RU2619619C1 - Method and gas-liquid system for multistage gas extraction from downhole gas-liquid mixture - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: method for multistage gas extraction from a downhole gas-liquid mixture includes a pressure input of a gas-liquid mixture flow through a supply line into a vertical chamber of the first stage separator tangentially guiding its cylindrical shell, swirling the flow into a descending spiral, removing partially dried gas from the upper part of the chamber and removing partially degassed liquid from the bottom of the chamber. At the same time, the flow of partially dried gas from the chamber of the first separation stage is further sent to the gas-dryer separator, from the gas outlet of which dried gas is obtained. The separated liquids and gas condensate, produced at the liquid outlet of the gas-dryer separator, are directed to the suction inlet of the ejector installed at the inlet of the first stage separator. The gas-liquid system includes a pipeline supplying a gas-liquid mixture, a first stage separator containing a shell, in the form of a circular cylinder, arranged vertically. At the same time, at least one gas-dryer separator is included in the system, and an ejector is connected to the supply line of the downhole mixture at the inlet of first stage the separator, to the suction inlet of which a pipeline is connected from the liquid outlet of the gas-dryer separator.

EFFECT: improved quality of gas-liquid mixture separation by extracting gas without additional energy-intensive equipment.

5 cl, 2 dwg

Description

FIELD OF THE INVENTION

The group of inventions relates to the oil and gas industry, and in particular to the field of technical arrangement of oil production, and can be used to separate the liquid and gaseous phases, for example, for the purpose of subsequent measurement of quantitative and qualitative indicators of the main components of the produced gas-liquid mixture.

State of the art

A gravity-type separator is known, for example, a test separator, which is widely used in oil production practice to assess the quality of well fluid and associated petroleum gas. It is a vessel in which gravitational separation of a gas-liquid mixture takes place into components that are, as a rule, in various states of aggregation. In this case, predominantly gaseous components are removed from the separator through a pipeline connected to the upper part of the separator, and liquid ones - through a pipeline (s) connected (s) to the lower part of the separator.

The principle scheme of centrifugal separation, i.e. separation of phases and components of different densities as a result of centrifugal processes in the vessel.

To accelerate the process of phase separation and reduce the required size of the separator, the combined method is also used, introducing a gas-liquid jet into the vertical container of the gravitational separator tangentially to its shell, so as to create a wall-mounted flow of gas-liquid mixture on the inner surface of the cylinder shell due to gravity, from which heavier (inertial), mainly liquid, components squeeze lighter, mainly gas, inclusions in the direction of the cylinder axis and centrifugal force patterns (see., e.g., [1] RF patent №2425709, IPC B01D 19/00, publ. 10.08.2011).

As the closest analogue, a method for separating gas-liquid mixtures is adopted (see [2] RF patent No. 2409411, IPC B01D 45/12, B01D 19/00, published January 20, 2011), which consists in swirling the flow of the gas-liquid mixture entering the separator, using a jet of degassed liquid, taken at the outlet of the lower part of the cylinder with a constant flow rate (for example, a pump), introduced tangentially to the guide of the inner side of the separator wall, having the shape of a round cylinder, and the gas phase is discharged from the gas phase formed along the cylinder axis the bones. The method is implemented by a gas-liquid separator containing a cylinder fixed on its upper part to a nozzle for supplying a gas-liquid mixture, mounted on its upper end to a gas outlet pipe and fixed to its lower part to a nozzle for removing a degassed liquid. Near the mixture supply pipe, a nozzle is mounted on the cylinder tangentially to the cylinder wall and connected via a pipe to a pump with an internal cavity of the lower part of the cylinder.

The disadvantage of the prototype is the incompleteness of drainage of gas obtained as a result of single-stage separation, as well as the need to use a pump for the return pumping of degassed liquid.

Disclosure of invention

The objective of the group of inventions is to create a method and device that provides improved quality of separation of a gas-liquid mixture and does not require additional energy-intensive and expensive equipment.

The technical result of the implementation of the group of inventions is to improve the quality of separation of a gas-liquid mixture by extracting gas, without requiring additional energy-intensive equipment, and reduce costs.

The gas is extracted from the borehole gas-liquid mixture by introducing a pressure stream of the gas-liquid mixture through a supply pipe into the vertical chamber of the first stage separator tangentially directing its cylindrical shell, twisting the flow into a falling spiral, removing partially dried gas from the upper part of the chamber and removing partially degassed liquid from the lower part cameras. Next, the partially dried gas stream emanating from the chamber of the first separation stage is sent to a gas-separator, which is structurally similar to the first stage separator. From the gas outlet of the separator-gas dryer receive dried gas. In this case, the separated liquids and gas condensate obtained at the liquid outlet of the separator-gas dryer are sent to the suction inlet of the ejector installed at the inlet of the first stage separator.

Possible implementations of the described process (see, for example, Fig. 2):

increased requirements to the degree of gas dehydration may necessitate the use of two or more successive stages of gas dehydration;

the necessary pressure in the supply pipe, as a rule, is ensured by the state of the produced fluid. With insufficient pressure in the pipeline for supplying the gas-liquid mixture to the inlet of the first stage separator, as well as with significant pulsation of the gas-liquid mixture flow, which does not allow to realize fully stable twisting of the gas-liquid mixture flow into a falling spiral in the first stage separator and a stable liquid intake through the suction inlet of the ejector, it is possible to use the pump in a return liquid pipeline branch between the outlet of the separator-gas dryer and the inlet of the separator of the previous stage.

The gas-liquid system necessary for the implementation of the process includes a pipeline supplying a gas-liquid mixture; a first stage separator comprising a circular cylinder shell, arranged vertically, a cylindrical partition, arranged coaxially inside the separator’s cylindrical shell, a trapezoidal fitting mounted at the inlet of the gas-liquid mixture to form a flat jet guided tangentially to the cylindrical shell in the annular gap between the cylindrical shell and the cylindrical partition commensurate with the thickness of the wall gas-liquid flow. In this case, the system includes at least one separator-gas dryer, structurally similar to the first stage separator; an ejector is included in the supply pipe of the well mixture at the inlet to the first stage separator, to the suction inlet of which a pipeline is connected from the liquid outlet of the separator-gas dryer.

In the lower part of the separator of the first stage there is an oblique tray for collecting solid impurities; in the separator body along the inclined tray there is a hatch for removing them. To ensure the flow of fluid into the bottom of the separator, tubular channels are made in the pan.

A gas-liquid separation system for providing gas dehydration may contain more than one separator-gas dryer, installed in series with the first stage separator, one after the other, depending on the required degree of dehydration of the gas and the suction capacity of the ejector.

A pump is included in the pipeline for returning liquid and condensate from the liquid outlet of the separator-gas dryer.

The technical result is achieved:

through the use of the claimed stepwise gas extraction in a sequential separator system;

due to the return of the separated liquid using a liquid ejector to the suction inlet of the previous separation stage;

due to the use of the separation method with the twisting of the flow in a falling spiral flowing in a narrow annular gap.

Brief Description of the Drawings

In FIG. 1 is a hydraulic diagram of a two-stage gas recovery from a borehole gas-liquid mixture.

In FIG. 2 shows a variant of a three-stage gas recovery hydraulic circuit with two gas-separator separators installed in series.

Items shown in the drawings:

1 - a separator of the first stage;

2, 10 - input node of the working environment;

3, 8 - cylindrical partition;

4, 9 - annular gap;

5 - pallet;

6 - hatch;

7, 12 - separator gas dryer;

11 - ejector;

13 - pump.

The implementation of the invention

The flow of the borehole gas-liquid mixture with an inherent pressure is directed into a vertical axisymmetric chamber of the gravitational gas-liquid separator 1 with a tangential inlet, due to which the gas-liquid flow is twisted in a cylindrical shell of the separator into a falling wall spiral; in this case, more dense components (a mixture of liquids and mechanical impurities) are pressed against the cylindrical shell of the separator, and partially dried gas is pushed out in the direction of the cylinder axis and then rises upward, into the zone of lower pressure. To activate the processes of liquid capture from the mixture by surface tension and condensation of vapors present in the gas-liquid mixture, a cylindrical partition 3 was introduced into the structure, separating the flow zone of the spiral gas-liquid flow from the internal free space of the separator. In this case, the width of the formed annular gap 4 should be selected so that it is commensurate with the most probable thickness of the wall gas-liquid flow (to ensure greater efficiency of liquid capture from the stream by surface tension forces in contact with the cylindrical partition), but at the same time the possibility of outflow from cracks of released gas. It is also advisable to equip the end section of the supply pipe with a flat tip (trapezoidal fitting) in order to create a large contact area of the jet with the enclosing surfaces.

In the lower part of the separator 1 of the first stage, a pallet 5 is provided for collecting and removing solid impurities falling out of the gas-liquid flow, mounted obliquely and provided with a hatch 6 in the separator shell.

Since the primary objective of this device is the effective separation of the liquid and gaseous phases of the gas-liquid mixture, partially dried gas after the first separation stage 1 through the pipe outlet located in the upper part of the separator is sent to the separator-gas dryer 7. The liquid separated in the first stage is removed from this technological process and sent to the further technological process.

Partially drained gas in the separator-gas dryer 7 should be freed from most of the liquid phase and liquid condensate carried by the stream, picked up by the gas stream from the walls of pipelines and tanks. The physical processes in the separator-gas dryer 7 are basically similar to the processes in the separator 1 of the first stage; with the difference that the working environment here is mainly gas (or steam). Accordingly, other geometric parameters of the main structural elements must be selected, in particular, a substantially smaller width of the annular gap 9 between the outer wall of the container and the cylindrical partition 8. The liquid flows along the walls to the lower part of the separator tank.

The separated liquids and condensate from the separator-gas dryer are sent to the suction inlet of the ejector 11, which ensures the necessary vacuum in the separator-gas dryer. The use of an ejector 11 in this system, as a rule, allows you to perform the removal of the liquid phase from the separator-gas dryer 7 without the use of energy-intensive means of pumping. A borehole gas-liquid mixture flows through the flow channel of the ejector at high speed; by lowering the pressure in the flow of the mixture in the narrowed area organized in the ejector body, the suction of the liquid entering the ejector through the suction inlet is ensured.

Gas-liquid system operates as follows.

The downhole gas-liquid mixture is fed into the first stage separator 1 through the inlet pipe through the input unit 2 and, using a flat tip (trapezoidal fitting), a large area jet is created by directing it into the annular gap 4 formed by the separator shell and cylindrical partition 3. Partially drained gas from the separator the first stage through a pipe outlet in its upper part is directed to a separator-gas dryer 7. The liquid phase, separated in the separator of the first stage, is removed from the process through a fitting in the lower part of the Arathor first stage. The solid impurities deposited on the pallet 5 in the first stage separator are removed, as necessary, through the hatch 6. The partially dried gas entering the gas separator 7 is sent via an input unit 10 to the annular gap 9 between the separator-gas dryer wall and the cylindrical partition 8 Dried gas is taken from the separator-gas dryer through the pipe outlet in its upper part for further processing or to the next stage of the separator for drying. The separated liquids and condensate from the separator-gas dryer are sent to the suction inlet of the ejector 11, which ensures the necessary discharge in the separator-gas dryer.

A variant of the hydraulic circuit of a three-stage gas recovery with two separators, gas dryers 7 and 12, installed in series. To activate the return fluid flow, a pump 13 can be used here.

Claims (7)

1. A method for the stepwise extraction of gas from a borehole gas-liquid mixture, including the pressure input of the gas-liquid mixture flow through the supply pipe into the vertical chamber of the first stage separator tangentially directing its cylindrical shell, twisting the flow into a falling spiral, removing partially dried gas from the upper part of the chamber and removing partially degassed liquid from the lower part of the chamber, characterized in that the flow of partially dried gas coming from the chamber of the first separation stage is further directed in the separator gas dryer, from the gas outlet of which dried gas is obtained, while the separated liquids and gas condensate obtained at the liquid outlet of the separator gas dryer are sent to the suction inlet of the ejector installed at the inlet of the first stage separator. 2. A gas-liquid system for implementing the method according to claim 1, comprising a pipeline supplying a gas-liquid mixture, a first stage separator containing a shell in the form of a circular cylinder, located vertically, characterized in that the system includes at least one separator-gas dryer, an ejector is included in the supply pipe of the well mixture at the inlet to the first stage separator, to the suction inlet of which a pipeline is connected from the liquid outlet of the separator-gas dryer. 3. The gas-liquid system according to claim 2, characterized in that a cylindrical partition is installed coaxially inside the cylindrical shell of the first stage separator, forming an annular gap into which the gas-liquid mixture is directed tangentially to the cylinder guide using a trapezoidal fittings integrated in the separator shell. ; moreover, the size of the gap is selected in proportion to the thickness of the wall gas-liquid flow. 4. The gas-liquid system according to claim 2, characterized in that in the lower part of the first stage separator there is an inclined sump for collecting solid impurities, equipped with a hatch in a cylindrical shell to remove them, while tubular channels are built into the inclined sump, which ensure fluid flow into the bottom part of the separator. 5. The gas-liquid system according to claim 2, characterized in that a pump is included in the liquid and condensate return pipe from the liquid outlet of the separator-gas dryer.

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