SU1420147A1 - Apparatus for determining string seizure zone - Google Patents

Abstract

The invention relates to a technique for well logging. The purpose of the invention is to improve the accuracy of the release of a stuck zone in deep wells and with improved drill pipes. In the non-ferromagnetic housing 1 are four coils (K) 2-5 inductance. The axes K 2 and 3 lie in the plane M, normal to the side surface of the casing 1. The axes K 4 and 5 lie in another normal plane / V. The K 2 and 4 axes are perpendicular to one generatrix AB, and the K 3 and 5 axes are to another generatrix CD. The windings K 3, 4 and 2. The p are connected differentially. The first pair of windings K 3, 4 is connected to the generator of alternating voltage 8, and the second pair K 2, 5 to the recorder 9. When passing an alternating electric current from generator 8, EMF is induced through the windings Kzi4vK2i5. By changing the distance between K 2-5, the total current in the measuring circuit can be reduced to zero. Magnetic anisotropy of the pipe material leads to an imbalance of the currents, which will be recorded by the registrar 9. 1 Il. UZ (L

Description

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The invention relates to a technique for well surveying and can be used to determine the sticking zone of a drill pipe in a well.

The purpose of the invention is to improve the accuracy of the release of a stuck zone in deep wells and with improved drill pipes.

The drawing shows a diagram of the device.

The device contains a non-ferro-magnetic case 1, inside of which there are four inductors. The axes of the coils 2: And 3 lie in a flat M, normal to the surface of the casing of the device. The axes of the pegs 4 and 5 lie in the other normal plane; the brightness of N. The axes of the coils 2 and 4 are perpendicular to one shape, its AV is the cylindrical surface, and the axes of the coils 3 and 5 are the other forming CD. The device contains | 1t instrument head 6 and tip 7. 0 (the coils of coils 3 and 4 are connected differentially and form an oscillator circuit of the device, fed from an electrical voltage source 8 of MfJHHoro (Tdpa), coils 2 and 5 are also connected differentially and form a measuring circuit of the instrument connected to the recorder 9. The electrical circuit of the instrument is connected to the logging cable by means of an electrical input 10.

The device works as follows. : When an alternating electric current from the generator 8 is passed through the windings of coils 3 and 4 in coils 2 and 5, EMFs are created, creating in the measuring circuit e- | their coils opposite in direction, so that the total current in the measuring circuit due to the differential connection coils 2 and 5 is equal to the difference of these currents. By changing the distance between coils 2-5, the total current in the measuring circuit can be reduced to zero. Stopping the device inside the ferromagnetic column will entail changes in E5 values and redistribution of magnetic fluxes in the area of the generator and measuring windings of the coils. The balance of currents in the electrical circuit of the measuring windings is broken, which will be fixed by the registrar 9 in the form of a current i. One of the reasons causing this imbalance may be the magnetic anisotropy of the shape of the material of the pipes making up the drill string. If longitudinal loads are applied to the string, then in its body there is a mechanical sign of internal stress in the vehicle of the corresponding sign, leading to changes in the magnetoelastic anisoropia of the drill string body.

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Since the magnitudes of the magnetic permeability of the material of the column with magnetoelastic anisotropy are different in the longitudinal and transverse directions, the magnitudes and signs of the increment of magnetic fluxes in the windings of the measuring coils 2 and 5 will be different, which will cause the appearance of an additional current ia in the measuring circuit caused by the appearance of longitudinal loads in the column

Technological work to determine the zone of stuck drill string may be as follows. .

The column is loaded in the axial direction to the maximum values of mechanical stresses permitted by the instruction. The device is lowered to a predetermined depth, after which control is carried out along the entire length of the column, registering the amount of current in the measuring circuit. For the zone of sticking take the depth interval of the well, which corresponds to a sharp decrease in the current in the measuring circuit to a value close to the value of i.

The placement of additional coils and their differential inclusion allows to increase the accuracy and efficiency of detection of a stuck zone, including in deep wells and with enhanced drill pipes. This is due to the high sensitivity of the device to low mechanical loads. It is important in principle to determine the entire sticking zone due to additional mechanical deformations occurring directly in the sticking zone due to the impact of rocks.

Claims (1)

Invention Formula A device for determining a sticking zone of a drill string containing a non-ferromagnetic housing, an inductance coil and a recorder, characterized in that, in order to improve the accuracy of the sticking zone selection in deep wells and with wet drill pipes, it is equipped with an alternating electrical voltage generator and three additional coils inductance, with the axis of the coils intersect the side surface of the casing of the device along the two generators and are arranged in pairs in two normal sections of the casing, while washing ki coils with axes lying in different normal and peresekayuts sectional x:, a side surface of the housing along different generatrices are interconnected differentially, one pair of windings is connected to the alternating voltage generator, and the other - with the registrar.