A method for directional drilling through a casing break based on magnetic detection

Abstract

The application relates to the technical field of directional through drilling of oil-water wells, in particular to a casing breakage directional through drilling method based on magnetic detection, which comprises the following steps: acquiring the upper breakage depth in the casing breakage oil well, electromagnetic signals of each direction angle at each depth; acquiring the magnetic field intensity of each direction angle based on the electromagnetic signals of each direction angle, and then screening all response depths; constructing a comprehensive index based on the symmetry degree of the magnetic field intensity of all direction angles at each response depth and the magnetic field intensity difference of all same direction angles at each response depth and its adjacent response depth; acquiring the comprehensive magnetic field intensity based on the comprehensive index and the maximum magnetic field intensity at each response depth, and then acquiring the offset distance of the lower breakage casing, and combining the direction angle with the maximum magnetic field intensity, the upper breakage depth and the lower breakage depth to directionally through drill the broken casing. The application improves the success rate of the directional through drilling of the broken casing by correcting the magnetic field intensity.

Description

Technical Field

[0001] This application relates to the field of directional drilling technology for oil and water wells, specifically to a method for directional drilling of casing misalignment based on magnetic detection. Background Technology

[0002] During the long-term use of oil wells, the casing is in an environment of high temperature, high pressure and complex geostress coupling. Affected by uneven formation settlement, changes in tectonic stress and frequent fluctuations in injection and production conditions, it is prone to bending deformation or even breakage due to external forces, which makes it impossible to carry out exploration operations. Therefore, it is necessary to open up the staggered casing.

[0003] Current conventional channel-making techniques lack precise positioning methods, easily leading to channel-making failures due to unclear orientation and distance of the lower break point on the casing. When grinding and milling or forced-alignment grinding and milling fail to create channels, reverse forging milling of the casing is required to expand the channel range. However, there is no theoretical basis for calculating the forging length, which can easily result in insufficient forging to form an effective channel space or excessive forging that damages the casing integrity. While hydraulic large-angle grinding and milling can create channels over a large area, it is prone to causing the lower break point to be squeezed off-center during grinding, leading to the complete loss of the channel.

[0004] Magnetic detection positioning technology is a method that uses the magnetic anomaly characteristics of metallic objects to invert azimuth and distance, which can improve the accuracy of drilling by locating the lower break casing. However, in actual measurement, the influence of complex strata (such as changes in geomagnetic intensity and superimposed interference from metallic bodies in the strata) can interfere with the magnetic field strength data of the lower break casing, leading to inaccurate positioning of the lower break casing and thus affecting the accuracy of directional drilling of the misaligned casing. Summary of the Invention

[0005] To address the aforementioned technical problems, this application provides a method for directional connection of sleeve misalignment based on magnetic detection, thereby resolving the existing issues.

[0006] The present application proposes a method for directional connection of sleeve misalignment based on magnetic detection, which adopts the following technical solution:

[0007] One embodiment of this application provides a method for directional connection of sleeve misalignment based on magnetic detection, the method comprising the following steps:

[0008] Electromagnetic signals were obtained for the upper fracture depth and the directional angle at each depth in a casing misalignment well.

[0009] Based on the amplitude of the electromagnetic signal at each direction angle at each depth and the pre-acquired Hall sensitivity, the magnetic field strength at each direction angle is obtained, and then all response depths are selected from all depths; based on the symmetry of the rearranged magnetic field strength at each direction angle at each response depth, the first index at each response depth is constructed.

[0010] Based on the difference between the magnetic field strength at each response depth and all the same directional angles at its nearest neighbor response depth, a second index is constructed at each response depth, and combined with the first index, a comprehensive index is constructed.

[0011] Based on the comprehensive index at all response depths and the maximum value among the magnetic field strengths at all directional angles at each response depth, the comprehensive magnetic field strength of the lower fracture sleeve is obtained, and then the offset distance of the lower fracture sleeve is obtained; the lower fracture depth is obtained, and based on the directional angle with the maximum magnetic field strength, the upper fracture depth, the lower fracture depth, and the offset distance, the misaligned sleeve is directionally opened.

[0012] Preferably, the magnetic field strength at each directional angle refers to the ratio between the effective value of the response voltage amplitude in the electromagnetic signal at each directional angle at each depth and the Hall sensitivity of the pre-acquired magnetic detection sensor.

[0013] Preferably, the method for obtaining the response depth is as follows:

[0014] Calculate the average magnetic field strength at each depth.

[0015] Using the mean magnetic field strength at all depths as input to the three-standard-deviation rule, the lower limit threshold is output. ,in, This is the mean of the magnetic field strength at all depths. represents the standard deviation of the mean magnetic field strength at all depths;

[0016] The depth at which the average magnetic field strength is greater than or equal to the lower threshold is denoted as the response depth.

[0017] Preferably, the average magnetic field strength at each depth refers to the average magnetic field strength at all directional angles at each depth.

[0018] Preferably, the method for constructing the first index at each response depth is as follows:

[0019] Arrange the magnetic field strength at all directions at each response depth in ascending order of direction angle, and denote it as the magnetic field strength sequence at each response depth.

[0020] The magnetic field intensity sequence at each response depth is regarded as a cyclic sequence. The phase is shifted with the maximum magnetic field intensity as the center point, while keeping the angular displacement relationship between the original sampling points unchanged, so as to obtain the new magnetic field intensity sequence at each response depth after rearrangement.

[0021] Calculate the absolute difference between the mean of all data before the point of maximum magnetic field strength in the new magnetic field strength sequence and the mean of all data after the point of maximum magnetic field strength.

[0022] The first index at each response depth is positively correlated with the absolute difference.

[0023] Preferably, the method for constructing the second index at each response depth is as follows:

[0024] Based on the difference between the magnetic field strength at each response depth and the magnetic field strength at the same directional angle at each nearest response depth, a deviation factor for each directional angle at each response depth is constructed.

[0025] The second index at each response depth is positively correlated with the deviation factor of all orientation angles at each response depth.

[0026] Preferably, the method for constructing the deviation factors of each direction angle at each response depth is as follows:

[0027] The absolute differences between the magnetic field strength at each response depth and the magnetic field strength at each same direction angle of all its nearest neighbor response depths are calculated separately.

[0028] The deviation factor of each directional angle at each response depth is positively correlated with the absolute difference.

[0029] Preferably, the composite index is positively correlated with both the first index and the second index.

[0030] Preferably, the formula for calculating the comprehensive magnetic field strength of the lower break sleeve is: In the formula, The overall magnetic field strength of the lower break bushing; This is the comprehensive index at the nth response depth; It is the maximum value of the magnetic field strength at all directional angles at the nth response depth; The total number of response depths; It is a preset minimum positive number.

[0031] Preferably, the method for obtaining the offset distance of the lower break sleeve is as follows:

[0032] Magnetic field strength data were collected when the distance between the well casing and the magnetic detection sensor was different, and multiple sets of coordinates were obtained. Each set of coordinates consisted of the corresponding magnetic field strength and distance.

[0033] A polynomial fitting method was used to fit all coordinates, with magnetic field strength as the independent variable and distance as the dependent variable, to obtain the fitting function between magnetic field strength and distance.

[0034] Substituting the combined magnetic field strength of the lower break sleeve into the fitting function, the resulting distance is the offset distance of the lower break sleeve.

[0035] Preferably, the method for obtaining the lower fracture depth is as follows:

[0036] The mean magnetic field strength at each response depth is arranged in ascending order of depth, and the difference between the mean magnetic field strength at each response depth and the mean magnetic field strength at the previous response depth is recorded as the magnetic field rise coefficient at each response depth.

[0037] Starting from the second response depth, the response depth at which the magnetic field rise coefficient first appears to be greater than a preset multiple of the magnetic field rise coefficient of the previous response depth is recorded as the lower fracture depth.

[0038] Preferably, the specific process of directionally opening the misaligned sleeve is as follows:

[0039] Calculate the mean magnetic field strength at all response depths for each direction angle, and obtain the direction angle corresponding to the maximum value among the mean magnetic field strengths;

[0040] Based on the upper fracture depth, lower fracture depth, offset distance of the lower fracture sleeve, and the direction angle corresponding to the maximum value among the average magnetic field strengths, the placement position and direction of the slant, as well as the forging and milling length, are determined.

[0041] Based on the forging and milling length, a spherical sleeve window-opening tool is used to open the channel between the upper and lower fracture surfaces along the inclined plane of the inclined device.

[0042] This application has at least the following beneficial effects:

[0043] This application addresses the problem of interference with magnetic field strength data and difficulty in accurately locating the offset distance of the lower broken casing during magnetic detection and positioning of misaligned casings due to the heterogeneity of the strata and the coupling interference of the induced magnetic field of the magnetic medium. By analyzing the symmetry characteristics of the induced magnetic field generated by the casing's annular structure, a first index is constructed to reflect the degree of interference of the electromagnetic signal with the magnetic medium at each response depth. Then, by analyzing the consistency characteristics of magnetic field strength changes at different depths, a second index is constructed to reflect the degree of interference of the electromagnetic signal at each response depth from a new perspective. Based on the first and second indices, a comprehensive index is constructed to evaluate the reliability of the data at each response depth and is used as a weight to correct the magnetic field strength at each response depth. This ensures that the comprehensive magnetic field strength of the lower broken casing more accurately represents its true magnetic field strength, thereby improving the accuracy of magnetic detection and positioning of the lower broken casing and ultimately increasing the success rate of directional drilling of the misaligned casing. Attached Figure Description

[0044] To more clearly illustrate the technical solutions and advantages in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 A flowchart illustrating the steps of a sleeve misalignment directional repair method based on magnetic detection provided in this application;

[0046] Figure 2 A flowchart illustrating the process of obtaining the comprehensive index at each response depth provided in this application. Detailed Implementation

[0047] To further illustrate the technical means and effects adopted by this application to achieve the intended purpose of the invention, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a sleeve misalignment directional connection method based on magnetic detection proposed in this application. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0049] The following description, in conjunction with the accompanying drawings, details a specific scheme for a sleeve misalignment directional connection method provided in this application.

[0050] This application provides an embodiment of a method for directional connection of sleeve misalignment based on magnetic detection. Specifically, it provides the following method for directional connection of sleeve misalignment based on magnetic detection. Please refer to [link to relevant documentation]. Figure 1 The method includes the following steps:

[0051] Step 1: Obtain electromagnetic signals of the upper fracture depth and the directional angle at each depth in the casing misalignment well.

[0052] For oil wells with casing misalignment, the drill bit is inserted along the upper fracture section of the wellbore. When the drill bit reaches the bottom of the well, the depth to which the drill bit descends is recorded as the upper fracture depth. The drill bit is then used to drill a short open-hole section downwards from the upper fracture depth, with the drilling distance set as [specified value]. m, to avoid the magnetic detection sensor failing to detect when it touches the bottom during downward detection. The size can be set by the implementer according to the implementation scenario, without special restrictions. In this embodiment... Take 10.

[0053] Then, a magnetic detection sensor is lowered from the wellhead. Once the sensor reaches the depth of the upper fracture, it begins to move downwards along the drilled open hole section to collect electromagnetic signals. Each descent... If cm, the probe is used to collect electromagnetic signals in a 360° direction. During the process of rotating and collecting electromagnetic signals, I (180 in this embodiment) directional angles are evenly set in the 360° direction to segment the electromagnetic signals collected at the current depth. The electromagnetic signal data segment collected between each directional angle and its next directional angle is recorded as the electromagnetic signal of each directional angle. Its size can be set by the implementer according to the implementation scenario. This application does not impose any special restrictions. In this embodiment, Take 2.

[0054] The probe of the magnetic detection sensor includes an electromagnetic transmitter and a receiver, which can receive electromagnetic signals of the secondary magnetic field generated by the medium under the excitation of electromagnetic waves emitted by the transmitter. The probe has a built-in gyro inclinometer for locating the geographical direction angle of the current probe orientation. In addition, the probe can rotate 360° to receive electromagnetic signals at different directional angles to detect the orientation of the lower break sleeve. In this embodiment, the sampling frequency of the electromagnetic signal data is 1kHz.

[0055] At this point, electromagnetic signals at various directional angles at different depths have been obtained.

[0056] Step 2: Based on the amplitude of the electromagnetic signal at each direction angle at each depth and the pre-acquired Hall sensitivity, obtain the magnetic field strength at each direction angle, and then filter out all response depths from all depths; based on the symmetry of the rearranged magnetic field strength at all direction angles at each response depth, construct the first index at each response depth.

[0057] During the detection process using a magnetic detection sensor, the scenario involves an open-hole section surrounded by underground reservoir structures. The wellbore contains sandstone, shale, and other formations with magnetic minerals or magnetic oil reservoirs, which act as barriers between the lowered casing and the magnetic detection sensor. Due to the strong heterogeneity of the reservoir, the conductivity varies spatially at different locations as the formation changes. These variations in conductivity within the rock layers also affect the electromagnetic excitation emitted by the magnetic detection sensor. This causes the secondary magnetic field signal generated by the lowered casing to experience uneven attenuation or scattering during propagation due to interference from these rock layers. This results in unstable fluctuations in the electromagnetic signal acquired by the receiver (e.g., metal particles in the formation can cause abnormal peaks in the electromagnetic signal), affecting the accuracy of the magnetic field strength calculation. Consequently, deviations occur when subsequently assessing the offset distance and orientation angle of the lowered casing based on the magnetic field strength, making accurate positioning difficult.

[0058] Since the well casing is approximately cylindrical, when probed at a certain depth, the electromagnetic excitation emitted by the magnetic detector acts on the lower fracture casing, generating an eddy current magnetic field. Because the casing's cross-sectional geometry is circular, this eddy current magnetic field can be approximated as the magnetic field produced by a current-carrying circular ring. According to the Biot-Savart law applied to the magnetic field produced by a current-carrying circular ring, the magnetic field strength at different locations near the ring is related to the distance from that location to the center of the ring; that is, the magnetic field strength is greatest at the center and gradually decreases as the ring moves away from the center.

[0059] Based on this principle, in this scenario, during the rotational detection process of the magnetic detection sensor, the magnetic field strength sensed by the receiver is at its maximum when the probe's rotation angle is exactly aligned with the center of the lower broken sleeve. Furthermore, as the probe rotates, the magnetic field sensed by the receiver gradually deviates from the center in the energized ring scenario, and the magnetic field strength gradually decreases. Since the sleeve's cross-section is an approximately symmetrical ring shape, when the probe's rotation angle is directly opposite the center, the rate of decrease in magnetic field strength is approximately equal if rotating in both directions. That is, under conditions of no external interference, rearranging the magnetic field strength data for all directions at a single depth with the maximum magnetic field strength as the center results in a magnetic field strength curve with a certain degree of symmetry.

[0060] Based on the above analysis, taking the j-th orientation angle at the h-th depth as an example, calculate the effective value of the response voltage amplitude in the electromagnetic signal at the j-th orientation angle at the h-th depth. ,in, Let the root mean square of the response voltage amplitude at all sampling points in the electromagnetic signal at the j-th direction angle at the h-th depth be used; then calculate... The ratio between the magnetic field strength at the h-th depth and the pre-acquired Hall sensitivity of the magnetic detection sensor yields the magnetic field strength at the j-th orientation angle. The mean magnetic field strength at all orientation angles at each depth is calculated and denoted as the mean magnetic field strength at each depth. Then, the mean magnetic field strength at all depths is used as input to the three-standard-deviation rule to output a lower limit threshold. ,in, This is the mean of the magnetic field strength at all depths. This represents the standard deviation of the mean magnetic field strength at all depths. When the mean magnetic field strength at any depth is less than the lower threshold, it indicates that the lower broken sleeve was not detected at that depth, meaning the magnetic detection sensor did not receive the electromagnetic response generated by the lower broken sleeve, and its mean magnetic field strength is extremely small. When the mean magnetic field strength at any depth is greater than or equal to the lower threshold, it indicates that the lower broken sleeve was detected at that depth. This depth is then recorded as the response depth, and the electromagnetic signal data collected at the response depth is the electromagnetic signal data of the lower broken sleeve response.

[0061] Furthermore, taking the nth response depth as an example, the magnetic field strength of all directions at the nth response depth is arranged in ascending order of direction angle, and denoted as the magnetic field strength sequence at the nth response depth. The obtained magnetic field strength sequence is regarded as a cyclic sequence, and the phase is shifted with the maximum magnetic field strength as the center point, while keeping the angular displacement relationship between the original sampling points unchanged, to obtain the new magnetic field strength sequence at the nth response depth after rearrangement.

[0062] As a preferred implementation, a first index is constructed for each response depth based on the symmetry of the rearranged magnetic field strengths at all directional angles. This index characterizes the degree of interference from the magnetic medium on the electromagnetic signals collected at each response depth. The method for constructing the first index at each response depth is as follows: The magnetic field strengths at all directional angles at each response depth are arranged in ascending order of directional angle, denoted as the magnetic field strength sequence at each response depth. This sequence is treated as a cyclic sequence, and a phase shift is performed with the maximum magnetic field strength as the center point, maintaining the original angular displacement relationship between sampling points, resulting in a new magnetic field strength sequence at each response depth after rearrangement. The absolute difference between the mean of all data before the point of maximum magnetic field strength in the new sequence and the mean of all data after the point of maximum magnetic field strength is calculated. The first index at each response depth is positively correlated with this absolute difference. This positive correlation means that the dependent variable increases (decreases) as the independent variable increases (decreases).

[0063] In this embodiment, the first exponent at the nth response depth is denoted as... Its specific expression is: In the formula, The first exponent at the nth response depth; This refers to the i-th data point in the new magnetic field strength sequence at the n-th response depth. This represents the total number of orientation angles at a single response depth. It should be noted that in this embodiment, it is assumed that the first [value] in the new magnetic field strength sequence... The first index is calculated using the data as the central data.

[0064] Explanation of the calculation principle: Based on the approximate symmetry of the rearranged magnetic field strength data, the symmetry of the magnetic field strength data is represented by calculating the absolute difference between the sums of the magnetic field strengths on the left and right sides of the highest magnetic field strength point. This reflects the deviation characteristics of the energy concentration on the radial magnetic field of the casing. When probing at the nth response depth, if there are media with strong magnetic interference (such as metallic mineral particles, magnetic oil reservoirs, etc.) in the underground rock strata, the magnetic field strength data at different points will fluctuate to varying degrees during the probe's rotation. This will lead to a larger deviation in the radial magnetic field strength data on the casing's annular cross-section, and consequently, a larger first exponent. This will distort the accuracy of the magnetic field strength at this response depth, resulting in deviations in casing positioning. Conversely, if the magnetic interference in the formation at the nth response depth is small, the rearranged magnetic field strength sequence will have strong symmetry, and the first exponent at the nth response depth will tend to 0.

[0065] Step 3: Based on the difference between the magnetic field strength at each response depth and all the same direction angles at its nearest neighbor response depth, construct a second index at each response depth, and combine it with the first index to construct a comprehensive index.

[0066] Furthermore, as the detection depth gradually decreases, the response of the lower break sleeve to electromagnetic excitation at each depth segment can be approximated as the magnetic field generated by the energized ring. Therefore, the corresponding magnetic field at the same angle remains unchanged. That is, at the same direction angle, as the depth gradually decreases, the magnetic field strength at these same direction angles has a continuous and stable numerical distribution characteristic.

[0067] Based on the above analysis, a second index is constructed by calculating the deviations of electromagnetic data at different depths at various directional angles. This index is used to reflect the severity of interference from the formation's magnetic medium on electromagnetic data at different depths.

[0068] Specifically, the F nearest response depths above and below each response depth are recorded as the nearest neighbor response depths, where F is a preset number, taken as 50 in this embodiment. In particular, when there are fewer than F response depths above or below each response depth, the 2F nearest response depths to each response depth are recorded as the nearest neighbor response depths. Since the lower casing may have a slight inclination, calculating the magnetic field strength deviation at the same directional angle based on the nearest neighbor response depths allows for calculations that assume the casing is approximately parallel to the open hole section within a local area, improving the accuracy of data statistics.

[0069] In a preferred embodiment, a deviation factor for each direction angle at each response depth is constructed based on the difference between the magnetic field strength at each response depth and the magnetic field strength at the same direction angle at each nearest response depth. This deviation factor characterizes the degree of deviation in the magnetic field strength at each direction angle at each response depth. The method for constructing the deviation factor for each direction angle at each response depth is as follows: the absolute difference between the magnetic field strength at each response depth and the magnetic field strength at the same direction angle at all nearest response depths is calculated. The deviation factor for each direction angle at each response depth is positively correlated with the absolute difference.

[0070] In this embodiment, the deviation factor of the i-th orientation angle at the n-th response depth is denoted as... Its specific expression is: In the formula, It is the deviation factor of the i-th orientation angle at the n-th response depth; Let be the magnetic field strength at the i-th direction angle at the n-th response depth; Let be the magnetic field strength at the i-th orientation angle at the m-th nearest neighbor response depth of the n-th response depth; This represents the total number of nearest neighbor response depths of the nth response depth.

[0071] The magnitude of the deviation factor reflects the degree of deviation between the magnetic field strength data at the nth response depth under the i-th direction angle and the magnetic field strength data at different depths. The larger the value, the greater the possibility of magnetic medium interference at the i-th direction angle under the n-th response depth.

[0072] Furthermore, based on the deviation factors of all directional angles at each response depth, a second index is constructed for each response depth to characterize the degree of interference of the electromagnetic signal with the magnetic medium at each response depth. The second index at each response depth is positively correlated with the deviation factors of all directional angles at each response depth.

[0073] In this embodiment, the sum of the deviation factors of all directional angles at the nth response depth is recorded as the second exponent at the nth response depth, which characterizes the degree of interference of the electromagnetic signal at the nth response depth with the magnetic medium. The larger the value, the stronger the magnetic medium in the formation section at the nth response depth, and the greater the interference of the acquired electromagnetic signal with the magnetic medium. Therefore, the reliability of the magnetic field strength data at this response depth in evaluating the casing offset distance is lower, making it difficult to accurately calculate the actual offset distance of the casing.

[0074] Based on the above analysis, as a preferred implementation, a comprehensive index is constructed based on the first and second indices at each response depth to characterize the degree of comprehensive interference of the electromagnetic signal with the magnetic medium at each response depth. The comprehensive index is positively correlated with both the first and second indices. The flowchart for obtaining the comprehensive index at each response depth is shown below. Figure 2 As shown.

[0075] To avoid the impact of inconsistent dimensions on subsequent calculations, the min-max normalization method is used to normalize the first and second exponents at each response depth. The maximum and minimum values ​​are determined based on the corresponding parameter sets at all response depths. The min-max normalization method is a well-known technique, and its specific process will not be elaborated further.

[0076] In this embodiment, the comprehensive index at the nth response depth is denoted as... Its specific expression is: In the formula, This is the comprehensive index at the nth response depth; , These are the normalized values ​​of the first exponent and the second exponent at the nth response depth, respectively.

[0077] income The larger the value, the greater the interference of the electromagnetic data at the nth response depth with the magnetic medium in the formation, and the more difficult it is to accurately represent the true induced magnetic field strength of the lower fracture casing. Therefore, the weight ratio in the subsequent calculation of the comprehensive magnetic field strength of the lower fracture casing will be lower.

[0078] Step 4: Based on the comprehensive index at all response depths and the maximum value among the magnetic field strengths of all directional angles at each response depth, obtain the comprehensive magnetic field strength of the lower fracture sleeve, and then obtain the offset distance of the lower fracture sleeve; obtain the lower fracture depth, and based on the directional angle with the maximum magnetic field strength, the upper fracture depth, the lower fracture depth, and the offset distance, perform directional drilling on the misaligned sleeve.

[0079] Furthermore, the comprehensive magnetic field strength of the lower break sleeve is calculated, and its specific expression is as follows: In the formula, The overall magnetic field strength of the lower break bushing; This is the comprehensive index at the nth response depth; It is the maximum value of the magnetic field strength at all directional angles at the nth response depth; The total number of response depths; The value is set to a minimum positive number to prevent the denominator from being 0; in this embodiment, it is set to 0.01.

[0080] The magnetic field strength at each response depth is corrected using a comprehensive index as a weight. The larger the comprehensive index (i.e., the more severe the interference), the lower the reliability of the magnetic field strength data, and therefore the smaller its weight in the calculation of the comprehensive magnetic field strength. A weighted average of the maximum magnetic field strength at each response depth yields a comprehensive magnetic field strength that more accurately represents the true magnetic field strength of the casing at the fracture point, thus allowing for a more accurate calculation of the offset distance from the center of the casing at the fracture point to the magnetic detection sensor.

[0081] Furthermore, the strength of the electromagnetic signal is related to the excitation current of the sensor coil, the cross-sectional area of ​​the bushing being measured, the permeability of the iron core, the magnetic noise, and the distance to the bushing being measured. Since the excitation current, the cross-sectional area of ​​the bushing being measured, and the permeability of the iron core are all constants, and the magnetic noise is filtered out, the strength of the electromagnetic signal is only related to the distance to the bushing being measured. Therefore, by obtaining the response relationship between the magnetic field strength and the distance to the object through calibration experiments, the offset distance of the bushing at the break can be calculated based on the comprehensive magnetic field strength measured during the actual magnetic detection process.

[0082] The specific process of the calibration experiment is as follows: Using the magnetic detection sensor described in step one, a calibration test is conducted on the same type of well casing under the same operating current. First, set... Several distance parameters were used to collect magnetic field strength data when the distance between the well casing and the magnetic detection sensor was set to each distance parameter. A set of coordinates, each consisting of the corresponding magnetic field strength and distance, is then used to fit the coordinates using a polynomial fitting method. A set of coordinates was fitted, with magnetic field strength as the independent variable and distance as the dependent variable, to obtain a fitting function between magnetic field strength and distance, thus completing the calibration experiment. Its size can be set by the implementer and is not subject to special restrictions. In this embodiment, Take 15.

[0083] Finally, the combined magnetic field strength of the lower break sleeve is substituted into the fitting function between the magnetic field strength and the distance, and the resulting distance is the offset distance of the lower break sleeve.

[0084] Furthermore, the mean value of the magnetic field strength at all response depths is calculated for each direction angle, and the direction angle corresponding to the maximum value of the mean magnetic field strength is recorded as the direction angle of the lower fracture sleeve relative to the upper fracture sleeve.

[0085] Furthermore, as the magnetic detection sensor descends from the upper fault depth to the bottom of the open hole section, the average magnetic field strength at each response depth is arranged in ascending order of depth. The difference between the average magnetic field strength at each response depth and the previous response depth is calculated and recorded as the magnetic field rise coefficient at each response depth. Starting from the second response depth, the response depth where the magnetic field rise coefficient first appears to be greater than w times the magnetic field rise coefficient of the previous response depth is recorded as the lower fault depth. Here, w is a preset multiple, and in this embodiment, w is taken as 1.5.

[0086] Furthermore, based on the upper fracture depth, lower fracture depth, offset distance of the lower fracture sleeve, and the orientation angle of the lower fracture sleeve relative to the upper fracture sleeve, the placement position and orientation of the diagonal device, as well as the forging and milling length, are determined. Then, based on the forging and milling length, a ball-type sleeve windowing tool is used to directionally open the channel between the upper and lower fractures along the inclined surface of the diagonal device. The method for determining the placement position and orientation of the diagonal device is a known technique, and the specific process will not be elaborated further.

[0087] It should be noted that the order of the embodiments described above is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. Furthermore, specific embodiments of this specification have been described above. Additionally, the processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired results. In some implementations, multitasking and parallel processing are possible or may be advantageous.

[0088] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0089] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them; modifications to the technical solutions described in the foregoing embodiments, or equivalent substitutions of some of the technical features, do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for directional connection of sleeve misalignment based on magnetic detection, characterized in that, The method includes the following steps: Electromagnetic signals were obtained for the upper fracture depth and the directional angle at each depth in a casing misalignment well. Based on the amplitude of the electromagnetic signal at each direction angle at each depth and the pre-acquired Hall sensitivity, the magnetic field strength at each direction angle is obtained, and then all response depths are selected from all depths; based on the symmetry of the rearranged magnetic field strength at each direction angle at each response depth, the first index at each response depth is constructed. Based on the difference between the magnetic field strength at each response depth and all the same directional angles at its nearest neighbor response depth, a second index is constructed at each response depth, and combined with the first index, a comprehensive index is constructed. Based on the comprehensive index at all response depths and the maximum value among the magnetic field strengths of all directional angles at each response depth, the comprehensive magnetic field strength of the lower fracture sleeve is obtained, and then the offset distance of the lower fracture sleeve is obtained; the lower fracture depth is obtained, and based on the directional angle with the maximum magnetic field strength, the upper fracture depth, the lower fracture depth, and the offset distance, the misaligned sleeve is directionally opened. The method for constructing the first index at each response depth is as follows: Arrange the magnetic field strength at all directions at each response depth in ascending order of direction angle, and denote it as the magnetic field strength sequence at each response depth. The magnetic field intensity sequence at each response depth is regarded as a cyclic sequence. The phase is shifted with the maximum magnetic field intensity as the center point, while keeping the angular displacement relationship between the original sampling points unchanged, so as to obtain the new magnetic field intensity sequence at each response depth after rearrangement. Calculate the absolute difference between the mean of all data before the point of maximum magnetic field strength in the new magnetic field strength sequence and the mean of all data after the point of maximum magnetic field strength. The first index at each response depth is positively correlated with the absolute difference; The method for constructing the second index at each response depth is as follows: Based on the difference between the magnetic field strength at each response depth and the magnetic field strength at the same directional angle at each nearest response depth, a deviation factor for each directional angle at each response depth is constructed. The second index at each response depth is positively correlated with the deviation factor of all orientation angles at each response depth; The method for constructing the deviation factors of each direction angle at each response depth is as follows: The absolute differences between the magnetic field strength at each response depth and the magnetic field strength at each same direction angle of all its nearest neighbor response depths are calculated separately. The deviation factor of each directional angle at each response depth is positively correlated with the absolute difference.

2. The method for directional connection of sleeve misalignment based on magnetic detection as described in claim 1, characterized in that, The magnetic field strength at each directional angle refers to the ratio between the effective value of the response voltage amplitude in the electromagnetic signal at each directional angle at each depth and the Hall sensitivity of the pre-acquired magnetic detection sensor.

3. The method for directional connection of sleeve misalignment based on magnetic detection as described in claim 1, characterized in that, The method for obtaining the response depth is as follows: Calculate the average magnetic field strength at each depth. Using the mean magnetic field strength at all depths as input to the three-standard-deviation rule, the lower limit threshold is output. ,in, This is the mean of the magnetic field strength at all depths. represents the standard deviation of the mean magnetic field strength at all depths; The depth at which the average magnetic field strength is greater than or equal to the lower threshold is denoted as the response depth.

4. The method for directional connection of sleeve misalignment based on magnetic detection as described in claim 3, characterized in that, The average magnetic field strength at each depth refers to the average magnetic field strength at all directional angles at each depth.

5. The method for directional connection of sleeve misalignment based on magnetic detection as described in claim 1, characterized in that, The composite index is positively correlated with both the first index and the second index.

6. The method for directional connection of sleeve misalignment based on magnetic detection as described in claim 1, characterized in that, The formula for calculating the comprehensive magnetic field strength of the lower break sleeve is as follows: In the formula, The overall magnetic field strength of the lower break bushing; This is the comprehensive index at the nth response depth; It is the maximum value of the magnetic field strength at all directional angles at the nth response depth; The total number of response depths; It is a preset minimum positive number.

7. The method for directional connection of sleeve misalignment based on magnetic detection as described in claim 1, characterized in that, The method for obtaining the offset distance of the lower break sleeve is as follows: Magnetic field strength data were collected when the distance between the well casing and the magnetic detection sensor was different, and multiple sets of coordinates were obtained. Each set of coordinates consisted of the corresponding magnetic field strength and distance. A polynomial fitting method was used to fit all coordinates, with magnetic field strength as the independent variable and distance as the dependent variable, to obtain the fitting function between magnetic field strength and distance. Substituting the combined magnetic field strength of the lower break sleeve into the fitting function, the resulting distance is the offset distance of the lower break sleeve.

8. The method for directional connection of sleeve misalignment based on magnetic detection as described in claim 1, characterized in that, The method for obtaining the lower fracture depth is as follows: The mean magnetic field strength at each response depth is arranged in ascending order of depth, and the difference between the mean magnetic field strength at each response depth and the mean magnetic field strength at the previous response depth is recorded as the magnetic field rise coefficient at each response depth. Starting from the second response depth, the response depth at which the magnetic field rise coefficient first appears to be greater than a preset multiple of the magnetic field rise coefficient of the previous response depth is recorded as the lower fracture depth.

9. The method for directional connection of sleeve misalignment based on magnetic detection as described in claim 1, characterized in that, The specific process for directional connection of the misaligned bushing is as follows: Calculate the mean magnetic field strength at all response depths for each direction angle, and obtain the direction angle corresponding to the maximum value among the mean magnetic field strengths; Based on the upper fracture depth, lower fracture depth, offset distance of the lower fracture sleeve, and the direction angle corresponding to the maximum value among the average magnetic field strengths, the placement position and direction of the slant, as well as the forging and milling length, are determined. Based on the forging and milling length, a spherical sleeve window-opening tool is used to open the channel between the upper and lower fracture surfaces along the inclined plane of the inclined device.

Images