Method for accurately measuring high side in small well deviation dynamic environment

Abstract

The invention belongs to the technical field of petroleum drilling, and particularly relates to a high-edge accurate measurement method used in a small well deviation dynamic environment, which comprises the following steps of: firstly, installing a near-bit measurement unit on an underground instrument, acquiring the output of an X-axis fluxgate and a Y-axis fluxgate, calculating the rotating speed, and then calculating the output which is influenced by the rotating speed of an X-axis accelerometer; the method comprises the following steps of: collecting the output of an X-axis accelerometer and the output of a Y-axis accelerometer, calculating the detection gravity output of the X-axis accelerometer and the detection gravity output of the Y-axis accelerometer in combination with the collected output of the X-axis accelerometer and the collected output of the Y-axis accelerometer, and calculating each attitude angle in combination with the collected output of the Z-axis accelerometer and the output of the X-axis fluxgate, the output of the Y-axis fluxgate and the output of the Z-axis fluxgate. According to the method, high edge influence factors under the small well deviation dynamic condition are analyzed, the rotating speed is calculated by using three paths of vertical fluxgates under the small well deviation dynamic condition by utilizing the characteristic that the rotating speed has no influence on the output of the fluxgate sensor, and the acceleration influence factors under the dynamic condition are reflected in an algorithm mode and are filtered and eliminated, so that an accurate attitude angle is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of oil drilling, and in particular relates to a high side accurate measurement method used in a small well deviation dynamic environment. Background Art

[0002] Slightly deviated drilling is one of the most difficult drilling problems in the world today. It can be used in deep wells, ultra-deep wells and vertical sections of complex wells in conditions of high-steep structures, high-angle formations and strong natural deflection ability. It has the advantages of reducing casing layers and casing sizes, improving mechanical drilling speed and reducing drill string accidents. As an active anti-deflection method, the anti-deflection and straightening effect of slowly deviating drilling is not affected by drilling pressure, which is conducive to improving drilling speed. The automatic slowly deviated drilling tool is an advanced drilling tool with a downhole closed-loop control system, which can realize downhole active deflection correction, keep the well wall vertical and has extremely high technical content. This tool is particularly suitable for vertical drilling of steeply structured formations and deep wells. Therefore, it has a good application prospect in the development of oil and gas resources in my country, especially in the development of oil resources in the west. In order to solve the problem of anti-deflection and fast drilling in steeply structured and high-angle formations, the research on high-side precise measurement technology under the dynamic environment of slowly deviated drilling is very important.

[0003] In the prior art, there is a Chinese invention patent with publication number CN113153270A, entitled "A method for measuring the dynamic well inclination angle and tool face angle near the drill bit while drilling", which discloses the following content: The present invention discloses a method for measuring the dynamic well inclination angle and tool face angle near the drill bit while drilling. The method for measuring the dynamic well inclination angle and tool face angle near the drill bit while drilling uses a limiting filter to filter out the step excitation interference signal caused by the impact noise, and then uses a UKF filter to filter out the colored noise generated by most of the vibration acceleration and the magnetic interference colored noise in the output signal of the three-axis fluxgate, and then uses a sliding filter to smooth the radial acceleration signal in the three-axis acceleration sensor. Finally, the radial or tangential magnetic field signal of the three-axis fluxgate is used as a reference signal to establish an accurate extraction of the gravity acceleration component near the drill bit based on the cross-correlation detection method, thereby realizing the dynamic real-time and accurate solution of the dynamic well inclination angle and tool face angle of the drilling tool.

[0004] Another example is the Chinese invention patent with publication number CN118292851A, entitled "A Method for Measuring Near-Drill-Bit Well Deviation and Multi-Sector Azimuth Gamma for Oil Drilling", which discloses the following content: The present invention discloses a method for measuring near-drill-bit well deviation and multi-sector azimuth gamma for oil drilling, which relates to the field of drilling engineering technology in oil, coal mines and geological exploration, and solves the technical problem that simple natural gamma and upper and lower gamma cannot accurately judge the formation changes for thin formations with large changes, and cannot be applied in actual production, including obtaining directional gamma measurement through a directional windowed gamma sensor, obtaining gamma pointing and near-drill-bit well deviation through a 3-axis quartz accelerometer, obtaining real-time dynamic gamma sensor pointing through a 2-axis flux gate, and obtaining 16-sector azimuth gamma through algorithm calculation.

[0005] Although the above-mentioned comparative documents have proposed improvements to the related measurement methods of well inclination, the influence of acceleration under dynamic conditions cannot be eliminated, making it difficult to obtain accurate high edges. Summary of the invention

[0006] In order to solve the above-mentioned problems existing in the prior art, a method for accurately measuring the high side under small well inclination and dynamic environment is provided to obtain accurate high side under small well inclination and dynamic environment, and provide technical and data support for key links such as judgment of the inclination state of drilling tools and control of guiding force.

[0007] In order to achieve the above technical effects, the technical solution of this application is as follows:

[0008] A method for accurately measuring high side in a dynamic environment with small well deviation comprises the following steps:

[0009] First, a near-drill-bit measurement unit is installed on the downhole instrument. The near-drill-bit measurement unit includes an X-axis fluxgate, a Y-axis fluxgate, and a Z-axis fluxgate, as well as an X-axis accelerometer, a Y-axis accelerometer, and a Z-axis accelerometer. The outputs of the X-axis fluxgate and the Y-axis fluxgate are collected, the rotation speed is calculated, and then the output affected by the rotation speed of the X-axis accelerometer is calculated. Combined with the collected outputs of the X-axis accelerometer and the Y-axis accelerometer, the gravity output detected by the X-axis accelerometer and the Y-axis accelerometer is calculated. Combined with the collected output of the Z-axis accelerometer and the outputs of the X-axis fluxgate, the Y-axis fluxgate, and the Z-axis fluxgate, the well inclination angle, the high side angle, and the azimuth are calculated.

[0010] Specifically, the first step is to obtain the rotation speed: through the phase difference output between the X-axis flux gate and the Y-axis flux gate, the rotation speed of the near-drill bit measurement unit is measured and a signal is output;

[0011] When the downhole instrument is at a small well inclination and rotates, the outputs of the X-axis fluxgate and the Y-axis fluxgate change periodically. The period of change is the period of the downhole rotation speed. The output is related to the azimuth. The relevant magnetic field strength output is calculated according to the well inclination angle, and then the change period of the output of the X-axis fluxgate and the Y-axis fluxgate is obtained.

[0012] There is a phase difference between the X-axis fluxgate output and the Y-axis fluxgate output. The speed is calculated based on the time and phase difference. The relationship between the X-axis fluxgate output change and the speed is shown in the following formula:

[0013]

[0014] Where: Mx is the speed calculated by the X-axis fluxgate, M x is the X-axis fluxgate output, t is the time, and the relationship between the Y-axis fluxgate output change and the speed is shown in the following formula:

[0015]

[0016] Where: My is the speed calculated by the Y-axis fluxgate, M y is the Y-axis fluxgate output, and t is the time. In order to more accurately calculate the speed of the downhole instrument, the speed expression of the downhole instrument is as follows:

[0017]

[0018] Where: ω is the rotation speed of the downhole instrument.

[0019] The second step is to calculate the output of the accelerometer to eliminate the influence according to the rotation speed;

[0020] After subtracting the rotation speed influence of the X-axis accelerometer, Y-axis accelerometer and Z-axis accelerometer according to the rotation speed in the first step, the acceleration output of the X-axis accelerometer and the Y-axis accelerometer is obtained, and the accurate high-side quantity can be calculated;

[0021] The X-axis accelerometer, Y-axis accelerometer and Z-axis accelerometer are installed perpendicularly to each other in the near-drill-bit measurement unit of the downhole instrument. The direction of the Z-axis accelerometer is consistent with the axial direction of the instrument, the direction of the X-axis accelerometer points to the circumferential direction of the instrument, and the direction of the Y-axis accelerometer forms the right-hand rule with the X-axis accelerometer and the Z-axis accelerometer, which is the same as the tangential direction of the instrument circumference.

[0022] Furthermore, during the rotation of the downhole instrument, the accelerometer can detect not only gravity but also centripetal acceleration and tangential acceleration.

[0023] Furthermore, the centripetal acceleration detected by the X-axis accelerometer is expressed as follows:

[0024] axcen =rω 2

[0025] Where: r is the distance between the center of mass of the accelerometer and the center of rotation axis, unit: mm; ω is the rotation speed, unit: ° / s. After obtaining the rotation speed, the noise signal brought by the rotation speed can be eliminated.

[0026] Furthermore, the Y-axis accelerometer detects tangential acceleration, which is expressed as follows:

[0027]

[0028] Where: r is the distance between the center of mass of the accelerometer and the center of rotation, unit: mm; is the angular acceleration, unit: ° / S 2 ,

[0029]

[0030] Furthermore, the exact outputs of the X-axis accelerometer and the Y-axis accelerometer are given by:

[0031] a x =A x -rω 2

[0032]

[0033] Where: A x and A y are the total outputs of the X-axis accelerometer and the Y-axis accelerometer, a x and a y are the gravity output measured by the X-axis accelerometer and the Y-axis accelerometer respectively.

[0034] The third step is to calculate the downhole angle, high side angle and azimuth angle based on the mutually perpendicular X-axis accelerometer, Y-axis accelerometer and Z-axis accelerometer with eliminated influence, and three mutually perpendicular X-axis fluxgates, Y-axis fluxgates and Z-axis fluxgates.

[0035] Furthermore, the X-axis fluxgate, the Y-axis fluxgate and the Z-axis fluxgate are installed perpendicularly to each other on the near-drill-bit measurement unit, wherein the axial direction of the Z-axis fluxgate is consistent with the axial direction of the system, the axial direction of the Y-axis fluxgate is perpendicular to the axial direction of the system and tangent to the circumferential direction, and the axial direction of the X-axis fluxgate is perpendicular to the axial direction of the system and points to the axis.

[0036] Furthermore, the data output by the X-axis fluxgate, the Y-axis fluxgate and the Z-axis fluxgate are amplified and filtered by a rebalancing circuit, and then the signal is detected by a phase-sensitive detection circuit, and finally the signal of the fluxgate is output.

[0037] Furthermore, the expression for the well inclination is as follows:

[0038] or

[0039] Where: θ is the downhole angle, unit: rad; a i is the accelerometer output, where i = X, Y, Z.

[0040] Going further, the high side angle expression is as follows:

[0041]

[0042] Where: T is the high side angle.

[0043] Furthermore, the azimuth angle expression is as follows

[0044]

[0045] Where: is the azimuth, a i is the accelerometer output, M i is the fluxgate output, where i=X, Y, Z.

[0046] This application has the following technical effects:

[0047] The small well inclination dynamic high side measurement method provided in the present application analyzes the influencing factors of the high side under small well inclination dynamics, utilizes the characteristic that the rotation speed has no effect on the output of the fluxgate sensor, calculates the rotation speed using three vertical fluxgates under small well inclination dynamics, reflects the acceleration influencing factors under dynamics in the form of an algorithm and filters and eliminates them to obtain an accurate attitude angle. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 Schematic diagram of the application method flow chart.

[0049] Figure 2 Schematic diagram of the X-axis fluxgate and Y-axis fluxgate output diagram.

[0050] Figure 3 Schematic diagram of the installation relationship of the X-axis accelerometer, the Y-axis accelerometer and the Z-axis accelerometer.

[0051] Figure 4 Schematic diagram of the effects of accelerometer rotation.

[0052] Figure 5 This is a schematic diagram of the near-drill-bit measurement unit structure.

[0053] In the attached figure:

[0054] 1 is a near-drill-bit measurement unit, 2 is three flux gates, 3 is three accelerometers, 4 is a rebalancing circuit, 5 is a collection and transmission circuit, and 6 is a filtering circuit. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0056] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0057] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0058] In the description of the present application, it should be noted that the terms "upper", "vertical", "inner", "outer", etc. indicate the orientation or position relationship based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the product of the application is usually placed when in use, or the orientation or position relationship commonly understood by those skilled in the art. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0059] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "set", "install", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0060] Example 1

[0061] like Figure 1As shown, a method for accurate high side measurement in a dynamic environment with small well deviation includes the following steps:

[0062] First, a near-drill-bit measurement unit is installed on the downhole instrument. The near-drill-bit measurement unit includes an X-axis fluxgate, a Y-axis fluxgate, and a Z-axis fluxgate, as well as an X-axis accelerometer, a Y-axis accelerometer, and a Z-axis accelerometer. The outputs of the X-axis fluxgate and the Y-axis fluxgate are collected, the rotation speed is calculated, and then the output affected by the rotation speed of the X-axis accelerometer is calculated. Combined with the collected outputs of the X-axis accelerometer and the Y-axis accelerometer, the gravity output detected by the X-axis accelerometer and the Y-axis accelerometer is calculated. Combined with the collected output of the Z-axis accelerometer and the outputs of the X-axis fluxgate, the Y-axis fluxgate, and the Z-axis fluxgate, the well inclination angle, the high side angle, and the azimuth are calculated.

[0063] Example 2

[0064] like Figure 1 As shown, a method for accurate high side measurement in a dynamic environment with small well deviation includes the following steps:

[0065] Step 1: Get the rotation speed: Through the phase difference between the X-axis flux gate and the Y-axis flux gate, measure the rotation speed of the near-drill bit measurement unit and output a signal, that is, measure the rotation speed of the entire system;

[0066] When the downhole instrument is in a small well inclination and rotates, the outputs of the X-axis flux gate and the Y-axis flux gate change periodically. The period of change is the period of the downhole rotation speed. The output is related to the azimuth. The relevant magnetic field strength output is calculated according to the well inclination angle, and then the change period of the output of the X-axis flux gate and the Y-axis flux gate is obtained, and the period of the rotation speed can be obtained.

[0067] The second step is to calculate the output of the accelerometer to eliminate the influence according to the rotation speed;

[0068] After subtracting the rotation speed influence of the X-axis accelerometer, Y-axis accelerometer and Z-axis accelerometer according to the rotation speed in the first step, the acceleration output of the X-axis accelerometer and the Y-axis accelerometer is obtained. Since the rotation speed has a small influence on the Z-axis accelerometer, it can be ignored in this method, and the accurate high-side quantity can be calculated;

[0069] The third step is to calculate the downhole angle, high side angle and azimuth angle based on the mutually perpendicular X-axis accelerometer, Y-axis accelerometer and Z-axis accelerometer with eliminated influence, and three mutually perpendicular X-axis fluxgates, Y-axis fluxgates and Z-axis fluxgates; the downhole angle, high side angle and azimuth angle are the attitude angles.

[0070] Example 3

[0071] like Figure 1 As shown, a method for accurate high side measurement in a dynamic environment with small well deviation includes the following steps:

[0072] First, a near-drill-bit measurement unit is installed on the downhole instrument. The near-drill-bit measurement unit includes an X-axis fluxgate, a Y-axis fluxgate, and a Z-axis fluxgate, as well as an X-axis accelerometer, a Y-axis accelerometer, and a Z-axis accelerometer. The outputs of the X-axis fluxgate and the Y-axis fluxgate are collected, the rotation speed is calculated, and then the output affected by the rotation speed of the X-axis accelerometer is calculated. Combined with the collected outputs of the X-axis accelerometer and the Y-axis accelerometer, the gravity output detected by the X-axis accelerometer and the Y-axis accelerometer is calculated. Combined with the collected output of the Z-axis accelerometer and the outputs of the X-axis fluxgate, the Y-axis fluxgate, and the Z-axis fluxgate, the well inclination angle, the high side angle, and the azimuth are calculated.

[0073] Specifically, the first step is to obtain the rotation speed: through the phase difference between the output of the X-axis flux gate and the Y-axis flux gate, the rotation speed of the near-drill bit measurement unit is measured and a signal is output, that is, the rotation speed of the entire system is measured;

[0074] like Figure 2 As shown, when the downhole instrument is at a small well inclination and rotates, the outputs of the X-axis flux gate and the Y-axis flux gate change periodically, and the period of change is the period of the downhole rotation speed. The output is related to the azimuth. The relevant magnetic field strength output is calculated according to the well inclination angle, and then the change period of the output of the X-axis flux gate and the Y-axis flux gate is obtained, and the period of the rotation speed can be obtained.

[0075] There is a phase difference between the X-axis fluxgate output and the Y-axis fluxgate output. The speed is calculated based on the time and phase difference. The relationship between the X-axis fluxgate output change and the speed is shown in the following formula:

[0076]

[0077] Where: Mx is the speed calculated by the X-axis fluxgate, M x is the X-axis fluxgate output, t is the time, and the relationship between the Y-axis fluxgate output change and the speed is shown in the following formula:

[0078]

[0079] Where: My is the speed calculated by the Y-axis fluxgate, M y is the Y-axis fluxgate output, and t is the time. In order to more accurately calculate the speed of the downhole instrument, the speed expression of the downhole instrument is as follows:

[0080]

[0081] Where: ω is the rotation speed of the downhole instrument.

[0082] The second step is to calculate the output of the accelerometer to eliminate the influence according to the rotation speed;

[0083] After subtracting the rotation speed influence of the X-axis accelerometer, Y-axis accelerometer and Z-axis accelerometer according to the rotation speed in the first step, the acceleration output of the X-axis accelerometer and the Y-axis accelerometer is obtained. Since the rotation speed has a small influence on the Z-axis accelerometer, it can be ignored in this method, and the accurate high-side quantity can be calculated;

[0084] The installation diagram of three accelerometers, near-bit measurement unit and downhole instruments is shown in the figure below. Figure 3 As shown, the X-axis accelerometer, Y-axis accelerometer and Z-axis accelerometer are installed perpendicularly to each other in the near-drill-bit measurement unit of the downhole instrument. The direction of the Z-axis accelerometer is consistent with the axial direction of the instrument, the direction of the X-axis accelerometer points to the circumference of the instrument, and the direction of the Y-axis accelerometer forms the right-hand rule with the X-axis accelerometer and the Z-axis accelerometer, which is the same as the tangential direction of the instrument circumference.

[0085] like Figure 4 As shown, during the rotation of the downhole instrument, the accelerometer can detect not only the gravity, but also the centripetal acceleration and the tangential acceleration.

[0086] The centripetal acceleration detected by the X-axis accelerometer is expressed as follows:

[0087] a xcen =rω 2

[0088] Where: r is the distance between the center of mass of the accelerometer and the center of rotation axis, unit: mm; ω is the rotation speed, unit: ° / s. After obtaining the rotation speed, the noise signal brought by the rotation speed can be eliminated.

[0089] The Y-axis accelerometer detects tangential acceleration, and the expression is as follows:

[0090]

[0091] Where: r is the distance between the center of mass of the accelerometer and the center of rotation, unit: mm; is the angular acceleration, unit: ° / S 2 , From the above formula, it can be seen that if the tangential acceleration is detected, the angular acceleration needs to be known.

[0092]

[0093] The exact outputs of the X-axis accelerometer and the Y-axis accelerometer are given by:

[0094] a x =A x -rω 2

[0095]

[0096] Where: A x and A y are the total outputs of the X-axis accelerometer and the Y-axis accelerometer, a x and a y are the gravity output measured by the X-axis accelerometer and the Y-axis accelerometer respectively.

[0097] The third step is to calculate the downhole angle, high side angle and azimuth angle based on the mutually perpendicular X-axis accelerometer, Y-axis accelerometer and Z-axis accelerometer with eliminated influence, and three mutually perpendicular X-axis fluxgates, Y-axis fluxgates and Z-axis fluxgates; the downhole angle, high side angle and azimuth angle are the attitude angles.

[0098] The X-axis fluxgate, Y-axis fluxgate and Z-axis fluxgate are installed perpendicularly to each other on the near-drill-bit measurement unit, wherein the axial direction of the Z-axis fluxgate is consistent with the axial direction of the system, the axial direction of the Y-axis fluxgate is perpendicular to the axial direction of the system and tangent to the circumferential direction, and the axial direction of the X-axis fluxgate is perpendicular to the axial direction of the system and points to the axis.

[0099] like Figure 5 As shown, the data output by the X-axis fluxgate, the Y-axis fluxgate and the Z-axis fluxgate are amplified and filtered by the rebalancing circuit, and then the signal is detected by the phase-sensitive detection circuit, and finally the signal of the fluxgate is output.

[0100] The expression for the well inclination is as follows:

[0101] or

[0102] Where: θ is the downhole angle, unit: rad; a i is the accelerometer output, where i = X, Y, Z.

[0103] Going further, the high side angle expression is as follows:

[0104]

[0105] Where: T is the high side angle.

[0106] Furthermore, the azimuth angle expression is as follows

[0107]

[0108] Where: is the azimuth, a i is the accelerometer output, M i is the fluxgate output, where i=X, Y, Z.

[0109] Example 4

[0110] Measurement method: Small well inclination is a special mode for the drilling process. At this time, the outputs of the X-axis and Y-axis accelerometers of the three mutually perpendicular accelerometers are close to zero, and the output of the Z accelerometer is close to the maximum value. Therefore, the dynamic rotation state has a great influence on the output of the X-axis and Y-axis accelerometers. The rotation speed measurement algorithm is used to eliminate the error of the accelerometer in the rotation state, so it is necessary to measure the rotation speed.

[0111] In the downhole instrument, the attitude angle is calculated by measuring the earth's magnetic field component using a fluxgate. Small well inclination and rotation state have no effect on the fluxgate. Using the output of the fluxgate, the fluxgate output shows periodic changes in dynamic conditions. Using the law of periodic changes and the integral measurement method, the rotation speed of the downhole instrument can be calculated, thereby calculating the impact value of the output of the three accelerometers. By eliminating the impact value, accurate acceleration output can be obtained. By obtaining accurate three mutually perpendicular acceleration quantities and three mutually perpendicular magnetic field quantities, accurate high-side quantities can be obtained through the attitude algorithm.

[0112] In the case of small well deviation, since the downhole rotation speed is basically uniform, the rotation speed mainly affects the X-accelerometer, and the influence on the Y-axis accelerometer is negligible, and the influence on the Z-accelerometer can also be ignored, so the dynamic influence of the X-accelerometer is mainly eliminated. The rotation speeds measured by the three mutually perpendicular flux gates are mutually verified to obtain accurate rotation speeds. The rotation acceleration in the output of the X-accelerometer is filtered and eliminated by using the characteristics of rotation acceleration to obtain accurate X-acceleration output, thereby obtaining three mutually perpendicular acceleration outputs and three mutually perpendicular magnetic field strength outputs, and calculating accurate high-side attitude.

[0113] Three vertical accelerometers and three vertical flux gates are installed in a near-drill-bit device of a rotary steering system. The near-drill-bit device is installed in a bin of the rotary steering system and is installed on the outer edge of the bin.

[0114] The measuring device includes an accelerometer, a fluxgate, an acceleration filter circuit, a rebalancing circuit and an acquisition and transmission circuit. The acceleration filter circuit first filters the output signal of the accelerometer, and the rebalancing circuit filters and amplifies the output signal of the fluxgate. The acquisition and transmission circuit is used for high-speed acquisition, and then the algorithm is used for high-speed calculation and processing to obtain the high side under the dynamic state of small well deviation, and transmit it to the control system of the rotary steering system.

[0115] The present invention uses specific embodiments to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

[0116] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific variations and combinations that do not deviate from the essence of the present invention based on the technical revelations disclosed by the present invention, and these variations and combinations are still within the protection scope of the present invention.

Claims

1. A high side accurate measurement method in a small well deviation dynamic environment, characterized in that: The steps include: First, a near-drill-bit measurement unit is installed on the downhole instrument. The near-drill-bit measurement unit includes an X-axis fluxgate, a Y-axis fluxgate, and a Z-axis fluxgate, as well as an X-axis accelerometer, a Y-axis accelerometer, and a Z-axis accelerometer. The outputs of the X-axis fluxgate and the Y-axis fluxgate are collected, the rotation speed is calculated, and then the output affected by the rotation speed of the X-axis accelerometer is calculated. Combined with the collected outputs of the X-axis accelerometer and the Y-axis accelerometer, the gravity output detected by the X-axis accelerometer and the Y-axis accelerometer is calculated. Combined with the collected output of the Z-axis accelerometer and the outputs of the X-axis fluxgate, the Y-axis fluxgate, and the Z-axis fluxgate, the well inclination angle, the high side angle, and the azimuth are calculated.

2. The method for accurately measuring high side in a dynamic environment with small well deviation according to claim 1 is characterized in that: Step 1: Get the rotation speed: Through the phase difference between the X-axis flux gate and the Y-axis flux gate, measure the rotation speed of the near-drill bit measurement unit and output the signal to obtain the rotation speed of the entire system; The second step is to calculate the output of the accelerometer after eliminating the influence according to the rotation speed; after subtracting the rotation speed influence of the X-axis accelerometer, the Y-axis accelerometer and the Z-axis accelerometer according to the rotation speed in the first step, the acceleration output of the X-axis accelerometer and the Y-axis accelerometer is obtained; The third step is to calculate the downhole angle, high side angle and azimuth angle based on the mutually perpendicular X-axis accelerometer, Y-axis accelerometer and Z-axis accelerometer with eliminated influence, and the mutually perpendicular X-axis fluxgate, Y-axis fluxgate and Z-axis fluxgate.

3. The method for accurately measuring high side in a dynamic environment with small well deviation according to claim 2 is characterized in that: When the downhole instrument is at a small well inclination and rotates, the outputs of the X-axis fluxgate and the Y-axis fluxgate change periodically. The period of change is the period of the downhole rotation speed. The output is related to the azimuth. The relevant magnetic field strength output is calculated according to the well inclination angle, and then the change period of the output of the X-axis fluxgate and the Y-axis fluxgate is obtained.

4. The method for accurately measuring high side in a dynamic environment with small well deviation according to claim 3 is characterized in that: There is a phase difference between the X-axis fluxgate output and the Y-axis fluxgate output. The speed is calculated based on the time and phase difference. The relationship between the X-axis fluxgate output change and the speed is shown in the following formula: Where: Mx is the speed calculated by the X-axis fluxgate, M x is the X-axis fluxgate output, t is the time; The relationship between the Y-axis fluxgate output change and the speed is shown in the following formula: Where: My is the speed calculated by the Y-axis fluxgate, M y is the Y-axis fluxgate output, t is the time; In order to more accurately calculate the rotation speed of the downhole instrument, the rotation speed expression of the downhole instrument is as follows: Where: ω is the rotation speed of the downhole instrument.

5. The method for accurately measuring high side in a dynamic environment with small well deviation according to claim 1 is characterized in that: The X-axis accelerometer, Y-axis accelerometer and Z-axis accelerometer are installed perpendicularly to each other in the near-drill-bit measurement unit of the downhole instrument. The direction of the Z-axis accelerometer is consistent with the axial direction of the instrument, the direction of the X-axis accelerometer points to the circumferential direction of the instrument, and the direction of the Y-axis accelerometer forms the right-hand rule with the X-axis accelerometer and the Z-axis accelerometer, which is the same as the tangential direction of the instrument circumference.

6. The method for accurately measuring high side in a dynamic environment with small well deviation according to claim 5 is characterized in that: During the rotation of downhole instruments, the accelerometer can detect not only gravity, but also centripetal acceleration and tangential acceleration; The centripetal acceleration detected by the X-axis accelerometer is expressed as follows: a xcen =rω 2 Where: r is the distance between the center of mass of the accelerometer and the center of rotation axis, unit: mm; ω is the rotation speed, unit: ° / s. After obtaining the rotation speed, the noise signal brought by the rotation speed can be eliminated; The Y-axis accelerometer detects tangential acceleration, and the expression is as follows: Where: r is the distance between the center of mass of the accelerometer and the center of rotation, unit: mm; is the angular acceleration, unit: ° / S 2 , 7. The method for accurately measuring high side in a dynamic environment with small well deviation according to claim 6 is characterized in that: The exact outputs of the X-axis accelerometer and the Y-axis accelerometer are given by: a x =A x -rω 2 Where: A x and A y are the total outputs of the X-axis accelerometer and the Y-axis accelerometer, a x and a y are the gravity output measured by the X-axis accelerometer and the Y-axis accelerometer respectively.

8. The method for accurately measuring high side in a dynamic environment with small well deviation according to claim 1 is characterized in that: The X-axis fluxgate, Y-axis fluxgate and Z-axis fluxgate are installed perpendicularly to each other on the near-drill-bit measurement unit, wherein the axial direction of the Z-axis fluxgate is consistent with the axial direction of the system, the axial direction of the Y-axis fluxgate is perpendicular to the axial direction of the system and tangent to the circumferential direction, and the axial direction of the X-axis fluxgate is perpendicular to the axial direction of the system and points to the axis.

9. The method for accurately measuring high side in a dynamic environment with small well deviation according to claim 8, characterized in that: The data output by the X-axis fluxgate, Y-axis fluxgate and Z-axis fluxgate are amplified and filtered by the rebalancing circuit, and then the signal is detected by the phase-sensitive detection circuit, and finally the signal of the fluxgate is output.

10. The method for accurately measuring high side in a dynamic environment with small well deviation according to claim 9, characterized in that: The expression for the well inclination is as follows: Where: θ is the downhole angle, unit: rad; a i is the accelerometer output, where i = X, Y, Z.

11. The method for accurately measuring high side in a dynamic environment with small well deviation according to claim 9, characterized in that: The high side angle expression is as follows: Where: T is the high side angle.

12. The method for accurately measuring high side in a dynamic environment with small well deviation according to claim 9, characterized in that: The azimuth angle expression is as follows: Where: is the azimuth, a i is the accelerometer output, M i is the fluxgate output, where i=X, Y, Z.

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