CN101982734A - Calculation method for underground magnetic navigation - Google Patents

Abstract

A calculation method for underground magnetic navigation, the method steps are: step 1, the underground magnetic navigation method preprocesses the magnetic signal collected; step 2, establishing a calculation model of the induced magnetic field intensity generated by a magnetic source at any point in space; step 3. Starting from the magnetic dipole model; step 4, adopting the least squares linear fitting method to obtain the undetermined coefficient in the relational expression; step 5, the calculation of the magnetic induction intensity produced by the magnetic source established in step 3 at any point in space Model; step 6, the magnetic field strengths of three pairs of x, y, z collected by three fluxgate sensors; step 7, the position of the magnetic source relative to the magnetic vector sensor can be judged. The invention has the advantages of adopting artificial magnetic beacon, long navigation distance and high angle measurement precision. The calculation method is simple, the computer programming is convenient to realize, and the calculation efficiency is high.

Description

A Calculation Method for Underground Magnetic Navigation

technical field

The invention relates to a calculation method for navigation, in particular to a calculation method for underground magnetic navigation.

Background technique

my country's coalbed methane reserves are abundant, the social demand and growth are huge, and the utilization prospects are broad. At present, the single well production of CBM is low and the number of wells is small. The current development attempts show that in the future, a model will be formed in which multi-branch horizontal wells will be the mainstay and vertical wells will be the supplementary. However, my country's multi-branch horizontal well technology basically relies on foreign companies. The domestic drilling technology is not matched, and special tools and equipment are lacking. The large-scale development is severely restricted. The key problem is how to realize the main branch of the horizontal well and the vertical well. The development of an underground magnetic navigation system can solve this problem, which can greatly increase the production of oil and gas fields and coalbed methane development, and improve the mining efficiency. The calculation method used for underground magnetic navigation is whether the underground navigation system can successfully navigate the drill collar, and the connection between the two wells is the most important thing.

Contents of the invention

The purpose of the present invention is to provide a calculation method for underground magnetic navigation, which can provide an effective high-tech means for realizing the communication between the main branch of the horizontal well and the vertical well.

The present invention is realized like this, it is characterized in that method step is:

Step 1, the underground magnetic navigation method preprocesses the collected magnetic signals: FIR digital filtering is performed on the original magnetic signals collected by the magnetic vector sensor to filter out the geomagnetic signals and noise contained in the signal, because the noise signals are generally high Therefore, let the signal pass through a low-pass filter to filter the high-frequency noise first, and then perform FIR digital filtering on the signal. After filtering out the geomagnetic signal, the magnetic signal generated by the permanent magnet joint can be obtained;

Step 2. Establish a magnetic dipole model on the basis of the two basic laws of the Ampere molecular circulation hypothesis and the Biot-Savart law, and establish a calculation model for the induced magnetic field intensity generated by the magnetic source at any point in space;

Step 3, starting from the magnetic dipole model, deduce the relationship between the distance and the magnetic induction intensity in the x, y, and z directions generated by the magnetic source at any point in space;

Step 4, adopting the least squares linear fitting method to obtain the undetermined coefficient in the relational expression;

Step 5, the calculation model of the magnetic induction intensity generated by the magnetic source at any point in space established in step 3, using the method of taking extreme values to invert the azimuth, inclination angle and x, y, z generated by the magnetic source at any point in space The relational expression of the magnetic induction intensity in the direction;

Step 6, using the magnetic field strengths of three pairs of x, y, and z collected by three fluxgate sensors, using multi-sensor data fusion technology can further improve the accuracy of angle measurement;

In step 7, the position of the magnetic source relative to the magnetic vector sensor can be judged by using the magnetic field strengths of three pairs of x, y, and z collected by the three fluxgate sensors.

The invention has the advantages of adopting artificial magnetic beacon, long navigation distance and high angle measurement precision. The calculation method is simple, the computer programming is convenient to realize, and the calculation efficiency is high.

Description of drawings

Fig. 1 is the induced magnetic field intensity generated by the magnetic source of the present invention at any point in space.

Fig. 2 is a schematic diagram of judging the deviation direction of the magnetic source according to the present invention.

Fig. 3 is a basic principle diagram of the underground magnetic navigation system of the present invention.

Detailed ways

The present invention is achieved like this:

Step 1, the underground magnetic navigation method preprocesses the collected magnetic signals: FIR digital filtering is performed on the original magnetic signals collected by the magnetic vector sensor to filter out the geomagnetic signals and noise contained in the signal, because the noise signals are generally high Therefore, let the signal pass through a low-pass filter to filter the high-frequency noise first, and then perform FIR digital filtering on the signal. After filtering out the geomagnetic signal, the magnetic signal generated by the permanent magnet joint can be obtained;

，

，

：Step 2. Establish the magnetic dipole model on the basis of the two basic laws of Ampere's molecular circulation hypothesis and the Biot-Savart law, and establish a calculation model for the induced magnetic field intensity generated by the magnetic source at any point in space; as shown in Figure 1 It shows that when calculating the induced magnetic field intensity generated by the magnetic source at any point in space, the permanent magnet short joint is regarded as a pair of magnetic dipoles, and the magnetic field intensity generated at any point in space has three direction components x, y, and z

,

,

:

，

，

，in,

,

,

,

是永磁短节转动的角频率，x，y，z为永磁短节中心到空间任意点三个方向的坐标。

is the angular frequency of the rotation of the permanent magnet sub, and x, y, z are the coordinates in three directions from the center of the permanent magnet sub to any point in space.

Step 3. Starting from the magnetic dipole model, deduce the relationship between the distance and the magnetic induction intensity in the x, y, and z directions generated by the magnetic source at any point in space; the distance between the center of the magnetic source and the magnetic vector sensor and the y direction There is a linear relationship between the third root of the magnetic field strength that is

。Step 4. Use the least squares linear fitting method to find the undetermined coefficients in the relational expression; use the least squares method to fit the test data curve to obtain the undetermined coefficients in the relational expression A=38.28, B=0.2192, so the magnetic source The distance relationship between the center and the magnetic vector sensor is:

.

Step 5, the calculation model of the magnetic induction intensity generated by the magnetic source at any point in space established in step 3, using the method of taking extreme values to invert the azimuth, inclination angle and x, y, z generated by the magnetic source at any point in space The relational expression of the magnetic induction intensity in the direction; the relational expression of the magnetic induction intensity in the x, y, and z directions generated by the azimuth and the magnetic source at any point in space by taking the extreme value method is:

，其中

，

是权利3所述的磁矢量传感器采集的磁源产生的x方向磁感应强度和z方向磁感应强度。

,in

,

It is the x-direction magnetic induction intensity and the z-direction magnetic induction intensity generated by the magnetic source collected by the magnetic vector sensor described in claim 3.

From the symmetry, it can be seen that the relationship between the inclination angle and the magnetic induction intensity in the x, y, and z directions generated by the magnetic source at any point in space is:

，其中

，是权利3所述的磁矢量传感器采集的磁源产生的x方向磁感应强度和y方向磁感应强度。

,in

, is the x-direction magnetic induction intensity and the y-direction magnetic induction intensity generated by the magnetic source collected by the magnetic vector sensor described in claim 3.

Step 6, using the magnetic field strengths of three pairs of x, y, and z collected by three fluxgate sensors, using multi-sensor data fusion technology can further improve the accuracy of angle measurement;

Step 7, using the magnetic field strengths of three pairs of x, y, and z collected by three fluxgate sensors, the position of the magnetic source relative to the magnetic vector sensor can be judged, as shown in Figure 2, according to the three magnetic field in the magnetic vector sensor The fluxgate sensors are arranged on the same axis with an angle difference of 7.5°. When the sensor is facing the magnetic source, one of the fluxgate sensors is facing the magnetic source, one is offset to the left by 7.5 degrees, and the other is Offset to the right by 7.5 degrees. Then the magnetic field intensity generated by any point p in the y direction of the Cartesian coordinate system where the three sensors are located is

Therefore, according to the data collected by these three sensors within one cycle, which sensor has the smallest magnetic induction intensity indicates which sensor the drill bit is biased to, thereby judging the direction of the drill bit's deviation from the normal track.

Through the above steps, the distance and relative position between the drill bit and the magnetic vector sensor can be calculated, and then displayed by the computer, and the people on the ground can know the position of the drill bit in the horizontal well at any time.

As shown in Figure 3, the drill bit 1 is fixedly connected to the permanent magnet sub-joint 2, and the magnetic vector sensor 4 receives the magnetic signal of the permanent magnet sub-joint 2. The magnetic signal collected by the magnetic vector sensor 4 = geomagnetic signal + signal generated by the magnetic source + noise , therefore, first digitally filter the collected magnetic signal to filter out the geomagnetic signal and noise to obtain the short section signal generated by the magnetic source. Using the distance and angle calculation formulas derived in steps 5 and 6 above for the preprocessed signal, the distance and angle of the magnetic source relative to the magnetic vector sensor can be obtained, and then the multi-sensor data fusion technology described in step 7 can be used to obtain a The more accurate angle value is finally transmitted to the computer on the ground with the obtained distance and angle, and the computer analyzes the navigation trajectory 3 for directional drilling of the navigation drill collar.

Claims (1)

1. A calculation method for underground magnetic navigation, characterized in that the method steps are: Step 1, the underground magnetic navigation method preprocesses the collected magnetic signals: FIR digital filtering is performed on the original magnetic signals collected by the magnetic vector sensor to filter out the geomagnetic signals and noise contained in the signal, because the noise signals are generally high Therefore, let the signal pass through a low-pass filter to filter the high-frequency noise first, and then perform FIR digital filtering on the signal. After filtering out the geomagnetic signal, the magnetic signal generated by the permanent magnet joint can be obtained; Step 2. Establish a magnetic dipole model on the basis of the two basic laws of the Ampere molecular circulation hypothesis and the Biot-Savart law, and establish a calculation model for the induced magnetic field intensity generated by the magnetic source at any point in space; Step 3, starting from the magnetic dipole model, deduce the relationship between the distance and the magnetic induction intensity in the x, y, and z directions generated by the magnetic source at any point in space; Step 4, adopting the least squares linear fitting method to obtain the undetermined coefficient in the relational expression; Step 5, the calculation model of the magnetic induction intensity generated by the magnetic source at any point in space established in step 3, using the method of taking extreme values to invert the azimuth, inclination angle and x, y, z generated by the magnetic source at any point in space The relational expression of the magnetic induction intensity in the direction; Step 6, utilizing the magnetic field strengths of three pairs of x, y, and z collected by the three fluxgate sensors, using multi-sensor data fusion technology can further improve the angle measurement accuracy; In step 7, the position of the magnetic source relative to the magnetic vector sensor can be judged by using the magnetic field strengths of three pairs of x, y, and z collected by the three fluxgate sensors.

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