SU523373A1 - Gamma Gamma Well Logging Induction System - Google Patents

Description

one

The device relates to the field of nuclear geophysical downhole tools.

In well-known gamma-gamma logging tools, accelerator tubes with an accelerating system based on multi-turn transformers 1 are used. Such tubes, with small dimensions due to well diameter, do not allow sufficient energy and intensity of the beam to be accelerated in the tube. The devices currently used for gamma-gamma logging, in which gamma-radiation sources are radioactive isotopes (Co or), create the danger of radioactive damage to the staff, especially in field conditions.

The well-known induction system of a gamma-gamma logging tool consists of successively located along the axis of the system of ferromagnetic toroidal cores of single-turn pulse transformers, the primary windings of which are connected to a pulse generator, and the total secondary winding is covered by all the cores of the accelerator tube of the device 2.

With strictly limited diametral dimensions of the induction system corresponding to standard borehole diameters, an increase in the output power of the device leads to the fact that the intensity of the electric field "E in the gap" b between the cores of the conductors and the common secondary winding reaches a large value, which reduces the reliability of the device. Since the gap between the cores and the secondary winding over the entire length of the system is the same, it is essential to increase the output

the power of the device by increasing the pairing on the secondary side is not possible.

The aim of the invention is to reduce the voltage of the electric field in the gap between the cores and the common secondary winding with increased output power and reliability of the device.

The goal is achieved by the fact that the average internal diameter and the longitudinal size of each subsequent core are larger than the previous one, while the cross-sectional areas of the cores are the same.

FIG. 1 shows the proposed induction system with cores made of a ribbon ferromagnet; in fig. 2 - system with cores of monolithic ferromagnet.

Toroidal ferromagnetic cores 1 of single-turn pulse transformers, primary windings 2, are sequentially located along the axis of the induction system.

which are connected to the pulse generator 3. The common secondary winding of 4 transformers is covered by all the cores connected to the cathode 5 of the device. The outer diameters of the cores are constant along the entire length of the induction system, and their width increases. The inner diameters of cores of tape material (see Fig. I) increase in steps from core to core, and the inner diameters of cores of monolithic ferromagnet (see Fig. 2) monotonously increase along the axis of the system.

When the pulse generator 3 is turned on, the primary windings 2 of the transformers are applied to the voltage Ui, which is traced to the common secondary winding 4 and becomes equal to U2 nU: where n is the number of cores 1 of the pulse transformers. Thus, the accelerating voltage from core to core increases. Since the gap, b between the cores and the secondary winding along the length of the system increases bz ... bp, the intensity of the electric field in these gaps will be approximately equal to the same value .... For cores made of a monolithic ferromagnet with monotonously increasing internal diameters, so that the core holes forming the same electric field equipotential gap b are variable within each core and the entire induction system, and the intensity B is the same along the entire length of the EZ system. . . Bp

Shown above are the voltage distribution on the system electrodes and the voltage

in the gaps, it allows to significantly increase the accelerating voltage and output power of the device with high reliability of its operation. This ensures higher logging accuracy and an increase in the range of the installation while maintaining safe conditions for the staff.

Claims (2)

1.Anatsky A.I. and others. Linear induction accelerator “Atomic energy, 21, no. 6, s. 4E9, 1966. 2. Works of the 11th All-Union Conference on Accelerators of Charged Particles, Moscow, 11–18 November 1970, Vol. 11, p. 172 (prototype).