CN101982734A - Calculation method for underground magnetic navigation - Google Patents

Abstract

The invention discloses a calculation method for underground magnetic navigation, comprising the following steps: step 1, preprocessing acquired magnetic signals by an underground magnetic navigation method; step 2, establishing a model for calculating the strength of induced magnetic fields generated at any point in space by a magnetic source; step 3, starting from a magnetic dipole model; step 4, solving the undetermined coefficient in a relational expression shown in the specification by adopting the least square linear fitting method; step 5, adopting the model established in step 3 to solve the relation among an azimuth, a hole deviation angle and the strengths of magnetic inductions generated by the magnetic source at any point in space in the directions of x, y and z through back calculation; step 6, adopting three pairs of magnetic field strengths in the directions of x, y and z acquired by three fluxgate type sensors; and step 7, judging the position of the magnetic source relative to a magnetic vector sensor. The method has the advantages of adopted artificial magnetic beacon, long navigation distance and high angle measurement precision. The calculation method is simple, can be programmed conveniently by a computer, and has high operation efficiency.

Description

A kind of computing method that are used for underground magnetic navigation

Technical field

The present invention relates to a kind of computing method of navigation, relate in particular to a kind of computing method that are used for underground magnetic navigation.

Background technology

China's coal-seam gas reserves are abundant, and social demand and growth are very big, and utilization has a extensive future.Coal-seam gas per-well production at present is low, the well number is few.Exploitation is at present attempted showing: will form future based on multi-branched horizontal well, straight well is the pattern of assisting.And China's multi-branched horizontal well technology is to rely on offshore company substantially, domestic drilling technique does not match, specific purpose tool and equipment are deficient, be used for the scale exploitation and be subjected to serious restriction, the key issue that is faced is that the master that how to realize horizontal well props up and being communicated with of straight well, developing underground magnetic navigation system can address this problem, can significantly improve oil gas field and cbm development output, improve production efficiency.And the computing method that are used for underground magnetic navigation the are underground navigational system drill collar that can successfully navigate, the connection that realizes two wells is the most important thing.

Summary of the invention

The object of the present invention is to provide a kind of computing method that are used for underground magnetic navigation, can prop up for the master who realizes horizontal well and effective new and high technology means are provided being communicated with of straight well.

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

Step 1, underground magnetic navigation method are carried out pre-service to the magnetic signal of gathering: the original magnetic signal by the magnetic vector sensor acquisition is carried out the FIR digital filtering well, the ground magnetic signal and the noise that comprise in the filtered signal, because noise signal generally is high-frequency signal, therefore allow signal pass through a low-pass filter filtering high frequency noise earlier, and then signal carried out the FIR digital filtering, behind the filtering ground magnetic signal, then can obtain the magnetic signal that the permanent magnetism pipe nipple produces;

Step 2, on the basis of ampere molecule circulation hypothesis and two philosophys of Biot-Savart law, set up dipole model of magnetic, set up induced field strength model that magnetic source a bit produces in space arbitrarily;

Step 3, from dipole model of magnetic, derive x that distance and magnetic source produce arbitrarily a bit in the space, y, the relational expression of the magnetic induction density of z direction;

Step 4, employing least square linear fit method are obtained the undetermined coefficient in the relational expression;

Step 5, the computation model of the magnetic induction density that the magnetic source of being set up by step 3 a bit produces arbitrarily in the space adopts the method for getting extreme value to be finally inversed by the position angle, the x that hole drift angle and magnetic source a bit produce arbitrarily in the space, y, the relational expression of the magnetic induction density of z direction;

Step 6 is utilized three couples of x of three fluxgate type sensor acquisition, y, and the magnetic field intensity of z, the utilization sensor Data Fusion can further improve the measurement of angle degree of accuracy;

Step 7 is utilized three couples of x of three fluxgate type sensor acquisition, y, and the magnetic field intensity of z can be judged the position of magnetic source with respect to the magnetic vector sensor.

Advantage of the present invention is: adopt artificial magnetic beacon, navigation distance is far away, the angle-measurement accuracy height.These computing method are simple, and computer programming is realized convenient, the operation efficiency height.

Description of drawings

Fig. 1 is the induced field intensity that magnetic source of the present invention a bit produces arbitrarily in the space.

Fig. 2 is that magnetic source offset direction of the present invention is judged synoptic diagram.

Fig. 3 is the underground magnetic navigation of the present invention ultimate principle figure of system.

Embodiment

The present invention is achieved in that

Step 1, underground magnetic navigation method are carried out pre-service to the magnetic signal of gathering: the original magnetic signal by the magnetic vector sensor acquisition is carried out the FIR digital filtering well, the ground magnetic signal and the noise that comprise in the filtered signal, because noise signal generally is high-frequency signal, therefore allow signal pass through a low-pass filter filtering high frequency noise earlier, and then signal carried out the FIR digital filtering, behind the filtering ground magnetic signal, then can obtain the magnetic signal that the permanent magnetism pipe nipple produces;

Step 2, on the basis of ampere molecule circulation hypothesis and two philosophys of Biot-Savart law, set up dipole model of magnetic, set up induced field strength model that magnetic source a bit produces in space arbitrarily; As shown in Figure 1, when calculating induced field intensity of magnetic source any some generation in the space, the permanent magnetism pipe nipple is regarded as a pair of magnetic dipole, it is any some magnetic field intensity x of generation in the space, y, three durection components of z

,

,

:

Wherein,

,

,

,

Be the angular frequency that the permanent magnetism pipe nipple rotates, x, y, z are the coordinate of permanent magnetism pipe nipple center to three directions in arbitrfary point, space.

Step 3, from dipole model of magnetic, derive x that distance and magnetic source produce arbitrarily a bit in the space, y, the relational expression of the magnetic induction density of z direction; Exist the relation of a linearity to be between three/roots of the distance between magnetic source center and the magnetic vector sensor and the magnetic field intensity of y direction

Step 4, employing least square linear fit method are obtained the undetermined coefficient in the relational expression; Adopt least square method that the test figure curve is carried out match and can try to achieve undetermined coefficient A=38.28 in the relational expression, B=0.2192, so the distance relation formula between magnetic source center and the magnetic vector sensor is:

Step 5, the computation model of the magnetic induction density that the magnetic source of being set up by step 3 a bit produces arbitrarily in the space adopts the method for getting extreme value to be finally inversed by the position angle, the x that hole drift angle and magnetic source a bit produce arbitrarily in the space, y, the relational expression of the magnetic induction density of z direction; The method that extreme value is got in employing is finally inversed by x that position angle and magnetic source a bit produce arbitrarily in the space, y, and the relational expression of the magnetic induction density of z direction is:

, wherein

,

Be the x direction magnetic induction density and the z direction magnetic induction density of the magnetic source generation of right 3 described magnetic vector sensor acquisition.

By symmetry x of a bit producing arbitrarily in the space of hole drift angle and magnetic source as can be known, y, the relational expression of the magnetic induction density of z direction is:

, wherein

, Be the x direction magnetic induction density and the y direction magnetic induction density of the magnetic source generation of right 3 described magnetic vector sensor acquisition.

Step 6 is utilized three couples of x of three fluxgate type sensor acquisition, y, and the magnetic field intensity of z, the utilization sensor Data Fusion can further improve the measurement of angle degree of accuracy;

Step 7, utilize three couples of x of three fluxgate type sensor acquisition, y, the magnetic field intensity of z can be judged the position of magnetic source with respect to the magnetic vector sensor, as shown in Figure 2, on same axle center, differ 7.5 ° of angles according to three fluxgate type sensors in the magnetic vector sensor and arrange, when sensor and magnetic source over against the time, one of them fluxgate sensor and magnetic source begin over against, one is offset 7.5 degree left, and one is offset 7.5 degree to the right.Then arbitrfary point p in the magnetic field intensity that the rectangular coordinate system y at three sensor places direction produces is

Therefore, can data one-period according to these three sensor acquisition in, the minimum of the magnetic induction density of which sensor illustrates that then drill bit is which sensor of deflection, thereby judges the direction that departs from normal trace of drill bit.

Just can calculate the distance of drill bit and magnetic vector sensor through above-mentioned steps, relative position, and then show by computing machine, ground people just can know the position in horizontal well of any time drill bit.

As shown in Figure 3, drill bit 1 fixedly connected permanent magnetism pipe nipple 2, magnetic vector sensor 4 receives the magnetic signal of permanent magnetism pipe nipple 2, signal+noise that magnetic signal=ground magnetic signal+magnetic source of being gathered by magnetic vector sensor 4 produces, so, at first the magnetic signal of gathering is carried out digital filtering filtering ground magnetic signal and noise and obtains the pipe nipple signal that produces by magnetic source.Can obtain distance and the angle of magnetic source to distance and the angle calculation formula that adopts above-mentioned steps 5 and step 6 to derive through pretreated signal with respect to the magnetic vector sensor, re-use the described sensor Data Fusion of step 7 and can try to achieve a more accurate angle value, distance that will obtain and angle are passed to ground computing machine at last, Computer Analysis goes out navigation path 3, the directional drilling of the drill collar that is used to navigate.

Claims (1)

1. computing method that are used for underground magnetic navigation is characterized in that method step is:

Step 1, underground magnetic navigation method are carried out pre-service to the magnetic signal of gathering: the original magnetic signal by the magnetic vector sensor acquisition is carried out the FIR digital filtering well, the ground magnetic signal and the noise that comprise in the filtered signal, because noise signal generally is high-frequency signal, therefore allow signal pass through a low-pass filter filtering high frequency noise earlier, and then signal carried out the FIR digital filtering, behind the filtering ground magnetic signal, then can obtain the magnetic signal that the permanent magnetism pipe nipple produces;

Step 2, on the basis of ampere molecule circulation hypothesis and two philosophys of Biot-Savart law, set up dipole model of magnetic, set up induced field strength model that magnetic source a bit produces in space arbitrarily;

Step 3, from dipole model of magnetic, derive x that distance and magnetic source produce arbitrarily a bit in the space, y, the relational expression of the magnetic induction density of z direction;

Step 4, employing least square linear fit method are obtained the undetermined coefficient in the relational expression;

Step 5, the computation model of the magnetic induction density that the magnetic source of being set up by step 3 a bit produces arbitrarily in the space adopts the method for getting extreme value to be finally inversed by the position angle, the x that hole drift angle and magnetic source a bit produce arbitrarily in the space, y, the relational expression of the magnetic induction density of z direction;

Step 6 is utilized three couples of x of three fluxgate type sensor acquisition, y, and the magnetic field intensity of z, the utilization sensor Data Fusion can further improve the measurement of angle degree of accuracy;

Step 7 is utilized three couples of x of three fluxgate type sensor acquisition, y, and the magnetic field intensity of z can be judged the position of magnetic source with respect to the magnetic vector sensor.

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