RU136082U1 - INSTALLATION OF PREPARATION AND INJECTION OF A FINE DISPERSED WATER-GAS MIXTURE (MDVHS) IN A PLAST - Google Patents

Abstract

1. Installation for injecting a water-gas mixture into an oil reservoir, containing an ejector-mixer with gas and water supply lines, at the outlet of which a pump unit is installed, a high pressure separator to separate excess water, the outlet of which is hydraulically connected to the pump unit, an injection well with a column tubing that forms the annulus with the well, the gas-water mixture supply line connecting the pump unit to the injection well, the water discharge line, hydraulically connected a separator and a water supply line to the pump unit, characterized in that the injection well is equipped with a packer, and the separator is mounted on a tubing string above the packer, the separator water discharge line passes through the annulus, the separator is made in the form of a cylindrical chamber at the inlet of which a screw flow swirl is installed motionlessly along the axis of the chamber, and the lower part of the chamber is made in the form of a nozzle directed into the chamber, on the outer side of which channels are made for the removal of the separated flow of water into the annulus, while on the gas, water and water discharge lines from the separator, flow meters and control valves are installed with the ability to control a controller, the input of which provides flow meters, and the output signal to the control valves to ensure optimal gas content in gas-gas mixture during its injection. 2. Installation according to claim 1, characterized in that it is additionally equipped with a container for a surfactant with a metering pump, the outlet of which

Description

The invention relates to the oil and gas industry, in particular to methods of displacing oil from the reservoir by pumping physical and chemical substances.

Gas injection, as a method of developing oil fields, has been used in the world for a long time. The main advantage over oilflooding is the implementation of the principle of miscible displacement. However, the return of associated petroleum gas (APG) to the reservoir to reduce greenhouse gas emissions into the atmosphere, on the one hand, and increased oil recovery, on the other hand, requires, as a rule, compression of this gas to pressures of 40-50 MPa. In this case, the energy consumption for compression is comparable to the energy obtained from burning the corresponding amount of hydrocarbon gas. In addition, the usual injection of APG into a heterogeneous permeability oil reservoir can lead to an accelerated breakthrough of the gas injected into the reservoir to the bottom of the producing wells and, accordingly, to a decrease in the coverage of the reservoir by the oil displacing agent and, consequently, to a decrease in oil recovery. This drawback is overcome by injecting gas in the form of a water-gas mixture - capillary forces prevent dagger gas breakthroughs. Nevertheless, one of the central unsolved problems of this method of stimulating the formation is the need to use compressors. Indeed, the associated gas coming from the units for preparing oil for transport has a pressure of the order of one MPa, and the pressure 10–11 MPa is required for the implementation of water-gas treatment (HBV). The use of compressors is associated with the acquisition of expensive equipment, difficult to operate, and high energy consumption for gas compression. In addition, a sufficiently complex and metal-intensive gas preparation system is needed for compression.

There are various devices for the preparation and injection of MDVG into the reservoir: “System for water-gas stimulation of a reservoir” (RF patent No. 2190760, 2002), “System for water-gas stimulation of a reservoir” (RF Patent No. 2293178, 2005), “Installation water-gas effects on the oil reservoir ”(RF Patent No. 2455472, 2010),“ System for water-gas effects on the reservoir ”(RF patent No. 2315859).

A common disadvantage of the known devices is the low volumetric gas content in the gas mixture when using low-pressure devices as separators of the first or second stage separators with a gas pressure of not more than 0.6 MPa. For example, when using gas from separators of I (II) stages of separation at the required injection pressure of the mixture into the reservoir 12.0 MPa and at a working fluid pressure of 20.0 MPa, the volumetric ejection coefficient will be no more than 0.11, i.e. in a gas-water mixture in each cubic meter of water will be mixed no more than 0.11 m ^{3 of} gas. Therefore, in a device for increasing the volumetric gas content in a water-gas mixture, gas must be compressed with compressors before being fed into the ejector, the use of which complicates the design of the device and significantly increases costs.

The closest technical solution to the claimed invention is an installation for implementing a method of increasing oil recovery by injecting a water-gas mixture into a formation containing an ejector-mixer with gas and water supply lines, at the outlet of which a pump unit, a high pressure separator is installed, to separate excess water, the inlet of which is hydraulically connected to the pump unit, a water-gas mixture supply line connecting the separator to the injection well, and a water discharge line, hydraulically connecting the separator and the water supply line to the separator (RF Patent 2357074, 2007).

A disadvantage of the known technical solution is the inability to obtain a stable water-gas mixture (HCV) that does not change the degree of dispersion when it moves from the mouth to the bottom of the injection well.

Also, this device does not allow its use for the disposal of low-pressure associated petroleum gas (APG). Oil is displaced from the reservoir by a water-gas mixture with a gas content in the mixture in the range from 30 to 75% of the volume of the mixture, under oil displacement conditions, which is done by separating excess water from the outlet of the centrifugal pumping unit and before injecting the gas-water mixture into the wells water-gas mixture using a separator, which is then fed into the intake manifold of a centrifugal pumping unit.

The objective of the invention is to simplify the design of the device and reduce energy consumption during the preparation and injection of MDGS into the reservoir.

In figure 1. a general installation diagram is shown; Fig. 2 shows a section of an injection well with a screw swirl in section.

The installation contains an ejector-mixer (1), a gas supply line (2) a water supply line (3), an outlet (5) from the ejector-mixer, a pump unit (4), a high pressure separator (A), an outlet (6) from the separator high pressure, injection well (7), tubing string (8), annulus (9), HCV supply line (10), water discharge line (11), packer (12), annulus (13), cylindrical separator chamber (14), screw flow swirl (15), nozzle (16), channels (17) for separating separated water, flow meters (18, 19, 20), regulating valves (21, 22, 23), controller (24), controller input (25), metering pump (26), surfactant tank (27), metering pump outlet pipe (28).

The installation works as follows.

Water and gas coming from the field through lines (3) and (2) enter the ejector-mixer (1), where they are mixed and dispersed to form a water-gas mixture (HCV). The obtained HCV is fed to the inlet (6) of the pump unit (4), where the pressure rises to the required value, and then the high-pressure HCV is fed through line (10) to the tubing string (8). Moving along the tubing string, the HCV enters the separator A, made in the form of a chamber (14) with a screw sweeper (15) installed in its upper part. Once in the separator A, the flow swirls, which leads to a redistribution of the concentration of gas bubbles in the flow, namely, an increase in their concentration in the flow core and a decrease in the near-wall region. Thus, under the action of centrifugal forces, excess water is thrown to the walls of the chamber (14), and a centrifugal gas stream with an increased gas content is formed in the center. Installing the packer (12) under the separator provides the ability to remove degassed water through the channels (17) into the annulus (13) and its further flow through line (11) to the inlet (6) of the pump (4). A gas-gas mixture with a gas content increased to the value required for effective oil recovery to exit through the pipe (16) into the tubing string and then into the oil reservoir. Performing the lower part of the separator body provides a more complete separation of excess water. Installation on the gas supply lines (2), water (3) and water discharge (11) from the separator of flow meters (18, 19 and 20) and control valves (21, 22, 23), and a controller (24), to the inlet (25) ) of which the flowmeter readings are supplied, and the output signal is supplied to the control valves provides the ability to control the flow of water and gas (i.e., control the gas content in the injected HCV and maintain it at a given level), thereby ensuring high efficiency of the oil displacement process. Dosed supply of surfactants from the tank (27) is carried out using a metering pump (26) through the outlet pipe (28).

The table shows the results of using the installation. P / G _gas MPa / m ³ / h R / G _water MPa / m ³ / h P _ejection. Gazoso R _mouth MPa Gazoso P _zab. MPa G _{excess water.} m ³ / h Gas content face. % holding _beginning % _mouth holding % 0.6 / 5 20/4 3 twenty twenty 3.6 42 3.52 fifteen 0.6 / 5 20/4 3 twenty twenty 42 3.715 25 0.6 / 5 20/4 3 twenty twenty thirty 3.666 thirty 0.6 / 5 20/4 3 twenty twenty thirty 3.5 twenty 0.6 / 5 20/4 3 twenty twenty thirty 3.8 fifty

The above results show that when using the installation, the following indicators were achieved: the volumetric gas content in the reservoir conditions was 20-25%, which allowed us to almost halve (compared with the prototype) the volume of injected gas while maintaining the efficiency of the oil extraction process. This, in turn, ensured a twofold reduction in the cost of gas compression and injection. When using the proposed technical solution, the gas-gas mixture does not stratify when it moves along the tubing, since the gas-gas mixture with the given parameters is obtained near the bottom of the well and its stratification does not have time to occur. An important feature of the proposed technical solution is the use of hydrostatic pressure of a water column in a well to compress gas, which also reduces the cost of pumping the HCV.

In this case, the use of compressor equipment on the surface was not needed, which greatly simplified the design of the installation and reduced the energy consumption for the preparation and injection of MDVGS into the reservoir.

Claims (2)

1. Installation for injecting a water-gas mixture into an oil reservoir, containing an ejector-mixer with gas and water supply lines, at the outlet of which a pump unit is installed, a high pressure separator to separate excess water, the outlet of which is hydraulically connected to the pump unit, an injection well with a column tubing that forms the annulus with the well, the gas-water mixture supply line connecting the pump unit to the injection well, the water discharge line, hydraulically connected a separator and a water supply line to the pump unit, characterized in that the injection well is equipped with a packer, and the separator is mounted on a tubing string above the packer, the separator water discharge line passes through the annulus, the separator is made in the form of a cylindrical chamber at the inlet of which a screw flow swirl is installed motionlessly along the axis of the chamber, and the lower part of the chamber is made in the form of a nozzle directed into the chamber, on the outer side of which channels are made for the removal of the separated flow of water into the annulus, while on the gas, water and water discharge lines from the separator, flow meters and control valves are installed with the ability to control a controller, the input of which provides flow meter readings, and the output signal to the control valves to ensure optimal gas content in gas-gas mixture during its injection. 2. Installation according to claim 1, characterized in that it is additionally equipped with a container for a surfactant with a metering pump, the outlet pipe of which is hydraulically connected to the water supply line to the ejector-mixer.

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