A fiber optic gyroscope inclinometer integrated navigation system and method

Abstract

This invention discloses a fiber optic gyroscope inclinometer integrated navigation system and method, comprising a retrieval head, an upper centralizer, a fiber optic gyroscope inclinometer, a navigation calculation and processing mechanism, a lower centralizer, and a six-axis inertial sensor connected in sequence. Four velocity measuring components are centrally symmetrically arranged on the circumferential sides of both the upper and lower centralizers. Each velocity measuring component includes a roller, a triangular elastic centralizer for pressing the roller against the well wall, and a wheel speed acquisition device for collecting the roller's rotational speed. Both the wheel speed meter and the six-axis inertial sensor can communicate with the navigation calculation and processing mechanism, which can obtain cable length information provided by a ground system. The fiber optic gyroscope inclinometer integrated navigation system of this invention, with the above structure, has advantages such as strong anti-magnetic interference capability, high reliability, and the ability to suppress navigation attitude error divergence for extended periods, thereby achieving long-term, high-precision continuous measurement.

Description

Technical Field

[0001] This invention relates to a casing well oil well inclination measurement technology, and more particularly to a fiber optic gyroscope inclination measurement instrument combined navigation system and method. Background Technology

[0002] To increase oil and gas production, it is necessary to achieve higher precision in the secondary development of old oilfields, and to achieve high-precision target acquisition rates for complex wells, cluster wells, and highly deviated wells. Whether from a safety perspective or for measurement accuracy, the ultimate goal is to achieve high-precision measurement of wellbore trajectories.

[0003] The existing technologies have the following disadvantages:

[0004] 1. Under long-duration pure inertial measurement schemes, the attitude angle tends to diverge due to the integral of sensor error, which affects the high-precision reconstruction of wellbore trajectory and cannot guarantee high-precision measurement over long periods of time.

[0005] 2. High-precision fiber optic gyroscopes are too large to meet usage requirements.

[0006] 3. Traditional fluxgate inclinometers are affected by electromagnetic interference in the working environment, which degrades their measurement accuracy. They need to be used with non-magnetic sleeves to meet the requirements. Summary of the Invention

[0007] To address the aforementioned issues, this invention provides a fiber optic gyroscope inclinometer integrated navigation system and method. Utilizing a medium-precision fiber optic gyroscope overcomes size limitations and avoids the shortcomings of traditional magnetic surveying methods. To suppress navigation dedivergence, axial velocity information is added via rollers, and position information is added based on cable length. Combined navigation calculations are performed with auxiliary information to maintain navigation accuracy over extended periods, compensating for the lack of available auxiliary information in underground conditions.

[0008] To achieve the above objectives, the present invention provides a fiber optic gyroscope inclinometer integrated navigation system, comprising a retrieval head, an upper stabilizer, a fiber optic gyroscope inclinometer, a navigation calculation and processing mechanism, a lower stabilizer, and a six-axis inertial sensor connected in sequence. Multiple velocity measuring components are arranged symmetrically on the circumferential sides of the upper stabilizer and the lower stabilizer.

[0009] The speed measuring component includes a roller, a triangular elastic support frame for pressing the roller tightly against the well wall, and a wheel speed meter for collecting the rotational speed of the roller. Both the wheel speed meter and the six-axis inertial sensor can communicate with the navigation calculation and processing mechanism. The navigation calculation and processing mechanism can also obtain cable length information through the ground system.

[0010] Preferably, four sets of speed measuring components are centrally symmetrically arranged on both the circumferential side of the upper stabilizer and the circumferential side of the lower stabilizer.

[0011] Preferably, the six-axis inertial sensor includes a three-axis accelerometer and a three-axis fiber optic gyroscope arranged in an I-shape.

[0012] Preferably, the triaxial accelerometer includes three mutually orthogonally arranged quartz flexural accelerometers; the triaxial fiber optic gyroscope includes three mutually orthogonally arranged fiber optic gyroscopes.

[0013] Preferably, the navigation calculation mechanism includes a fiber optic gyroscope digital processing module, an accelerometer digital processing module, a navigation calculation module, and a power management module;

[0014] The fiber optic gyroscope and the quartz flexible accelerometer are respectively connected to the navigation calculation module via the fiber optic gyroscope digital processing module and the accelerometer digital processing module;

[0015] The navigation calculation module is connected to the wheel speed gauge and the cable length measuring mechanism via nonlinear filters.

[0016] A fiber optic gyroscope inclinometer integrated navigation method includes the following steps:

[0017] S1, the quartz flexible accelerometer and the fiber optic gyroscope are all output after zero bias and scaling factor compensation, and then enter the navigation calculation module through coordinate transformation and attitude update respectively. Then, the position, velocity and attitude angle information of the instrument are calculated together with the Earth's rotation angular velocity and gravitational acceleration information.

[0018] S2. The wheel speed information and cable length information collected by the wheel speed meter and cable length measuring mechanism, respectively, are fed into the nonlinear filter and combined with the position and speed obtained from the navigation solution to form the observation equation, and then filtered and solved.

[0019] S3. Output the integrated navigation solution results.

[0020] Preferably, step S1 specifically includes the following steps:

[0021] S11. Obtain the axial velocity of the instrument by using a weighted average:

[0022]

[0023] in, V is the axial velocity, N is the number of velocity outputs, and v i w represents the speed collected by the i-th wheel speedometer. i These are weighting coefficients.

[0024] S12. Establish the Kalman filter velocity observation equation to suppress axial velocity error divergence:

[0025]

[0026] Among them, v b For the axial velocity calculated for navigation, z v For velocity error observation.

[0027] Preferably, step S2 specifically includes the following steps:

[0028] S21. By obtaining the change in cable length Δl over a certain period of time, the positional changes of northward ΔN, eastward ΔE, and groundward Δd are obtained using the minimum curvature approximation geometric method.

[0029] S22. By using the longitude, latitude, and altitude information output by the fiber optic gyroscope, record the changes in longitude, latitude, and altitude information over a certain period of time to obtain the changes in navigation calculations during that period of time.

[0030] S23. Using the change in cable length over this period as a reference, establish a Kalman filter position observation equation to suppress position error divergence:

[0031] z p =[ΔL*R m -ΔN;Δλ*R n -ΔE;Δh-Δd]

[0032] Where ΔL is the latitude change calculated by navigation, Δλ is the longitude change calculated by navigation, Δh is the altitude change calculated by navigation, and R... m and R n These are the radii of the meridian and the radii of the east-west meridian, respectively. p These are the observed values ​​for position error.

[0033] Preferably, the nonlinear filter is a Kalman filter, UKF filter, EKF filter, or CKF filter.

[0034] The present invention has the following beneficial effects:

[0035] 1) Strong resistance to magnetic interference

[0036] The measurement scheme based on fiber optic gyroscopes is unaffected by magnetic field interference and can achieve highly reliable measurements in all weather conditions.

[0037] 2) The wheel speed gauge measurement results are highly reliable.

[0038] The instrument is prone to wheel speed slippage when moving inside the wellbore, which affects the actual speed measurement. To improve the reliability of speed measurement, an 8-wheel speed orthogonal design is adopted, and then a weighted average method is used to improve the accuracy and reliability of speed output.

[0039] 3) Suppress long-term navigation attitude error divergence

[0040] Wheel speed assistance is used to provide reliable speed information to correct the inertial navigation speed output, suppress the influence of cumulative speed error on attitude angle, and meet the long-endurance requirements of wellbore trajectory measurement.

[0041] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the fiber optic gyroscope inclinometer integrated navigation system of the present invention;

[0043] Figure 2 This is a schematic diagram of the information processing principle of the fiber optic gyroscope inclinometer integrated navigation system of the present invention;

[0044] Figure 3 This is a diagram of the minimum curvature approximation geometric method.

[0045] The components include: 1. Speed ​​measuring component; 11. Triangular elastic support frame; 12. Roller; 2. Navigation calculation and processing mechanism; 3. Upper stabilizer; 4. Retrieval head; 5. Lower shock absorber; 6. Lower stabilizer. Detailed Implementation

[0046] The present invention will be further described below with reference to the accompanying drawings. It should be noted that this embodiment is based on the present technical solution and provides detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to this embodiment.

[0047] A fiber optic gyroscope inclinometer integrated navigation system includes a retrieval head 4, an upper stabilizer 3, a six-axis inertial sensor, a navigation calculation and processing mechanism 2, a lower stabilizer 6, and a lower vibration damper 5 connected in sequence. The six-axis inertial sensor and the navigation calculation and processing mechanism 2 constitute a standard IMU to realize acceleration and angular velocity measurement and output inertial navigation calculation parameters. Multiple velocity measuring components 1 are centrally symmetrically arranged on the circumferential side of the upper stabilizer 3 and the circumferential side of the lower stabilizer 6.

[0048] The speed measuring component 1 includes a roller 12, a triangular elastic support frame 11 for pressing the roller 12 tightly against the well wall, and a wheel speed meter for collecting the rotational speed of the roller 12. The wheel speed meter can communicate with the navigation calculation and processing mechanism 2, which can also obtain cable length measurement information from the ground system.

[0049] Preferably, four sets of speed measuring components 1 are centrally symmetrically arranged on the circumferential side of the upper stabilizer 3 and the circumferential side of the lower stabilizer 6. That is, in this embodiment, the speed of 8 channels is output in real time, thereby preventing inaccurate speed measurement results due to slippage on one side.

[0050] Preferably, the six-axis inertial sensor includes a three-axis accelerometer and a three-axis fiber optic gyroscope arranged in an I-shape.

[0051] Preferably, the triaxial accelerometer includes three mutually orthogonally arranged quartz flexural accelerometers; the triaxial fiber optic gyroscope includes three mutually orthogonally arranged fiber optic gyroscopes.

[0052] Preferably, the navigation calculation mechanism includes a fiber optic gyroscope digital processing module, an accelerometer digital processing module, a navigation calculation module, and a power management module;

[0053] The fiber optic gyroscope and the quartz flexible accelerometer are connected to the navigation calculation module via the fiber optic gyroscope digital processing module and the accelerometer digital processing module, respectively.

[0054] The navigation calculation module obtains speed and cable length through wheel speedometer and ground system respectively, and then enters nonlinear filter to achieve filtering estimation.

[0055] A fiber optic gyroscope inclinometer integrated navigation method includes the following steps:

[0056] S1, the quartz flexible accelerometer and the fiber optic gyroscope are all output after zero bias and scaling factor compensation, and then enter the navigation calculation module through coordinate transformation and attitude update respectively. Then, the position, velocity and attitude angle information of the instrument are calculated together with the Earth's rotation angular velocity and gravitational acceleration information.

[0057] S2. The wheel speed information and cable length information collected by the wheel speed meter and cable length measuring mechanism, respectively, are fed into the nonlinear filter and combined with the position and speed obtained from the navigation solution to form the observation equation, and then filtered and solved.

[0058] S3. Output the integrated navigation solution results.

[0059] Preferably, step S1 specifically includes the following steps:

[0060] S11. Obtain the axial velocity of the instrument by using a weighted average:

[0061]

[0062] in, V is the axial velocity, N is the number of velocity outputs, and v i w represents the speed collected by the i-th wheel speedometer. i These are weighting coefficients.

[0063] S12. Establish the Kalman filter velocity observation equation to suppress axial velocity error divergence:

[0064]

[0065] Among them, v b For the axial velocity calculated for navigation, z vFor velocity error observation.

[0066] Preferably, step S2 specifically includes the following steps:

[0067] S21. By obtaining the change in cable length Δl over a certain period of time, the positional changes of northward ΔN, eastward ΔE, and groundward Δd are obtained using the minimum curvature approximation geometric method.

[0068] S22. By calculating the longitude, latitude, and altitude information output by the fiber optic gyroscope IMU, record the changes in longitude, latitude, and altitude information within a certain period of time to obtain the navigation calculation changes within that period of time.

[0069] S23. Using the change in cable length over this period as a reference, establish a Kalman filter position observation equation to suppress position error divergence:

[0070] z p =[ΔL*R m -ΔN;Δλ*R n -ΔE;Δh-Δd]

[0071] Where ΔL is the latitude change calculated by navigation, Δλ is the longitude change calculated by navigation, Δh is the altitude change calculated by navigation, and R... m and R n These are the radii of the meridian and the radii of the east-west meridian, respectively. p These are the observed values ​​for position error.

[0072] Preferably, the nonlinear filter is not limited to UKF filtering, EKF filtering or CKF filtering.

[0073] Therefore, the fiber optic gyroscope inclinometer combined navigation system of the present invention has the advantages of strong anti-magnetic interference capability, high reliability, and long-term suppression of navigation attitude error divergence, thereby suppressing wellbore trajectory and attitude divergence and realizing long-term high-precision continuous measurement.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A fiber-optic gyro inclinometer integrated navigation system, comprising, in sequence, a fishing head, an upper centralizer, a fiber-optic gyro inclinometer, a navigation solution processing mechanism, a lower centralizer, and a six-axis inertial sensor, characterized in that: The circumferential side of the upper centralizer and the circumferential side of the lower centralizer are both arranged in a central symmetry with four velocity measurement assemblies; The velocity measurement assembly comprises a roller, a triangular elastic centralizer for tightly attaching the roller to the well wall, and a wheel speed meter for collecting the rotation speed of the roller, the wheel speed meter and the six-axis inertial sensor can communicate with the navigation calculation processing mechanism, and the navigation calculation processing mechanism can obtain the cable length information provided by the ground system; The circumferential side of the upper centralizer and the circumferential side of the lower centralizer are both arranged in a central symmetry with four velocity measurement assemblies; The six-axis inertial sensor comprises a three-axis accelerometer and a three-axis fiber-optic gyroscope arranged in a H-shaped manner; The combined navigation method of the fiber-optic gyro inclinometer comprises the following steps: S1, after the quartz flexible accelerometer and the fiber-optic gyroscope are compensated for zero offset and scale factor and output, they are respectively input into a navigation calculation module through coordinate transformation and attitude updating, and then the position, speed and attitude angle information of the instrument is calculated based on the earth rotation angular velocity and the gravity acceleration information; Step S1 specifically comprises the following steps: S11, the axial speed of the instrument is obtained by weighted averaging: wherein, is the axial velocity, is the number of velocity outputs, is the velocity collected by the i-th wheel speed meter, is the velocity collected by the i-th wheel speed meter, is the weighting coefficient, ; S12, the Kalman filter speed observation equation is established to suppress the divergence of the axial speed error: wherein, is the axial velocity for the navigation solution, is the velocity error observation; S2, the wheel speed information and the cable length information collected by the wheel speed meter and the cable length measurement mechanism are input into a nonlinear filter and the position and speed obtained by the navigation calculation to form an observation equation for filtering calculation; Step S2 specifically comprises the following steps: S21, obtain the cable length change amount of the acquisition cable in a certain time , the position changes of north direction , east direction and ground direction are obtained by minimum curvature approximation geometry method; S22, the longitude, latitude and height information output by the inclinometer is used to record the changes of the longitude, latitude and height information within a certain period of time, and the navigation calculation change amount within the period of time is obtained; S23, the cable length change amount of the period of time is taken as a reference benchmark to establish a position observation equation to suppress the divergence of the position error: wherein, is a change in latitude of the navigation solution, is a change in longitude of the navigation solution, is a change in altitude of the navigation solution, and are the meridian radius and the prime vertical radius, respectively, is a position error observation; S3, the combined navigation calculation result is output.

2. The fiber-optic gyroscope inclinometer integrated navigation system according to claim 1, characterized in that: The three-axis accelerometer comprises three mutually orthogonal quartz flexible accelerometers; and the three-axis fiber-optic gyroscope comprises three mutually orthogonal fiber-optic gyroscopes.

3. The fiber-optic gyroscope inclinometer integrated navigation system according to claim 2, characterized in that: The navigation calculation processing mechanism comprises a fiber-optic gyroscope digital processing module, an accelerometer digital processing module, a navigation calculation module and a power management module; The fiber-optic gyroscope and the quartz flexible accelerometer are connected to the navigation calculation module through the fiber-optic gyroscope digital processing module and the accelerometer digital processing module, respectively; The navigation calculation module uses a nonlinear filtering algorithm to form a measurement equation with the speed information output by the wheel speed meter and the cable length information provided by the ground system to realize error suppression.

4. The fiber-optic gyroscope inclinometer integrated navigation system of claim 1, wherein: The nonlinear filter can not only use UKF filtering, EKF filtering or CKF filtering.

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