RU2487991C1 - Cumulative well perforator - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: cumulative well perforator includes a frame with sockets and cumulative charges placed in sockets; each of them has a metal casing, metal cladding, main charge of explosive agent, detonation unit in the rear part of the main charge casing with two parallel grooves. In detonation unit there are two detonating cords that connect cumulative charges and axial socket with additional charge of explosive agent closed by one side of surface with axial part of the main part charge of explosive agent charge and by the opposite sides with detonating cords. Detonating cords along their length between cumulative charges are spaced from each other at the distance preventing reciprocal transmission of detonation. The detonation unit is capable of explosive wave damping at explosion of detonating cords in order to stabilise detonation front spreading along the main charge of explosive agent. Cumulative perforator has a sealed enclosure. Detonation unit is made of material with low sound speed. Detonation unit is made as a collar of elastic material.

EFFECT: invention allows improvement in reliability of complete actuation and efficiency of cumulative perforator operation due to optimisation of detonation circuit redundancy and increase of tunnel depth.

7 cl, 2 dwg

Description

The invention relates to the oil and mining industries and can be used for shooting and blasting in wells for the secondary opening of reservoirs.

A well-known cumulative perforator for a well, including the assembly of cumulative charges with a system for their initiation in the form of a detonating cord, which is attached to the top of each cumulative charge (see, for example, Grigoryan N.G., Quick reference to shooting-blasting operations, Moscow, Nedra, 1990, p. 70-75).

When each of the cumulative charges is triggered, an asymmetric development of the detonation wave front and collapse of the charge lining with the formation of a direct cumulative jet occur. Moreover, the deviation of the initiation point from the axis of the cumulative charge leads to a curvature of the cumulative jet and a decrease in the depth of the perforation channel.

In recent years, there has been a tendency to increase the length of cumulative rock drills lowered into the well in a single run on the cable and, especially, on the pipes. In this case, the reliability problem of detonating cords arises, since the length of the assemblies of cumulative perforators launched on pipes reaches several hundred meters in horizontal wellbores. The termination of detonation in the detonating cord due to defects leads, as a rule, to the destruction of the cumulative perforator and jamming it in the casing of the well.

Known cumulative perforator for the well, including the assembly of cumulative charges with a system for their initiation in the form of two detonating cords adjacent to the tail of each of the cumulative charges (see, for example, SU 1111528, 30.03.1991).

Such a system is designed to increase the reliability of operation of long assemblies of cumulative perforators. In the event of termination of detonation along one of the cords, it is assumed that cumulative charges from the other — a duplicating detonating cord — can be triggered.

However, in reality it turned out that:

it is practically very difficult to ensure the simultaneous passage of the detonation front along two detonating cords at the same speed. In the case of a small lead or lag of the detonation front along one of the cords, which happens quite often in practice, a high-speed gas flow in the cumulative charge does not form, converging in the plane and passing precisely through the axis of this charge, As a result, the perforation efficiency is the penetration depth of the channel;

the system of duplication of detonating cords with their tight arrangement will be reliable if the brands of detonating cords used reliably ensure the transfer of detonation to each other. However, for example, heat-resistant detonating cords based on hexonitrostilbene or plasticized detonating cords of the DShTV-150/800, DShTV-150 brands, as well as a number of others, do not transmit detonation from one to another even when pressed tightly, but only interrupt each other;

detonating cords have contacts in several places with the metal charge case and, when triggered, in addition to initiating, create shock waves in the cumulative charge case, which, interacting with reflected detonation waves, distort the detonation front of the cumulative charge and thus reduce the depth of the perforation channel (penetration efficiency) .

As a result, in a cumulative punch, not all of its charges are triggered, the efficiency and reliability of the punch decreases, the depth of the perforation channels decreases.

The technical result of the invention is to increase the reliability of the full operation and the efficiency of the cumulative perforator by optimizing the duplication of the entire detonation circuit of the perforator and increasing the depth of the perforation channels.

The required technical result is achieved by the fact that the cumulative perforator for the well includes a frame with sockets and cumulative charges placed in the sockets, each of which has a metal body, metal lining, the main explosive charge is explosive, a detonation unit in the rear of the main charge body with two parallel grooves, where two detonating cords are placed, connecting cumulative charges, and an axial socket between parallel grooves, where an additional explosive charge is placed, closed by one side surface with the axial part of the main explosive charge, and the other sides of the surface, mutually opposite, with detonating cords, which in the rest along their length between the cumulative charges are separated from each other by a distance that prevents mutual transfer of detonation, while the knock knot is made with the possibility of shock wave damping in the explosion of detonating cords to stabilize the front of detonation propagation along the main explosive charge.

Besides:

the cumulative perforator has a sealed enclosure;

plasticized RDX or HMX or hexonitrostilbene is accepted as the main explosive charge, and the mentioned explosives in pure form are used as an additional explosive charge;

knock knot is made of material with a low speed of sound;

knock knot is made in the form of a cuff of elastic material;

the tail portion of the cumulative charge housing has a protrusion, and the cuff has a corresponding internal groove for the said protrusion for the possibility of fixing the cuff on the cumulative charge with an interference fit;

rubber or polyurethane is used as the cuff material.

Figure 1 shows a cross section of a cumulative punch.

Figure 2 shows a diagram of the installation of the cumulative charge in the cumulative perforator.

The cumulative perforator includes a frame 1 with sockets (not shown conventionally), cumulative charges placed in the sockets, each of which has a metal casing 2, a metal lining 3, the main explosive charge is BB 4, a detonation unit 5 in the tail of the main charge of the explosive 4 with two parallel grooves, where two detonating cords 6 are placed, connecting the cumulative charges of the perforator, and an axial socket between parallel grooves with detonating cords 6, where an additional explosive charge 7 is placed, closed one side surface with the axial part of the main explosive charge 4, and the other sides of the surface, mutually opposite, with two detonating cords 6. The tail part of the body of the cumulative charge may have a protrusion 8, and the detonation unit can be made of material with a low sound velocity, for example, not higher than 2.5 km / s. As such material, for example, plastics such as Armamide can be used. For ease of assembly, this node is endowed with additional properties of elasticity - elasticity. In this case, the detonation unit 5 can be made, for example, in the form of a cuff made of rubber or polyurethane and have a corresponding groove for the protrusion 8. In addition, a cumulative perforator can be made case-shaped to further increase the reliability of operation. For this case, the frame 1 with sockets and cumulative charges in them can be placed in the housing 9.

The prefabricated main part of the cumulative charge (pos. 2, 3, 4) is connected to the detonation unit 5, in which there is an additional explosive charge 7. For convenience of assembly, an elastic cuff made of polyurethane or rubber can be used. Prepared cumulative charges are installed in the holes of the frame 1 of the cumulative perforator. The holes of the frame can be made, for example, so that the smaller hole has an oval shape. Its size along the frame axis is 1.1-1.2 times greater than the maximum cuff diameter, and the smaller oval size is 0.75-0.9 times smaller than the cuff diameter. Due to this, the cumulative charge assembly, subject to the elasticity of the cuff, can be snapped into the frame. After installing all the cumulative charges in the frame, two detonating cords 6 are laid in two parallel grooves of the detonation unit 5, for example, an elastic cuff. Next, the detonating cords 6 parallel to each other are laid in the frame 1 at the required distance, preventing mutual transmission of detonation (from each other) and similarly connected to the next cumulative charge. In particular, when using detonating cords of the DShT-200 type, they are placed from each other at a distance of 7-10 mm. To prevent displacements of detonating cords from a given distance, gaskets between them can be used. After the frame is fully equipped with cumulative charges and detonating cords, it can be placed in the housing 9 of the cumulative perforator, which is sealed, for example, with a threaded tip and a head.

Such a cumulative perforator assembly, after installing an explosive cartridge to the detonating cords, is lowered into the well when descending on a cable, or a firing head, when descending on pipes.

In the perforation interval, an explosive cartridge or firing head simultaneously initiates two detonating cords.

In the detonation unit 5 and, in particular, the elastic cuff, it is possible to transfer detonation from the detonating cords 6 to one surface, for example, a side additional charge of explosive 7, which initiates the main charge of cumulative charge 4 with the other surface, for example, end-face, which is strictly aligned in axis. To increase the susceptibility, an additional charge of explosive 7 can be made of pure hexogen or pure octogen, or pure hexonitrostilbene. In this case, the main explosive charge of the cumulative charge can be performed, for example, on the basis of RDX or on the basis of HMX, or on the basis of hexonitrostilbene.

For normal initiation of cumulative charges, it is enough if one of the detonating cords is triggered. The passage of detonation through cords with different speeds does not affect the efficiency of perforation. Detonating cords must be laid parallel to each other at a distance at which there is no mutual transfer of detonation from one detonating cord to another and they are not interrupted by shock waves from each other (can be determined by calculation or experimentally). But in the event of termination of detonation due to defects in one of the detonating cords, the remaining part of the cumulative charges will work from another detonating cord. Moreover, the design of the cumulative perforator provides the transmission of detonation from one cord to another on each additional explosive charge located in the detonation assembly. Such a "detonation ladder" is very effective because it allows you to bypass many defective areas of detonating cords, then one or the other, arising, for example, in the well from unforeseen situations. The reliability of such a detonation circuit is much higher than the reliability of a known circuit, and in comparison with a chain of one detonating cord, this reliability is higher by orders of magnitude.

The knock knot made of a material with a low speed of sound allows damping shock waves that occur when detonating cords explode, which stabilizes the front of detonation propagation along the main explosive charge (improves the front of detonation propagation), increasing the efficiency of the cumulative perforator - the depth of the perforation channels.

The detonation unit, made, in addition to the property of low speed of sound, from an elastic material makes it possible to conveniently connect the parts of the cumulative charge with each other and quickly mount the said charge in the frame without additional elements.

Claims (7)

1. Cumulative perforator for a well, including a frame with sockets, cumulative charges placed in the sockets, each of which has a metal body, metal lining, the main explosive charge is an explosive, a detonation unit in the rear of the main charge body with two parallel grooves, where two detonating cords connecting the cumulative charges, and an axial socket between parallel grooves, where an additional explosive charge is placed, closed on one side of the surface with the axial part of the main explosive charge, and on the other sides of the surface, mutually opposite, with detonating cords, which in the rest along their length between the cumulative charges are separated from each other by a distance that prevents the mutual transfer of detonation, while the detonation unit is configured to dampen shock waves when detonating cords explode for stabilization of the detonation propagation front along the main explosive charge. 2. The cumulative perforator according to claim 1, characterized in that it has a sealed enclosure. 3. The cumulative perforator according to claim 1, characterized in that plasticized hexogen or octogen or hexonitrostilbene is adopted as the main explosive charge, and said explosives are used as an additional explosive charge in its pure form. 4. The cumulative perforator according to claim 1, characterized in that the knock knot is made of material with a low speed of sound. 5. The cumulative perforator according to claim 1, characterized in that the knock knot is made in the form of a cuff of elastic material. 6. The cumulative perforator according to claim 5, characterized in that the tail of the cumulative charge body has a protrusion, and the cuff has a corresponding internal groove for said protrusion to allow the cuff to be fixed on the cumulative charge with an interference fit. 7. The cumulative punch according to claim 5, characterized in that rubber or polyurethane is adopted as the cuff material.

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