A multi-stage pressure crude oil stabilizing and natural gas dewatering system offshore
By recirculating the condensate in a multi-stage offshore pressure system to a medium-pressure separator for step-by-step depressurization and flash evaporation to merge with the gas phase, combined with deep dehydration using triethylene glycol, the problem of insufficient condensate dehydration depth is solved, enabling safe and efficient natural gas export, reducing equipment investment and energy consumption, and making it suitable for the compact space of offshore platforms.
Patent Information
- Application Number
- CN202611462611.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-09-20
- Publication Date
- 2026-11-03
AI Technical Summary
In existing multi-stage pressure systems at sea, insufficient condensate dehydration depth leads to substandard gas-water dew point in the mixed gas, resulting in poor safety for external transport. Furthermore, existing solutions increase equipment investment, consume more energy, require more land, and have higher carbon emissions.
The condensate is returned to the medium-pressure separator by the compression system and then gradually depressurized and flashed to merge with the gas phase. Combined with deep dehydration by triethylene glycol, the condensate is prevented from directly entering the dry gas process. The liquid phase is driven by gravity flow using the multi-stage pressure gradient at the wellhead, which reduces the heat load of the heater and eliminates the need for a large heat medium boiler.
It improves the gas-water dew point compliance rate, ensures the safety of external transportation, reduces equipment investment, energy consumption and carbon emissions, and simplifies the space occupation of offshore platforms.
Smart Images
Figure CN123027043A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of offshore oil and gas gathering and transportation technology, and in particular relates to an offshore multi-stage pressure crude oil stabilization and natural gas dehydration system. Background Technology
[0002] In recent years, with the continuous advancement of reserve and production increases in my country's offshore oil industry, several high-temperature and high-pressure oil and gas fields have been put into development. These oil and gas fields generally have characteristics such as multiple wellhead pressure levels, complex production processes, and high acid gas content, which put forward higher requirements for crude oil stabilization and deep dehydration of natural gas, and also bring huge challenges to the process layout within the compact space of offshore platforms.
[0003] In the existing multi-stage pressure system production process at the offshore site, the wellhead produced stream enters each stage of separators according to its pressure level for stepwise gas-liquid separation. The liquid phase is heated and then enters a secondary flash separator to stabilize the crude oil. The gas phase from each stage of separator is pressurized by a wet gas compression system and a flash vapor compression system before entering a triethylene glycol dehydration system for deep dehydration. In the current technology, the condensate separated from each scrubbing tank in the compression system is usually dehydrated by a coalescing separator and then directly fed into the dry gas process for external transmission. However, for oil and gas fields with large condensate production, the dehydration effect of the coalescing separator cannot meet the dew point requirements for dry gas transmission. Direct mixing and transmission will result in substandard water dew points in the mixed gas, and may even cause corrosion of downstream gas pipelines, threatening the safety of the gas transmission system. If a process with the addition of a large heat medium boiler and a high-load heater is adopted, although the above problems can be solved, it will increase equipment investment, fuel consumption, platform footprint, and carbon emissions.
[0004] Existing technologies suffer from drawbacks such as insufficient condensate dehydration depth leading to substandard gas-water dew point and poor export safety, or reliance on large-scale heat medium boilers resulting in high investment, high energy consumption, large footprint, and high carbon emissions. To address these issues, we provide a multi-stage offshore pressure crude oil stabilization and natural gas dehydration system. Summary of the Invention
[0005] The purpose of this invention is to provide a multi-stage pressure crude oil stabilization and natural gas dehydration system for offshore applications. By combining the condensate from the compression system with the intermediate-pressure separator for step-by-step depressurization and flash evaporation, and the gas phase with the triethylene glycol for deep dehydration, this system solves the problems of substandard gas-water dew point, poor safety of external transportation, high investment, high energy consumption, large land area, and high carbon emissions in the prior art.
[0006] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution.
[0007] This invention relates to a multi-stage offshore pressure crude oil stabilization and natural gas dehydration system, comprising a manifold system, a separation system, a wet gas compression system, a flash vapor compression system, a triethylene glycol dehydration system, and a condensate return pipeline. The manifold system includes a test manifold, a high-pressure production manifold, a medium-pressure production manifold, a low-pressure production manifold, and a very low-pressure production manifold, used for graded collection of oil well produced streams according to wellhead pressure levels. The separation system includes a high-pressure separator, a medium-pressure separator, a low-pressure separator, a first-stage flash separator, a heater, and a second-stage flash separator connected in sequence. The high-pressure separator, medium-pressure separator, low-pressure separator, and first-stage flash separator respectively receive the material from the high-pressure production manifold, medium-pressure production manifold, low-pressure production manifold, and low-low-pressure production manifold. The liquid phase outlet of each stage separator is sequentially connected to the next stage separator with a lower pressure. The liquid phase outlet of the first-stage flash separator is connected to the second-stage flash separator via a heater. The second-stage flash separator is used to perform deep flash evaporation on the heated liquid phase to obtain stable crude oil. The wet gas compression system includes a low-pressure compression inlet scrubbing tank and a low-pressure... The system comprises a dual compressor, a low-pressure compressor outlet cooler, a low-pressure compressor outlet scrubber tank, an intermediate-pressure compressor inlet cooler, an intermediate-pressure compressor inlet scrubber tank, and an intermediate-pressure centrifugal compressor, used to receive and pressurize the gas phase generated by the intermediate-pressure separator and the low-pressure separator; the flash vapor compression system includes a first-stage flash vapor inlet cooler, a first-stage flash vapor inlet scrubber tank, a first-stage flash vapor screw compressor, a first-stage flash vapor outlet cooler, a second-stage flash vapor inlet scrubber tank, a second-stage flash vapor screw compressor, and a second-stage flash vapor outlet cooler, used to recover and pressurize the first-stage flash vapor. The flash vapor generated by the separator and the secondary flash separator, and the outlet of the secondary flash vapor outlet cooler are connected to the low-pressure section of the wet gas compression system; the triethylene glycol dehydration system includes a triethylene glycol dehydration device, the inlet of which is connected to the outlet of the wet gas compression system and the gas phase outlet of the high-pressure separator via a confluence pipeline for deep dehydration of natural gas; the condensate return pipeline pressurizes the condensate separated from each scrubbing tank in the wet gas compression system and the flash vapor compression system and returns it to the inlet of the medium-pressure separator after being pressurized by the condensate booster pump, where it flashes with the liquid phase through a step-by-step depressurization process.
[0008] The present invention is further configured such that a multiphase flow meter is connected downstream of the test manifold for single-well metering of oil, gas and water production of each oil well during the production stage.
[0009] The present invention is further configured such that the crude oil outlet of the secondary flash separator is connected to an external pump, and the saturated vapor pressure of the crude oil obtained after deep flash evaporation meets the external export standard.
[0010] The present invention is further configured such that, in the flash vapor compression system, the flash vapor from the secondary flash separator is sequentially cooled by the primary flash vapor inlet cooler, dehydrated by the primary flash vapor inlet scrubbing tank, pressurized by the primary flash vapor screw compressor, and cooled by the primary flash vapor outlet cooler, before merging with the flash vapor from the primary flash separator in front of the secondary flash vapor inlet scrubbing tank.
[0011] The present invention is further configured such that the triethylene glycol dehydration device includes an absorption tower, a regeneration tower, a heat exchanger, a filter, and a buffer tank, and the water dew point of the natural gas after dehydration is not higher than -38°C under operating pressure.
[0012] The invention is further configured such that the heater is used to heat the liquid phase of the first-stage flash separator to 60-80°C before sending it into the second-stage flash separator.
[0013] The present invention is further configured such that the condensate booster pump includes a primary condensate booster pump, a secondary condensate booster pump, a low-pressure condensate booster pump, and a medium-pressure condensate booster pump, which are respectively connected to the condensate outlets of the gas washing tanks in the flash vapor compression system and the wet gas compression system.
[0014] The present invention is further configured such that the gas phase outlet of the high-pressure separator is directly connected to the inlet of the triethylene glycol dehydration device, and the gas phase generated by the high-pressure separator is directly dehydrated without compression.
[0015] The present invention is further configured such that the system does not have a condensate oil coalescing separator, the heater is a heating device that utilizes waste heat from the platform process, and the system does not have a heat medium boiler.
[0016] The present invention is further configured such that the working pressure of the high-pressure separator, medium-pressure separator, low-pressure separator, first-stage flash separator and second-stage flash separator decreases stepwise along the flow direction to form a pressure gradient, and the liquid phase of each stage separator flows by gravity to the next stage separator by means of the pressure difference.
[0017] The present invention has the following beneficial effects.
[0018] 1. In this invention, the condensate separated from each scrubbing tank in the wet gas compression system and the flash vapor compression system is pressurized by the condensate booster pump and then returned to the medium-pressure separator. As the liquid phase descends the pressure gradient, it undergoes flash vaporization. The water in the condensate flows down with the liquid phase of the crude oil processing system and is removed. The light components in the condensate are re-vaporized and enter the compression system. Finally, they enter the triethylene glycol dehydration unit for deep dehydration along with the natural gas. The condensate is no longer dehydrated by the coalescing separator and then mixed into the dry gas process. This avoids the problem of insufficient dehydration depth in the coalescing separator leading to unqualified water dew point in the mixed gas and corrosion of downstream gas pipelines. The water dew point of the dehydrated dry gas is not higher than -38°C under the operating pressure, which meets the requirements for external transmission and improves the safety of external transmission.
[0019] 2. In this invention, the condensate is returned to the medium-pressure separator with a matching operating pressure, without entering the low-pressure flash section, thus not increasing the heat load of the heater. The heater only needs to use the waste heat from the platform process to heat the liquid phase of the first-stage flash separator to 60-80°C. The system does not require a heat medium boiler or a condensate coalescing separator. The liquid phase between each stage of the separator flows by gravity according to the pressure difference, without the need for external power transmission. This reduces equipment investment, fuel consumption, platform footprint, and carbon emissions, making it suitable for offshore platforms with limited space and energy.
[0020] 3. In this invention, the gas phase from each stage of the separator enters the wet gas compression system and the flash vapor compression system for staged pressurization according to the pressure source. After being pressurized by a screw compressor, the flash vapor merges into the low-pressure section of the wet gas compression system and is pressurized together with the main natural gas. The gas phase pressure of the high-pressure separator is equivalent to the dehydration pressure, and it merges directly without compression. After the gas phases merge, they enter a set of triethylene glycol dehydration devices to complete deep dehydration, avoiding the resource waste and emissions caused by flash vapor venting and combustion, reducing the compression power consumption of the high-pressure gas phase. The entire process only requires one dehydration device to meet the processing requirements of all exported gas. The equipment is centralized, the process is simplified, and the land area and structural weight of the offshore platform are saved. Attached Figure Description
[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below.
[0022] Figure 1 This is an overall flow chart of a multi-stage pressure crude oil stabilization and natural gas dehydration system at sea.
[0023] Figure 2 This is a flow chart of the separation system and condensate reflux in a multi-stage offshore pressure crude oil stabilization and natural gas dehydration system.
[0024] Figure 3 This is a flow chart of a wet gas compression system in a multi-stage pressure crude oil stabilization and natural gas dehydration system at sea.
[0025] Figure 4 This is a flow chart of flash vapor compression and natural gas dehydration in a multi-stage offshore pressure crude oil stabilization and natural gas dehydration system. Detailed Implementation
[0026] The technical solutions of the present invention will be described below with reference to the accompanying drawings. The described embodiments are only some embodiments of the present invention, and not all embodiments.
[0027] Please see Figure 1-4This invention relates to a multi-stage offshore pressure crude oil stabilization and natural gas dehydration system, comprising a manifold system, a separation system, a wet gas compression system, a flash vapor compression system, a triethylene glycol dehydration system, and a condensate return pipeline. The manifold system includes a test manifold, a high-pressure production manifold, a medium-pressure production manifold, a low-pressure production manifold, and a low-low-pressure production manifold, used to collect oil well produced streams in stages according to wellhead pressure levels. The separation system includes a high-pressure separator, a medium-pressure separator, a low-pressure separator, a first-stage flash separator, a heater, and a second-stage flash separator connected in sequence. The high-pressure separator, medium-pressure separator, low-pressure separator, and first-stage flash separator receive feed streams from the high-pressure production manifold, medium-pressure production manifold, low-pressure production manifold, and low-low-pressure production manifold, respectively. The liquid phase outlets of each stage separator are sequentially connected to the next stage separator with lower pressure. The liquid phase outlet of the first-stage flash separator is connected to the second-stage flash separator via a heater. The second-stage flash separator is used for deep flash evaporation of the heated liquid phase to obtain stable crude oil. The wet gas compression system includes a low-pressure compression inlet scrubbing tank and a low-pressure reciprocating... The system includes a compressor, a low-pressure compressor outlet cooler, a low-pressure compressor outlet scrubber tank, an intermediate-pressure compressor inlet cooler, an intermediate-pressure compressor inlet scrubber tank, and an intermediate-pressure centrifugal compressor, used to receive and pressurize the gas phase generated by the intermediate-pressure separator and the low-pressure separator; the flash vapor compression system includes a first-stage flash vapor inlet cooler, a first-stage flash vapor inlet scrubber tank, a first-stage flash vapor screw compressor, a first-stage flash vapor outlet cooler, a second-stage flash vapor inlet scrubber tank, a second-stage flash vapor screw compressor, and a second-stage flash vapor outlet cooler, used to recover and pressurize the first-stage flash vapor. The flash vapor generated by the separator and the secondary flash separator, and the outlet of the secondary flash vapor outlet cooler are connected to the low-pressure section of the wet gas compression system; the triethylene glycol dehydration system includes a triethylene glycol dehydration unit, the inlet of which is connected to the outlet of the wet gas compression system and the gas phase outlet of the high-pressure separator via a merging pipeline, for deep dehydration of natural gas; the condensate return pipeline pressurizes the condensate separated from each scrubbing tank in the wet gas compression system and the flash vapor compression system and returns it to the inlet of the medium-pressure separator after being pressurized by the condensate booster pump, where it flashes with the liquid phase through a step-by-step depressurization process.
[0028] Specifically: The wellhead produced stream is collected in stages by the manifold system according to pressure level, and then enters a high-pressure separator, a medium-pressure separator, a low-pressure separator, and a first-stage flash separator to complete gas-liquid separation. The liquid phase from the high-pressure separator flows by gravity into the medium-pressure separator, where it merges with the medium-pressure stream and enters the low-pressure separator together, then into the first-stage flash separator. In each stage of the separator, the liquid phase flashes as the pressure decreases, continuously releasing dissolved gas. Finally, after being heated by a heater, it enters the second-stage flash separator for deep flashing, where light hydrocarbon components are fully removed from the crude oil, resulting in... The saturated vapor pressure of the crude oil meets the export standards. The gas phase generated by the medium-pressure separator and the low-pressure separator enters the wet gas compression system, and after two stages of compression, cooling, and scrubbing, it is pressurized to the pressure required for dehydration. The low-pressure flash vapor generated by the first-stage flash separator and the second-stage flash separator enters the flash vapor compression system for pressurization and then merges into the low-pressure section of the wet gas compression system, where low-grade flash vapor is recovered. The outlet gas of the wet gas compression system merges with the gas phase of the high-pressure separator and then enters the triethylene glycol dehydration unit for deep dehydration. The water dew point of the resulting dry gas meets the export requirements. In the above process, the condensate separated from each scrubbing tank of the wet gas compression system and the flash vapor compression system is pressurized by the condensate booster pump and then flows back to the inlet of the medium-pressure separator. The water in the condensate flows down with the liquid phase of the crude oil processing system and is removed during the crude oil processing. The light components in the condensate are re-vaporized and recovered in the staged depressurization flash evaporation and enter the compression system. Finally, they enter the triethylene glycol dehydration unit for deep dehydration along with the natural gas. Therefore, the condensate does not need to be dehydrated separately by a coalescing separator before being mixed into the dry gas process, avoiding the problem of insufficient dehydration depth of the coalescing separator causing the water dew point of the mixed gas to be unqualified and causing corrosion of downstream gas transmission pipelines. At the same time, the condensate flows back to the medium-pressure separator with a matching operating pressure, without entering the low-pressure flash section, without increasing the heat load of the heater, and without the need to add a large heat medium boiler. The entire system relies on the pressure gradient of the multi-stage pressure system at the wellhead to drive the liquid phase to flow step by step, which significantly reduces equipment investment, energy consumption, platform footprint and carbon emissions.
[0029] Downstream of the test manifold is a multiphase flow meter for single-well metering of oil, gas, and water production from each well during the production phase; the crude oil outlet of the secondary flash separator is connected to an export pump, ensuring that the saturated vapor pressure of the crude oil obtained after deep flash evaporation meets export standards; a heater is used to heat the liquid phase from the primary flash separator to 60–80°C before sending it to the secondary flash separator; the heater utilizes waste heat from the platform process; the triethylene glycol dehydration unit includes an absorption tower, a regeneration tower, a heat exchanger, a filter, and a buffer tank; the condensate booster pumps include a primary condensate booster pump, a secondary condensate booster pump, and a low-pressure condensate booster pump. The liquid booster pump and the medium-pressure condensate booster pump are connected one-to-one with the condensate outlets of each gas tank in the flash vapor compression system and the wet gas compression system, respectively; the gas phase outlet of the high-pressure separator is directly connected to the inlet of the triethylene glycol dehydration unit, and the gas phase generated by the high-pressure separator is directly dehydrated without compression; the system does not have a condensate coalescing separator or a heat medium boiler; the working pressure of the high-pressure separator, medium-pressure separator, low-pressure separator, first-stage flash separator and second-stage flash separator decreases step by step along the material flow direction to form a pressure gradient, and the liquid phase of each stage separator flows by gravity to the next stage separator by pressure difference.
[0030] Specifically: The flash vapor from the two-stage flash separator has the lowest pressure. It first enters the first-stage flash vapor inlet cooler for cooling, then enters the first-stage flash vapor inlet scrubber to remove entrained condensate. Next, it is pressurized by the first-stage flash vapor screw compressor, cooled by the first-stage flash vapor outlet cooler, and then merges with the flash vapor from the first-stage flash separator before the second-stage flash vapor inlet scrubber. The merged flash vapor enters the second-stage flash vapor inlet scrubber for further dehydration, is further pressurized by the second-stage flash vapor screw compressor, and cooled by the second-stage flash vapor outlet cooler before entering the low-pressure section of the wet gas compression system. The low-pressure flash vapor is pressurized in two stages by a screw compressor, connecting with the pressure level of the wet gas compression system. The flash vapor does not need to be vented or burned, thus recovering resources and reducing emissions.
[0031] The working principle of this invention is as follows: First, wellhead fluid is graded, collected, and metered. Based on the wellhead flow pressure, oil wells are classified into high-pressure, medium-pressure, low-pressure, and low-low-pressure wells. The produced fluid from each well is connected to the high-pressure, medium-pressure, low-pressure, and low-low-pressure production manifolds, respectively. When metering is required for a single well, the fluid from the well to be tested is switched to the test manifold. After the oil, gas, and water production is measured by a multiphase flow meter, the fluid is returned to the corresponding production manifold. Graded collection according to pressure level ensures that each stream of fluid enters a separator matching its pressure, avoiding energy loss caused by direct pressure reduction of high-pressure fluid.
[0032] The second step involves multi-stage pressure separation and crude oil stabilization. The crude oil from each production manifold enters a high-pressure separator, a medium-pressure separator, a low-pressure separator, and a first-stage flash separator for gas-liquid two-phase separation. The liquid phase from the high-pressure separator flows by gravity into the medium-pressure separator due to pressure difference, and then sequentially into the low-pressure separator and the first-stage flash separator. During the gradual pressure reduction process, dissolved gases are continuously flashed away from the liquid phase. The liquid phase from the first-stage flash separator is heated to 60-80°C by a heater and then enters the second-stage flash separator for deep flash evaporation, removing residual light hydrocarbon components. The resulting crude oil has a saturated vapor pressure that meets export standards and is pumped out by an export pump. The liquid phase flows by gravity throughout the process, requiring no external power. The heater utilizes waste heat from the platform process, eliminating the need for a heat transfer boiler.
[0033] The third step is staged gas-phase compression. The gas phase generated by the medium-pressure separator and the low-pressure separator enters the low-pressure compression inlet scrubber tank for dehydration. It is then pressurized by the low-pressure reciprocating compressor, cooled by the low-pressure compression outlet cooler, and dehydrated again by the low-pressure compression outlet scrubber tank. After being cooled by the medium-pressure compression inlet cooler and dehydrated again by the medium-pressure compression inlet scrubber tank, it is pressurized to the pressure required for dehydration by the medium-pressure centrifugal compressor. The flash vapor from the secondary flash separator is cooled by the primary flash vapor inlet cooler, dehydrated by the primary flash vapor inlet scrubber tank, pressurized by the primary flash vapor screw compressor, and cooled by the primary flash vapor outlet cooler. It then merges with the flash vapor from the primary flash separator, and is then dehydrated by the secondary flash vapor inlet scrubber tank, pressurized by the secondary flash vapor screw compressor, and cooled by the secondary flash vapor outlet cooler. It then merges into the low-pressure section of the wet gas compression system and is pressurized along with the main natural gas. The gas phase pressure of the high-pressure separator is equivalent to the dehydration pressure, and it directly participates in the merging without compression, reducing compression power consumption.
[0034] The fourth step is deep dehydration of natural gas. The outlet gas from the wet gas compression system merges with the gas phase from the high-pressure separator and enters the triethylene glycol dehydration unit. In the absorption tower, it comes into countercurrent contact with lean triethylene glycol to remove moisture. The rich triethylene glycol is regenerated in the regeneration tower and then recycled. The water dew point of the dehydrated gas is no higher than -38°C under the operating pressure, which meets the requirements for pipeline transportation.
[0035] The fifth step is condensate recirculation. Condensate separated from the gas washing tanks in the wet gas compression system and flash vapor compression system is pressurized by a primary condensate booster pump, a secondary condensate booster pump, a low-pressure condensate booster pump, and a medium-pressure condensate booster pump, and then uniformly recirculated to the inlet of the medium-pressure separator, where it undergoes progressively depressurized flash evaporation along with the liquid phase. Water in the condensate flows downstream with the liquid phase of the crude oil processing system and is removed during crude oil export. Lighter components in the condensate are re-vaporized and enter the compression system, ultimately undergoing deep dehydration in the triethylene glycol dehydration unit. Compared to existing technologies where condensate is dehydrated by a coalescing separator and then mixed with dry gas, this method eliminates the water in the condensate from entering the dry gas process, thus resolving issues such as substandard water dew point in the mixed gas and corrosion of downstream gas pipelines. Compared to adding a large heat medium boiler, recirculating the condensate to the medium-pressure separator does not increase the heater's heat load, requires no additional fuel consumption, and reduces equipment investment and carbon emissions.
Claims
1. A multi-stage offshore pressure crude oil stabilization and natural gas dehydration system, comprising a manifold system, a separation system, a wet gas compression system, a flash vapor compression system, a triethylene glycol dehydration system, and a condensate return pipeline, characterized in that: The manifold system includes a test manifold, a high-pressure production manifold, a medium-pressure production manifold, a low-pressure production manifold, and a low-low-pressure production manifold, used to collect oil well produced streams in stages according to wellhead pressure levels. The separation system includes a high-pressure separator, a medium-pressure separator, a low-pressure separator, a first-stage flash separator, a heater, and a second-stage flash separator connected in sequence. The high-pressure separator, medium-pressure separator, low-pressure separator, and first-stage flash separator receive streams from the high-pressure production manifold, medium-pressure production manifold, low-pressure production manifold, and low-low-pressure production manifold, respectively. The liquid phase outlet of each stage separator is connected to the next lower-pressure separator in sequence. The liquid phase outlet of the first-stage flash separator is connected to the second-stage flash separator via a heater. The second-stage flash separator is used to perform deep flash evaporation on the heated liquid phase to obtain stable crude oil. The wet gas compression system includes a low-pressure compression inlet scrubbing tank, a low-pressure reciprocating compressor, a low-pressure compression outlet cooler, a low-pressure compression outlet scrubbing tank, and a medium-pressure compression inlet cooler connected in sequence. The system comprises a medium-pressure compressor, a medium-pressure inlet scrubber tank, and a medium-pressure centrifugal compressor, used to receive and pressurize the gas phase generated by the medium-pressure separator and the low-pressure separator; the flash vapor compression system includes a first-stage flash vapor inlet cooler, a first-stage flash vapor inlet scrubber tank, a first-stage flash vapor screw compressor, a first-stage flash vapor outlet cooler, a second-stage flash vapor inlet scrubber tank, a second-stage flash vapor screw compressor, and a second-stage flash vapor outlet cooler, used to recover and pressurize the flash vapor generated by the first-stage and second-stage flash vapor separators, and the outlet of the second-stage flash vapor outlet cooler is connected to the low-pressure section of the wet gas compression system; the triethylene glycol dehydration system includes a triethylene glycol dehydration device, the inlet of which is connected to the outlet of the wet gas compression system and the gas phase outlet of the high-pressure separator via a confluence pipeline, used for deep dehydration of natural gas; the condensate return pipeline returns the condensate separated from each scrubber tank in the wet gas compression system and the flash vapor compression system to the inlet of the medium-pressure separator after being pressurized by a condensate booster pump, where it flashes with the liquid phase through a step-by-step depressurization process.
2. The offshore multi-stage pressure crude oil stabilization and natural gas dehydration system according to claim 1, characterized in that: The downstream of the test manifold is connected to a multiphase flow meter, which is used to measure the oil, gas and water production of each oil well during the production phase.
3. The offshore multi-stage pressure crude oil stabilization and natural gas dehydration system according to claim 1, characterized in that: The crude oil outlet of the secondary flash separator is connected to an external pump, and the saturated vapor pressure of the crude oil obtained after deep flash evaporation meets the external export standards.
4. The offshore multi-stage pressure crude oil stabilization and natural gas dehydration system according to claim 1, characterized in that: In the flash vapor compression system, the flash vapor from the secondary flash separator is successively cooled by the primary flash vapor inlet cooler, dehydrated by the primary flash vapor inlet scrubbing tank, pressurized by the primary flash vapor screw compressor, and cooled by the primary flash vapor outlet cooler before merging with the flash vapor from the primary flash separator in front of the secondary flash vapor inlet scrubbing tank.
5. The offshore multi-stage pressure crude oil stabilization and natural gas dehydration system according to claim 1, characterized in that: The triethylene glycol dehydration unit includes an absorption tower, a regeneration tower, a heat exchanger, a filter, and a buffer tank. The water dew point of the natural gas after dehydration is no higher than -38°C under operating pressure.
6. The offshore multi-stage pressure crude oil stabilization and natural gas dehydration system according to claim 1, characterized in that: The heater is used to heat the liquid phase of the first-stage flash separator to 60-80°C before sending it to the second-stage flash separator.
7. The offshore multi-stage pressure crude oil stabilization and natural gas dehydration system according to claim 1, characterized in that: The condensate booster pump includes a primary condensate booster pump, a secondary condensate booster pump, a low-pressure condensate booster pump, and a medium-pressure condensate booster pump, which are respectively connected to the condensate outlets of the gas washing tanks in the flash vapor compression system and the wet gas compression system.
8. The offshore multi-stage pressure crude oil stabilization and natural gas dehydration system according to claim 1, characterized in that: The gas phase outlet of the high-pressure separator is directly connected to the inlet of the triethylene glycol dehydration device, and the gas phase generated by the high-pressure separator is dehydrated directly without compression.
9. A multi-stage offshore pressure crude oil stabilization and natural gas dehydration system according to claim 1, characterized in that: The system does not have a condensate coalescing separator, and the heater is a heating device that utilizes waste heat from the platform process. The system does not have a heat medium boiler.
10. A multi-stage offshore pressure crude oil stabilization and natural gas dehydration system according to claim 1, characterized in that: The working pressures of the high-pressure separator, medium-pressure separator, low-pressure separator, first-stage flash separator, and second-stage flash separator decrease progressively along the flow direction, forming a pressure gradient. The liquid phase in each stage of the separator flows by gravity to the next stage of the separator based on the pressure difference.