RU2683467C1 - Thermal source for thermogasdynamic fracturing - Google Patents

Abstract

FIELD: technological processes.SUBSTANCE: invention relates to the well bottom zone processing device due to the formation fracturing with solid fuels combustion gaseous products and can be used to increase the oil wells productivity. Proposed is the thermogasdynamic fracturing thermal source, which includes a housing with sealed ends, filled with the gas-generating during combustion composite material consisting of a mixture of granulated B grade ammonium nitrate, catalyst, energy additive, combustible binder, and triggered by the electrical coil igniter, where the said composite material contains potassium permanganate as a catalyst, carbon black of the P-803 grade as the energy additive, and epoxy compound as the combustible binder, comprising, in wt%: ED-20 brand epoxy resin – 76, EDOS brand plasticizer – 8, agidol of AF-2M brand – 16, in the following ratio of components of the composition, wt.%: granulated B grade ammonium nitrate 75.0–80.0, potassium permanganate 7.0–11.0, carbon black P-803 brand 4.0–6.0, epoxy compound 7.0–14.0 and introduced by its forming with layer-by-layer pressing directly into the thermal source body in the form of a solid monolithic material.EFFECT: increase in the thermogasdynamic fracturing device energy performance and the manufacturing process simplification.1 cl, 1 tbl, 2 dwg

Description

The invention relates to the oil industry, in particular to devices for increasing the productivity of oil wells by treating the bottom-hole zone due to formation fracturing by the gaseous products of combustion of gunpowder and solid fuels.

One of the rational and effective methods for treating the bottom-hole zone in order to establish reliable hydrodynamic connection between the well and the formation is a method of fracturing the gaseous products of combustion of a powder charge and thermogas effect on the bottom-hole zone of the formation. As is known, for these purposes, powder generators of the PGD.BK type are used or pressure accumulators of the ADS type [Rifle-blasting apparatus. Directory. Ed. L.Ya. Friedlyander, 2nd ed., Revised. and add. Moscow "Nedra", 1990, p. 10-116]. The PGD.BK pressure generator consists of several interconnected powder charges with axial channels that are mounted on a support pipe, are coated with a waterproofing compound over the entire surface, and with an additional coating on the outer side surface, which protects the charge from friction and impacts on the column and provides a progressive burning from the surface of the channel.

Gunpowder pressure accumulators ADS-5 and ADS-6 differ in the design of the powder charge. The ADS-6 pressure accumulator consists of flammable and combusting powder charges with axial channels, and the ADS-5 burning powder charge is channelless. An igniting powder charge differs from a burning one in that it has a sealed incandescent spiral to ignite the powder charge when an electrical voltage is applied. Powder charges ADS-5 and ADS-6 do not have an airtight shell and are in contact with the well fluid.

Currently known pressure generators and pressure accumulators for gas-dynamic fracturing of a formation consist mainly of charges of ballistic powder or mixed solid fuel and are distinguished mainly by improvements aimed at regulating the magnitude and duration of the pressure pulse of powder gases affecting the processing interval of the reservoir. So, for example, a gas generator is known [RF Patent No. 2242600, publ. 12/20/2004 bull. No. 35], consisting of an assembly of a group of charges with axial channels, means for igniting them, a load-carrying cable for delivering the gas generator to the well, and a mounting unit for the gas generator to the cable. In this case, the first group of charges is made of mixed solid fuel, which ensures a pressure pulse exceeding rock pressure during combustion, and the second group of charges is made of ballistic or mixed solid fuel, which creates a secondary pressure front with a value of at least 0.7 of the value of the first pressure pulse during time exceeding the duration of the first pulse by 3-15 times. The means of ignition of charges is made in the form of pieces of detonating and fire-conducting cords located in the axial channel of the assembly of charges and interconnected using a docking unit, while the detonating cord is installed with the possibility of igniting the charges of the first group, and the fire-conducting cord is the charges of the second group. The disadvantage of a gas generator is the unreliability of ignition of powder charges from a detonating cord, as well as from a detonating cord to a fire-conducting cord.

A common disadvantage of the above charges from ballistic or solid mixed fuels used as generators and pressure accumulators for gas-dynamic fracturing is their detonation ability and the associated high danger, which can lead to disruption of the integrity of the well in the event of an emergency during detonation . Such charges, in addition, require special conditions during storage, transportation and operation, since they are essentially explosives.

The so-called thermal sources are known that are used independently or in devices for thermoimplosion treatment of the bottom-hole zone of wells. So, for example, a thermal source for processing the bottom-hole zone of a well [RF Patent No. 2436827, publ. 12/20/2011, bull. No. 35] is formed from a composition comprising granulated ammonium nitrate of grade B, potassium dichromate, epoxy resin of grade ED-20, EDOS plasticizer, hardener Agidol of grade AF-2M, while it additionally contains a mixture of powders as components that increase its combustion temperature aluminum dispersion of not more than 50 microns and barium nitrate dispersion of not more than 0.5 mm in the following ratios of the components of the composition, wt. %: granulated ammonium nitrate, grade B - 52.5-53.0; potassium dichromate - 2.4-2.5; epoxy resin brand ED-20 - 14.3-14.4; plasticizer brand EDOS - 1.3-1.4; hardener Agidol brand AF-2M - 2.1-2.2; aluminum - 10.5-10.9 and barium nitrate - 16.0-16.5. The advantage of this heat source for treating the bottomhole zone of the well is that it is equipped with a composition having a combustion temperature of 2360 ° C, which is at the level of this indicator for ballistic gunpowder, another advantage is the non-explosive nature of the composition used in it. The disadvantage of the heat source is that from its composition it is possible to produce gas-generating material only end-face burning in a sealed enclosure due to the hygroscopicity of the composition based on ammonium nitrate. In this case, the combustion time of the end-face combustion material in downhole conditions is several minutes. However, to create a high and short-term impulse in order to break the formation, it is necessary that the composition material burns over time in the range of 0.3-1.0 sec.

Closest to the proposed invention is a thermal source for thermohydraulic fracturing [RF Patent No. 2492319, publ. 09/10/2013, bull. No. 25] including a housing that is equipped with a gas-generating composite material during combustion, an ignitor fired by an electric spiral. The gas-generating composite material of the heat source during combustion contains as a combustible binder in an effective amount of 20% wt. powdered polyvinyl chloride chlorinated resin grade PSX-LS with the following ratio of composition components,% May: granular ammonium nitrate grade B - 57.0 ± 0.2; potassium dichromate - 3.0 ± 0.1; aluminum powder of the ASD-4 brand - 5.0 ± 0.1; barium nitrate - 15.0 ± 0.2; PSX-LS polyvinyl chloride resin - 20.0 ± 0.2, with the possibility of forming composite material by pressing in the form of a group of pieces with central channels. In this case, the checkers are made separately, and then they are equipped with the body of the heat source. The gap formed by the equipment between the pieces and the body of the heat source is filled with a curing mortar capable of curing. Between the igniter and the composite material, the thermal source contains a layer of an additional igniter composition with the possibility of igniting it from the igniter, which makes it possible to ignite the gas-generating composition from the end and along the surface of the channel of the heat source. The possibility of forming a composite material of a heat source by pressing in the form of a group of checkers with central channels in the prototype method is realized by replacing a liquid curable epoxy compound including ED-20 epoxy resin, EDOS plasticizer and hardener Agidol and making the whole composition incapable, according to the authors, to pressing, due to its high adhesion to the metal of the pressing tool, on the solid powdery polyvinyl chloride chlorinated resin brand PSX-LS. The formation of the heat source material in the form of pressed pieces with central channels, as in pressure generators and pressure accumulators based on ballistic powder, allows to increase the surface of ignition and combustion, which significantly reduces the burning time of the gas-generating material, since in the presence of the channel this time is determined by the thickness of the burning the arch. However, despite the fact that an increase in the burning surface can significantly reduce the total time of combustion of the charge of the heat source and bring it to several seconds (about 2), the very composition of the composition of the heat source is not quick-burning, it contains catalysts (potassium dichromate) and energy additives (aluminum) allowing to significantly increase the burning rate of ammonium nitrate. This does not allow using this device to create short-term pressure pulses (0.3-1.0 sec.) And effectively produce fracturing. Also, the formation of the material of the heat source in the form of separately pressed pieces made with central channels and a layer of additional igniter composition, followed by filling the gap between the body of the heat source and the pieces with a special solution, is generally a laborious, low-tech and low-productivity process.

The present invention solves the problem of improving the heat source and the gas-generating material of the composition during combustion by eliminating these drawbacks.

The problem is solved in that in a thermal source for thermogasdynamic fracturing, a body with sealed ends is equipped with a gas-generating composite material consisting of a mixture of ammonium nitrate of granular grade B, a catalyst, an energy additive, a combustible binder, an ignitor that is fired from an electric spiral, according to the invention in as a catalyst, the composite material contains permanganate

potassium, as an energy additive carbon black brand P-803, as a combustible binder, an epoxy compound including, by weight. %: epoxy resin brand ED-20 - 76; plasticizer brand EDOS - 8; agidol brand AF-2M - 16, in the following ratio of components of the composition, wt. %:

Ammonium nitrate granular grade B 75.0-80.0 Potassium permanganate 7.0-11.0 Carbon black of the P-803 brand 4.0-6.0 Epoxy compound 7.0-14.0

by forming a composite material by layer pressing directly into the body of the heat source in the form of a solid monolithic material.

The proposed thermal source is shown in figure 1 and includes a housing 1, which is equipped with a gas-generating composite material in the form of a solid monolithic material 2. In the lower end part there is an igniter 3 with an electric spiral 4. The body of the thermal source is sealed from both ends with layers of epoxy compound 5 and sealant based on thiokol 6. The heat source is placed in a metal container with windows 7, in the upper part of which there is a cable head 8 for connection to a cable cable.

The thermal source works as follows. Using a cable cable connected to the cable head 8, the device is lowered to the bottom of the well and set opposite the treated interval of the formation. An electric impulse is supplied to the igniter 3 from the wellhead through a cable-cable. Ignition of the gas generating composition occurs from the latter. The combustion of the gas generating composition occurs in a split second due to the implementation of the volumetric (convective) combustion mode. Combustion products expire through windows

container 7 into the wellbore. Due to the short time of combustion of the heat source material in the processing interval, a pressure pulse of high-temperature gaseous products of combustion is generated that exceeds the reservoir pressure, which leads to thermo-gas-dynamic fracture of the formation with an extensive network of cracks around perforation channels.

The formation of a composite material of a heat source by layer-by-layer pressing in the form of a homogeneous monolithic material in the present invention is realized by introducing into the composition of a composition capable of curing an epoxy compound in an amount of 7-14% of May, including an epoxy resin ED-20, an EDOS plasticizer (EDOS plasticizer with a wide range of applications It is a mixture of polyfunctional compounds: hydroxyl and ether groups, oxygen-containing cycles [TU 2493-003-13004749-93] and hardener agidol AF-2 (represents product of the interaction of phenol and ethylene diamine in formaldehyde [TU 2494-052-00205423-2004 CJSC Himex Limited]). Moreover, with the indicated amount of liquid compound in the initial mixture, the material of the pressed mixture is semi-dry and perfectly compacted without signs of adhesion to the tool of the press tool. The heat source material is formed by batch, layer-by-layer pressing (with a pressure not exceeding 20 MPa) directly into the body in equal portions of the mixture with a height of about 20 mm and occurs continuously until the desired density and mass of the gas-generating composition are reached. The curing of the composite material of the heat source occurs within 12 hours at a temperature of 20 ° C, while achieving a compressive strength of the material of at least 45 MPa. The composite material in the body of the heat source is formed in a sealed design, so its end parts are coated with curing layers of epoxy compound and thiol-based sealant.

As studies have shown, the use of potassium permanganate in an effective amount of 7-11% wt. As a combustion catalyst instead of potassium dichromate it can significantly increase the burning rate of ammonium nitrate, while the nature of combustion changes - it goes into the volumetric, convective combustion mode, characteristic of gunpowders and mixed solid fuels. Introduction to the composition of a heat source as an energy additive of P-803 brand carbon black (carbon black (carbon black) is a highly dispersed carbon material that is formed during incomplete combustion or thermal decomposition of hydrocarbons contained in natural or industrial gases, as well as in liquid products of petroleum or coal origin [GOST 7885-86]) in an amount of 4-6% wt. allows not only to ensure a high combustion temperature of the material of the gas-generating composition (about 2200 ° C), but also plays an additional catalytic role of the combustion process. As a source of ignition for a heat source, a composition is used, including,% May: ammonium nitrate - 70, potassium permanganate - 10, epoxy resin of the ED-20 grade - 13.2, plasticizer of the EDOS grade - 1.6, hardener agidol of the AF-2 grade - 5, 2 and triggered by an electric glow plug.

It should be noted that the composite material of the heat source is non-explosive, according to the hazard class it belongs to category 913, which ensures high safety during its use, transportation and storage.

The operability of the proposed thermal source for thermodynamic fracturing is confirmed by the results of bench tests at the installation simulating borehole conditions. The installation is an elongated pressure vessel with an internal diameter of 122 mm and a height of 1800 mm, filled to a certain level with water and sealed with a lid. By adjusting the height of the airspace above the water level, the achievement of the value

working pressure in the vessel, not exceeding the permissible. A pressure sensor is located in the vessel body for continuous recording of pressure changes over time.

For bench tests, a full-scale sample of the heat source was used, the design corresponding to the drawing of figure 1, with an outer diameter of the case made of PVC (polyvinyl chloride) of 63 mm and an inner diameter of 57 mm, equipped with composite material with a total mass of 400 g. The ratio of the components of the composite material of the heat source was taken in the following quantities % wt .:

Ammonium nitrate granular grade B 79.5 Potassium permanganate 8.6 Carbon black of the P-803 brand 4.8 Epoxy compound 7.1

For comparison, samples of a thermal source according to the invention — a prototype (US Pat. No. 2492319) of the same mass — were made and tested. The average test results according to three parallel experiments are shown in the table.

The results of bench tests of a sample of a heat source in the form

the dependences of the pressure change on the time of its burning are also presented in figure 2, which show that the gases released during the combustion of the composite material of the heat source create within 0.44 seconds. pressure pulse with a maximum value of 28.7 MPa.

These data confirm the operability of the proposed thermal source in borehole conditions, the main advantages of which are high technical characteristics, ease of manufacture and safety during operation, transportation and storage.

Claims (3)

Thermal source for thermogasdynamic fracturing, comprising a housing with sealed ends, equipped with a gas-generating composite that is generated by combustion, consisting of a mixture of granulated ammonium nitrate of grade B, a catalyst, an energy additive, a combustible binder, and an ignitor that is fired from an electric spiral, characterized in that it is gas-generated when The composite material contains potassium permanganate as a catalyst, P-803 carbon black as an energy additive, and the quality of the combustible binder is an epoxy compound, including, wt.%: epoxy resin grade ED-20 - 76, plasticizer grade EDOS - 8, agidol grade AF-2M - 16, in the following ratio of components of the composition, wt.%: Ammonium nitrate granular grade B 75.0-80.0 Potassium permanganate               7.0-11.0 Carbon black of the P-803 brand     4.0-6.0 Epoxy compound   7.0-14.0 and introduced by its formation by layer pressing directly into the body of the heat source in the form of a solid monolithic material.

Images