RU2495015C2 - Firing device for powder pressure generators - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention is referred to an oil-and-gas industry, ferrous industry, oil and gas wells, water-supply wells, injection wells, and also to blasting works and it is purposed for equipment of powder pressure generators, first of all, capsule-type sealed generators designed for explosion and thermal-gas-chemical treatment of bottomhole formation zone by fire gases in order to intensify extraction of mineral products. Firing device contains blasting cartridge of electric type in protective shell or safe mechanical detonator without initial detonating agent, secondary cartridge of mixed solid fuel placed inside a perforated metal tube and detonating cord in a metal shell or exploding wire placed in a channel of secondary cartridge block at its symmetry axis.

EFFECT: invention allows essential increase in stability of ignition of the secondary and primary charge of a gas generator thus reducing costs for wells retreatment, elimination of expensive equipment and accessories such as exploders, logging cable, and increase in safety of well operations.

2 cl, 1 dwg

Description

The invention relates to the oil and gas, mining (oil, gas, water, injection wells), as well as to the field of blasting and is intended for manning powder gas pressure generators, allowing fracturing and thermogas-chemical treatment of the bottom-hole formation zone with gaseous products of combustion of solid fuel charges in order to intensify extraction of minerals: oil, gas, including from coal seams, metals during their extraction by underground leaching, water and etc.

Improving the productivity of wells in world practice is carried out by a variety of technological methods and technical means. The most effective and most commonly used technologies include: hydraulic fracturing, blasting of the near-wellbore zone, chemical treatment of productive reservoirs, treatment with hydroacoustic and high-pulse vibrations, heat exposure, treatment with powder pressure generators. The most universal, with a full range of effects (mechanical, chemical, physical, thermal) on the borehole formation zone is a method based on the combustion of solid fuel charges in the well in the treatment zone. The devices that allow this treatment are powder pressure generators. Work on the creation of such downhole pressure generators has been carried out in our country and abroad (mainly in the USA) sometime since the beginning of the 60s of the last century. It may be noted that the development of gas generators in the United States with the use of gunpowder and rocket fuels is aimed at creating reusable hull apparatuses that create high-speed short-pulse power loads, which lead to the formation of many small cracks in the rock. The development of gas generators in the USSR (later - in the Russian Federation) was mainly aimed at the creation of housingless units using solid rocket propellant charges in the form of channel blocks, after burning of which basically only a load-bearing geophysical cable is removed to the surface. Such gas generators received the abbreviation PGDBK - the powderless pressure generator of the open case. PHDBKs with fast and slowly burning charges are known, capable of correspondingly forming many small cracks or single large cracks.

Regardless of the type of gas generator, one of the most important components of its design is an ignition device (or ignition system). For a large number of gas generators used in practice (both open-frame and case-mounted), the ignition device includes an ignition or explosive cartridge, a detonating cord segment (DS) and a channel rocket of solid rocket fuel, in the channel of which there is DS. The ignition device may include a metal perforated tube, inside of which the entire structure described above is placed [1 ÷ 4]. A practically similar ignition device of detonation action, but without a perforated tube, placed in the channels of armored charges of mixed solid fuel, containing an explosive cartridge and detonation cord, and included in the design of a gas generator for degassing a coal seam, is described in the patent [5]. It should be noted that the use of an igniter cartridge to initiate LH is not entirely justified. According to the “Terminology of Electric Blasting” recommended by the Interdepartmental Commission for Blasting (Issue No. B-248, M., IAG named after A. Skochinsky, 1976), with some additions and changes in accordance with GOST for terminology in the field of tools initiation and terminological dictionary "Mining" (M., Nedra, 1981) incendiary cartridge is designed for simultaneous group ignition of a bundle of fire-resistant cords (OSH). An electric incendiary tube (EZT) and an electric igniter of a fire-conduit cord (EZ-OSh) are intended to excite the combustion of one section of the OSh electrically. The main form of explosive transformation LH is not combustion, but detonation. Thus, only detonators (electric or non-electric) and explosive cartridges should be the standard means of initiating explosive transformation (explosive) of the firearm.

Therefore, the detonation type ignition device as part of the design of the gas generator [4], made according to the scheme of figure 4, is taken as a prototype.

The device consists of an explosive cartridge in a protective shell, a perforated tube and a mixed fuel charge, in the channel of which a detonating cord is placed.

The main disadvantage of the ignition device adopted as a prototype is associated with the use of the DS segment in its design as a detonation igniter of an additional charge from mixed solid fuel. Detonating cord - an extended charge of high-explosive explosive (BB) that does not have a dense shell. Liners, cotton yarn, cellulose, polyamide, fluoroplastic films, polyvinyl chloride and polyethylene plastic compounds, coatings based on silicone rubbers, etc., which practically do not prevent lateral expansion of detonation products (PD) at the initial moment of detonation, are used as a DS shell. and not giving the destruction of fragments. The volume of gaseous products of the explosion is very small, and therefore the velocity of the radial expansion of the PD is not large; in turn, this leads to the fact that the determining factor of ignition is the heat transfer from highly heated explosion products to the surface of the channel of the flammable additional fuel charge. A consequence of the thermal mechanism of detonation ignition is the need for a sufficiently long exposure to hot gases on fuel (the ignition delay period can be of the order of tens of milliseconds or more). As a result, the ignition stability is not very high.

The objective of the invention is to develop a design of an ignition device with very small and, most importantly, very stable ignition delays, due to which a high uniformity of action of the entire gas generator will be ensured.

The problem is solved in that in the design of the ignition device adopted for the prototype, the detonating cord is replaced by a detonating elongated charge (DPS). DPS is an extended charge of a high-explosive high explosive substance (most often from HMX or RDX) of high density (0.9 and higher of the density of a single crystal), enclosed in a metal (copper, aluminum, steel, etc.) shell. DUZs can have a cumulative recess along the generatrix of the shell (for explosive cutting of structures) or be without a recess (round section). For all the variety of designs, types of detonating elongated charges currently being produced in our country, the most suitable for ignition devices are the DLDs (or their "semi-finished products" - tubes equipped with TSN) developed by the Krasnoznamenets Scientific Production Enterprise, manufactured in small batches according to GOST Muromsky instrument-making plant, as well as elongated cumulative charges (UKZ) and elongated charges (US) developed by the Military Academy. F.E. Dzerzhinsky, produced by TU. The main type of explosives used in DUZs (TSN) is octogen; in UKZ and US - RDX. In fairness, it should be noted that octogen is more heat-resistant explosive than hexogen, which must be taken into account when operating gas generators in wells at elevated temperatures and hydrostatic pressures. It is fundamentally possible to equip DUZs and UKZ (UZ) with more heat-resistant explosives - such as NTFA, GNDS, GNS. Copper and aluminum are used as materials for the shells of elongated charges (according to GOST and TU). DUZs made according to GOST are delivered with caps glued to the ends equipped with explosives. They perform two functions at the same time: enhance the initiating impulse from the means of initiation and seal the ends of the remote sensing device, which is also of great importance when the gas generator is operating in a well fluid.

The ignition of a fuel charge (additional charge) during the detonation of a remote sensing device in a checker channel occurs not by the thermal (as in the case of the LH) mechanism, but by the shock mechanism. The leading factor determining the dynamics of ignition is the shock-wave heating of fuel from the channel surface under the action of high-speed metal fragments of the DUZ shell. Impact pressures (pressures arising from the impact of a fragment of a shell of a remote sensing system on fuel) exceed the so-called critical pressures at which the excitation of an explosive transformation in the form of combustion is guaranteed in the fuel. In addition, the shock pressures created by DPS fragments in any mixed solid fuel are at least two orders of magnitude higher than the pressures: the so-called quasistatic, created by detonation products of DPS, and the pressure created in the checker channel by an air shock wave. Such a situation is realized, as shown by the results of direct experiments, with gaps between the remote sensing system and the vault of the fuel checker constituting 5–8 mm. With very small gaps, there is a tendency to equalize the values of all three pressures noted above.

As a result of the implementation of the shock mechanism of fuel ignition, ignition delays turn out to be very small (in tenths or hundredths of a millisecond) and very stable; due to this, a high uniformity of action of the ignition device and the gas generator as a whole is ensured.

Another technical result that can be obtained by using the proposed technical solution is a significant reduction in the mass (weight) of explosives in a detonation igniter - ДУЗе in comparison with ДС, since in the latter the equipment has a density close to the initial one (only cords of ДДТТ types equip with tablet EXPLOSIVES; in this case, the tablets have significant geometric dimensions), and in the DPS, the density of the EXPLOSIVES is close, as already noted, to the density of the single crystal. In addition, the explosive in the case of the use of remote sensing as an igniter is necessary, mainly, only for the destruction of the metal shell of the charge and throwing of the resulting fragments, and not for heating and ignition of the fuel bomb, as in the case of LH. Excessive power of the remote sensing system is even harmful, since it can cause crushing of an additional charge of fuel into multiple fragments and lead to convective burning of it (instead of layer-by-layer). Evaluation calculations show that replacing the LH in the ignition device with a remote sensing device reduces the weight of explosives in the apparatus by 1.5–2 times.

The proposed ignition device also provides non-electric methods for initiating detonation in a remote sensing device. So, for example, instead of an explosive cartridge (1), a mechanical heat-resistant detonator of the MDT-260 type developed by the RFNC-VNII EF that does not contain initiating explosives can be successfully used. Normally, it is designed to initiate detonation of the explosive chain of cumulative punchers and torpedoes launched on tubing into oil and gas wells with temperatures up to 260 ° C. It is installed in a sealed cavity of the blasting head and is driven by mechanical shock of a steel piston, accelerated by the pressure of the borehole fluid.

Features of mechanical detonators type MDT-260 are:

- insensitivity to stray currents, electromagnetic interference and discharges of static electricity;

- safety during quasistatic loading and falling on a rigid base;

- non-excitation of detonation in case of unauthorized mechanical shock and fire.

Thus, when replacing the design of the device for ignition of an explosive cartridge with a mechanical detonator, the safety of work in the well increases sharply. In addition, there is no need to use a very expensive geophysical cable, on which the gas generator is lowered to the near-well zone of the formation. It can be successfully replaced, for example, with a steel cable or rope. Blasting devices are also not needed; the cost of maintaining a team of highly skilled explosives will be significantly reduced.

The claimed technical solution differs from the prototype in the presence of a number of new significant features. In the design of the device for ignition, the LH, which plays the role of a detonation igniter, is replaced by a remote sensing device; An electric type explosive cartridge with an initiating explosive has been replaced by a mechanical detonator without an initiating explosive. These differences allow us to conclude that the claimed solution meets the criterion of "Novelty."

No solutions with such essential features were found in the scientific and technical literature, therefore, the claimed solution meets the criterion of "Inventive step".

The claimed device contains standard elements and products from the field of blasting, therefore, the present invention meets the criterion of "Industrial significance". Schematically, the design of the proposed device is shown in the figure, where 1 is an explosive cartridge or mechanical detonator; 2 - DUZ with reinforcing caps mounted on the ends equipped with explosives; 3 - checker additional charge of mixed solid fuel; 4 - perforated metal tube.

The principle of operation of the proposed device is quite simple and understandable from the figure. When an electric signal is applied to the explosive cartridge electric detonator (1) or during a mechanical shock of a steel piston accelerated by the pressure of the borehole fluid (for a mechanical detonator), the latter is triggered and through the cap excites detonation in the remote sensing device (2) from the end face adjacent to the explosive cartridge (detonator). During detonation of a DLD (2), high-speed fragments of its metal shell (and caps, too) are formed, as well as gaseous detonation products with a high temperature and an air shock wave in the channel of the additional charge fuel bomb (3), on the axis of which the DLD is located. When fragments hit the wall of the additional charge channel (3), shock pressures arise in the fuel, significantly exceeding the so-called critical values necessary for igniting this type of fuel. At the same time, pressures arise in the additional charge (3), which are created by the detonation products of the DPS equipment and the air shock wave, which also contribute to the ignition of the additional charge (3). However, the decisive contribution to the ignition process is made by the fragments of the DPS shell, since the shock pressures, as already noted, are no less than two orders of magnitude higher than the pressures created by the PD and the air shock wave. Through the holes in the perforated tube (4), an additional charge (3) ignites the igniter charge of the gas generator (not shown in the figure), in the channel of which the claimed ignition device is placed.

A positive effect of the application of the proposed device is that replacing the LH with a remote sensing device significantly reduces the ignition delay of the fuel checker of the additional charge and makes them very stable, due to which a high uniformity of action of the gas generator as a whole is ensured. The proposed device can also significantly reduce the weight of explosives in the apparatus, dramatically increase the safety of blasting in the well and reduce costs.

Information sources

1. Haney B., Cuthill D. Technikal review of the high energy gas stimulation technigue. Computalog Ltd., 1996.

2. Pat. 2018508 Russian Federation, IPC ⁷ C06, C5 / 00. Solid fuel well gas generator / Kroshchenko V.D., Kolyasov S.M., Pavlov V.I., Chelyshev V.P .; Applicant and patent holder of the All-Union. scientific research and design engineer. Institute of explosive methods geophysical. intelligence. - No. 4800099/23; declared 01/02/90; publ. 08/30/94, Bull. No. 16.

3. Pat. 2047744 Russian Federation, IPC ⁷ C1.6, E21B 43/11, 43/26. Device for stimulating the formation / Gaivoronsky I.N., Kroshchenko V.D .; applicant and patent holder Vseros. scientific research and design engineer. Institute for the use of explosion energy in geophysics. - No. 5033540/03; declared 03/23/92; publ. 11/10/95; Bull. No. 31.

4. Pat. 2175059 Russian Federation, IPC ⁷ Е21В 43/263. Solid fuel gas generator with an adjustable pressure pulse for stimulation of wells / Kroshchenko VD, Gribanov N.I. Gavoronsky I.N. and etc.; applicant and patent holder Vseros. scientific research and design engineer. Institute for the use of explosion energy in geophysics; Federal Scientific Production. Center "Altai". - No. 99121133/03; stated; 10/06/99; publ. 10/20/01; Bull. No. 29.

5. Pat. 2401385 Russian Federation, IPC ⁷ E21F 7/00, E21B 43/263. Solid fuel gas generator for coal seam degassing / Shilov A.A., Gribanov N.I., Agarkov A.V. and etc.; Applicant and patent holder Limited Liability Company “TechService Research and Production Company”. - No. 2008133398/03; declared 08/15/08; publ. 10/10/10; Bull. No. 28.

Claims (2)

1. A detonation ignition device for powder pressure generators, including a cartridge blasting in a protective shell, a perforated metal tube and an additional charge of mixed solid fuel, characterized in that a detonating elongated high-explosive explosive charge is placed along the channel axis of the additional charge in a metal shell with tightly set at its ends with sealing and simultaneously reinforcing caps equipped with explosives, the detonating elongated the charge is set so that a gap is maintained between its shell and the set of checkers of the additional charge. 2. The detonation device according to claim 1, characterized in that the explosive cartridge is made in the form of a safe mechanical heat-resistant detonator that does not contain an initiating explosive.

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