Electromagnetic flaw detection method of steel pipes

FIELD: oil and gas industry.

SUBSTANCE: method consists in emission of sounding pulses by means of a generator solenoid located inside tested pipes, the axis of which coincides with axis of the tested pipes, and measurement of EMF induced in receiving coils by means of an electromagnetic field decrease process. Magnetic flux is measured, which is caused by sounding pulses of the generator solenoid, by means of sensors located along the instrument perimetre at distance r from the probe axis, opposite the end face of the generator solenoid, in N sectors on radial direction.

EFFECT: enlarging application area and improving quality of pipe flaw detection.

10 dwg


The title of the invention: Method electromagnetic testing of steel pipes.

The technical field to which the invention relates: geophysical data analysis.

The invention relates to geophysical studies in the borehole and can be used in electromagnetic testing multi-column structures of steel pipes (drilling, casing and tubing), with simultaneous calculation of the wall thickness of each column.

The level of technology

1. Known magnetic introscope MI-5 (Fadeev VG, Abakumov A., Bazhenov, V.V., etc. // Technology magnetic nde for flaw detection survey exploitating columns of wells// Sat. proc. Reports V Russian - Chinese Symposium on field Geophysics M., 2008 H 1. s.89-104.) (LU Mogilner, A. Abakumov, E.E. Semin / NTV Carotene, Tver: ed. AIS 2010 VIP, No. 3, pp.28-36), which is based on registration field scattering from defects and allows to detect the leakage of the columns, the position of the intervals and the quality of the perforation, to determine the quality of couplings, the wall thickness of the column.

The measuring sensors are located on springs that provide the clamp to the wall of the column. This arrangement does not allow to assess Slipknot columns and changes in the internal diameter.

2. A device that allows you determined the ü defects columns and the perforations - downhole electromagnetic flaw detector, containing the generator coil, the magnetic axis of which is oriented along the axis of the investigated pipe and the magnetic axis of the measuring coil is oriented perpendicular (U.S. Pat. Of the Russian Federation No. 2215143, publ. 27.10.2003, bull. No. 30).

The disadvantage of this device is the inability to determine Slipknot pipes, changes in the internal diameter and zheloboobraznogo wear.

3. The closest to the technical nature of the claimed invention is a method of electromagnetic inspection of pipes in the well (U.S. Pat. Of the Russian Federation No. 2176317, 27.11.2001, based on radiation probing bipolar electromagnetic pulse through the generator coil and measuring the EMF induced in the receiving coil by the process of decay of the electromagnetic field, and additionally measured a natural magnetic field along the tube, its value is judged on the presence or absence of break columns.

This device does not allow to determine Slipknot columns, zheloboobraznogo wear, change of the internal diameter of pipes.

The essence of the invention. When electromagnetic flaw detection in multi-column wells emissive probe pulses using generator solenoid whose axis coincides with the axis of the borehole, and measured the EMF induced in the receiving coils of the device by the process of decline of the electromagnet the CSO field.

Encouraged to measure the magnetic flux caused by the probing pulse generator solenoid, using sensors located around the perimeter of the device at a distance r from the axis of the probe, the opposite end of the generator solenoid, for N sectors, in the radial direction.

The magnetic flux in each of the sectors depends on the distance between the surface of the solenoid and the inner surface of the investigated pipe.

The magnetic flux is described by the formula:


where N is the number of turns of the solenoid,

I - the number of turns of the solenoid,

RMSmagnetic resistance of the core,

RMCmagnetic resistance plot columns

ToMoHmagnetic resistance of the gap


1C- length of the magnetic gap,

S3- the area of the magnetic gap,

µC- the magnetic permeability of the substance.

Such measurements shall indicate the additional information not only about the condition of the pipe (gutter wear, Slipknot, crushing, internal and cross-cutting corrosion), but also allows to determine the position of the device in the pipe.

The misalignment of the instrument usually leads to additional errors in the measurement of the wall thickness of the investigated pipe.

The technical result of the invention is the expansion of the scope and improving the quality inspection of pipes.

Brief description of drawings

1 is a Solenoid in the double-pipe structure.

1 - inner tube

2 is an external pipe

3 - lines of the magnetic field

4 - a solenoid coaxially with the pipe

5 - Hall sensors

2 is a Solenoid in the pipe.

1 - pipe

3 - the direction of the lines of magnetic field

4 - solenoid

6 - radii R denoting the distance from the surface of the solenoid to the inner surface of the investigated pipe.

This distance varies in the research process, when moving along the pipe.

When the pipe is right cylindrical shape, and the probe is properly aligned, the distance R in all directions are equal.

Figure 3 the location of the Hall sensors.

5 - Hall sensors

7 is a distance r from the surface of the solenoid to the Hall sensors. Are the constructive parameter of the device.

In the study of pipes, in the process of movement, the distance r unchanged.

Figure 4 Solenoid in the pipe with the chute wear

8 - channel deterioration, deficiency of metal in one of issection investigated pipe.

This defect pipe distance R, in the sector of wear increases by the same amount Δ, which leads to the decrease of the magnetic flux in this direction.

5 Solenoid ellipses pipe.

The dashed line shows a cylindrical pipe profile.

If such breach pipe distance R in the same plane increases (horizontal in this case) by a certain amount Δ, and the other plane is reduced.

6 is a Solenoid in the pipe with a defect.

9 - through the defect in the pipe.

This violation of the distance from the surface of the solenoid to the inner surface of the pipe remains in all sectors is almost the same.

But in the sector defect changes the direction of the magnetic flux, which is already misses on a corresponding sector of a Hall sensor that is logged.

Fig.7. a Solenoid in the pipe is offset from the center.

The offset of the probe portion of the device from the center of the investigated pipe (misalignment) is well interpreted according to the testimony of Hall sensors, which are located in opposite sectors.

Readings in the same sector when the misalignment increases, opposite sector - decrease.

The implementation of the invention

Fig description of the Device

1 - centering device

2 - non-magnetic sealed enclosure

3 - electronics

4 - Hall sensors

5 - probe generator and receiving inductors

6 - the direction of the magnetic lines

Using the centering device, the device is placed coaxially in the tube. Apply centralizers with rubber elastic elements or metallic elastic springs, as shown.

Non-magnetic sealed case allows you to work in different environments, including aggressive, at high pressures and temperatures. However, he does not distort the natural direction of the magnetic flux from the probe.

The electronics module provides power to all nodes of the device, the synchronization of their work, measurement and transmission of data.

Fig.9 Entry in the pipe-through defects

1 - box charts standard probe electromagnetic flaw detector

2 is a box diagram of Hall sensors (8 curves)

3 - image of the investigated pipe

4 - interval misalignment of the probe during the transition from the pipe to the shank. Movement charts moving in opposite directions.

5 in response to the defects of the standard probe electromagnetic flaw detector.

6 - the reaction of one of the Hall sensors on the defects belonging to a corresponding sector.

Figure 10 an entry in the pipe with external grooves.

1 - box charts standard probe electromagnetic flaw detector

2 is a box diagram of Hall sensors (8 curves)

3 - Window Range", is formed from 8 diagrams. The signal amplitude is modulated color: (is - black; max - red.

4; 5 - the standard response of the probe electromagnetic flaw detector on the outer groove of the pipe. The Hall sensors on the external grooves of the pipe does not respond.

6 - interval misalignment of the device in the pipe, the simulation with rotation of the probe around the perimeter of the pipe (alternately bringing the Hall sensors to the pipe wall). On all diagrams are visible periodic increase and decrease of the signal level.

7, the rotation of the probe around the perimeter of the pipe shown in figure "Range". Clearly visible spiral rotation.

Way electromagnetic testing of steel tubes, which consists in the emission of pulses by using a generator solenoid located inside the pipes, the axis of which coincides with the axis of the pipes, and the measurement of the EMF induced in the receiving coils by the process of decay of the electromagnetic field, characterized in that the measured magnetic flux in the generator end of the solenoid at a distance r from its axis by N sectors in the radial direction.


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