}

[0014] Where H1 represents the initial calculated position of the shock wave cementing plug in the downhole string, H i , H i+1 They respectively represent the calculated positions of the shock wave cementing plug in the downhole tubing string when the shock wave cementing plug moves the preset travels of i-1 segments and i segments.

[0015] In a possible implementation, when the shock wave cementing plug moves i-1 preset strokes, the calculated position H of the shock wave cementing plug in the downhole tubular string is i It is obtained by the following equation:

[0016]

[0017] Among them, t i1 and t i2 They respectively represent the propagation time of the upper shock wave signal and the lower shock wave signal detected for the i-th time when the shock wave cementing plug moves the i-1 preset stroke, L0 represents the total well depth, V1 and V2 represent the initial values ​​of the drilling fluid propagation velocity and the initial values ​​of the cement slurry propagation velocity, respectively.

[0018] From the above equation, we can get H i The expression is as follows:

[0019]

[0020] Among them, t i2 -t i1 That is, the detection time difference obtained by the i-th detection.

[0021] In a possible implementation, in step 3, the error sequence is as follows:

[0022] {e1,e2,e3,...,e i}

[0023] Among them, e i It represents the error between the calculated position of the shock wave cementing plug in the downhole string and the theoretical position when the shock wave cementing plug moves i preset strokes, e i =H i+1 -H i -H0, where H0 represents the preset stroke.

[0024] In a possible implementation, in step 4, the mathematical optimization algorithm includes: least squares method and Kalman filter algorithm.

[0025] In one possible implementation, step four includes: defining an error optimization index, optimizing the error optimization index using a mathematical optimization algorithm, and continuously changing the initial value of the drilling fluid propagation velocity and the initial value of the cement slurry propagation velocity. When the error optimization index is minimized, the corresponding initial value of the drilling fluid propagation velocity and the initial value of the cement slurry propagation velocity are the corrected drilling fluid propagation velocity and the corrected cement slurry propagation velocity.

[0026] In a possible implementation, step 5 further includes:

[0027] Step six: predicting the current actual position of the shock wave cementing plug according to the corrected position sequence.

[0028] In a possible implementation, step six includes: calculating the shock wave signal propagation time according to the corrected position sequence, and predicting the current actual position of the shock wave cementing plug according to the corrected position sequence and the shock wave signal propagation time.

[0029] The method for correcting the positioning measurement error of cementing plugs by shock tube excitation in this application has the following advantages:

[0030] The position of the shock wave cementing plug in the downhole tubing is calculated according to the initial value of the drilling fluid propagation velocity, the initial value of the cement slurry propagation velocity and the detection time difference to obtain a solved position sequence. The error sequence is obtained by combining the solved position sequence with the preset stroke. A mathematical optimization algorithm is used to correct the propagation velocity according to the error sequence, thereby reducing the estimated error of the shock wave signal propagation velocity and improving the accuracy of the cementing plug positioning measurement.

[0031] It is proposed to define an error optimization index, use a mathematical optimization algorithm to optimize the error optimization index, continuously change the initial value of the drilling fluid propagation velocity and the initial value of the cement slurry propagation velocity, when the error optimization index is minimum, the corresponding initial value of the drilling fluid propagation velocity and the initial value of the cement slurry propagation velocity are the corrected drilling fluid propagation velocity and the corrected cement slurry propagation velocity, and the accuracy of the corrected propagation velocity is improved through continuous optimization of the mathematical optimization algorithm.

[0032] The proposed method calculates the shock wave signal propagation time according to the corrected position sequence, and predicts the current actual position of the shock wave cementing plug according to the corrected position sequence and the shock wave signal propagation time, thereby improving the prediction accuracy of the current actual position of the shock wave cementing plug. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 A schematic flow chart of a method for correcting cementing plug positioning measurement errors by shock tube excitation provided in an embodiment of the present application;

[0035] Figure 2 A schematic diagram of the structure of the cementing plug positioning and measuring system provided in an embodiment of the present application;

[0036] Figure 3 A schematic diagram of the structure of the shock wave cementing plug provided in an embodiment of the present application.

[0037] Description of reference numerals:

[0038] 1- shock wave cementing plug, 2- wellhead pipe geophone, 3- wellhead annulus geophone, 4- solution module, 11- plug body, 12- control module, 13- power supply module, 14- fixed air chamber, 15- deformation air chamber, 16- air valve, 17- pressurized air pump, 18- trip meter roller, 19- trip meter sensor. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0040] like Figure 1 As shown, the embodiment of the present application provides a method for correcting the positioning measurement error of a cementing plug by shock tube excitation, comprising the following steps:

[0041] Step 1: Every time the shock wave cementing plug 1 moves a preset distance, a lower shock wave signal and an upper shock wave signal are generated in the downhole tubing.

[0042] Step 2: Detect the upper shock wave signal at the wellhead pipe string, detect the lower shock wave signal at the wellhead annulus, and obtain the detection time difference between the upper shock wave signal and the lower shock wave signal.

[0043] Step three, preset the initial value of the drilling fluid propagation velocity and the initial value of the cement slurry propagation velocity, calculate the position of the shock cementing plug 1 in the downhole tubing according to the initial value of the drilling fluid propagation velocity, the initial value of the cement slurry propagation velocity and the detection time difference, and obtain a solution position sequence; and obtain an error sequence according to the preset stroke combined with the solution position sequence.

[0044] Step 4: Using a mathematical optimization algorithm to correct the propagation velocity according to the error sequence, to obtain a corrected drilling fluid propagation velocity and a corrected cement slurry propagation velocity.

[0045] Step five, calculating the position of the shock wave cementing plug 1 in the downhole tubular according to the corrected drilling fluid propagation velocity, the corrected cement slurry propagation velocity and the detection time difference, and obtaining a corrected position sequence.

[0046] Specifically, for ease of understanding, in this embodiment, a cementing plug positioning measurement system is provided to perform each step of the cementing plug positioning measurement error correction method with shock tube excitation in this application. Figure 2 and Figure 3 As shown, the cementing plug positioning and measuring system includes: a shock wave cementing plug 1, a wellhead pipe column geophone 2, a wellhead annulus geophone 3 and a solution module 4.

[0047] The shock wave cementing plug 1 is used to generate a lower shock wave signal and an upper shock wave signal in the downhole tubular; the wellhead tubular detector 2 is used to detect the upper shock wave signal at the wellhead tubular; the wellhead annulus detector 3 is used to detect the lower shock wave signal at the wellhead annulus; the solution module 4 is used to calculate the position of the shock wave cementing plug 1 in the downhole tubular according to the detection time difference between the upper shock wave signal and the lower shock wave signal.

[0048] The shock wave cementing plug 1 comprises: a plug body 11 , a shock wave generating mechanism, a control module 12 and a power supply module 13 .

[0049] The shock wave generating mechanism is fixedly disposed on the lower side of the plug body 11 , the control module 12 and the power supply module 13 are both fixedly and sealedly disposed inside the plug body 11 , and the control module 12 is electrically connected to the power supply module 13 and the shock wave generating mechanism, respectively.

[0050] The control module 12 is used to control the shock wave generating mechanism to generate the lower shock wave signal and the upper shock wave signal by expanding the telescopic air chamber.

[0051] Specifically, the wellhead pipe geophone 2 and the wellhead annulus geophone 3 may be communicatively connected or electrically connected to the solution module 4. In the present embodiment, they are electrically connected. The solution module 4 is a portable computer.

[0052] Exemplarily, the shock wave generating mechanism includes: a fixed air chamber 14 , a deformable air chamber 15 , an air valve 16 and a pressurized air pump 17 .

[0053] The fixed air chamber 14 is fixedly arranged on the lower side of the plug body 11, the upper side of the deformable air chamber 15 is fixedly connected to the lower side of the fixed air chamber 14, the air valve 16 and the pressurized air pump 17 are fixedly arranged between the fixed air chamber 14 and the deformable air chamber 15, and the air valve 16 and the pressurized air pump 17 are electrically connected to the control module 12.

[0054] The control module 12 is configured to: when the pressure of the fixed air chamber 14 is equal to that of the deformable air chamber 15, close the air valve 16, and control the pressurized air pump 17 to pump the gas in the deformable air chamber 15 into the fixed air chamber 14, so that the pressure of the fixed air chamber 14 increases and the deformable air chamber 15 contracts; whenever the shock wave cementing plug 1 moves for a preset stroke or a preset time, open the air valve 16 to expand the deformable air chamber 15, thereby generating the lower shock wave signal and the upper shock wave signal.

[0055] Specifically, in this embodiment, the working process of the shock wave generating mechanism is as follows: when the shock wave cementing plug 1 is driven downward by the pressure of the drilling fluid on its upper side, the deforming air chamber 15 is subjected to the pressure of the cement slurry on the lower side, and the gas in the deforming air chamber 15 is pressurized and enters the fixed air chamber 14 through the air valve 16. When the pressure of the fixed air chamber 14 is equal to that of the deforming air chamber 15, the control module 12 closes the air valve 16; the control module 12 controls the pressurized air pump 17 to continue to pump the gas in the deforming air chamber 15 into the fixed air chamber 14, so that the pressure of the fixed air chamber 14 increases and the deforming air chamber 15 contracts; in this embodiment, every time the shock wave cementing plug 1 moves a stroke of 10m (in other possible embodiments, it can also be set to Set other preset strokes, or set it to every preset time, such as 20s), the control module 12 opens the air valve 16, and the compressed gas in the fixed air chamber 14 quickly enters the deformed air chamber 15, causing the deformed air chamber 15 to expand rapidly, generating a lower shock wave signal for the lower cement slurry. After the lower shock wave signal reaches the bottom of the well through the lower cement slurry, it propagates upward along the annulus between the pipe string and the well wall to the wellhead annulus. At the same time, due to the rapid expansion of the deformed air chamber 15, a reaction force will be generated, so that the movement of the shock wave cementing plug 1 is hindered, and an upper shock wave signal is generated for the upper drilling fluid. The upper shock wave signal propagates to the wellhead pipe string through the upper drilling fluid, thus completing the generation of the lower shock wave signal and the upper shock wave signal. When the pressure of the fixed air chamber 14 and the deformed air chamber 15 is equal again, the next cycle of generating the lower shock wave signal and the upper shock wave signal is entered. In this way, a lower shock wave signal and an upper shock wave signal are generated every preset stroke or preset time (set according to actual conditions). Since the lower shock wave signal and the upper shock wave signal are generated almost simultaneously, the position of the shock wave cementing plug 1 in the downhole tubular string can be calculated by the detection time difference between the upper shock wave signal and the lower shock wave signal.

[0056] Exemplarily, the shock wave cementing plug 1 further includes: a trip meter sensing mechanism.

[0057] The odometer sensing mechanism is fixedly disposed on the upper side of the rubber plug body 11 , and the odometer sensing mechanism is electrically connected to the control module 12 .

[0058] The odometer sensing mechanism is used to measure the stroke of the shock wave cementing plug 1 and send the measured stroke to the control module 12 .

[0059] Specifically, the stroke of the shock wave cementing plug 1 is measured by the odometer sensing mechanism, so that the control module 12 can control the shock wave generating mechanism at intervals of a preset stroke to generate an upper shock wave signal and a lower shock wave signal.

[0060] Exemplarily, the odometer sensing mechanism includes: a odometer roller 18 and a odometer sensor 19 .

[0061] The meter roller 18 is fixedly connected to the upper side of the plug body 11 through a fixing rod. The meter roller 18 is rotationally connected to one end of the fixing rod away from the plug body 11 and is rollingly connected to the inner wall of the downhole pipe string.

[0062] The odometer sensor 19 is fixedly disposed on the upper side of the rubber plug body 11 and is electrically connected to the control module 12 .

[0063] The trip meter sensor 19 is used to obtain the travel of the shock wave cementing plug 1 according to the rolling of the trip meter roller 18 and send the travel to the control module 12 .

[0064] Specifically, in other possible embodiments, the mileage sensing mechanism may also adopt the roller, rocker arm, tension spring and magnetic sensor in the intelligent cementing plug and positioning method of Chinese patent CN117868743A, or other mileage sensing mechanisms, as long as the function of measuring the stroke of the shock wave cementing plug 1 can be achieved.

[0065] Exemplarily, in step 3, the solution position sequence is shown in the following formula:

[0066] {H1,H2,H3,...,H i ,H i+1}

[0067] Where H1 represents the initial calculated position of the shock wave cementing plug 1 in the downhole string, H i , H i+1 They respectively represent the calculated positions of the shock wave cementing plug 1 in the downhole tubular string when the shock wave cementing plug 1 moves i-1 segments and i segments of preset travel.

[0068] For example, when the shock wave cementing plug 1 moves a preset distance i-1, the calculated position H of the shock wave cementing plug 1 in the downhole pipe string is i It is obtained by the following equation:

[0069]

[0070] Among them, t i1 and t i2 They represent the propagation time of the upper shock wave signal and the lower shock wave signal detected for the i-th time when the shock wave cementing plug 1 moves the preset stroke i-1 (the upper shock wave signal propagates through the upper drilling fluid H i The distance to the wellhead pipe string, the lower shock wave signal propagates through the lower cement slurry L0-H i After reaching the bottom of the well, it propagates upward along the annulus between the tubing string and the well wall for a distance of L0 to the annulus at the wellhead), L0 represents the total length of the well depth, V1 and V2 represent the initial values ​​of the drilling fluid propagation velocity and the initial values ​​of the cement slurry propagation velocity, respectively.

[0071] From the above equation, we can get H i The expression is as follows:

[0072]

[0073] Among them, t i2 -t i1 That is, the detection time difference obtained by the i-th detection.

[0074] Specifically, the propagation speed of the upper shock wave signal and the lower shock wave signal in the downhole liquid is affected by parameters such as the propagation medium, the propagation channel and the propagation temperature, and is generally between 1100-1300 m / s. In this embodiment, the initial value V1 of the drilling fluid propagation speed and the initial value V2 of the cement slurry propagation speed are both preset to 1200 m / s.

[0075] Since there is an estimated error between the initial value of the drilling fluid propagation velocity V1 and the initial value of the cement slurry propagation velocity V2 and the actual propagation velocity, the calculated position H of the shock wave cementing plug 1 in the downhole pipe string is i There are also errors, which need to be corrected.

[0076] Exemplarily, in step three, the error sequence is as follows:

[0077] {e1,e2,e3,...,e i}

[0078] Among them, e i represents the error between the calculated position of the shock wave cementing plug 1 in the downhole string and the theoretical position when the shock wave cementing plug 1 moves a preset stroke of i segments, e i =H i+1 -H i -H0, where H0 represents the preset stroke.

[0079] Specifically, theoretically, the calculated position H of the shock cementing plug 1 in the downhole pipe string is i+1 Should be equal to the previous position H i Add the preset stroke H0, that is, H i+1 The theoretical position is H i +H0, but due to the estimated error between the initial value of the drilling fluid propagation velocity V1 and the initial value of the cement slurry propagation velocity V2 and the actual propagation velocity, the calculated position H of the shock wave cementing plug 1 in the downhole pipe string is i+1 With the theoretical position H i +H0 also has an error, defined as e i =H i+1 -H i -H0.

[0080] Exemplarily, in step 4, the mathematical optimization algorithm includes: least squares method and Kalman filter algorithm.

[0081] Exemplarily, step four includes: defining an error optimization index, optimizing the error optimization index using a mathematical optimization algorithm, and continuously changing the initial value of the drilling fluid propagation velocity and the initial value of the cement slurry propagation velocity. When the error optimization index is minimized, the corresponding initial value of the drilling fluid propagation velocity and the initial value of the cement slurry propagation velocity are the corrected drilling fluid propagation velocity and the corrected cement slurry propagation velocity.

[0082] Specifically, in this embodiment, the error optimization index is defined as follows:

[0083]

[0084] Among them, J represents the error optimization index, e k represents the kth error, i represents the preset travel of the shock wave cementing plug 1 for i segments, Q represents the weighting coefficient matrix. In this embodiment, the weighting coefficient matrix is ​​defined as an exponential function with a diagonal line A diagonal matrix of Make sure that the weight multiplied each time is within the range of (0.5, 1).

[0085] In this embodiment, the least square method is used to optimize the error optimization index, specifically, the initial value of the drilling fluid propagation velocity and the initial value of the cement slurry propagation velocity are iteratively calculated to minimize the error optimization index J. The iterative formula is as follows:

[0086]

[0087] The initial values ​​of the drilling fluid propagation velocity and cement slurry propagation velocity obtained by iterative calculation should be constrained in a reasonable range, as follows: V1∈(V 1min ,V 1max ), V2∈(V 2min ,V 2max ), where V 1min and V 1max They represent the lower and upper limits of the initial value of the drilling fluid propagation velocity, V 2min and V 2max They represent the lower and upper limits of the initial value of cement slurry propagation velocity, respectively. The specific upper and lower limits are set according to the actual environmental factors and prior knowledge. When the error optimization index J is the smallest, the corresponding initial values ​​of drilling fluid propagation velocity and cement slurry propagation velocity, i.e., the corrected drilling fluid propagation velocity and the corrected cement slurry propagation velocity, are substituted into H i The expression of can be used to obtain the corrected position sequence.

[0088] In other possible embodiments, a Kalman filter algorithm or other mathematical optimization algorithms may also be used to correct the propagation speed.

[0089] Exemplarily, step five further includes:

[0090] Step six: predicting the current actual position of the shock wave cementing plug 1 according to the corrected position sequence.

[0091] Exemplarily, step six includes: calculating the shock wave signal propagation time according to the corrected position sequence, and predicting the current actual position of the shock wave cementing plug 1 according to the corrected position sequence and the shock wave signal propagation time.

[0092] Specifically, since it takes time for the shock wave signal to propagate from the shock wave cementing plug 1 to the wellhead, the latest position in the corrected position sequence does not represent the actual position of the shock wave cementing plug 1 at the latest shock wave detection time, but the position corresponding to the latest shock wave detection time minus the shock wave signal propagation time. Assuming that the movement speed of the shock wave cementing plug 1 remains unchanged, the actual position of the shock wave cementing plug 1 at the latest shock wave detection time is shown in the following formula:

[0093]

[0094] Among them, H 实new It represents the actual position of shock wave cementing plug 1 at the latest shock wave detection time, H new represents the latest position in the corrected position sequence, V 1i represents the modified drilling fluid propagation velocity (in this embodiment, the moment when the upper shock wave signal is detected is taken as the shock wave detection moment, so the shock wave signal propagation time is defined as ), V j Indicates the movement speed of the shock wave cementing plug 1.

[0095] Movement speed V of shock wave cementing plug 1 j It can be obtained by the ratio of the preset stroke H0 and the time difference between two adjacent shock wave detection moments, as shown in the following formula:

[0096]

[0097] Among them, T i represents the shock wave detection time corresponding to the movement of the shock wave cementing plug 1 for a preset stroke of i segments, T i-1 It indicates the shock wave detection time corresponding to when the shock wave cementing plug 1 moves i-1 preset strokes.

[0098] Specifically, let the time difference between the current time and the latest shock wave detection time be Δt j , then the actual position H of the shock wave cementing plug 1 at the latest shock wave detection time 实new Add the time difference Δtj During this period, the moving distance of the shock wave cementing plug 1 is equal to the current actual position. The current actual position H 当前 As shown below:

[0099]

[0100] This covers the entire time period and obtains the accurate current actual position.

[0101] Specifically, in this embodiment, steps 3 to 6 are all implemented by the solving module 4 .

[0102] The embodiment of the present application calculates the position of the shock wave cementing plug 1 in the downhole tubing according to the initial value of the drilling fluid propagation velocity, the initial value of the cement slurry propagation velocity and the detection time difference, obtains a solution position sequence, combines the solution position sequence with a preset stroke, obtains an error sequence, and uses a mathematical optimization algorithm to correct the propagation velocity according to the error sequence, thereby reducing the estimation error of the shock wave signal propagation velocity, thereby improving the accuracy of the cementing plug positioning measurement.

[0103] It is proposed to define an error optimization index, use a mathematical optimization algorithm to optimize the error optimization index, continuously change the initial value of the drilling fluid propagation velocity and the initial value of the cement slurry propagation velocity, when the error optimization index is minimum, the corresponding initial value of the drilling fluid propagation velocity and the initial value of the cement slurry propagation velocity are the corrected drilling fluid propagation velocity and the corrected cement slurry propagation velocity, and the accuracy of the corrected propagation velocity is improved through continuous optimization of the mathematical optimization algorithm.

[0104] The proposed method calculates the shock wave signal propagation time according to the corrected position sequence and predicts the current actual position of the shock wave cementing plug 1 according to the corrected position sequence and the shock wave signal propagation time, thereby improving the prediction accuracy of the current actual position of the shock wave cementing plug 1.

[0105] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0106] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A method for correcting the positioning measurement error of cementing plugs by shock tube excitation, characterized in that: The following steps are involved: Step 1: Every time the shock wave cementing plug moves a preset distance, a lower shock wave signal and an upper shock wave signal are generated in the downhole tubing string; Step 2: detecting the upper shock wave signal at the wellhead pipe string, detecting the lower shock wave signal at the wellhead annulus, and obtaining a detection time difference between the upper shock wave signal and the lower shock wave signal; Step 3: Preset the initial value of the drilling fluid propagation velocity and the initial value of the cement slurry propagation velocity, calculate the position of the shock wave cementing plug in the downhole tubing according to the initial value of the drilling fluid propagation velocity, the initial value of the cement slurry propagation velocity and the detection time difference, and obtain a solution position sequence; obtain an error sequence according to the preset stroke combined with the solution position sequence; Step 4, using a mathematical optimization algorithm to correct the propagation velocity according to the error sequence to obtain a corrected drilling fluid propagation velocity and a corrected cement slurry propagation velocity; Step five: calculating the position of the shock wave cementing plug in the downhole tubing string according to the corrected drilling fluid propagation velocity, the corrected cement slurry propagation velocity and the detection time difference to obtain a corrected position sequence.

2. The method for correcting the positioning measurement error of cementing plugs by shock tube excitation according to claim 1, characterized in that: In step 3, the solution position sequence is shown as follows: {H1,H2,H3,...,H i ,H i+1 } Where H1 represents the initial calculated position of the shock wave cementing plug in the downhole string, H i , H i+1 They respectively represent the calculated positions of the shock wave cementing plug in the downhole tubing string when the shock wave cementing plug moves the preset travels of i-1 segments and i segments.

3. The method for correcting the positioning measurement error of cementing plugs by shock tube excitation according to claim 2, characterized in that: When the shock wave cementing plug moves i-1 preset strokes, the calculated position H of the shock wave cementing plug in the downhole pipe string is i It is obtained by the following equation: Among them, t i1 and t i2 They respectively represent the propagation time of the upper shock wave signal and the lower shock wave signal detected for the i-th time when the shock wave cementing plug moves the i-1 preset stroke, L0 represents the total depth of the well, V1 and V2 represent the initial value of the drilling fluid propagation velocity and the initial value of the cement slurry propagation velocity, respectively; From the above equation, we can get H i The expression is as follows: Among them, t i2 -t i1 That is, the detection time difference obtained by the i-th detection.

4. The method for correcting the positioning measurement error of cementing plugs by shock tube excitation according to claim 2, characterized in that: In step three, the error sequence is shown as follows: <h2 style=";text-align:left;direction:ltr">{e1,e2,e3,...,e<h2 style=";text-align:left;direction:ltr"> i <h2 style=";text-align:left;direction:ltr">} Among them, e i It represents the error between the calculated position of the shock wave cementing plug in the downhole string and the theoretical position when the shock wave cementing plug moves i preset strokes, e i =H i+1 -H i -H0, where H0 represents the preset stroke.

5. The method for correcting the positioning measurement error of cementing plugs by shock tube excitation according to claim 1, characterized in that: In step 4, the mathematical optimization algorithm includes: least squares method and Kalman filter algorithm.

6. The method for correcting the positioning measurement error of cementing plugs by shock tube excitation according to claim 1, characterized in that: Step 4 includes: defining an error optimization index, optimizing the error optimization index by using a mathematical optimization algorithm, continuously changing the initial value of the drilling fluid propagation velocity and the initial value of the cement slurry propagation velocity, and when the error optimization index is the minimum, the corresponding initial value of the drilling fluid propagation velocity and the initial value of the cement slurry propagation velocity are the corrected drilling fluid propagation velocity and the corrected cement slurry propagation velocity.

7. The method for correcting the positioning measurement error of cementing plugs by shock tube excitation according to claim 1, characterized in that: Step 5 and beyond also include: Step six: predicting the current actual position of the shock wave cementing plug according to the corrected position sequence.

8. The method for correcting the positioning measurement error of cementing plugs by shock tube excitation according to claim 7, characterized in that: Step six includes: calculating the shock wave signal propagation time according to the corrected position sequence, and predicting the current actual position of the shock wave cementing plug according to the corrected position sequence and the shock wave signal propagation time.

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