RU2293860C2 - Method of producing inert gas-liquid high-pressure mixtures - Google Patents

Abstract

FIELD: oil industry.

SUBSTANCE: method comprises burning fuel-air mixture in the combustion chamber of a power plant with subsequent using the combustion products as inert agents. The power plant represents a drive for a two-stage pump-compressor plant or one of its stages. The fuel is burnt out in the air with a stoichiometric ratio providing the safety concentration of oxygen in air with subsequent supplying hot gas combustion products to the generator of the power plant for doing a useful work. The inert combustion products are supplied to the finishing system and, after additional compression, to the consumer.

EFFECT: simplified method.

1 dwg

Description

The invention relates to the oil and gas industry, where the preparation and injection under high pressure of neutral (inert) gas-liquid mixtures to prevent ignition of hydrocarbon gas and gas-liquid mixtures. In particular, in operations using gas-liquid treatment with inert mixtures on the formation during the operation of wells that stopped flowing due to a drop in reservoir pressure or an increase in water cut, in the absence of a high-pressure gas source, which contributes to the intensification of oil production and an increase in oil recovery due to replacement of water flooding reservoir gas-liquid exposure. The invention can also be used in drilling using aerated drilling fluids, developing oil and gas wells, calling up and intensifying fluid inflow in oil and gas wells, testing production cores for leaks by lowering the level, opening productive formations using gas-liquid mixtures, flushing wells after Hydraulic fracturing, foam and foam acid treatments of the bottomhole zone. In addition, the invention can be used to fill and pressure cavities, gas and oilfield equipment and pipelines and in some other cases when in the process of work creation of an explosion-proof environment is required.

Methods and equipment for the preparation and injection of inert gas and gas-water mixtures have been used in the world oil and gas industry for more than thirty years. Nitrogen-based mixtures are mainly used as inert gas mixtures. They have proven themselves in secondary methods of operating oil and gas wells; well cementing when light but strong cement is required in formations with natural fracturing; when emptying wells for artificially inducing fluid flow; at the opening of formations using gas-liquid mixtures; during foam acid treatment of the bottomhole zone and in a number of other cases.

Nitrogen mixtures are obtained mainly by "cryogenic" and "membrane" methods. These are laborious and costly processes. The use of liquid "cryogenic" nitrogen requires the use of complex, expensive cryogenic equipment and significant costs for the purchase of liquid nitrogen, significant transportation costs for delivering it from the nitrogen manufacturing plant to the place of consumption (well). The process of converting liquid nitrogen to gas requires significant energy costs.

The use of "membrane" technology also requires the use of expensive equipment and high energy costs. In addition, the implementation of this technology requires sophisticated air preparation technology, which is practically unacceptable in the field. It should be noted and low volumetric efficiency of the method.

Known inventions in which attempts are made to simplify and reduce the cost of the process of producing inert gases. Oxygen is not removed, but chemically bound. This is achieved through the binary use of a driving diesel engine, which simultaneously performs two different functions - the power plant, which drives the entire device, and the "supplier" of neutral gas.

So, there is a known (RU 2083812 C1 Е 21 В 43/25 dated 02.10.1994) method for developing wells by supplying an inert gas to the annulus of a well using a compressor, characterized in that a nitrogen-containing mixture of diesel exhaust gases is used as an inert gas motor, cleaned in the separator, and the gas supply to the annular space is carried out in a closed cycle diesel engine - compressor - well.

Closest to the application, a technical solution (prototype) is a booster pump and compression unit known from the prior art for the preparation and injection of inert gas and gas-water mixtures RU 2121077 C1 F 04 B 41/00 from 02.10.1994 g, which can be taken as a prototype . The installation includes an internal combustion engine equipped with an exhaust pipe, a pressure pipe and a booster pump with a receiving pipe, a gas manifold and a discharge pipe, characterized in that the pressure pipe is connected to the exhaust pipe of the internal combustion engine through a check valve and a first valve, and the other end through the second valve - with the receiving pipe of the booster pump, and between the specified exhaust pipe and the booster pump into the pressure pipe in series troeny apparatus for the direct injection of water and apparatus for increasing the intermediate pressure gas-water mixture, made, for example, as a twin-screw multiphase pumps.

But in internal combustion engines, which also includes diesel, two functions - ensuring optimal engine traction characteristics and obtaining exhaust gas with maximum oxygen burning for further use - are poorly combined with each other, since the resulting air-fuel mixture In the combustion chamber of the engine, the gases are the working fluid and their composition is determined by the requirement to ensure maximum engine throttle response. Consequently, a change in the composition of the air-fuel mixture towards a more complete burning of oxygen means an inevitable deterioration in the traction characteristics of the engine, and an improvement in the traction characteristics will necessitate a violation of the stoichiometric ratio in the direction of incomplete combustion of the fuel. As a result, there is a need for continuous operation of the diesel engine on a re-enriched air-fuel mixture for burning oxygen out of air to a safe percentage. As a result, the drop in the power of the diesel engine is primarily due to a decrease in torque, a large number of solid mechanical particles and unburned coked fuel, which sharply reduce the diesel engine’s service life, and the diesel engine overheats.

Also a feature of combustion of the air-fuel mixture in an internal combustion engine is the need for the transience of the combustion process. As a result, the presence of incompletely oxidized radicals in the exhaust gases, including aggressive acid compounds such as NO _x , CO. A shift in the ratio of the air-fuel mixture towards re-enrichment with fuel will inevitably lead to a sharp increase in the number of such radicals in the exhaust. The presence of such chemically aggressive compounds in the exhaust gas leads to accelerated destruction of the surfaces of nodes and parts of tubing units in contact with the gas, and will sharply reduce the motor resource of the latter. This will be especially intense when working under pressure. To neutralize such compounds, a complex neutralization system will be needed.

Depending on the change in pressure at the outlet of the installation (unavoidable during technological operations), the power consumption and the required torque on the drive shaft will change. At a constant speed (and this is dictated by the desire to maintain the volumetric flow), a change in power and torque means a change in the amount of fuel burned. This, in turn, means a violation of the stoichiometric ratio towards incomplete combustion of the fuel. The need to maintain a certain percentage of oxygen in the exhaust will inevitably lead to the need to change the amount of air supplied to the combustion chamber of a diesel engine when changing the load on the engine shaft, which will also increase the inconsistency of the volumetric characteristics of the compressor (booster) and diesel engine. This means that a complex system of adjustments with high speed, working in an aggressive environment, will be required. In addition, the need to control the amount of air supplied to the combustion chamber of the engine will inevitably lead to a decrease in the volumetric supply of the installation and, as a result, will make it difficult to operate such installations for a number of technological operations.

In connection with the foregoing, it can be concluded that the use of diesel engine exhaust (or another currently known internal combustion engine) as an inert (explosionproof and fireproof in a hydrocarbon medium) is very problematic.

There are a number of technical contradictions: inside the engine - compressor system (or multiphase and gas booster pumps) and between the two functions of the drive motor.

The technical task of the invention is the resolution of technical contradictions and the creation of an alternative method of producing inert gases based on the combustion of fuel in air in a stoichiometric ratio in power plants and forcing them as part of fluids (and as a result of utilization of combustion products - reduction of harmful emissions into the atmosphere) possessing higher energy and technological efficiency.

Features of the patented method are as follows. If in the patent RU 2083812 C1 Е 21 В 43/25 dated October 2, 1994, inert (explosion and fireproof) gases in a hydrocarbon medium are produced according to the following scheme: engine exhaust gas → inert high-pressure gases. In the prototype RU 2121077 C1 F 04 B 41/00 dated 10/02/1994 g according to the scheme: engine exhaust gas → inert gas-liquid mixture of low pressure → inert gas-liquid mixture of high pressure. The application proposes to apply the sequence: air of relatively low pressure → exhaust gas of an engine of relatively low pressure → inert gas-liquid mixture of high pressure. Another feature of the patented method is the use of energy released in the production of inert low-pressure gases (in the second stage) for the implementation of other stages (or at least one).

The method of obtaining inert in a hydrocarbon medium gas-liquid high-pressure media using a power power plant (figure 1) is that the process of burning fuel in air in the combustion chamber of a power power plant, which is the power drive of a two-stage tubing, or at least one from her steps. The compressor stage compressing air is used as the first stage. The second stage is a booster device that compresses gas using a flowing liquid piston (booster unit).

Combustion is carried out in a stoichiometric ratio, which ensures that oxygen is burned out of air to a safe percentage, and occurs at excess air pressure (in air compressed by a first stage compressor) (0.4-4 MPa). This ensures a rational distribution of the degree of compression and overall power characteristics between the steps, followed by the direction of the hot gaseous products of combustion into the generator of the power plant. The thermal energy released during the combustion of the air-fuel mixture is transferred to the working fluid through the insulating heat-conducting wall or is directly converted into electrical energy and used to perform useful work - driving at least one stage of the installation. As a result, the combustion products cool down after the release of internal energy to perform useful work. Then, combustion products inert in the hydrocarbon medium are sent to the final preparation system, where their temperature is brought to the optimum temperature to ensure maximum throttle response of the second stage booster device. Also, with the help of the final preparation system, the excess of thermal energy, which appears when the unit switches to partial load modes, is extinguished. Cooled gases are sent to the gas inlet of the second stage of the installation, where they are compressed by means of a flowing liquid piston to the required pressure and sent to the consumer as part of gas-liquid media inert in a hydrocarbon medium. As a second stage, a gas booster pump or other device that compresses the exhaust gases using a flowing liquid piston is used.

At the same time, a separator can be installed between the consumer and the unit, separating the gas-liquid mixture into gas and liquid phases and used separately in further technological operations, for example, when using inert gas in a hydrocarbon medium, separated carbonated water to ensure the most complete oil displacement from deposits can be injected into injection wells as a working agent. By adjusting the gas-liquid ratio by changing the amount of liquid supplied to the formation of the flowing gas-liquid piston, and using liquids with different surface tension coefficients and different densities, it is possible to choose the most effective technology in specific conditions. Inhibiting solutions may also be added to the gas-liquid mixture to reduce corrosion.

Advantages of this scheme: high resource compressor working with clean air and with relatively stable parameters, ease of maintaining combustion at more stable parameters. Engine life also increases significantly, as there is no contact between aggressive combustion products and engine parts.

The combination of technical solutions allows us to establish compliance with their criterion of "novelty." The claimed features allow in this method to have new properties in comparison with known technical solutions. The new properties consist in the fact that the proposed method for producing high pressure gas-liquid media inert in a hydrocarbon medium using a power plant provides the creation of a complex of equipment with high technical parameters due to the rational consumption of thermal energy and resolves technical inconsistencies arising in devices using a drive internal combustion engine.

Thus, the invention meets the criterion of "inventive step".

The method is as follows:

The stage of compression of air II produces the injection of air with a predetermined overpressure through the line of injection of air 11 into the combustion chamber 7 of the power plant I. There, fuel is supplied through the fuel supply line 10. In the chamber using mixing elements (not shown in the diagram), they are mixed. After that, the ignition systems (not shown in the diagram) ignite the fuel and burn it. Fuel combustion can also be carried out in a flameless manner (in a catalyst medium). The thermal energy released during this is converted by means known from the prior art in the power plant I into mechanical energy. Mechanical energy is used to drive the installation. Due to this (doing useful work), the combustion products (exhaust gases) are cooled. After that, the pre-cooled gases enter the stage of pumping high-pressure media III, where the gases are finally compressed and sent to the consumer as part of gas-liquid mixtures.

Between the power plant I and stage III, there may be a system of final preparation of gases 5. In this unit, their temperature is brought to an optimum temperature to ensure maximum throttle response of the booster high-pressure device. The selected heat can be directed to the heating of process fluids. Residual heat dissipates in the environment. The selection of heat (including residues) can take place using devices known from the prior art. The final binding of active radicals (up to CO ₂ ) can also be carried out there, including by injecting water or appropriate solutions into the exhaust gas. Then it is advisable to include a two-phase separator in the preparation system. The separated gas is sent to stage III, and the carbonated liquid (including water) can be used in other technological operations or returned to the system for reuse.

The conversion of energy in a power plant is as follows:

Hot combustion products enter the generator 6, where they transfer the internal (thermal) energy released during the combustion of the air-fuel mixture to the working fluid of the external combustion engine or go for direct conversion into electrical energy through a sealed heat-conducting wall. The received energy, depending on the type of power plant, is transmitted to the drive motor in a “suitable” form for it.

The driving engine (s) can be either an electric motor or combinations of several electric motors (when used as a generator - a thermionic emission generator), or a heat engine of external combustion, for example a steam (volumetric or dynamic type (turbine)), or a Sterling engine. In the case of using an electric motor (or a combination of several electric motors), the following chain can also be used as generator 6: external combustion engine - generator or other combination known from the prior art. In the case of using heat engines as a generator 6, a steam generator or another generator of the working fluid is used.

Energy supply and removal lines 8 and 9, depending on the type of energy, can have a different view. It can be electric wires (tires), steam lines, etc.

The transfer of mechanical energy can occur using a volumetric hydraulic transmission. This paves the way for a direct-acting gas booster pump.

A combination of heat and electric motors is possible.

As a stage for pumping high-pressure media III, a piston gas booster pump or other device that compresses gases using a flowing liquid piston is used. The liquid piston is formed by the fluid entering the gas booster pump through the fluid supply line 15. The fluid supply (back-up) can be carried out from an external source, from the booster pump, or through an additional metering plunger.

The formation of the liquid piston can be carried out at the suction stroke with a pressure slightly higher than the gas pressure at the gas inlet of the gas booster pump. In this case, the fluid backing can go on continuously. It can be carried out at the discharge stroke or at its end with a pressure not lower than the discharge pressure of the gas booster pump. In this case, the backwater will be intermittent.

The possibility of implementing the present invention is proved by domestic and foreign practice of using in the gas and oil industry the methods of preparation and injection of inert gas mixtures, implemented in a number of specialized installations.

Technical features that are distinctive for the proposed method can be implemented using tools used in various fields of technology (steam turbines, thermionic generators, pressure pipelines, valves, devices for intermediate pressure increase of gas-water mixtures, gas booster pumps, separators, etc. )

Examples of the use of the proposed method:

The above allows us to declare the possibility of creating, through the use of the proposed method, fully autonomous operation complexes. First of all, in small reserves of natural resources and remote deposits that are not of interest in traditional production methods and which stopped flowing due to a drop in reservoir pressure or an increase in water cut. It ensures well operation in the absence of a high pressure gas source.

When developing an oil deposit of the claimed method through injection wells, it is possible to pump a gas-liquid mixture, and not a liquid. Oil is extracted through production wells with further separation of produced water and associated gas from oil. Associated gas is burned in the power plant. A flowing piston is formed on the basis of separated formation water. Production water and combustion products are used to produce a gas-liquid mixture, which is injected into the formation using a flowing fluid piston in a gas booster pump. Thereby, production wastes are found to be useful, the disposal of which now requires significant funds.

The inventive method allows the operation of wells in one way throughout the life of the operation. The result of this operation will be the replacement of waterflooding with a gas-liquid impact on the formation, the possibility of complete utilization of associated gas and produced water, which does not have industrial significance, and, as a result, the failure of flare devices. This will remove the "environmentally dirty" associated gas utilization technologies and reduce environmental pollution. As a result of using combustion products with a safe percentage of oxygen as inert gases, it becomes possible to compensate for oil extracted from the reservoir fluid by injecting an inert gas-liquid mixture and maintain the production compensation coefficient close to unity or even more.

In addition, the operation according to the claimed method will reduce the investment in the arrangement and operation and accelerate the commissioning of the field due to the absence of the need to build pipelines of the pressure maintenance system, systems for collecting associated gas and flare devices, laying power lines to the field and building substations.

Also, the availability of such operational equipment at the field will significantly reduce the cost of well repair and development due to the refusal to attract additional equipment for work (as well overhaul can be carried out using existing equipment) and a significant reduction in the after-repair period.

Claims (1)

A method of producing high pressure gas-liquid media inert in a hydrocarbon medium using a power plant, in which the internal energy of the combustion products in the generator of the power plant is transferred to the working fluid or is directly converted into electrical energy through a sealed heat-conducting wall based on the combustion of the air-fuel mixture in the combustion chamber power plant with the subsequent use of combustion products as inert media, while the above I power plant is the drive of a two-stage pump or compressor unit, or at least one of its stages, in which the compressor stage compresses the air as the first stage, and the booster device compresses the gas using a flowing liquid piston as the second stage (booster installation), characterized in that the process of burning fuel in air in the combustion chamber of a power power plant is carried out in a stoichiometric ratio, providing for burning and from oxygen air to a safe percentage, occurs at excess air pressure (in the air compressed by the compressor of the first stage), which provides a rational distribution of the degree of compression and overall power characteristics between the stages, followed by the direction of the hot gaseous products of combustion to the generator of the power plant, where there is a transfer of internal energy of the combustion products to the power plant for the implementation of useful work (driving at least one of the steps installation), as a result of which the combustion products reduce the temperature, then the combustion products inert in the hydrocarbon medium are sent to the final preparation system, where their temperature is brought to a temperature optimal for ensuring maximum throttle response of the booster device of the second stage, and sent to the gas inlet of the aforementioned booster device, where are compressed by means of a flowing fluid piston to the required pressure and sent to the consumer as a part of gas-liquid inert in the hydrocarbon medium tn environments.