RU2692164C1 - Method for automatic maintenance of density of unstable gas condensate supplied to the main condensate line, using the air cooling apparatus, at the units of low-temperature gas separation in areas of the far north - Google Patents

Abstract

FIELD: technological processes.SUBSTANCE: invention relates to the field of production and preparation of gas and gas condensate for long-distance transport. Method includes purification of incoming gas-condensate mixture coming from production wells, from mechanical impurities and separation of gas-condensate mixture into UGC, gas and aqueous solution of inhibitor (ASI), with subsequent removal UGC and ASI into separator of liquids for degassing. From separator of liquids ASI is withdrawn for regeneration of inhibitor in inhibitor regeneration shop, and UGC is fed by pump into MCL. Weathering gas from liquid separator is fed for use for own needs, for compression with subsequent pumping into main gas line or for recycling. To control density UGC APCS monitoring density sensor density UGC, supplied to MCL. Simultaneously APCS temperature sensor controls temperature of gas in low-temperature separator and compares it with a task, the value of which is determined automatically by cascade of two proportional-integral-differentiating (PID) of regulators implemented based on APCS plant. To this end, the SP input PID-density maintenance regulator UGC at liquids separator output signal of density setting value is sent, which value is set by maintenance personnel. And to feedback input PV of same PID-controller transmits actual density signal from density sensor UGC, installed at fluid separator outlet. Comparing said signals, PID-regulator generates temperature setting signal at its output CV, to which it is necessary to cool the gas-liquid mixture coming from the separator of the first separation stage by air cooling devices (ACO) to ensure required density UGC at the liquids separator output, and supplied to SP input PID-regulator to maintain temperature in low-temperature separator, and to feedback input PV of this PID-controller is fed current temperature value from temperature sensor, installed in low-temperature gas separator, comparing PID-regulator at its output CV generates control signal, which is supplied to input ACS, control modes of functioning ACO. ACS ACO taking into account current parameters of environment selects optimum mode of operation ACO. Simultaneously with it APCS controls pressure in fluid separator, automatically maintaining its value set by process procedure of plant, by means of regulating valve.EFFECT: disclosed method enables automatic monitoring and maintaining a given density UGC, supplied to MCL; preventing formation of gas plugs and their accumulations in condensate line; reduced risk of occurrence of emergencies during operation MCL, associated with density fluctuations UGC.1 cl, 2 dwg

Description

The invention relates to the field of production and preparation of gas and gas condensate for long-distance transport in the Far North, in particular, to automatically maintain the installation of low-temperature gas separation (hereinafter installation) the density of unstable gas condensate (NGK) supplied to the main condensate line (MCP).

There is a method of automation installation of low-temperature gas separation, including automatic maintenance of the separation temperature, gas flow rate and pressure at the installation. [See, for example, p. 112, B.F. Taranenko, V.T. Hermann. Automatic control of gas field facilities. M., "Nedra", 1976, 213 p.],

The disadvantage of this method is that it does not provide for the management of the degree of degassing and, accordingly, maintaining the density of the NGK when it is fed to the MCP. And this can cause a number of problems associated with the appearance of gas jams and their accumulations in the condensate line. The presence of such traffic jams can cause serious complications and accidents that lead to material, human and environmental losses. [Cm. for example, A.A. Korshak, A.I. Zabaznov, V.V. Novoselov et al. Pipeline transport of unstable gas condensate. - M .: VNIIOENG, 1994.].

The closest to the technical nature of the claimed invention is a method of automating the installation of low-temperature gas separation, including the automatic maintenance of temperature and pressure at the installation. [See, for example, p. 406, R.Ya. Isakovich, V.I. Loginov, V.E. Popadko. Automation of production processes in the oil and gas industry. Textbook for high schools, M., Nedra, 1983, 424 p.]. The degree of NGK degassing in this method is maintained by heating it, using a coil heater installed in the degassing separator tank.

A significant disadvantage of this method is that, due to the inertia of the heating process and the lack of control over the density of NGK supplied to the MCP, the degree of degassing and maintenance of the density of NGK when it is fed into the MCP is almost blind, without precise process control.

The task, which the present invention is directed to, is to automatically maintain the density of OGC supplied to the MCP, taking into account the norms and restrictions stipulated by the technological regulations of the installation for the conditions of the Far North.

Technical results achieved from the implementation of the invention, is the automatic maintenance of the density of the NGK in the framework of the norms and restrictions provided by the technological regulations of the installation for various modes of its operation. The inventive method provides control and maintenance of a given density of NGK supplied to the MCP, in order to prevent the formation of gas jams and their accumulations in the condensate line. This increases the reliability of the operation of the MCP and reduces the likelihood of risks of complications and accidents, which can lead to serious environmental, human and material losses.

This problem is solved, and the technical result is achieved due to the fact that the method of automatically maintaining the density of NGK supplied to the MCP using an air-cooling unit (ABO) at low-temperature gas separation plants in the Far North includes cleaning the incoming gas-condensate mixture into the installation mechanical impurities and separation of gas-condensate mixture to NGK, gas and an aqueous solution of the inhibitor (VRI), followed by removal of NGK and VRI in the separator for liquids for degassing. From the liquid separator, the VRI is diverted to the inhibitor regeneration to the inhibitor regeneration workshop, and the NGK is pumped to the MCP. The weathering gas from the liquid separator is supplied for use for own needs, for compression with subsequent injection into the main gas pipeline (IHL) or for recycling.

To achieve this goal, the density sensor of the NGK supplied to the MCP is monitored by the density sensor. At the same time, the gas temperature in the low-temperature separator is monitored by the temperature sensor and compared with the task, the value of which is determined automatically by a cascade of two proportional-integral-differentiating (PID) controllers implemented on the basis of the automated process control system of the installation.

For this purpose, the input of the SP PID-regulator's job of maintaining the NGK density at the output of the liquid separator is given a NGK density setting signal, the value of which is set by the service personnel. And to the feedback input PV of the same PID controller, a signal is sent to the actual density value from the NGK density sensor installed at the output of the liquid separator. Comparing these signals, the PID controller generates at its CV output a temperature setpoint to which the gas-liquid mixture coming from the ABO first-stage separator must be cooled to ensure that the required NGK density is reached at the output of the liquid separator. temperature maintenance regulator in a low-temperature separator, and the PV input of this PID regulator serves the current temperature value from a temperature sensor installed in a low-temperature separator g ase, comparing which PID controller at its CV output generates a control signal that feeds an automatic control system (ACS) to an ABO, which controls the modes of operation of an ABO. ACS AVO, taking into account the current environmental parameters, selects the optimal mode of operation of the AVO. At the same time, the automated process control system (APCS) controls the pressure in the liquid separator, automatically maintaining its value set by the process regulations using a valve-regulator.

During the implementation of the process of maintaining a given density of NGK, the temperature in the low-temperature separator can reach its limiting values — upper or lower. Their values are indicated in the installation process regulations. In such cases, the automated process control system generates a message to the operator about the impossibility of achieving the specified density of the oil and gas complex supplied to the MCP and the need to make a decision on changing the operating mode of the installation.

FIG. 1 shows the flowchart of the installation and the following notation is used in it:

1 - installation input line;

2 - separator of the first stage of separation;

3 - ABO;

4 - ACS ABO;

5 - installation APCS;

6 - gas-gas recuperative heat exchanger;

7 - gas-condensate recuperative heat exchanger;

8 - pressure sensor installed in the separator for liquids 9;

9 - liquid separator;

10 - gas pressure regulating valve installed at the outlet of the liquid separator 9;

11 - NGK density sensor installed at the outlet of the liquid separator;

12 - pump unit;

13 - MCP;

14 - reducing valve-regulator of gas flow;

15 - low temperature separator;

16 - temperature sensor installed in the low-temperature separator;

17 - IHL.

FIG. 2 shows the block diagram of the automatic control of maintaining density on the installation and the following notation is used in it:

18 is a signal input to the feedback input PV of the PID controller 22 from the gas temperature sensor 16, installed in the low-temperature separator 15;

19 - the signal from the NGK 11 density sensor to the PV input feedback of the PID controller 21;

20 - the signal of the NGK density setting, which is fed to the input of the SP reference of the PID controller 21;

21 - PID-regulator maintain the density of the NGK at the output of the installation;

22 - PID-regulator maintain the temperature in the low-temperature separator;

23 - the control signal supplied to the input of the ACS of the ACO gas.

The method of automatically maintaining the density of NGK supplied to the MCP using the AVO, at low-temperature gas separation plants in the Far North, is implemented as follows.

Gas-liquid mixture through the input line 1 is fed to the inlet of the separator of the first stage of separation 2, where it is cleaned from mechanical impurities and partial separation of NGK and VRI, which as accumulation in the lower part of the separator 2 is diverted to the separator liquids 9. Partially cleaned from drip moisture and The reservoir fluid gas-liquid mixture from the outlet of the separator of the first separation stage 2 is fed to the inlet of ABO 3, where it is pre-cooled by heat exchange with the air medium. At the outlet of the air-cooling unit, the gas-liquid mixture stream is divided into two parts and fed to the inputs of the first sections of recuperative heat exchangers 6 “gas-gas” and 7 “gas-condensate”. Further, from the outputs of the first sections of the heat exchangers 6 and 7, the flows of the gas-liquid mixture are combined and fed to the inlet of the gas flow control valve 14, in which the mixture is cooled due to the reduction effect. From the outlet of the valve-regulator 14, the mixture is fed to the low-temperature separator 15, equipped with a temperature sensor 16, which monitors the temperature of the gas in the low-temperature separator 15.

In the low-temperature separator 15, the final separation of the gas from the oil and gas complex and the VRI occurs. Drained and cooled gas from the outlet of the low-temperature separator 15 enters the second section of the recuperative heat exchanger 6 "gas-gas", and from it into the IHP for delivery to the consumer.

NGK and VRI, as they accumulate in the lower part of the separator 15, are led through the second section of the recuperative heat exchanger 7 "gas-condensate" into the liquid separator 9 equipped with a pressure sensor 8. A mixture of NGK and VRI is supplied to the liquid separator 9 from separators 2 and 15 separation and degassing. The flow of released gas (weathered gas) from the liquid separator 9 through the valve-pressure regulator 10 is removed for use for their own needs, for compression, followed by injection into MGP 17 or for recycling. Dedicated BPI is diverted for regeneration into the regeneration workshop of the inhibitor of the complex gas treatment unit. NGK from the liquid separator 9 through a pipeline equipped with a density sensor 11, is fed to the input of the pump unit 12, which sends it to the MCP 13.

The density of the NGK supplied to the MCP 13 is automatically maintained by changing the degree of extraction of light fractions of NGKs from the gas-liquid mixture in the low-temperature separator 15. This is achieved by controlling the temperature mode of the low-temperature separator 15, which is implemented by changing the degree of pre-cooling of the gas-liquid mixture on the ABO 3 controlled by the specialized ACS four.

The principle of controlling the operation of an air-cooling unit with the help of a specialized automatic control system in the conditions of the Far North is known and can be implemented as described in the RF patent №2397372.

The density of the NGK is set by the service personnel in the form of a setpoint, a signal 20, which is fed to the input of the SP reference of the PID controller 21 to maintain the density of the NGK in the MCP. The PV input of the connection of the same PID controller is given a signal 19 of the actual density value of the NGK detected by the density measurement sensor 11. As a result of their processing, the PID controller 21 at its CV output forms the temperature setpoint to which it is necessary to pre-cool the gas-liquid mixture with using ABO 3. This setpoint is fed to the input of the SP setpoint control of the PID controller 22 in the low-temperature separator 15. An actual 18 signal is sent to the PV input of the same PID controller. Achen temperature measured by sensor 16 in a low temperature separator 15. As a result of processing the input signals PID regulator 22 at its output 23 CV generates a control signal as a setpoint temperature to which the pre-cooling the liquid mixture should be implemented. The signal setpoint 23 is fed to the input of the SAU AVO 4 task, which automatically selects the appropriate mode of operation of the device, providing the required pre-cooling of the gas-liquid mixture passing through the AVO 4.

If the current NGK density value, which arrives in the form of a signal 19 at the PV input of the PID regulator 21 to maintain the NGK density, exceeds the value specified by the setpoint signal 20, this means that in a low-temperature separator it is necessary to lower the temperature to reduce the release of “light” fractions from the NGK . Accordingly, the PID controller 21, practicing the difference between the signals at its inputs PV and SP, reduces the temperature setpoint, which must be maintained in the low-temperature separator 15. The signal of this setpoint The PID controller 21 from its CV output supplies the SP reference of the PID controller 22 maintain temperature This PID controller 22 compares the value of the setpoint received at its SP input with the temperature signal 18 at the PV input from the sensor 16. As a result of the comparison and processing of the signals input at the PV and SP inputs, the PID controller 22 generates and issues a reference signal 23 which enters the ACS 4 input, which controls the operation of the ABO 3. Accordingly, the ACS 4 that controls the operation of the ABO 3, taking into account the current parameters of the atmosphere, sets the mode of operation of the ABO 3.

In the case where the density needs to be increased, the operation will occur in the opposite direction.

There may be cases, the temperature in the low-temperature separator 15 controlled by the sensor 16 will reach its limit values (upper or lower) indicated in the installation process regulations, then the automated process control system 5 of the installation generates a message to the operator about the impossibility of achieving the specified density in the MCP .

At the same time, the automated process control system 5 automatically maintains the pressure set in the liquid separator 9 specified by the operating staff of the installation and specified by the service personnel as a setpoint. For this, the automatic process control system controls the pressure in the liquid separator 9 by the sensor 8 and adjusts the pressure by controlling the opening degree of the switch 10. Thanks to this ensures the required pressure head in the liquid separator 9, which is necessary to prevent the formation of a vacuum and maintain the level of condensate in it.

The adjustment of the parameters of the PID-regulators is carried out by the service personnel at the time of launching the system into operation under specific production conditions according to the method described, for example, in the Encyclopedia of the Industrial Control System, Section 5.5, the PID-regulator. Resource: http://www.bookasutp.ru/Chapter5_5.aspx#HandTuning.

The method of automatically maintaining the density of the oil and gas complex supplied to the MCP using ABO at low-temperature gas separation plants in the Far North is implemented at Gazprom's Gazprom Dobycha Yamburg LLC at the Zapolyarnoye gas condensate field at the integrated gas treatment plants 1B and 2B.

The implementation of the method is most effective in the period when the reservoir energy of the field is no longer sufficient to operate the field using the Joule-Thompson throttling effect and additional energy is required to separate condensate from the gas-liquid mixture.

The results of operation showed its high efficiency. The claimed invention can be widely used in other existing and newly developed gas condensate fields of the Russian Federation.

The use of this method allows you to automatically maintain the temperature value in the low-temperature separator, ensuring its efficient operation. At the same time, the method allows one to control and maintain a predetermined density of the NGK supplied to the MCP in order to prevent the formation of gas jams and their accumulations, which makes it possible to increase the reliability of operation of the condensate line and reduce the likelihood of complications and accidents that could lead to serious environmental, human material losses.

Claims (2)

1. A method of automatically maintaining the density of an unstable gas condensate - NGK supplied to the main condensate line - MCP using an air cooling apparatus - ABO, at low-temperature gas separation units in the Far North, including cleaning the incoming gas-condensate mixture into the installation from mechanical impurities and separating it on NGK, gas and water solution of inhibitor - VRI, removal of NGK and VRI in a separator of liquids for decontamination, and further from a separator of liquids VRI take away for regeneration inhibition torus to the inhibitor regeneration workshop, and the NGK is pumped to the main condensate condensate pipeline of the MCP, and the weathering gas from the liquid separator is supplied for own use, compressed, followed by injection into the main gas pipeline - IHL or its density is controlled by a density sensor OGK supplied to the MCP and the temperature sensor of the gas temperature in the low-temperature separator, the value of which is set automatically by a cascade of two proportional-integral-differential PID regulators implemented on the basis of an automated process control system - a process control system for the installation, for which the input of the SP PID regulator to maintain the density of the NGK at the output of the fluid separator is given a signal of the density setpoint specified by the operating personnel, and PV feedback The same PID controller gives a signal to the actual density values from the density sensor of the NGK installed at the output of the liquid separator, comparing these signals, the PID controller forms on its output CV signal setpoint temperature, which is necessary to cool the gas-liquid mixture coming from the separator of the first stage of separation ABO, to ensure that the required density of the NGK at the output of the liquid separator, and supplies it to the SP input of the PID controller of maintaining the temperature in the low-temperature separator and return to the input the PV connections of this PID controller supply the current temperature value from the temperature sensor installed in the low-temperature gas separator, comparing which PID controller at its output CV forms There is a control signal that feeds the ACS ACS, which controls the modes of operation of the ACS, which, taking into account the current environmental parameters, selects the optimal mode of operation of the ACS, while the ACS TP simultaneously controls the pressure in the liquid separator, automatically maintaining its set value using the control valve installed at the gas outlet of the liquid separator. 2. The method according to p. 1, characterized in that if during the implementation of the process of maintaining a given density of NGK temperature in a low-temperature separator reaches its limit values - upper or lower, indicated in the installation process regulations, then the automated process control system generates a message to the operator about the impossibility of achieving the specified the density of NGK supplied to the ITUC, and the need to make a decision on changing the operating mode of the installation.

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