RU2500453C1 - Method of field preparation of condensate pool products with high content of heavy hydrocarbons and plant to this end - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to gas industry, particularly, to gas condensate processing in the fields. Proposed method comprises primary separation of blanket mix, gas cooling. Gas low-temperature separation of water-methanol solution and gases from unstable condensate of primary separation and low-temperature separation, heating of primary separation condensate to be fed to deethinising column, condensate heating and fed to said column for refluxing. It differs from known processes in that deethanisation gases from deethinising column are compressed, heated and fed into blanket mix flow along with paraffin deposition inhibitors. Note here that, after compression and heating, condensate primary separation gas is fed into said flow as well as deethanisation gases separated from unstable condensate produced after separation of low-temperature separation condensate. Invention covers also the pant for implementation of said method.

EFFECT: decreased intensity of paraffin deposition and consumption of appropriate inhibitors.

5 cl, 1 dwg

Description

The invention relates to the field of the gas industry and can be used in field preparation of products of gas condensate deposits.

Recently, formation fluids of the Achimov deposits are becoming more and more widely involved in industrial development.

These deposits are characterized by elevated reservoir temperatures - up to 110 ° C, and high initial reservoir pressures - up to 70 MPa.

The condensates of the Achimov deposits contain a significant amount of fractions of heavy hydrocarbons with boiling points from 350 ° C. These heavy fractions contain significant amounts of normal paraffin hydrocarbons. For this reason, at temperatures of about 30 ° C and lower, paraffin deposition processes begin in condensates.

The gas condensate of the Achimov deposits produced in gas condensate fields, after preparation at the complex gas and condensate treatment plants (UKPG and K), loses its structure uniformity.

Changes in conditions, including a decrease in pressure and temperature, lead to crystallization of linear paraffins and the formation of deposits on the inner surface of pipelines and apparatuses.

Paraffin deposition causes many problems, such as:

- a decrease in the inner diameter of the pipes, which leads to an increase in the pressure drop across the pipeline and, ultimately, to a complete stop of the flow;

- filling process equipment and tanks with paraffin deposits, which leads to disruption of the normal functioning of the systems;

- reduced productivity of heat exchange equipment;

- difficulty in the operation of valves and instrumentation, which leads to disruption of the process and poses a security risk.

Together, these problems lead to the suspension of the preparation, processing and transportation of gas condensate, which entails the need for a large amount of expensive repair work.

The most common way to combat paraffin deposits is to use inhibitors, but because of their high cost, this method is also not optimal. To increase its effectiveness is possible only by reducing the consumption of inhibitors as a result of more efficient use of heat and material flows of gas treatment plants and K.

In addition to the deposition of paraffins, during the deethanization of Achimov condensates, problems arise related to their viscosity. If viscous condensate is fed into a deethanization column operating at standard process parameters characteristic of the condensate of Valanginian deposits, then an excess amount of methane and ethane will be contained in the deethanized gas condensate. If the temperature in the deethanization column is raised, then the entrainment of propane and butane with deethanization gases will increase. Subsequently, after separation in the separators, propane and butane will again return to the deethanization column, forming a kind of recycling that reduces the performance of the installation as a whole.

Therefore, in the case of Achimov condensates, additional preparation of unstable gas condensate is required before being fed to the deethanization column.

A known installation for the preparation and processing of hydrocarbon feedstock of gas condensate deposits includes an inlet separator, a recuperative gas heat exchanger, an ejector, a low-temperature separator, three-phase separators of the first and second stages, a degasser (RU 2182035 C1, published on 05/10/2002). The installation is additionally equipped with a recuperative heat exchanger, a condensate deethanization column, a compressor, an air cooling apparatus and a recuperative gas-liquid heat exchanger connected in series, the inlet of the recuperative heat exchanger is connected to the condensate outlet from the degasser, the inlet to the top of the deethanization column is connected to the condensate outlet from the degasser, the recuperative gas-liquid recuperator is connected with the entrance of the low temperature separator. The installation is additionally equipped with a de-ethanized condensate stabilization unit, a stable condensate primary processing unit, a gasoline fraction catalytic processing unit, a dried gas liquefaction unit, and a dried gas catalytic processing unit. The installation allows to improve the quality of separation of gaseous hydrocarbons (methane and ethane) from liquefied and liquid hydrocarbons (propane + higher).

Closest to the proposed one is a method for field preparation of gas condensate fluid and deethanization of condensate, which includes gas separation from the inlet and low temperature separation stages, phase separation of the condensate of the inlet and low temperature separation stages, condensate degassing and deethanization of the condensate in a stripping distillation column (RU 2243815.01 .2001). All the condensate of the inlet separation stage after preliminary degassing and heating in a recuperative heat exchanger is supplied to the middle part of the stripping distillation column as power, the condensate of the low-temperature separation stage is divided into two streams. The first is fed to the top of the stripping distillation column as irrigation, the second to a degasser. The technological regime and composition of deethanization products are regulated depending on the condensate outlets and compositions of the inlet and low-temperature separation stages by changing the flow volumes. The installation for implementing the method comprises an inlet separator, a heat exchanger, an ejector, a low-temperature separator, three-phase separators for the inlet and low-temperature separation condensate, a degasser, and a deethanization distillation column.

A common disadvantage of the above methods and installations is the lack of technical solutions designed to reduce the intensity of paraffin deposition processes and increase the efficiency of deethanization of viscous condensates.

The technical result of the group of inventions is to reduce the intensity of the processes of deposition of paraffins and reduce the consumption of paraffin inhibitors.

The technical result is achieved by the fact that in the field preparation method for producing gas condensate deposits, including primary separation of the formation mixture, cooling the gas, its low-temperature separation, separation from the unstable gas condensate of the primary separation and low-temperature separation of the water-methanol solution and gases, heating the gas condensate of the primary separation and supplying it for feeding into the deethanization column and heating the gas condensate of low-temperature separation and supplying it for irrigation to the dee column According to the invention, the deethanization gases from the deethanization column are compressed, heated and fed into the formation mixture stream, to which paraffin deposition inhibitors are also fed, while after the compression and heating, the gas from the primary separation gas condensate obtained after its degassing is also supplied to the stream of the formation mixture as well as deethanization gases separated from the unstable gas condensate obtained after the separation of the gas condensate of the low-temperature separation.

In addition, after the initial separation, the gas is cooled and subjected to intermediate separation, after which it is cooled and low-temperature separated, and the gas condensate is sent to separate the water-methanol solution and the gases together with the low-temperature gas condensate.

The technical result is also achieved by the fact that in the installation for commercial preparation of gas condensate deposits containing a supply line of the reservoir mixture and connected by pipelines with heat exchange equipment, a primary separator, a low temperature separator, the first and second three-phase separators and a deethanization column, according to the invention, the output of the deethanization column for gas is connected through a compressor and a heat exchanger with a line for supplying the formation mixture, the gas outlet of the second three-phase separator connected to the outlet ohm of the low-temperature separator for gas condensate, is connected to the inlet of the low-temperature separator, and the output of the first three-phase separator for gas condensate is connected through the heat exchanger to the first buffer tank, the output of which for gas condensate is connected to the irrigation zone of the deethanization column, and the output for deethanization gases to the compressor inlet , the reservoir gas supply line is connected to the primary separator through a sample trap, the second input of which is connected to the output of the primary condensate separator, and the second output is with the input of the second three-phase separator, the output of which for gas is connected to the input of the low-temperature separator, and the output of gas condensate is connected to a weathering device, the output of which for gases is connected to the compressor input, and the output of gas condensate is connected through the second heat exchanger to the second buffer a tank whose output for deethanization gases is connected to the compressor inlet, and the gas condensate outlet is connected to a reboiler with a separation device, the output of which for degassed gas condensate is connected to th power deethanizer column and an outlet for gas - to the input of the compressor, the reservoir gas supply line is provided with an input for feeding it before paraffin inhibitors slug catcher.

In addition, the outlet of the primary gas separator is connected to the intermediate separator through cooling heat exchangers with the possibility of feeding paraffin inhibitors in front of them, and the annular space of which is connected to the outlet of the low-temperature separator for dried gas.

In addition, the output of the intermediate gas separator is connected to the low-temperature separator through an ejector, the passive nozzle of which is connected to the output of the first gas separator.

The drawing shows a diagram of the proposed installation. Flows are indicated on the diagram: I - formation mixture, II - deethanized gas condensate, III - dried gas, IV - water-methanol solution for regeneration, V - saline-containing water-methanol solution for disposal, IV - paraffin inhibitor.

The installation for field preparation of gas condensate reservoir products contains a formation mixture supply line 21 connected to a cork trap 1, the gas outlet of which is connected to a primary separator 2. The primary separator 2 is a vertical cylindrical apparatus with internal separation elements as part of a separation-washing and filtering section. The outlet at the bottom of the primary gas condensate separator 2 is connected to a plug trap, the outlet of which for condensate is connected to a second three-phase separator 3. The outlet of the gas condensate separator 3 is connected to a weathering device 4, the outlet of which for gas is connected to the compressor inlet 5, the output of which is through a heat exchanger 15 is connected to the formation gas supply line 21. The output of the gas separator 3 is connected to a low temperature separator 6, the output of which for gas condensate is connected to the first three-phase separator 7.

The outlet at the top of the primary gas separator 2 is connected through heat exchangers 9 to an intermediate separator 8, the gas outlet of which through the ejector 10 is connected to a low temperature separator 6. The gas outlet of the first three-phase separator 7 is connected to the passive nozzle of the ejector 10.

An installation scheme is possible without an intermediate separator 8, when the heat exchangers 9 are directly connected through an ejector 10 to a low-temperature separator 6.

The output of the gas condensate weathering device 4 is connected through a heat exchanger 11 to a second buffer tank 12, the output of which for gas is connected to the input of the compressor 5, and the output for gas condensate is connected to a reboiler 13 with a separation device. The output of the reboiler 13 for gas is also connected to the input of the compressor 5. The output of the reboiler 13 for degassed gas condensate is connected to the feed zone of the deethanization column 14.

The gas condensate outlet of the first three-phase separator 7 through the annular space of the heat exchanger 16 is connected to the first buffer tank 17, the gas outlet of which is connected to the inlet of the compressor 5, and the gas condensate outlet is connected to the irrigation zone of the deethanization column 14 and with a weathering device 4.

The method of field preparation of gas condensate deposits is as follows.

The method includes primary separation of the formation mixture in the primary separator 2, gas cooling in the heat exchangers 9, its low-temperature separation in the low-temperature separator 6, separation in the three-phase separator 7 from the unstable gas condensate of the primary separation and low-temperature separation of the water-methanol solution and gases, heating of the gas condensate of the primary separation after the first three-phase separator 3 and the weathering device 4 in the heat exchanger 11 and feeding it to a deethanization column 14 and heating the gas cone nsat low-temperature separation after the second three-phase separator 7 in the heat exchanger 16 and its supply for irrigation in the column 14 deethanization. In this case, the deethanization gases from the deethanization column 14 are compressed in the compressor 5, heated in the heat exchanger 15 and fed to the formation mixture supply line 21, which also contains paraffin deposition inhibitors. After compression in the compressor 5 and heating in the heat exchanger 15, gas from the primary separation gas condensate obtained after its degassing in the first three-phase separator 3 and additional degassing in the weathering device 4, as well as deethanization gases separated in the first buffer, is also supplied to the formation mixture supply line 21 tanks 17 from unstable gas condensate obtained after separation of gas condensate of low-temperature separation in the second three-phase separator 7.

It is possible that after the primary separation the gas is cooled and subjected to intermediate separation in the intermediate separator 8, after which it is cooled in the ejector 10 and low-temperature separation in the low-temperature separator 8, and the gas condensate is sent to the second three-phase separator 7 to separate the water-methanol solution and gases together with gas condensate low temperature separation.

The implementation of the method is described in more detail below when describing the operation of the installation for field preparation of gas condensate deposits.

The formation mixture flows from the ZPA through line 21 to the cork trap 1. In the cork trap 1, coarse separation of the formation mixture into gas and liquid occurs. Gas from the cork trap 1 enters the primary separator 2.

To prevent paraffin deposition processes in the cork trap 1 and primary separator 2, a paraffin deposition inhibitor is supplied to the formation stream before the cork trap 1.

The condensate from the trap 1 is sent to the separator 3, where in the mode close to the laminar flow degassing occurs, as well as the separation of the spent water-methanol solution (BMP) and gas condensate. The spent saline-containing BMP is discharged from the disposal unit, and gas condensate with a temperature of about 20 ° C enters the weathering unit 4.

After additional degassing and sedimentation of the residual BMP, gas condensate as a raw material enters the condensate preparation plant (UPC). Gas from the weathering device 4 is fed to the compressor 5, from the injection of which, in a mixture with deethanization gases, it is directed into the flow of the formation mixture in front of the sample catcher 1. The temperature of the deethanization gases is regulated in the heat exchanger 15 depending on the intensity of the paraffin deposition processes.

Gas from the primary separator 2 enters the heat exchangers 9 ("gas-gas"), where it is cooled by commercial dry gas and with a temperature (minus) of 5 ° C enters the intermediate separator 8. The intermediate separator 8 is designed to separate the gas condensate released as a result of cooling .

To prevent the deposition of paraffins, the supply of paraffin deposition inhibitors is provided in front of the heat exchanger 9.

After the intermediate separator 8 (or after heat exchangers 9 in the absence of an intermediate separator), the raw gas enters the active nozzle of the ejector 10 and is throttled to a pressure of the order of 5.5 - 7.0 MPa and with a temperature of (minus) 30 ÷ (minus) 50 ° C into the low temperature separator 6.

In the low-temperature separator 6, the final drying of the commercial gas occurs and the main amount of gas condensate is separated, which then enters the three-phase separator 7. In the separator 7, the gas condensate is separated into the hydrocarbon part (the gas condensate itself) and the saline-containing BMP, which in turn is sent for regeneration.

Gas condensate from the separator 7 is sent to the UPK. Gas from the separator 7 is discharged through the passive nozzle of the ejector 10. The dried gas from the low-temperature separator 6 is sent to the gas-gas heat exchangers 9, where it cools the raw gas, and then, after the metering unit, is sent to the main gas pipeline system.

Unstable gas condensate (OGC) from the weathering device 4 is heated in the heat exchanger 11 and the buffer tank 12 is supplied. As a result of the temperature increase in the buffer tank 12, the residual amount of the salt-containing water-methanol solution is separated from the unstable gas condensate, and an excess amount of deethanization gases is blown off. Deethanization gases from the buffer tank 12 are received by the compressor 5, heated in the heat exchanger 15 and then into the flow of the reservoir mixture. Unstable gas condensate from the buffer tank 12 due to the pressure drop enters the reboiler 13, where it is heated with deethanized gas condensate to the required temperature, degassed and sent as power to the deethanization column 14. The degassing gases from the reboiler 13 are discharged to the compressor 5. The reboiler 13 is equipped with a separation device in the degassing gas stream, which can significantly reduce the entrainment of the propane-butane fraction.

Gas condensate with a temperature of (minus) 30 to (minus) 50 ° C from the separator 7 enters the heat exchanger 16, where it is heated by utilizing the heat of the deethanized gas condensate and sent to the buffer tank 17.

The purpose of the buffer tank 17 is the separation from unstable gas condensate of methane and ethane to a residual amount that allows not to overload the upper part of the column deethanization 14 in the gas phase. In addition, in the buffer tank 17 is the separation of the residual amount of saline water-methanol solution. Deethanization gases from the tank 17 are sent to the compressor 5.

From the buffer tank 17, due to the pressure drop, unstable gas condensate with a temperature from (minus) 10 to (plus) 10 ° C in the amount necessary to maintain the regulated temperature of the top of the column 14 is sent to the deethanization column 14 as irrigation, and the balance amount is discharged into the weathering device 4.

The deethanization column 14 is a plate-type distillation column. The heat supply to the deethanization column 14 is provided by circulating a portion of the deethanized gas condensate by the pump 18 through the fire heater 19.

The deethanization gases from the top of the deethanization column 14 are sent to the compressor 5.

Deethanized gas condensate from the bottom of the deethanization column 14 is fed to a reboiler 13 and heat exchangers 11, 16, and also to an air cooling apparatus 20 and with a temperature of not higher than 0 ° C, is sent to a commercial metering station and then to the main condensate line.

This scheme allows you to achieve the following results:

1. Due to the supply of gases of deethanization and degassing with a certain temperature to the composition of the reservoir mixture, the intensity of the processes of deposition of paraffins in the cork trap 1 and primary separator 2 decreases, and, therefore, the need for paraffin inhibitors decreases;

2. Due to the gradual pre-heating in the heat exchanger 11 and the degassing of unstable gas condensate in the buffer tank 12 and the reboiler 13, the efficiency of the deethanization column 14 is increased;

3. Due to the completion of the reboiler 13 with a separation device on the deethanization gas stream, the propane-butane fraction removal to the compressor intake is significantly reduced. The paraffin deposition in the proposed installation was confirmed by studies conducted by TyumenNIIgiprogaz LLC. In the course of the study, the gas condensate of the Achimov deposits was investigated with the determination of the strength of the paraffin structure and the effectiveness of dynamic viscosity in the temperature range from minus 40 to plus 5 degrees Celsius. As a result of research, it was found that at temperatures above minus 5 degrees Celsius, gas condensate retains Newtonian properties and does not enter the state of a visco-plastic system. Solid paraffins in gas condensate do not fall into the solid phase. A pronounced dependence of the viscosity of gas condensate on the speed of the system is not observed. At higher temperatures, the Newtonian properties of the gas condensate sample are also preserved. Thus, when supplying hot gas to the composition of the reservoir mixture in order to maintain its temperature above minus 5 degrees Celsius, paraffin deposition in the primary separator will not occur.

Claims (5)

1. The method of field preparation of gas condensate deposits, including primary separation of the reservoir mixture, cooling the gas, its low-temperature separation, separation from the unstable gas condensate of the primary separation and low-temperature separation of water-methanol solution and gases, heating the gas condensate of the primary separation and feeding it to the deethanization column and heating the gas condensate of the low-temperature separation and supplying it for irrigation to the deethanization column, characterized in that the gases are deethane Compounds from the deethanization column are compressed, heated and fed to the formation mixture stream, to which paraffin deposition inhibitors are also fed, while after compression and heating, gas from the primary condensate gas separation gas obtained after its degassing, as well as deethanization gases, are also fed into the formation mixture stream separated from the unstable gas condensate obtained after separation of the gas condensate of low temperature separation. 2. The method according to claim 1, characterized in that after the primary separation, the gas is cooled and subjected to intermediate separation, after which it is cooled and low-temperature separation, and the gas condensate is sent to separate the water-methanol solution and gases together with the gas condensate of low-temperature separation. 3. Installation for field preparation of products of gas condensate deposits, containing the supply line of the reservoir mixture and connected by pipelines to the heat exchange equipment, a primary separator, a low temperature separator, the first and second three-phase separators and a deethanization column, characterized in that the outlet of the deethanization column for gas is connected through a compressor and a heat exchanger with a supply line for the formation mixture, the gas outlet of the second three-phase separator connected to the outlet of the low-temperature gas separator the condensate is connected to the inlet of the low-temperature separator, and the output of the first three-phase separator for gas condensate is connected through the heat exchanger to the first buffer tank, the output of which for gas condensate is connected to the irrigation zone of the deethanization column, and the output for deethanization gases to the compressor inlet, formation gas supply line connected to the primary separator through a trap, the second input of which is connected to the output of the primary separator for condensate, and the second output to the input of the second three-phase section an amplifier whose outlet for gas is connected to the inlet of the low-temperature separator, and the outlet for gas condensate is connected to a weathering device, the outlet of which for gases is connected to the compressor inlet, and the outlet for gas condensate through a second heat exchanger is connected to a second buffer tank, the outlet of which for deethanization gases is connected with the compressor inlet, and the gas condensate outlet with a reboiler with a separation device, the outlet of which for degassed gas condensate is connected to the deethanization column feed zone, and the gas outlet - with the compressor inlet, and the formation gas supply line is made with an input for supplying paraffin inhibitors to it in front of the cork trap. 4. Installation according to claim 3, characterized in that the outlet of the primary gas separator is connected to the intermediate separator through cooling heat exchangers with the possibility of feeding paraffin inhibitors in front of them, and the annular space of which is connected to the outlet of the low-temperature separator for dried gas. 5. Installation according to claim 4, characterized in that the output of the intermediate gas separator is connected to the low-temperature separator through an ejector, the passive nozzle of which is connected to the output of the first gas separator.

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