RU2401385C2 - Solid-fuel gas generator for coal bed degassing - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: proposed gas generator comprises armored and nonarmored tubular charges of solid fuel accommodated on geophysical cable with fireproof coat, detonation igniter including blast cartridge and detonating cord. Said detonation igniter is accommodated in armored charge, second is seen from below, and upper armored charges. Channel of lower armored charge accommodates igniter representing an electric igniter connected in series with blast cartridge at preset distance therefrom. Gas generator bottom face is tightly plugged.

EFFECT: producing multiple elongated fractures in coal bed at low hydrostatic pressure, ruling out of gas generator upward travel.

3 dwg

Description

The invention relates to the mining industry, and in particular to power impact devices using the energy of gaseous products of solid fuel combustion to increase the permeability and gas recovery of methane-bearing and outburst coal seams. It can be used to intensify the production of oil and gas and other minerals.

Known gas generators (1, 2, 3, 4, 5), consisting of a garland of powder tubular or cylindrical charges and devices that initiate their combustion. The resulting gaseous products of combustion create pressure pulses in the well lasting up to several seconds and with an amplitude equal to or greater than the rock pressure, i.e. sufficient for the development of natural and the creation of artificial cracks.

The disadvantages of these gas generators are: low pressure build-up rate, at which the formation of single, though extended, fractures in the formation occurs, i.e. there is no uniform treatment of the formation, which is so important for the implementation of degassing of the coal seam; in the process of burning charges under conditions of low hydrostatic pressure, which is typical of degassing wells, the generator moves upward under the action of the lifting force created by the gaseous products of combustion, which causes complications in the well in the form of seizures of the geophysical cable, its deformation and breakage and can lead to emergency situations .

A gas generator is known, including armored and unarmored tubular charges, consisting of solid fuel and placed on a geophysical cable, a detonating charge ignition device located in the lower charge channel and including an explosive cartridge, detonating cord and a charge of mixed fuel (6). This generator is taken by us as a prototype of the proposed generator.

This generator allows you to create many extended cracks in the reservoir and ensure uniform coverage of the fracture. However, like the gas generators described above, it is characterized by prolonged burning and undesirable and dangerous movement up the well.

The objective of the invention is the creation of numerous and extended cracks in the coal seam under low hydrostatic pressure and the exclusion of movement of the working gas generator up the well, which increases the effectiveness of the impact.

The required technical result is achieved by the fact that the gas generator for degassing a coal seam includes armored and unarmored tubular charges of solid fuel placed on a geophysical cable, a detonation ignition device located in the channels of the second lower and higher armored charges and containing an explosive cartridge and detonating cord, and also a fire ignition device in the form of an electric igniter located in the channel of the lower armored charge and connected in series with the explosive cartridge at a predetermined distance from it, while the lower end of the gas generator is hermetically sealed with a plug, and the cable has a fireproof coating that protects it from the thermal effects of the products of combustion of charges.

Figure 1 shows a gas generator for degassing a coal seam, and figure 2 is a view aa in figure 1; figure 3 - view BB in figure 1. The gas generator consists of unarmored tubular charges 1 and 2 of solid fuel located in its upper part, armored tubular charges 3 with the same fuel, located under unarmored charges, and a combined charge ignition system. The generator is mounted on a geophysical cable 4, passing through the central channel of charges, which are pulled together by tips 5 and stopper 6. As solid fuel, for example, mixed gunpowder or mixed compositions of the TKM-60 type (7), not belonging to the class of explosives, are used. The charge 2 of the gas generator is multi-tube, which provides a large combustion surface. The combined charge ignition system is located in the central channel of the armored charges and consists of a detonation ignition device, including an explosive cartridge 7 and detonating cord 8, laid along the cable from the cartridge to the multi-tube charge 2, and a fire ignition device in the form of an electric igniter 9, which is connected in series with an explosive cartridge. In this case, an electric igniter is installed under the detonation action device at a predetermined distance from it, eliminating the possibility of detonation products affecting the ignition of charges located below the explosive cartridge, and ensuring the creation of gaseous combustion products in the central energy channel, which is necessary to prevent the gas generator from moving up the well. The bottom end of the gas generator is hermetically sealed with a plug 10. The geophysical cable has a non-combustible protective coating that provides protection from the thermal effects of high-temperature hot gases, which makes it possible to extract unburned metal elements of the gas generator from the well. As a protective coating can be used, for example, a cotton insulating tape, laid by several passes, which is impregnated in the well with water and does not burn, ensuring the safety of the cable.

The gas generator operates as follows.

When treating a coal seam, the gas generator is lowered into a well filled with liquid at a predetermined interval on a geophysical cable 4. Then, an electrical impulse is sent to the explosive cartridge 7 and an electric igniter 9 through the cable, and they fire simultaneously. When the electric igniter 9 is activated, the process of burning an armored charge 3 in the interval from the lower end of the generator to the explosive cartridge proceeds in layers from the surface of the central channel to the outer surface, and the gaseous products of combustion, flowing up the channel, create reactive traction force that holds the gas generator and geophysical cable from moving up. Due to armor plating, the thickness of the burning dome of this charge is two or more times greater than that of unarmored gas generator charges, therefore, the reactive traction force acts throughout the entire burning time of the gas generator charges. When the explosive cartridge 7 is detonated, the cord 8 detonates, the upper part of the armored charges 3 ignites from the products of their detonation. The combustion of these charges occurs in the volumetric combustion mode, and they burn out in 0.02-0.10 s, which allows you to create a high rate of increase in pressure pulse gases equal to 10 ⁴ MPa / s and more. The gaseous products of the combustion of charges 3, moving upward, ignite charges 2 and then 1 with a certain delay. The combustion of multi-tube charges 2 occurs along the entire outer surface and inside their channels, and the combustion of charges 1 occurs along the outer surface and the surface of the central channel.

Under the influence of the pressure of the gaseous products of combustion, the borehole fluid and gases penetrate the formation, revealing natural and creating new fractures. Moreover, the high rate of rise of the pressure pulse provides the nucleation of many cracks in the reservoir, and the duration of the effective part of the pressure pulse increases their length. As a result of the formation of many extended cracks, the area of the free surface of the formation through which gas (methane) is filtered increases by several orders of magnitude compared to the exposed area of the formation exposed by the well. This allows you to increase gas recovery.

By selecting the number of different types of charges and corresponding calculations, the amplitude-time parameters of the pressure pulses created by the gaseous products of combustion in the well are set: the maximum pressure equal to no less than the rock pressure in the formation and the duration of the effective part of the pressure pulse.

As computer calculations showed for bedding conditions at depths of 200-1000 m, the maximum pressure created in the well by a gas generator should be equal to 5 to 1.5 rock pressures, depending on the bedding depth (200 to 1000 m and more accordingly). With the specified amplitude-time parameters, the length of the cracks during a single treatment is 10-12 m (calculation for the case of the formation of 9 radial vertical cracks with an opening of 3-6 mm).

According to the results of experimental work carried out with gas generators in degassing wells and including subsequent studies in underground mines and lava, it was established that numerous visually observable cracks in the coal seam up to 20-27 m long, a softening of the seam within a radius of 40-50 m, an increase in permeability are established formation by 2-3 orders of magnitude and methane production rate by 20-30 times.

Information sources

1. RF patent No. 933959, M.cl. ³ E21B 43/26. Gunpowder pressure generator for wells. Belyaev B.M., Sliozberg R.A. et al. 11/06/1980; Publ. 06/07/1982; Registered May 24, 1995.

2. Chazov G.A., Azamatov V.I. and others. Thermogasochemical effect on low-production and complicated wells. M .: Nedra, 1986.

3. Duvanov A.M., Gaivoronsky IN, Pavlenko GA. A new generation of powder gas generating devices for stimulation of wells. NTV "Logger", No. 58, 1999, p. 63.

4. RF patent No. 2151282 according to class. IPC ⁷ E21B 43/25 of 02/08/1999, Pelykh N.M. and etc.

5. Slastunov S.V., Shilov A.A., Gribanov N.I. Multi-crack fracture of the bottom-hole formation zone by high-energy carriers. GIAB. - M.: Publishing. MSTU, 2005, p. 19-24.

6. RF patent No. 2175059 for class. IPC ⁷ E21B 43/263 dated 10.20.2001. Bull. No. 29, (prototype).

7. Duvanov A.M. Gas-generating charge ZKI001. Specifications ZKI001. 000TU, Stimul LLC, 2003. - 12 p.

Claims (1)

A gas generator for degassing a coal seam, including armored and unarmored tubular charges of solid fuel, placed on a geophysical cable, a detonation ignition device containing an explosive cartridge and a detonating cord, characterized in that the detonation ignition device is located in the channels of the second armor charges lower and lower and in the channel of the lower armored charge a device of ignition of fire action in the form of electric ignite is installed A tube connected in series with an explosive cartridge at a predetermined distance from it, while the lower end of the gas generator is hermetically sealed with a plug, and the cable has a non-combustible coating that protects it from the thermal effect of the products of combustion of charges.

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