RU2630490C1 - Pumping plant for gas withdrawal from annular space in oil well - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: pumping plant includes two tanks with gas lines leading to them, connected to the annular space in the well, and discharge gas lines connected to the flow header of the well. Suction and discharge valves are installed respectively on the supply and discharge gas lines. There are also a pump for pumping working fluid and lines for fluid inflow and outflow in the lower parts of both tanks. Each of the lines is provided with receiving and outlet sides of the transfer pump. Between the pump and tanks there is a fluid flow switch, flexible stretchable membranes are placed in every tank. They hermetically divide the tanks into two equal parts. The space of each container above the membrane is filled with a liquid of a volume equal to the volume of dead space above the membrane in the gas line between the upper point of the tank and the valves for entering and exiting the evacuated gas in the cycle of its displacement from the tank.

EFFECT: increase of reliability and operational efficiency of the liquid transfer pump to the tank to displace gas from them to the pressure line.

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Description

The proposed installation relates to the oil industry and can be used to select gas from the annulus of an oil well and pump it into the flow header of the well.

The accumulation of gas separated at the reception of the borehole pump in the annulus leads to the extraction of the dynamic level of the liquid in the borehole until the pump is received, a decrease in oil flow to the bottom due to a decrease in depression on the formation, and ultimately to a disruption of the pump supply.

Known methods and devices for implementing forced pumping of gas from the annulus of the well into the discharge manifold.

For gas extraction from the annulus of two or more wells, an outboard compressor driven by a rocker of a rocking machine is known, the suction pipe of which is connected by a common manifold to the annular space of these wells, and at least one of the wells is connected to a common manifold and a discharge gas pipeline of the compressor through pressure regulators (RF patent No. 2102584, IPC E21B 43/00, claimed. 12/22/1995, publ. 01/20/1998).

Thus, in the suction stroke of the piston compressor, gas enters the cylinder cavity from the annulus of all connected wells, and gas is injected from the compressor cylinder by the piston into the discharge manifold of any of this group of wells.

The disadvantage of this system is the inability to take gas from the well with less gas pressure in the annulus. In the case of installing a pressure regulator, the amount of gas taken from the well with high pressure in the annulus will be significantly reduced.

A well-known installation of a rod oil pump (RF patent No. 49923 for a utility model, application form. 07/11/2005, publ. 10.12.2005, BI No. 34), including an additional cylinder with a flowing plunger, on both sides of which at the base of the couplings are non-return valves with spherical shut-off elements, allowing to bypass the gas from the annulus into the tubing string. A non-return valve is installed on the manifold line of the well. During the course of the rod string and the flow plunger upward, its valve closes and a certain decrease in pressure is formed in the subplunger zone, due to which gas will flow from the annulus to the zone along with the pumped oil through the lower sleeve. When the plunger moves down, the pressure will partially decrease in the supra-plunger zone, and oil from the sub-plunger zone and gas from the annulus will come into this zone with the open valve of the additional plunger open.

The installation has a drawback, which consists in the occurrence of significant hydraulic resistances at the time the rod string moves down during the extraction of high viscosity oil. The upper holes in the flowing plunger for fluid when connected to the rod will have insufficient cross sections for the flow of a viscous medium and significantly increase the resistance to the movement of the rods down. As a result, the so-called “freezing” of the rod string may occur and the installation will lose operability.

A known installation for oil production (RF patent No. 212105, IPC E21B 43/00, application. 21.01.1997, publ. 20.11.1998), in which the part of the outboard compressor, limited by the walls of the cylinder and the back of the piston, is hermetically connected to the annulus of this same or another well. This achieves the use of both sides of the piston for pumping gas by alternately filling the cylinder on both sides of the piston with gas from the annulus of two wells.

The analogue has the disadvantage of stopping the supply of the compressor in the event of wear of the piston pair.

The gas pressure in the annulus of operating wells will be different. This will lead to the fact that through the gap formed as a result of wear, gas will flow from the high-pressure region to the low-pressure region. Pumping gas from both wells will ultimately become impossible.

A known pump for pumping a gas-liquid mixture (A.S. USSR, No. 1590687. Declaration. 04.10.88. Publish. 07.09.90. BI No. 33), including two tanks for alternately pumping working fluid from them with a pump and thus create a "liquid "Piston in them. With a decrease in the level of the "liquid" piston in one of the containers, the gas-liquid mixture is sucked into the vacant volume. In the same period, the working fluid fills another container and displaces a previously filled gas-liquid mixture into the discharge manifold. Upon reaching a certain level of the working fluid in the tank, the flows are switched and the working fluid is pumped to another tank, from which the cycle of displacing the gas-liquid mixture into the discharge manifold begins. The transfer pump itself works, thus, in a continuous mode, constantly pumping liquid that does not contain a gas phase. The disadvantage of this device is the lack of automation of switching the pump from one tank to another and control over the levels of liquids in the tanks, which can lead to a violation of the cyclicity of the entire system.

Closest to the proposed solution is the installation for water-gas treatment of the oil reservoir (patent RU No. 2500003 C2. Claim. 08.22.2011. Publ. 10.12.2013), containing a centrifugal pump for pumping a working fluid without gas, receiving lines for gas and liquid, two tanks with suction and discharge valves, lines for the selection and discharge of fluid, connected with the discharge and intake of the pump. At the water inlet line, an additional pump is placed in parallel, connected to the working nozzle of the liquid-gas ejector, the receiving chamber of which is connected to the gas line, and the discharge to the upper parts of the tanks. In addition, at the inlet of the ejector there is a control valve and a throttle, and the shut-off element of the control valve is hydraulically connected to the ejector of the ejector and the inlet to the throttle.

After the water level in one of the tanks drops to the minimum value, the level sensor transmits a signal to switch the fluid supply in the opposite direction. Switching flows is carried out using controlled three-way valves.

The analogue selected as a prototype has the disadvantage of reducing the reliability of the pump due to the presence of solid suspended particles (HDTV) and partially oil in water. In commercial water related to aggressive media used as a working fluid and pumped by a centrifugal pump, up to 300 mg / l or more HDTV may be contained, which cause increased wear and corrosion of the pump impellers. As a result of wear, the pressure characteristic of the pump deteriorates, and ultimately its failure occurs.

The technical task of the invention is to increase the reliability and efficiency of the pump for transferring liquid in a tank for displacing gas from them into the discharge manifold.

The novelty of the technical solution lies in the fact that in the known installation, which includes two tanks with gas lines leading to them connected to the annulus of the well and gas outlet lines connected to the discharge manifold of the well, suction and discharge valves installed respectively on the inlet and outlet gas lines, a pump for pumping a working fluid, lines for entering and exiting fluid in the lower parts of both tanks, each of which is connected to the receiving and pressure sides of the pumped pump, a fluid flow switch located on these lines between the pump and containers, characterized in that each container has flexible stretchable membranes that hermetically separate the containers into two equal parts, and the space of each container above the membrane is filled with liquid, a volume equal to the volume dead space above the membrane in the gas line between the upper point of the tank and the valves for entering and exiting the pumped gas in the cycle of its displacement from the tank.

The drawing shows a schematic diagram of a pumping unit. It consists of two vertical tanks 1 and 2, the upper parts of which are connected respectively to the receiving 3 and 4, as well as discharge 5 and 6 valves. The receiving valves 3 and 4 are connected in parallel with the gas line 7, which through the valve 8 is connected to the annular space 9 of the well 10. The pressure valves 5 and 6 are also connected in parallel with the gas line 11 and then to the discharge manifold 12 of the well, which is connected through the valve 13 to tubing string 14, lowered into the well 10.

The lower parts of the tanks 1 and 2 by pipelines 15 and 16, respectively, are in communication with the electromagnetic valve 17 (shown conditionally). The valve 17 by pipelines 18 and 19 is connected respectively to the suction and pressure sides of the pump 20. On the suction line 18 of the pump 20 is installed a filter 21 for cleaning the working fluid from mechanical impurities. A pressure gauge 23 and a pressure sensor 24 are installed on the pressure line 22 of the pump 20, as well as a safety valve 25. On the line 26 connected to the line 18, a check valve 27 is installed, after which the line 26 is connected to the supply tank 28 filled with the working fluid under atmospheric pressure . The pressure vessel line 22 of the pump 20 enters the same tank after the safety valve 25. Inside the containers 1 and 2, flexible stretchable membranes 29 and 30 are placed, hermetically disconnecting the upper and lower halves of the tanks 1 and 2.

The cavities in containers 1 and 2 under the membranes 29 and 30 are completely filled with the working fluid, and the cavities above the membranes are filled with this fluid in small volumes 31 and 32.

As a working fluid, for example, technical oil with a low freezing temperature can be used.

The operation of the pump installation is as follows.

The binding of tanks 1 and 2 with the pump 20 through the electromagnetic valve 17 allows pumping the working fluid from the submembrane cavity of the tank 1 into the submembrane cavity of the tank 2 and after the filling of the latter completely, the switch switches on the reverse pumping of the liquid from the tank 2 into the tank 1. The drawing shows the pumping fluid from tank 1 to tank 2. In this cycle, the liquid through line 15 from the cavity of the tank under the membrane 29 enters the valve 17, line 18 and then through the filter 21 to the reception of the pump 20. The pump 20 there is no incoming liquid flowing through line 19 to the control valve 17 and then along line 19 to the cavity of the tank 2 under the membrane 30. During the pumping of the liquid from the tank 1 to the tank 2, the gas will flow from the annulus through the open space under pressure from the annular space above the membrane 29 under pressure a valve 8, a gas line 7 and a check valve 3. At the same time, the gas entering the previous cycle from the cavity of the container 2 above the membrane will be displaced into the discharge manifold 12 of the well 10 through the check valve 6 and gas line 11. At the time of reaching about filling the container 2 with the working fluid, the flexible stretchable membrane 30 will take the form of the upper half of the container 2 and will block access to the further flow of the liquid into the container 2. At this moment, the pressure of the working fluid will increase sharply in the pressure lines 19 and 22 and the pressure sensor 24 will signal to the control cabinet (in fig. not shown) for switching the electromagnetic hydraulic switch for the reverse pumping of the working fluid from the tank 2 into the tank 1. Switching the working fluid flow in the opposite direction is carried out by applying an electrical signal to one of the electromagnets of the control valve 17.

In order to avoid rupture of valves, the capacity of pipelines 16, 19 or 22 with a possible short-term increase in pressure in the pressure line of the pump 20 above the permissible value on line 22, the safety valve 25 is activated, dropping a small portion of the working fluid through it into the supply tank 28.

After switching, the working fluid from the cavity under the membrane 30 of the tank 2 will flow through line 16 to the valve 17 and then through line 18 to the pump 20, which will pump the working fluid through line 19, the valve 17 and line 15 into the cavity of the tank 1 under the membrane 29 .

At the same time, as the pumping fluid from the reservoir 2 of the working fluid into it through the gas line 7 and through the suction valve 4 will receive gas from the annulus 9 of the well 10. In the same cycle, gas from the cavity of the reservoir 1 above the membrane 29 will be displaced into the flow collector 12 of the well through the check valve 5 and the gas line 11.

In both injection cycles, the working fluid fills the reservoir 1 and 2 to the upper points of their spherical surfaces. Short vertical sections of gas pipelines above tanks 1 and 2, as well as sections between valves 3 and 5 and valves 4 and 6, remain filled with gas. These small volumes filled with gas form the so-called dead spaces, which reduce the gas injection pressure (compression ratio) in the cavities above the membranes 29 and 30, in the gas injection cycles from them. Filling the cavities above the membranes 29 and 30 with small volumes 31 and 32 of the working fluid allows filling the dead spaces with fluid and increasing the gas discharge pressure of the pump unit.

In the operation of the pump installation, leakage of the working fluid in the pump 20 is possible. This will lead to a deficit in the flow of working fluid to the pump intake, i.e. full filling of any of the tanks 1 or 2 may not be achieved. In this case, the pressure at the intake of the pump 20 will decrease to a value below atmospheric. Therefore, the intake of the pump 20 will additionally receive the necessary amount of working fluid from the supply tank 28 through the check valve 27. Thus, the pumping of the working fluid by the pump 20 occurs in a closed system without contact with the gas phase of the well production or with the produced oil, which prevents mechanical impurities at the pump intake.

To ensure the normal operation of the pump installation, the pressure created by the pump 20 must exceed the fluid pressure in the discharge manifold 12. The pump 20 is selected based on the required volumes of gas pumped from the annulus of the well.

The technical and economic advantages of the pump installation are to ensure high reliability of the pump due to the absence of mechanical impurities in the pumped working fluid, as well as the possibility of increasing the gas discharge pressure by filling the dead space of the tanks with liquid.

Claims (1)

A pumping unit for pumping gas from an annular space of an oil well, including two tanks with gas lines leading to them, connected to the annular space of the well, and exhaust gas lines connected to a discharge manifold of the well, suction and discharge valves installed respectively on the gas inlet and outlet lines, a pump for pumping a working fluid, lines for fluid inlet and outlet in the lower parts of both tanks, each of which is connected to the receiving and pressure sides and a transfer pump, a fluid flow switch located on these lines between the pump and containers, characterized in that in each of the containers flexible stretchable membranes are placed, hermetically separating the containers into two equal parts, and the space of each container above the membrane is filled with liquid with a volume equal to the volume dead space above the membrane in the gas line between the upper point of the tank and the valves for entry and exit of the pumped gas in the cycle of its displacement from the tank.

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