RU2488851C2 - Seal assembly for electrical logging probe - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: disclosed is a seal assembly for an electrical logging probe, having a cylindrical housing, a plurality of dielectric inserts placed in the housing, a plurality of annular electrodes coaxially placed in the housing between the dielectric inserts and touching the end faces of the dielectric inserts with their end faces, an insulating means placed on the cylindrical housing for electrical insulation of the plurality of annular electrodes from the housing. According to the invention, each of the plurality of annular electrodes and dielectric inserts in contact with the annular electrodes have bevel end faces. The bevel end faces of the electrodes are interfaced with the bevel end faces of the dielectric inserts that are in contact with them. The seal assembly has a means of generating a compression force and fixing, which is in contact with the end face of the dielectric insert, placed distally with respect to said dielectric insert which is in contact with the cylindrical housing.

EFFECT: high containment of electric equipment of the probe from the external medium of the well and improved probing data.

12 cl, 5 dwg

Description

Technical field

The present invention relates to equipment for researching wells, in particular, to probes for electric logging of wells, and more particularly, to a sealing assembly of the probe, ensuring the tightness of electrical equipment placed in the probe housing from the effects of the external environment of the well.

State of the art

In studies of rocks of high resistance (for example, carbonate and hydrochemical deposits) on the measurement results ρ_toconventional probes are significantly affected by the salt flushing fluid, which promotes the propagation of electric current along the well, and this leads to a strong smoothing of the ρ curves_to. They are not distinguished due to screen effects of interlayers of small thickness with their frequent alternation.

In such conditions, lateral logging is used, which is one of the modifications of the resistance measurement method. In this case, ρ _k in the well is measured by three-, seven- and nine-electrode probes.

The most common three-electrode lateral logging (figure 1). The lateral three-electrode probe consists of a central electrode A ₀ , the length l _{m of the} metal part of which is 0.15 m, and two screen electrodes A ₁ and A _{2 of the} same length, symmetrically located relative to A ₀ and separated from it by insulating gaps b of 0, 03 m. All electrodes are in the form of cylinders with a diameter d _z = 0.07 m, the probe size L is 3.2 m (the distance between the upper and lower ends of the probe). The shielding electrodes are short-circuited, and they are connected to the electrode A ₀ through a resistor (shunt) R _w = 0.01 Ohm, which is also used to measure the current through the central electrode A ₀ . Through all the electrodes of the probe from the generator G passes alternating current.

The second current electrode, on which the power source circuit is closed, is the sheath of the armored cable. Since the shunt R _w has a very low resistance, the potentials of all the electrodes will be almost the same, and therefore the current I _{0 of the} electrode A ₀ does not spread along the well, but propagates perpendicular to its wall, which is shown in Fig. 1 in the form of almost horizontal field lines, whose thickness in the central part is approximately equal to the length A ₀ . As a result of this, the influence of the well and the host rocks is manifested in the results of measuring the resistance ρ _k much less than with conventional probes.

Measured Resistance ρ_to determined by the voltage between the screen electrodes and equal to the voltage between the electrode A₀, since the potentials of all the electrodes are the same, and the remote electrode N, located on a multi-electrode probe.

Various devices are known for sealing the electrode assembly of a logging tool.

The closest in technical essence to the present invention is the sealing assembly (figure 2) of the probe for electrical logging described in the publication of Yu.M. Zavorotko “Physical foundations of geophysical methods for researching wells”, Kiev, 2010.

The known sealing assembly of the electric logging probe includes a cylindrical body, a plurality of dielectric bushings mounted on the housing, a plurality of ring-shaped electrodes coaxially placed on the housing between the dielectric bushings and contacting end surfaces with the end surfaces of the dielectric bushings, an insulating means placed on the cylindrical housing for electrical insulation many ring-shaped electrodes from the housing. Extreme dielectric bushings contact the end surface with a cylindrical body. Each of the plurality of ring-shaped electrodes and dielectric bushings in contact with the ring-shaped electrodes have end surfaces that are perpendicular to the axis of the probe. There are sealing means located in recesses made on the surfaces of the electrodes facing the housing.

The disadvantage of this nearest technical solution is the insufficient degree of sealing provided, as well as the complexity of assembly / disassembly during operation of the probe in the well.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a sealing assembly for an electric logging probe, which will provide improved sealing of the logging tool’s probe and also simplify the assembly / disassembly of the assembly.

The present invention is also the creation of a probe for electric logging containing the above-described sealing assembly. The specified probe, which uses the claimed sealing unit, is designed to conduct research using standard electric logging methods, side logging using three or more electrodes.

The problem is solved by creating a sealing assembly of a probe for electric logging, containing a cylindrical body, a plurality of dielectric bushings mounted on the housing, a plurality of ring-shaped electrodes coaxially placed on the housing between the dielectric bushings and contacting their end surfaces with the end surfaces of the dielectric bushings, an insulating means placed on a cylindrical housing for electrical isolation of many ring-shaped electrodes from the housing, with according to the invention

one of the dielectric bushings contacts the end surface with a cylindrical body,

wherein each of the plurality of ring-shaped electrodes and dielectric bushings in contact with the ring-shaped electrodes have beveled end surfaces, wherein the beveled end surfaces of the electrodes mate with the beveled end surfaces of the dielectric bushings in contact with them,

wherein the sealing assembly comprises a means of creating a pressing and fixing force in contact with the end surface of the dielectric sleeve located distally with respect to the dielectric sleeve in contact with the cylindrical body and designed to prevent axial movements of the ring electrodes and dielectric bushings relative to the body,

sealing means located in recesses made in the end surfaces of the electrodes, while

above the holes made in a cylindrical body, there is no insulation layer.

Preferably, the acute angle of inclination of the end surface of each ring electrode and dielectric sleeve relative to the longitudinal axis of the housing is in the range from 20 to 40 °.

Preferably, the insulating means is in the form of a tube of dielectric material.

Preferably, fiberglass is used as the dielectric material.

Preferably, the portion of the cylindrical body on which the plurality of ring electrodes and dielectric bushings are mounted has a reduced diameter to form an annular ledge whose end surface is in contact with the end surface of said one of the dielectric bushings.

Preferably, the means of creating a force of preload and fixing was made in the form of a nut, the end surface in contact with the end surface of the distal dielectric sleeve.

Preferably, the sealing assembly comprises sealing means located in recesses formed on the surface of the housing under the end dielectric bushings, the sealing means being made in the form of rubber rings.

Preferably in said sealing assembly, the electrode is a radiating element or a measuring element.

Preferably, the dielectric bushings are made of a polyester ether glassetron polymer material with 30% glass content of the total product volume (PEEK).

The problem is also solved by creating a probe for electric logging, which is characterized by the fact that it contains a sealing unit, made as described above.

The proposed sealing assembly of the probe for electrical logging will eliminate the mechanical effect of the external pressure of the well on the device. These loads significantly exceed the loads that occur during operation of the device (compression, tension and bending).

In the proposed design of the sealing assembly of the probe, due to the implementation of the end surfaces of a plurality of ring-shaped electrodes and end surfaces of dielectric bushings in contact with the ring-shaped electrodes, beveled and mating, it is possible to implement the device without a well pressure compensation system.

In the specified probe, all the elements of the measuring electronics are in a sealed volume, under the influence of external hydraulic pressure. The probe part can be considered as an electronic unit of a geophysical instrument having a casing that accepts mechanical loads caused by external pressure in the well and loads that occur during operation, i.e. tensile / compression and bending of the chassis.

The claimed design does not require the use of expensive technological equipment to maintain the device in working condition, i.e. installations for creating a vacuum and filtering oil, pouring oil into the device, no special room is required for carrying out these works, the room should only meet the increased fire safety requirements, and no specially trained personnel and expensive consumables (special oil) are required.

Brief Description of the Drawings

The invention is further explained in the description of the preferred embodiments with reference to the accompanying drawings, in which:

figure 1 depicts the distribution of current lines of force of a three-electrode lateral logging probe;

figure 2 depicts a known sealing assembly of the probe, according to the prior art;

figure 3 depicts a probe for electrical lateral logging (longitudinal section), according to the invention;

figure 4 depicts the sealing assembly of the probe (longitudinal section), according to the invention;

5 depicts a portion of an electric side logging probe (longitudinal section) comprising a plurality of sealing assemblies according to the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

Figure 3 shows a longitudinal section of a probe containing a sealing assembly 1 according to the present invention. The probe comprises a cylindrical body 2, on which a plurality of ring-shaped electrodes 3 and a plurality of dielectric bushings 4 are coaxially mounted, the ring-shaped electrodes 3 being placed between the dielectric bushings 4 and contacting their end surfaces 5 with the end surfaces 6 of the dielectric bushings.

To electrically isolate a plurality of ring-shaped electrodes 3 from the housing 2, an insulating means 7 is placed on the cylindrical housing 2 (Fig. 4), which is made in the form of a tube of dielectric material. As a dielectric material, fiberglass is used.

The end surfaces of the plurality of ring-shaped electrodes 3 and the plurality of dielectric sleeves 4 are beveled, which ensures better fit of the end surface 5 of the electrode to the end surface 6 of the sleeve.

Due to the fact that the contacting surfaces of the electrodes 3 and the bushings 4 are made beveled, a tight coupling of these surfaces is ensured. When assembling under the action of pressure F1 (FIG. 5), the beveled surface 5 of the ring electrode 3 is pressed against the beveled surface 6 of the insulating sleeve 4, and thereby provides good sealing.

Preferably, the acute angle of inclination of the end surface 5 of each ring electrode 3 and the end surface 6 of the dielectric sleeve 4 relative to the longitudinal axis of the housing 2 is in the range from 20 to 40 °.

Figure 4 shows an example when the probe contains two electrodes 3 and two dielectric sleeves 4, however, it is possible that the assembly contains an even number of ring electrodes and an odd number of dielectric sleeves (figure 5) or vice versa.

The sealing assembly comprises means 8 for generating a clamping and fixing force in contact with the end surface 9 of the dielectric sleeve 4a located distally with respect to the dielectric sleeve 4b in contact with the cylindrical body 2 and intended to prevent axial movements of the ring electrodes 3 and the dielectric bushings 4 relative to the housing 2. As a means 8 of creating a force of preload and fixation, a nut can be used that provides fastening and preloading of the ring electrodes 3 and di electrical bushings 4. The end surface of the nut is in contact with the end surface 9 of the distal dielectric sleeve 3a.

In the recesses 10 (figure 4) made in the end surfaces 5 of the ring electrodes 3 are placed sealing means 11.

Above the holes 12 made in the cylindrical body 2, there is no layer of dielectric material (insulation). The holes 12 are designed to accommodate the node 13 of the electrical connection of the electrode.

In the described embodiment, the part of the cylindrical body 2 on which the plurality of ring electrodes 3 and dielectric sleeves 4 are mounted has a reduced diameter to form an annular ledge 14, the end surface 15 of the ledge 14 is in contact with the end surface 16 of the dielectric sleeve 4b adjacent to the housing 2.

On the surfaces of the electrodes 3 in contact with the insulating tube 7, recesses 17 are made in which sealing means 18 are placed, in this case rubber rings.

On the surface of the housing 1 under the end dielectric bushings 4a and 4b, recesses 19 are made, in which sealing means 20 are placed, which are also made in the form of rubber rings.

The ring electrode 2 is a radiating or measuring element.

Dielectric bushings 3 are made of polymeric material PEEK polyetheretherketron glass-filled with 30% glass content of the total product volume. In the manufacture of the dielectric sleeve, glass is poured into the polymer powder in the form of "dust", after which injection molding occurs at high temperature.

O-rings 11b 20 cover all possible gaps and prevent the probe assembly from penetrating the external environment.

The electric logging probe comprises a sealing assembly as described above.

The proposed embodiment of the invention is not restrictive.

Claims (11)

1. The sealing assembly of the electric logging probe, comprising a cylindrical body, a plurality of dielectric bushings mounted on the housing, a plurality of ring-shaped electrodes coaxially placed on the housing between the dielectric bushings and contacting their end surfaces with the end surfaces of the dielectric bushings, an insulating means placed on the cylindrical housing for electrical isolation of many ring-shaped electrodes from the housing, characterized in that one of the dielectric x the bushings are in contact with the end surface with a cylindrical body, each of the plurality of ring-shaped electrodes and dielectric bushings in contact with the ring-shaped electrodes have beveled end surfaces, the beveled end surfaces of the electrodes being mated with the beveled end surfaces of the dielectric bushings in contact with them, and the sealing assembly comprises means creating a force of preload and fixation in contact with the end surface of the dielectric sleeve, placed for true with respect to the specified dielectric sleeve in contact with the cylindrical body, and designed to prevent axial movements of the ring electrodes and dielectric sleeves relative to the body, sealing means placed in recesses made in the end surfaces of the ring electrodes, while above the holes made in the cylindrical body No insulation layer. 2. The sealing assembly according to claim 1, characterized in that the acute angle of inclination of the end surface of each ring electrode and the dielectric sleeve relative to the longitudinal axis of the housing is in the range from 20 ° to 40 °. 3. The sealing assembly according to claim 1, characterized in that the insulating means is made in the form of a tube of dielectric material. 4. The sealing assembly according to claim 3, characterized in that fiberglass is used as the dielectric material. 5. The sealing assembly according to claim 1, characterized in that the part of the cylindrical body on which the plurality of ring electrodes and dielectric sleeves are mounted has a reduced diameter to form an annular ledge, the end surface of which contacts the end surface of the dielectric sleeve adjacent to the body. 6. The sealing assembly according to claim 1, characterized in that the means of creating a force of preload and fixing is made in the form of a nut, the end surface in contact with the end surface of the distal dielectric sleeve. 7. The sealing unit according to claim 1, characterized in that it contains sealing means located in recesses made on the surface of the housing under the terminal dielectric bushings. 8. The sealing assembly according to claim 1 or 7, characterized in that the sealing means is made in the form of rubber rings. 9. The sealing assembly according to claim 1, characterized in that the ring electrode is a radiating or measuring element. 10. The sealing assembly according to claim 1, characterized in that the dielectric bushings are made of polymeric material PEEK polyetheretherketron glass filled with 30% glass content of the total volume of the product, the glass is poured into the powder in the form of "dust", after which injection molding occurs and when high temperature. 11. Probe for electrical logging, characterized in that it contains a sealing assembly according to claims 1-10.

Images