RU2752569C1 - Downhole metering pumping unit to prevent deposits - Google Patents

Abstract

FIELD: oil and gas industry.SUBSTANCE: invention relates to the oil and gas industry, in particular to installations for dosed introduction of chemical reagents. The installation contains a centrifugal pump with an electric motor lowered into the well on a tubing string, a device for dosing a chemical reagent located above the pump in the tubing cavity, connected to the heat exchanger by a chemical reagent injection line containing a jet apparatus, a process tank enclosed in a ground heat exchanger. The injection line runs from the wellhead to the connection with the circulation channels of the heat exchanger, made with the possibility of heating the reagent in the process vessel. The heat of the produced fluid from the well is used as a heat source. The line runs from the heat exchanger along the surface of the pumping pipe string to the junction with the jet pump nozzle, which has a jet apparatus as a dispenser.EFFECT: invention improves deposit prevention efficiency by reducing energy costs and improving metering accuracy.1 cl, 3 dwg

Description

The invention relates to methods and devices for oil production, in particular to downhole installations for dosed introduction of a chemical reagent into the cavity of an oil and gas well to prevent salt deposits, deposits of asphalt-resinous deposits, and the formation of corrosion.

Known downhole metering pumping unit, lowered into the well on a string of pumping pipes, containing a positive-displacement pump, a suction chamber, a dispenser, a metering plunger, a container with a chemical reagent, a system of valves and pipes. The chemical reagent, which is pre-filled in the container, is fed through a system of valves and nozzles to the intake of a volumetric pump, where it is mixed with the produced liquid. During operation, the dispenser plunger is driven by a vacuum in the lower cavity of the positive displacement pump. As the plunger moves downward, the excess pressure closes the valve, thereby preventing production fluid from entering the chemical container. The working cycle is repeated (A. s. USSR No. 1617198, 1990).

The disadvantage of the known design is the impossibility of its use when operating wells using pumping units of a dynamic principle of operation (electric submersible centrifugal pump), since the cycle of pumping a chemical reagent is periodic. Chemical reagent without additional heating. The volume of the chemical reagent is limited.

Known pump-ejector system containing an electric submersible centrifugal pump with a gas separator and a jet apparatus located on the discharge line of the electric submersible centrifugal pump. The gas-liquid mixture (GZHM) flows from the well to the intake of the gas separator, then, after separation, into an electric submersible centrifugal pump, then into the flow line and then into the nozzle of the jet apparatus. In this design, the ejector, playing the role of an additional pump, pumps gas liquids to the surface and therefore the system is conventionally named "Tandem" (Drozdov A.N., Andriyanov A.V. Oil industry. 1997. N 1. S. 51-54).

There is a known installation for dispensing a reagent during oil production from a well, capable of providing a continuous supply of a liquid chemical reagent in the dose prescribed by the regulations and for its intended purpose, containing a process container connected through a shut-off device to a dispenser pump installed on the reagent supply line, the flow line of which is connected to the process line equipped with a fine filter, check valve, flow meter, process tank filling line, level indicator and pressure gauge. An electric heater is installed in the process tank. (RF Patent No. 2242586, 2004).

Although the installation is equipped with the necessary heating system for the chemical reagent by means of an electric heater, the increased energy consumption significantly reduces its efficiency and is a disadvantage of the known installation. The disadvantage is also the imperfection of the dosing system due to the sludge entering the container with the reagent, clogging the small flow area of the throttle and rendering the entire installation inoperable.

Closest to the invention is a downhole dosing pump unit with a dosed supply of reagents to the pump intake, containing a pump of a dynamic principle of operation with a container filled with a chemical reagent made of the "pipe-in-pipe" type and a jet device as a dispenser, placed under the pump and equipped with check valves type "ball-spring". The chemical is pressed from below by the liquid. The dosage is carried out by selecting the diameters of the nozzle and throat (RF Patent No. 2135743C1, 1999).

The known installation closest to the invention can be adopted as a prototype. In it, the disadvantages of similar installations are partially eliminated, but the prototype is not devoid of disadvantages. The disadvantage of a construction close to the invention is the need to fill a container with a back-up fluid (kill fluid) and a container with a chemical reagent before running the installation into the well, and the volume of the back-up fluid and chemical reagent in the container is limited. Control over pressure drops is required. No heating of the chemical reagent.

Above-ground installations for dosing the reagent as independent structures are quite often used to prevent salt deposits, asphalt-resin-paraffin compounds, and the formation of corrosion. However, until now, the use of a metering unit heated by the produced fluid from the well has not been described.

No technical solutions have been identified that coincide with the set of essential features, which makes it possible to draw a conclusion about compliance with the “novelty” condition of patentability.

The technical solution is aimed at increasing the efficiency of preventing the deposition of asphalt-resin-paraffinic compounds and salts, the formation of corrosion in the inner cavity of the tubing and the surface injection line.

The technical problem posed is solved by the proposed downhole metering pumping unit for the prevention of deposits, containing the surface part and downhole equipment.

The above-ground part contains a process tank enclosed in a heat exchanger and a special discharge line.

Downhole equipment contains a centrifugal pump with an electric motor, which is lowered into the well on a tubing string. Above the pump, in the cavity of the tubing, there is a device for dosing a chemical reagent, connected to the process tank with a special injection line, containing a jet apparatus.

What is new is that the heating of the chemical reagent in the metering unit is carried out by the liquid produced from the well.

What is new is that the system for dosing the supply of a chemical reagent into the well is carried out by selecting the size of the flow section diameters of the throat and nozzle of the device for dosing directly in the well.

The claimed technical solution is illustrated by drawings, where:

- figure 1 shows a diagram of a downhole metering unit to prevent deposits.

- figure 2 shows the surface part of the downhole metering unit.

- figure 3 shows a fragment A - a device for dispensing a chemical reagent.

The downhole metering unit to prevent deposits (figure 1) includes a centrifugal pump 2, an electric motor 1, a tubing string 3, a device for dosing a chemical reagent (fragment A), an injection line of a chemical reagent 4, a heat exchanger 7, a line for pumping the produced liquid 6 , wellhead valves 5. Additionally, the diagram (figure 1) indicates the zone of deposition of asphalt-resin-paraphinic compounds, salts and corrosion (fragment B).

The onshore part (Fig. 2) includes a chemical reagent injection line 4, wellhead valves 5, a production fluid injection line 6, a sealing sleeve 8, a circulation channel of the produced fluid 9, a process tank 10, a filler neck 11.

Fragment A - a device for dispensing a chemical reagent (Fig. 3) consists of a jet device 12, an inlet 13, a throat 14 and a nozzle 15.

The downhole metering unit to prevent deposits (Fig. 1) includes a centrifugal pump 2 with an electric motor 1, which is lowered into the well on a tubing string 3. 1) connected to the heat exchanger 7 by the injection line of the chemical reagent 4.

Inside the heat exchanger 7 (figure 2) there is a process vessel 10, which is washed through the circulation channel 9 by the produced liquid. A chemical reagent is pumped into the process tank 10 through the filler neck 11 as it is consumed, which, through the injection line of the chemical 4 through the sealing sleeve 8, is fed into the well to the device for dosing the chemical (fragment A, Fig. 1).

The lower end of the injection line of the chemical reagent 4 is installed in the inlet 13 of the jet device 12 of the device for dosing the chemical reagent (Fig. 3). The jetting apparatus 12 includes a throat 14 and a nozzle 15.

The surface part (Fig. 2) is mounted at the wellhead. The injection line of the chemical reagent 4 is laid first along the surface, then through the sealing sleeve 8 in the pipe head of the wellhead fitting 5 it passes into the well and then goes along the tubing string 3.

The proposed downhole metering unit to prevent deposits operates as follows.

Before starting the installation, the process tank 10 is filled with a chemical reagent. The centrifugal pump 2, driven by the electric motor 1, supplies the pumped liquid to the tubing string 3, and then to the jet apparatus 12 of the device for dosing the chemical reagent (Fig. 3). From the well, the produced fluid through the wellhead valves 5 along the injection line of the produced fluid 6 enters the circulation channels 9 of the heat exchanger 7, where it transfers heat to the chemical in the process tank 10. The heated agent is fed into the well through the injection line of the chemical 4, which runs along the surface columns of pumping pipes to the inlet 13, then the reagent is mixed with the produced liquid through the nozzle 15 of the jet apparatus 12 of the device for dosing the chemical reagent (FIG. 3). Moving in the cavity of the tubing in the area of fragment B (Fig. 1), chemical reagents react with the pumped formation fluid, preventing the possibility of deposition of asphalt-resin-paraffin compounds, salts, and the formation of corrosion. The selection of the size of the diameters of the passage sections of the throat 14 and the nozzle 15 of the jet apparatus 12 provides a metered supply of the reagent into the inner cavity of the tubing string.

The advantage of the proposed downhole dosing system for the prevention of deposits is that:

- it allows using the thermal energy of the produced fluid passing through the heat exchanger as a heat carrier for heating the chemical reagent, therefore, it makes it possible to ensure continuous operation of wells regardless of the temperature regime;

- it provides an economical metered supply of a chemical reagent, due to the selection of the diameter of the flow section of the throat and the nozzle of the metering device, thereby preventing various deposits and increasing the turnaround time for wells equipped with centrifugal pumps;

- it can significantly reduce energy consumption, thereby increasing the efficiency of well operation.

Claims (1)

A downhole metering pump unit for preventing sediments, comprising a centrifugal pump with an electric motor lowered into the well on a tubing string, a device for dosing a chemical reagent located above the pump in the tubing cavity, connected to a heat exchanger by a chemical reagent injection line containing a jet apparatus, a technological tank enclosed in a surface heat exchanger, characterized in that the specified injection line, passing from the wellhead to the connection with the circulation channels of the heat exchanger, made with the possibility of heating the reagent located in the process vessel and using the heat of the produced fluid from the well as a heat source, is laid from the heat exchanger along the surface of the pump string to the junction with the nozzle a jet pump, which has a jet apparatus as a dispenser.

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