Method for removing interference signals from acceleration sensors during drilling operations

Abstract

The present invention provides a method for removing interference signals received by an acceleration sensor during drilling operations, including using an acceleration sensor and a magnetic field sensor to jointly measure data; removing interference signals received by the acceleration sensor in the x-axis and y-axis directions, including obtaining a first filter; calculating the real-time drill tool speed according to the raw data of the magnetic field sensor; selecting corresponding filter parameters from the low-pass filter library according to the real-time drill tool speed, and using the first filter under the filter parameters to filter the real-time acquired raw data of the acceleration sensor in the x-axis and y-axis directions; removing interference signals received by the acceleration sensor in the z-axis direction, including obtaining a second filter; using the second filter to filter the raw data of the acceleration sensor in the z-axis direction. The method of the present invention can ensure that the acceleration sensor data is accurately obtained during the dynamic continuous measurement of the drill tool attitude, and provide support for the wide application of the dynamic continuous measurement of the downhole drill tool attitude.

Description

Technical Field

[0001] The invention belongs to the technical field of drilling operations and relates to a method for removing interference signals suffered by an acceleration sensor in drilling operations. Background Art

[0002] During drilling operations, the combination of acceleration sensors and magnetic field sensors can be used to measure the drill tool attitude, such as well inclination, azimuth and tool face. Usually, the measurement is carried out when the pump is stopped when connecting a single root (about 10m long) or a column (about 30m long), that is, the measurement value is static and the position is discontinuous. In order to improve the geological and engineering effects of drilling operations, the continuous measurement of the drill tool attitude has received more and more attention. However, when the drill tool is rotating during drilling, the acceleration sensor is affected by the vibration of the drill bit and the centrifugal force of the rotation, and the measurement value is seriously distorted, which has become a technical difficulty restricting the continuous measurement of the downhole drill tool attitude. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art.

[0004] To this end, the present invention provides a method for removing interference signals received by an acceleration sensor during drilling operations.

[0005] The technical solution of the present invention is to provide a method for removing interference signals of an acceleration sensor during drilling operations, the method comprising:

[0006] S1, using an acceleration sensor and a magnetic field sensor to jointly measure data, and obtaining the original data of the magnetic field sensor and the original data of the acceleration sensor in the x, y, and z axis directions in real time;

[0007] S2, based on step S1, removing the interference signal of the acceleration sensor, including:

[0008] S20, removing interference signals in the x-axis and y-axis directions of the acceleration sensor, including:

[0009] S201, obtaining a first filter,

[0010] The first filter includes multiple groups of filter parameters corresponding to multiple drilling tool rotation speeds to form a low-pass filter library, wherein the first filter under any group of filter parameters can retain the first signal and remove the second signal when filtering, the first signal is a useful signal, and the second signal is an interference signal;

[0011] S202, calculating the real-time drilling tool rotation speed according to the raw data of the magnetic field sensor;

[0012] S203, selecting corresponding filter parameters from the low-pass filter library according to the real-time drilling tool rotation speed, and using the first filter under the filter parameters to filter the x-axis and y-axis raw data of the acceleration sensor acquired in real time;

[0013] S20', removing interference signals in the z-axis direction of the acceleration sensor, including:

[0014] S201', obtaining a second filter,

[0015] The second filter is a fixed low-pass filter, and the fixed low-pass filter can retain the DC signal and remove the third signal;

[0016] S202': Use the second filter to filter the Z-axis raw data of the acceleration sensor.

[0017] Furthermore, the step S20 further includes:

[0018] S204, obtaining the offset of the signal obtained in step S203;

[0019] S205: Correct the signal obtained in step S203 using the offset.

[0020] Furthermore, the offset of the signal obtained in step S203 is obtained in the following manner:

[0021] Acquire all peak values ​​of the signal data obtained in step S203, wherein the peak values ​​include wave crests and wave troughs;

[0022] The average value of all the peaks and the average value of all the troughs are calculated, and the average value of the two average values ​​is the offset.

[0023] Further, the signal obtained in step S203 is corrected using the offset in the following manner:

[0024] The offset is subtracted from the signal data obtained in step S203.

[0025] Furthermore, the filter parameters corresponding to any drilling tool speed are designed in the following way:

[0026] Obtaining the frequency of the drilling tool rotation speed;

[0027] The frequency of the drill rotation speed is designed as the cut-off frequency of the first filter;

[0028] The filter parameters are designed according to the cut-off frequency.

[0029] Furthermore, the first signal is a signal with a frequency less than or equal to RPM / 60, and the second signal is a signal with a frequency greater than or equal to n×RPM / 60, wherein RPM is the drill speed corresponding to the filter parameter, and n is the minimum number of blades of the drill bit.

[0030] Further, the third signal is a signal with a frequency greater than or equal to RPM1 / 60, wherein RPM1 is the minimum value that the rotation speed of the drill bit in actual drilling should have.

[0031] Furthermore, the z-axis of the acceleration and magnetic field sensor is parallel to the instrument axis, the x-axis and y-axis of the acceleration and magnetic field sensor are perpendicular to the instrument axis, and the x-, y-, and z-axes satisfy the right-hand rule.

[0032] Furthermore, the first filter and the second filter both include Butterworth filters.

[0033] Furthermore, the magnetic field sensor includes a fluxgate or a magnetoresistive sensor.

[0034] The above technical solution uses an acceleration sensor and a magnetic field sensor to measure data together, wherein a magnetic field sensor that is not affected by downhole vibration and centrifugal force of drilling tool rotation is used to obtain the drilling tool rotation speed, and cooperates with the designed first filter, thereby achieving the removal of vibration interference signals in the x-axis and y-axis directions of the acceleration sensor; at the same time, a second filter is designed to filter the original data of the z-axis of the acceleration sensor, thereby achieving the removal of interference signals in the z-axis direction of the acceleration sensor. The method of the present invention can ensure that the acceleration sensor data is accurately obtained during the dynamic continuous measurement of the drilling tool attitude, and provide support for the wide application of dynamic continuous measurement of downhole drilling tool attitude. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The included drawings are used to provide a further understanding of the embodiments of the present invention, which constitute a part of the specification, are used to illustrate the embodiments of the present invention, and together with the text description, explain the principles of the present invention. Obviously, the drawings in the following description are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 A schematic flow chart of a method for removing interference signals from an acceleration sensor during drilling operations according to a specific embodiment of the present invention is shown;

[0037] Figure 2 A schematic diagram of a sensor assembly according to a specific embodiment of the present invention is shown;

[0038] Figure 3The figure shows the signal form after the vibration interference signals in the x and y directions of the acceleration sensor provided by the specific embodiment of the present invention are removed;

[0039] a. Signal shape after the vibration interference signals in the x and y directions are removed; b. The offset caused by centrifugal force. DETAILED DESCRIPTION

[0040] It should be noted that, in the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0042] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0043] In one embodiment of the present invention, Figure 1 As shown, a method for removing interference signals from an acceleration sensor during drilling operations is provided, the method comprising:

[0044] S1, using an acceleration sensor and a magnetic field sensor to jointly measure data, and obtaining the original data of the magnetic field sensor and the original data of the acceleration sensor in the x, y, and z axis directions in real time;

[0045] S2, based on step S1, removing the interference signal of the acceleration sensor, including:

[0046] S20, removing interference signals in the x-axis and y-axis directions of the acceleration sensor, including:

[0047] S201, obtaining a first filter,

[0048] The first filter includes multiple groups of filter parameters corresponding to multiple drilling tool rotation speeds to form a low-pass filter library, wherein the first filter under any group of filter parameters can retain the first signal and remove the second signal when filtering, the first signal is a useful signal, and the second signal is an interference signal;

[0049] S202, calculating the real-time drilling tool rotation speed according to the raw data of the magnetic field sensor;

[0050] S203, selecting corresponding filter parameters from the low-pass filter library according to the real-time drilling tool rotation speed, and using the first filter under the filter parameters to filter the x-axis and y-axis raw data of the acceleration sensor acquired in real time;

[0051] S20', removing interference signals in the z-axis direction of the acceleration sensor, including:

[0052] S201', obtaining a second filter,

[0053] The second filter is a fixed low-pass filter, and the fixed low-pass filter can retain the DC signal and remove the third signal;

[0054] S202': Use the second filter to filter the Z-axis raw data of the acceleration sensor.

[0055] In this embodiment, the z-axis of the acceleration and magnetic field sensor is parallel to the instrument axis, the x-axis and y-axis of the acceleration and magnetic field sensor are perpendicular to the instrument axis, and the x-, y-, and z-axes satisfy the right-hand rule.

[0056] like Figure 2 As shown, Ax, Ay and Az represent the x, y and z component values ​​measured by the acceleration sensor, and Bx, By and Bz represent the x, y and z component values ​​measured by the magnetic field sensor. There is no restriction on the installation direction and type of the acceleration and magnetic field sensors.

[0057] In this embodiment, the first filter and the second filter may both include Butterworth filters, but are not limited thereto.

[0058] In this embodiment, the magnetic field sensor may include a fluxgate or a magnetoresistive sensor, but is not limited thereto.

[0059] It can be seen that the present embodiment uses an acceleration sensor and a magnetic field sensor to measure data together, wherein a magnetic field sensor that is not affected by downhole vibration and centrifugal force of drilling tool rotation is used to obtain the drilling tool rotation speed, and cooperates with the designed first filter, thereby achieving the removal of vibration interference signals in the x-axis and y-axis directions of the acceleration sensor; at the same time, a second filter is designed to filter the original data of the z-axis of the acceleration sensor, thereby achieving the removal of interference signals in the z-axis direction of the acceleration sensor. The method of the present invention can ensure that the acceleration sensor data is accurately obtained during the dynamic continuous measurement of the drilling tool attitude, and provide support for the wide application of dynamic continuous measurement of downhole drilling tool attitude.

[0060] In the above embodiment, in order to further ensure the accuracy of the data finally obtained, the step S20 further includes:

[0061] S204, obtaining the offset of the signal obtained in step S203;

[0062] S205: Correct the signal obtained in step S203 using the offset.

[0063] That is, in addition to being affected by downhole vibration, acceleration sensor measurement is also affected by the centrifugal force of drilling tool rotation. The method of this embodiment can correct the offset caused by the centrifugal force, thereby ensuring the accuracy of data measurement.

[0064] like Figure 3 As shown, the offset of the signal obtained in step S203 can be obtained in the following manner:

[0065] Acquire all peak values ​​of the signal data obtained in step S203, wherein the peak values ​​include wave crests and wave troughs;

[0066] The average value of all the peaks and the average value of all the troughs are calculated, and the average value of the two average values ​​is the offset.

[0067] In this embodiment, using Figure 3 The signal data after the vibration interference signals in the x and y directions are removed is shown. The algorithm for finding the peaks and troughs is used to obtain all the peak values. There are many types of specific peak finding algorithms, which are not limited. Then, the average values ​​of the peaks and the average values ​​of the troughs are averaged to obtain Figure 3 The offset of the signal shown in .

[0068] In this embodiment, the signal obtained in step S203 can be corrected by using the offset in the following manner:

[0069] The offset is subtracted from the signal data obtained in step S203.

[0070] In the above embodiment, in order to obtain the filter parameters, the filter parameters corresponding to any drilling tool speed are designed in the following manner:

[0071] Obtaining the frequency of the drilling tool rotation speed;

[0072] The frequency of the drill rotation speed is designed as the cut-off frequency of the first filter;

[0073] The filter parameters are designed according to the cut-off frequency.

[0074] For example,

[0075] In the above embodiment, in order to ensure better interference removal, the first signal is a signal with a frequency less than or equal to RPM / 60, and the second signal is a signal with a frequency greater than or equal to n×RPM / 60, wherein RPM is the drill speed corresponding to the filter parameter, and n is the minimum number of blades of the drill bit.

[0076] For example, when designing a specific set of filtering parameters, the corresponding speed frequency is set as the cutoff frequency of the low-pass filter, and the filter parameters are designed based on this cutoff frequency. In this way, multiple sets of corresponding filter parameters can be designed for different speeds. In practical applications, the filtering parameters corresponding to the speed are found according to the actual measured speed, and then the filtering parameters are used for filtering to remove vibration interference signals.

[0077] Specifically, when the acceleration sensor rotates with the drill bit, the measured useful signals in the x and y directions have the same frequency as the rotation speed, and the useful signal in the z direction is a constant value. The frequency of the downhole vibration signal is a multiple of the rotation speed, and the specific multiple is the number of blades of the drill bit. Under normal circumstances, the number of blades of the drill bit is greater than or equal to 3, that is, the frequency of the vibration signal is at least three times the rotation speed, and the signal is an interference signal. Then the useful signal frequency in the x and y directions is RPM / 60 (Hz), and the interference signal frequency is greater than or equal to 3×RPM / 60 (Hz). The filter designed at this speed is required to retain signals with a frequency lower than or equal to RPM / 60 (Hz) and remove signals with a frequency higher than 3×RPM / 60 (Hz). Using this principle, multiple sets of corresponding filter parameters can be designed for different rotation speeds to form a filter library.

[0078] In the above embodiment, in order to ensure better interference removal, the third signal is a signal with a frequency higher than RPM1 / 60, wherein RPM1 is the lowest value that the rotation speed of the drill bit in actual drilling should have.

[0079] For example, since the useful signal in the z-axis direction is a DC signal, a fixed low-pass filter can be designed. Considering that the rotation speed in actual drilling is generally higher than 30RPM, the designed filter is required to retain the DC signal and remove vibration interference signals greater than or equal to 30 / 60=0.5 (Hz).

[0080] It can be seen that the dynamic continuous measurement of the downhole drill tool attitude is helpful to realize more accurate and real-time well trajectory calculation and continuous geological parameter measurement related to the drill tool attitude (such as azimuth gamma and azimuth resistivity measurement, etc.), thereby improving the drilling operation effect. However, at this time, the measurement value of the acceleration sensor is seriously distorted by the vibration of the drill bit and the centrifugal force of rotation, and it is difficult to achieve accurate measurement. To solve this problem, an embodiment of the present invention provides a method for removing interference signals received by the acceleration sensor during drilling operations. The vibration interference and centrifugal force interference received by the three component values ​​of the acceleration sensor x, y, and z axes can be accurately removed by the method of the embodiment of the present invention (useful data is obtained from the original data). The method of the embodiment of the present invention ensures that the acceleration sensor data is accurately obtained during the dynamic continuous measurement of the drill tool attitude, and provides support for the wide application of dynamic continuous measurement of the downhole drill tool attitude.

[0081] Features described and / or illustrated above for one embodiment may be used in the same or similar manner in one or more other embodiments, and / or combined with or used in place of features in other embodiments.

[0082] It should be emphasized that the term "include / comprises" when used herein refers to the presence of features, integers, steps or components, but does not exclude the presence or addition of one or more other features, integers, steps, components or combinations thereof.

[0083] The above method of the present invention can be implemented by hardware, or by hardware combined with software. The present invention relates to such a computer-readable program, which, when executed by a logic component, enables the logic component to implement the above-mentioned device or component, or enables the logic component to implement the above-mentioned various methods or steps. The present invention also relates to a storage medium for storing the above program, such as a hard disk, a magnetic disk, an optical disk, a DVD, a flash memory, etc.

[0084] The many features and advantages of these embodiments are apparent from this detailed description, and thus the appended claims are intended to cover all such features and advantages of these embodiments that fall within their true spirit and scope. Furthermore, since numerous modifications and changes will readily occur to those skilled in the art, it is not intended that the embodiments of the invention be limited to the exact construction and operation illustrated and described, but rather all suitable modifications and equivalents falling within the scope thereof are intended to be covered.

[0085] Parts of the present invention that are not described in detail are well known to those skilled in the art.

Claims

1. A method for removing interference signals from an acceleration sensor during drilling operations, characterized in that: The method comprises: S1, using an acceleration sensor and a magnetic field sensor to jointly measure data, and obtaining the original data of the magnetic field sensor and the original data of the acceleration sensor in the x, y, and z axis directions in real time; S2, based on step S1, removing the interference signal of the acceleration sensor, including: S20, removing interference signals in the x-axis and y-axis directions of the acceleration sensor, including: S201, obtaining a first filter, The first filter includes multiple groups of filter parameters corresponding to multiple drilling tool rotation speeds to form a low-pass filter library, wherein the first filter under any group of filter parameters can retain the first signal and remove the second signal when filtering, the first signal is a useful signal, and the second signal is an interference signal; S202, calculating the real-time drilling tool rotation speed according to the raw data of the magnetic field sensor; S203, selecting corresponding filter parameters from the low-pass filter library according to the real-time drilling tool rotation speed, and using the first filter under the filter parameters to filter the x-axis and y-axis raw data of the acceleration sensor acquired in real time; S20', removing interference signals in the z-axis direction of the acceleration sensor, including: S201', obtaining a second filter, The second filter is a fixed low-pass filter, and the fixed low-pass filter can retain the DC signal and remove the third signal; S202', using the second filter to filter the Z-axis raw data of the acceleration sensor; The filter parameters corresponding to any drilling tool speed are designed in the following way: Obtaining the frequency of the drilling tool rotation speed; The frequency of the drill rotation speed is designed as the cut-off frequency of the first filter; The filter parameters are designed according to the cut-off frequency.

2. A method for removing interference signals from an acceleration sensor during drilling operations according to claim 1, characterized in that: The step S20 further includes: S204, obtaining the offset of the signal obtained in step S203; S205: Correct the signal obtained in step S203 using the offset.

3. A method for removing interference signals from an acceleration sensor during drilling operations according to claim 2, characterized in that: The offset of the signal obtained in step S203 is obtained in the following manner: Acquire all peak values ​​of the signal data obtained in step S203, wherein the peak values ​​include wave crests and wave troughs; The average value of all the peaks and the average value of all the troughs are calculated, and the average value of the two average values ​​is the offset.

4. A method for removing interference signals from an acceleration sensor during drilling operations according to claim 3, characterized in that: The signal obtained in step S203 is corrected using the offset in the following manner: The offset is subtracted from the signal data obtained in step S203.

5. The method for removing interference signals from an acceleration sensor during drilling operation according to claim 1, characterized in that: The first signal is a signal with a frequency less than or equal to RPM / 60, and the second signal is a signal with a frequency greater than or equal to n×RPM / 60, wherein RPM is the drill speed corresponding to the filter parameter, and n is the minimum number of blades of the drill bit.

6. The method for removing interference signals from an acceleration sensor during drilling operation according to claim 1, characterized in that: The third signal is a signal with a frequency greater than or equal to RPM1 / 60, wherein RPM1 is the minimum value that the rotation speed of the drill bit in actual drilling should have.

7. The method for removing interference signals from an acceleration sensor during drilling operation according to claim 1, characterized in that: The z-axis of the acceleration and magnetic field sensor is parallel to the instrument axis, the x-axis and y-axis of the acceleration and magnetic field sensor are perpendicular to the instrument axis, and the x-axis, y-axis and z-axis satisfy the right-hand rule.

8. The method for removing interference signals from an acceleration sensor during drilling operation according to claim 1, characterized in that: The first filter and the second filter both include Butterworth filters.

9. The method for removing interference signals from an acceleration sensor during drilling operations according to claim 1, characterized in that: The magnetic field sensor comprises a fluxgate or a magnetoresistive sensor.

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