A crude oil stabilizing gas recovery system and recovery process

Abstract

The application discloses a crude oil stable gas recovery system and recovery treatment process, and relates to the oil field technical field. The system comprises a crude oil normal-temperature negative-pressure cold drawing unit, a stable gas cooler, a mixed hydrocarbon booster pump, a stable gas separator, a mixed hydrocarbon separator, a booster separation unit and a mixed hydrocarbon stabilization unit. Purified oil is connected to the inlet of the crude oil normal-temperature negative-pressure cold drawing unit, the liquid phase outlet of the crude oil normal-temperature negative-pressure cold drawing unit is connected to a stable oil storage and transportation unit, and the gas phase outlet is connected to the inlet of the stable gas air cooler. The outlet of the stable gas air cooler is connected to the inlet of the stable gas separator. The mixed hydrocarbon outlet of the stable gas separator is connected to the inlet of the mixed hydrocarbon separator, the gas phase outlet is connected to the inlet of the stable gas booster separation unit, the gas phase outlet of the stable gas booster separation unit is divided into two paths, the gas phase outlet of the mixed hydrocarbon separator is connected to the inlet of the stable gas separator, the sewage outlet is connected to a sewage treatment unit, and the mixed hydrocarbon outlet is connected to the mixed hydrocarbon stabilization unit. The application solves the risk of oil and gas diffusion in the oil field storage and transportation area and improves the safety of oil field production.

Description

Technical Field

[0001] This invention belongs to the field of associated gas recovery and utilization technology in oilfields, specifically relating to a crude oil stable gas recovery system and recovery process. Background Technology

[0002] Purified crude oil after dehydration contains a large amount of dissolved gases (C1-C4) that are gaseous at normal temperature and pressure, resulting in a high crude oil vapor pressure. During storage and transportation, this leads to the release of large amounts of oil vapor into the atmosphere, wasting energy and polluting the environment. The commonly used crude oil stabilization process both domestically and internationally is negative pressure flash evaporation. The negative pressure flash evaporation pressure is mainly limited by the negative pressure achievable by the compressor. Domestically produced negative pressure compressors typically have an intake pressure of around -40 kPa. This pressure corresponds to an operating temperature of around 55°C to ensure that the saturated vapor pressure of the stabilized oil at an external output temperature of 50°C is less than 0.7 times the local atmospheric pressure. However, the temperature of the purified oil at the site is generally between 35 and 45°C. In order to ensure that the stabilized oil meets the standards for external transportation, the feed crude oil needs to be heated. If it is not heated, the corresponding stabilization tower pressure needs to be -60 kPa to meet the requirements of the stabilized oil when the purified oil temperature is 35°C. Currently, only imported negative pressure compressors can reach -60 kPa, but they have the problems of long purchase cycle and high price. Therefore, it is necessary to develop a low-cost, low-energy crude oil stabilization process to meet the increasing demand for closed crude oil gathering and transportation.

[0003] The crude oil stabilized gas composition includes methane content ≤15% (mol), ethane content around 25%, and propane and higher content ≥55% (mol). In recent years, both domestic and international efforts have focused on energy conservation, reduced consumption, increased liquid hydrocarbon yield, and reduced investment in NGL recovery units. These improvements primarily include oil absorption, refrigerant refrigeration technology, direct heat exchange (DHX) method, and expansion refrigeration technology. While these improvements have achieved a C3+ yield of approximately 95% for associated gas, actual field operation has revealed issues such as a large amount of heavy hydrocarbons being separated first in the crude oil stabilization unit during NGL recovery, and the refrigerant compressor consuming the most power in the stabilized gas processing. Therefore, a low-cost, low-energy-consumption crude oil stabilized gas processing technology is needed to eliminate carbon emissions and address safety and environmental concerns during production. Summary of the Invention

[0004] This invention provides a crude oil stabilized gas recovery system and recovery process, aiming to address the high energy consumption, high cost, and environmental pollution issues associated with turning waste into treasure during the pure crude oil stabilized gas recovery process.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A crude oil stabilizing gas recovery system includes a crude oil ambient temperature negative pressure cold drawing unit, a stabilizing gas cooler, a mixed hydrocarbon booster pump, a stabilizing gas separator, a mixed hydrocarbon separator, a stabilizing gas booster separation unit, and a mixed hydrocarbon stabilizing unit.

[0007] The purified oil is fed into the top inlet of the crude oil ambient temperature negative pressure cold drawing unit via a purified oil delivery pipeline. The liquid phase outlet of the crude oil ambient temperature negative pressure cold drawing unit is connected to the downstream stabilized oil storage and transportation unit via a pipeline. The gas phase outlet of the crude oil ambient temperature negative pressure cold drawing unit is connected to the inlet of the stabilized gas air cooler via a pipeline. The outlet of the stabilized gas air cooler is connected to the inlet of the stabilized gas separator via a pipeline. The mixed hydrocarbon outlet of the stabilized gas separator is connected to the inlet of the mixed hydrocarbon booster pump via a pipeline. The outlet of the mixed hydrocarbon booster pump is connected to the inlet of the mixed hydrocarbon separator via a pipeline. The wastewater outlet of the stabilized gas separator is divided into two paths: one path serves as spray water and is connected to the spray water inlet of the crude oil ambient temperature negative pressure cold drawing unit via a pipeline; the other path is connected to the main sewage pipe and then to the wastewater treatment unit. The gas phase outlet of the stabilized gas separator is connected to the inlet of the stabilized gas pressurization and separation unit via a pipeline. The gas phase outlet of the stabilized gas pressurization and separation unit is divided into two paths: one path, as stripping gas, is connected to the bottom inlet of the crude oil ambient temperature negative pressure cold drawing unit via a pipeline; the other path, as fuel gas, is connected to the downstream fuel gas storage and transportation unit via a pipeline. The gas phase outlet of the mixed hydrocarbon separator is connected to the inlet of the original stabilized gas separator via a pipeline. The wastewater outlet of the mixed hydrocarbon separator is connected to the wastewater treatment unit via a pipeline. The mixed hydrocarbon outlet of the mixed hydrocarbon separator is connected to the mixed hydrocarbon stabilization unit via a pipeline. The top gas phase outlet of the mixed hydrocarbon stabilization unit is connected to the inlet of the stabilized gas separator via a pipeline. The liquid phase outlet of the mixed hydrocarbon stabilization unit is connected to the mixed hydrocarbon storage and transportation unit via a pipeline.

[0008] Furthermore, the crude oil ambient temperature negative pressure cold drawing unit includes a crude oil stabilization tower, a stabilization oil pump, and a vacuum compressor. Purified oil is introduced into the inlet of the crude oil stabilization tower through a purified oil delivery pipeline. A buffer tank is installed at the bottom of the crude oil stabilization tower. The outlet of the buffer tank is connected to the inlet of the stabilization oil pump through a pipeline. The outlet of the stabilization oil pump is divided into two paths: one path is connected to the downstream stabilized oil storage and transportation unit through a pipeline, and the other path is connected to the inlet of the buffer tank through a pipeline. The gas phase at the top of the crude oil stabilization tower is connected to the gas phase inlet of the vacuum compressor through a pipeline, and the outlet of the vacuum compressor is connected to the inlet of the stabilized gas air cooler through a pipeline.

[0009] Further, the stabilized gas booster unit includes a first-stage booster compressor, a first-stage gas cooler, a first-stage gas separator, a second-stage booster compressor, a second-stage gas cooler, a heat exchanger, and a second-stage gas separator; the inlet of the first-stage booster compressor is connected to the gas phase outlet of the stabilized gas separator via a pipeline, the outlet of the first-stage booster compressor is connected to the inlet of the first-stage cooler via a pipeline, the outlet of the first-stage cooler is connected to the inlet of the first-stage gas separator via a pipeline, the liquid phase outlet of the first-stage gas separator is connected to the inlet of the raw material gas separator via a pipeline, and the gas phase outlet of the first-stage gas separator is connected to the inlet of the second-stage booster compressor via a pipeline. The compressor outlet is connected to the inlet of the secondary gas cooler via a pipeline. The outlet of the secondary gas cooler is connected to the secondary gas inlet of the heat exchanger via a pipeline. The secondary gas outlet of the heat exchanger is connected to the inlet of the secondary gas separator via a pipeline. The gas phase outlet of the secondary gas separator is divided into two paths: one path is used as stripped gas and connected to the bottom of the crude oil stabilizer via a pipeline, and the other path is used as fuel gas and connected to the downstream fuel gas storage and transportation unit via a pipeline. The liquid phase outlet of the secondary gas separator is connected to the cryogenic liquid inlet of the heat exchanger via a cryogenic liquid conveying pipeline. The cryogenic liquid outlet of the heat exchanger is connected to the inlet of the mixed hydrocarbon separator via a pipeline.

[0010] Furthermore, the mixed hydrocarbon stabilization unit includes a mixed hydrocarbon stabilization tower, a bottom reboiler, and a mixed hydrocarbon cooler. The inlet of the mixed hydrocarbon stabilization tower is connected to the gas phase outlet and feed of the bottom reboiler via a pipeline. The gas phase outlet at the top of the mixed hydrocarbon stabilization tower is connected to the inlet of the stabilized gas separator via a pipeline. The outlet at the bottom of the mixed hydrocarbon stabilization tower is connected to the feed inlet of the bottom reboiler via a pipeline. The gas phase outlet at the bottom reboiler is connected to the feed inlet at the bottom of the mixed hydrocarbon stabilization tower via a pipeline. The liquid phase outlet at the bottom reboiler is connected to the inlet of the mixed hydrocarbon cooler via a pipeline. The outlet of the mixed hydrocarbon cooler is connected to the mixed hydrocarbon storage and transportation unit via a pipeline.

[0011] As a further improvement of the present invention, a throttling valve is connected to the cryogenic liquid delivery pipeline.

[0012] As a further improvement of the present invention, the spray water inlet of the vacuum compressor is connected to the wastewater outlet of the stabilized gas separator via a spray water delivery pipe, and fresh water is also connected to the spray water delivery pipe.

[0013] Preferably, the operating pressure of the crude oil stabilization tower is -60 kPa and the temperature is 35°C.

[0014] This invention also provides a crude oil stabilized gas recovery and treatment process, comprising the following steps:

[0015] S1. The station's purified oil enters the crude oil stabilization tower. After the light components are flashed out in the tower, stable oil with a temperature ≤50℃ and a saturated vapor pressure of -60kPa is obtained. After the stable oil stays in the buffer tank for 10 to 15 minutes, it is pressurized by the stable oil pump and then transported to the stable oil storage and transportation unit through pipeline.

[0016] S2. The light components generated at the top of the crude oil stabilizer, namely stabilized gas and spray wastewater from the stabilized gas separator, form a mixed phase and then enter the inlet of the extraction compressor.

[0017] S3. The mixed phase generated in step S2 is pressurized to 0.3-0.5 MPa and 75-80°C by the vacuum compressor, then cooled to 40°C by the stabilizer cooler before entering the stabilizer separator. Part of the wastewater separated by the stabilizer separator is returned to the vacuum compressor spray water inlet as spray water, and part of the wastewater is connected to the wastewater treatment unit via pipeline. The mixed hydrocarbons separated by the stabilizer separator are connected to the mixed hydrocarbon booster pump inlet via pipeline. The gas phase separated by the stabilizer separator is connected to the stabilizer pressurization and separation unit via pipeline. The gas phase separated by the stabilizer pressurization and separation unit is divided into two paths: one path is used as stripping gas and connected to the bottom inlet of the crude oil ambient temperature negative pressure cold drawing unit via pipeline, and the other path is used as fuel gas and connected to the downstream fuel gas storage and transportation unit via pipeline.

[0018] S4. The mixed hydrocarbons generated in step S3 are pressurized by the mixed hydrocarbon booster pump and then connected to the inlet of the mixed hydrocarbon separator through a pipeline.

[0019] S5. The gas phase separated by the mixed hydrocarbon separator is connected to the inlet of the stabilized gas separator via a pipeline. The wastewater separated by the mixed hydrocarbon separator is connected to the wastewater treatment unit via a pipeline. The gas phase separated by the mixed hydrocarbon separator is connected to the inlet of the mixed hydrocarbon stabilizer via a pipeline.

[0020] S6. The mixed hydrocarbons generated in step S5 enter the upper part of the mixed hydrocarbon stabilization tower. The heat source provided by the bottom reboiler of the stabilization tower distills the ethane, propane and other components in the mixed hydrocarbons and they escape from the top of the tower. The escaped gas is connected to the inlet of the stabilizer gas separator through a pipeline. The mixed hydrocarbons at the bottom of the bottom reboiler of the stabilization tower are cooled to 40°C by the mixed hydrocarbon cooler and then connected to the mixed hydrocarbon storage and transportation unit through a pipeline.

[0021] As a further improvement of the present invention, the gas phase separated by the stabilized gas separator is connected to the stabilized gas pressurization and separation unit via a pipeline, specifically including the following steps:

[0022] a. The stabilized gas generated by the stabilized gas separator is pressurized by the first-stage booster and then cooled to 40°C by the first-stage gas cooler. It is then connected to the first-stage gas separator through a pipeline. The liquid phase separated in the first-stage gas separator is connected to the inlet of the stabilized gas separator through a pipeline to achieve further separation of the liquid phase dissolved gas. The gas phase separated by the first-stage gas separator is connected to the inlet of the second-stage booster through a pipeline.

[0023] b. The stabilized gas generated in step a is pressurized by a secondary booster and then cooled to 40°C by a secondary gas cooler. It is then connected to the secondary gas inlet of the heat exchanger via a pipeline. The secondary gas outlet of the heat exchanger is connected to the inlet of the secondary gas separator via a pipeline. The gas phase separated by the secondary gas separator is divided into two paths: one path is used as stripping gas and connected to the bottom of the crude oil stabilizer via a pipeline, and the other path is used as fuel gas and connected to the downstream fuel gas storage and transportation unit via a pipeline. The liquid phase separated by the secondary gas separator is connected to the cryogenic liquid inlet of the heat exchanger via a pipeline.

[0024] c. The cryogenic liquid produced in step b is depressurized by a throttle valve to provide cooling for the secondary gas. After being heated, the cryogenic liquid enters the mixed hydrocarbon separator for another gas-oil-water three-phase separation.

[0025] Furthermore, in step S2, the amount of sprayed wastewater is based on controlling the outlet temperature of the vacuum compressor to be ≤82℃.

[0026] Furthermore, in step a, the stabilized gas is pressurized to 0.8–1.0 MPa by a primary booster and then cooled to 40°C by a primary gas cooler, which can recover mixed hydrocarbons with a mass percentage of 20%–25%.

[0027] Furthermore, in step b, the stabilized gas is pressurized to 2-2.5 MPa by a two-stage booster, and then cooled to 10°C by water cooling and cryogenic liquid cooling, which can recover mixed hydrocarbons with a mass percentage of 65%-70%.

[0028] Furthermore, in step c, the throttle valve reduces the pressure of the liquid phase separated by the secondary separator from 2-2.5 MPa to 1-1.5 MPa to form a cryogenic liquid at 1-2°C to provide cooling for the secondary gas. The criterion for reducing the pressure is that the cryogenic liquid temperature is >0°C.

[0029] By adopting the above technical solution, the beneficial effects of the present invention are as follows:

[0030] 1. The crude oil stabilization tower of the present invention adopts the combination of internal components of "sieve plate + herringbone plate" and the mode of water spray screw compressor for air extraction, realizing the successful application of negative pressure room temperature cold drawing process, and meeting the requirement that the stabilized oil is 0.7 times lower than the local atmospheric pressure under the condition of external output temperature of 50°C.

[0031] 2. This invention employs a "three-stage pressurization + three-stage water cooling + throttling refrigeration" process to achieve a C3+ yield of over 95%; and employs a "two-stage three-phase separation + electrically heated packed stabilizing tower" process to ensure that the product mixed hydrocarbons meet the requirements of the standard Q / SYCQ002-2021 "Industrial Mixed Hydrocarbon Raw Materials".

[0032] 3. This invention utilizes a process of stabilizing crude oil at room temperature through cold drawing, pumping and pressurizing, cooling, pressurizing and cooling the stabilized gas, separating, and throttling heat exchange to recover and treat the stabilized gas from crude oil. This solves the risk of oil and gas diffusion in oilfield storage and transportation areas and improves the safety of oilfield production. The recovery of dissolved gas from crude oil meets the overall requirements of energy conservation, emission reduction, and clean production. The recovered and utilized dissolved gas forms mixed hydrocarbons, fuel gas, and other products that meet the specifications, with a C3+ yield of over 95%, resulting in significant economic benefits.

[0033] 4. Compared with conventional crude oil stabilization and processing technology, this invention eliminates the need for crude oil heaters and supporting heating facilities, gas-phase or liquid-phase molecular sieve dehydration facilities, and external refrigerant refrigeration facilities, thereby reducing the initial investment and operating costs of the equipment and achieving significant energy-saving and environmental protection effects.

[0034] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other design solutions and drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the crude oil stabilization gas recovery system of the present invention.

[0037] Explanation of reference numerals in the attached figures:

[0038] 1-Crude oil stabilization tower; 2-Stabilized oil pump; 3-Gas extraction compressor; 4-Stabilized gas cooler; 5-Stabilized gas separator; 6-Mixed hydrocarbon booster pump; 7-Mixed hydrocarbon separator; 8-First-stage booster compressor; 9-First-stage gas cooler; 10-First-stage gas separator; 11-Second-stage booster compressor; 12-Second-stage gas cooler; 13-Heat exchanger; 14-Second-stage gas separator; 15-Mixed hydrocarbon stabilization tower; 16-Stabilization tower bottom reboiler; 17-Mixed hydrocarbon cooler; 18-Purified oil; 19-Fresh water; 20-; 21-Wastewater treatment unit; 22-Fuel gas storage and transportation unit; 23-Mixed hydrocarbon storage and transportation unit; 24-Throttle valve.

[0039] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Detailed Implementation

[0040] The invention can be further understood in conjunction with the following detailed description of preferred embodiments and included examples. Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. If any definition of a specific term disclosed in the prior art differs from any definition provided herein, the definition provided herein shall prevail.

[0041] Specific embodiments of the present invention will now be described in detail. It should be noted that the embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0042] Example 1

[0043] Reference Figure 1 The present invention provides a crude oil stabilizing gas recovery system, including a crude oil ambient temperature negative pressure cold drawing unit, a stabilizing gas cooler 4, a stabilizing gas separator 5, a mixed hydrocarbon booster pump 6, a mixed hydrocarbon separator 7, a stabilizing gas booster separation unit, and a mixed hydrocarbon stabilizing unit.

[0044] Purified oil 18 is connected to the top inlet of the crude oil ambient temperature negative pressure cold drawing unit via a purified oil delivery pipeline. The liquid phase outlet of the crude oil ambient temperature negative pressure cold drawing unit is connected to the downstream stabilized oil storage and transportation unit 20 via a pipeline. The gas phase outlet of the crude oil ambient temperature negative pressure cold drawing unit is connected to the inlet of the stabilized gas air cooler 4 via a pipeline. The outlet of the stabilized gas air cooler 4 is connected to the inlet of the stabilized gas separator 5 via a pipeline. The mixed hydrocarbon outlet of the stabilized gas separator 5 is connected to the inlet of the mixed hydrocarbon booster pump 6 via a pipeline. The outlet of the mixed hydrocarbon booster pump 6 is connected to the inlet of the mixed hydrocarbon separator 7 via a pipeline. The wastewater outlet of the stabilized gas separator 5 is divided into two paths: one path serves as spray water and is connected to the spray water inlet of the crude oil ambient temperature negative pressure cold drawing unit via a pipeline; the other path is connected to the main sewage pipe and then to the wastewater treatment unit 21. The gas phase outlet of the stabilized gas separator 5 is connected to the inlet of the stabilized gas pressurization and separation unit via a pipeline. The gas phase outlet of the stabilized gas pressurization and separation unit is divided into two paths: one path is used as stripping gas and is connected to the bottom inlet of the crude oil ambient temperature negative pressure cold drawing unit via a pipeline; the other path is used as fuel gas and is connected to the downstream fuel gas storage and transportation unit 22 via a pipeline. The gas phase outlet of the mixed hydrocarbon separator 7 is connected to the inlet of the original stabilized gas separator 5 via a pipeline. The wastewater outlet of the mixed hydrocarbon separator 7 is connected to the wastewater treatment unit 21 via a pipeline. The mixed hydrocarbon outlet of the mixed hydrocarbon separator 7 is connected to the mixed hydrocarbon stabilization unit via a pipeline. The top gas phase outlet of the mixed hydrocarbon stabilization unit is connected to the inlet of the stabilized gas separator 5 via a pipeline. The liquid phase outlet of the mixed hydrocarbon stabilization unit is connected to the mixed hydrocarbon storage and transportation unit 23 via a pipeline.

[0045] Furthermore, the crude oil ambient temperature negative pressure cold drawing unit includes a crude oil stabilization tower 1, a stabilization oil pump 2, and a vacuum compressor 3. Purified oil 18 is connected to the inlet of the crude oil stabilization tower 1 via a purified oil delivery pipeline. A buffer tank is installed at the bottom of the crude oil stabilization tower 1, and the outlet of the buffer tank is connected to the inlet of the stabilization oil pump 2 via a pipeline. The outlet of the stabilization oil pump 2 is divided into two paths: one path is connected to the downstream stabilized oil storage and transportation unit 20 via a pipeline, and the other path is connected to the inlet of the buffer tank via a pipeline. The gas phase at the top of the crude oil stabilization tower 1 is connected to the gas phase inlet of the vacuum compressor 3 via a pipeline, and the outlet of the vacuum compressor 3 is connected to the inlet of the stabilized gas air cooler 4 via a pipeline. Preferably, the operating pressure of the crude oil stabilization tower 1 is -60 kPa, and the temperature is 35°C.

[0046] Specifically, the crude oil stabilization tower 1 adopts a tank-back tower type to ensure that the crude oil residence time is about 10 minutes, thereby improving the crude oil stabilization efficiency. The internal components of the crude oil stabilization tower 1 adopt a sieve plate + herringbone plate type. After the auxiliary suction compressor 3 extracts air, the stabilization tower pressure reaches -60kPa, which basically reaches the negative pressure level of the suction compressor.

[0047] The vacuum compressor 3 preferably adopts a water-spray screw compressor. Except for the small amount of fresh water required for the first start-up, the wastewater separated by the subsequent stabilizer gas separator 5 is used as spray water during normal operation, which saves the initial investment and replenishment cost of lubricating oil for the oil-spray screw compressor.

[0048] Furthermore, the stabilized gas booster unit includes a first-stage booster 8, a first-stage gas cooler 9, a first-stage gas separator 10, a second-stage booster 11, a second-stage gas cooler 12, a heat exchanger 13, and a second-stage gas separator 14. Specifically, the inlet of the first-stage booster 8 is connected to the gas phase outlet of the stabilized gas separator 5 via a pipeline; the outlet of the first-stage booster 8 is connected to the inlet of the first-stage cooler 9 via a pipeline; the outlet of the first-stage cooler 9 is connected to the inlet of the first-stage gas separator 10 via a pipeline; the liquid phase outlet of the first-stage gas separator 10 is connected to the inlet of the raw material gas separator 5 via a pipeline; and the gas phase outlet of the first-stage gas separator 10 is connected to the inlet of the second-stage booster 11 via a pipeline. The outlet of compressor 11 is connected to the inlet of secondary gas cooler 12 via a pipeline. The outlet of secondary gas cooler 12 is connected to the secondary gas inlet of heat exchanger 13 via a pipeline. The secondary gas outlet of heat exchanger 13 is connected to the inlet of secondary gas separator 14 via a pipeline. The gas phase outlet of secondary gas separator 14 is divided into two paths: one path is used as stripped gas and connected to the bottom of crude oil stabilization tower 1 via a pipeline, and the other path is used as fuel gas and connected to the downstream fuel gas storage and transportation unit 22 via a pipeline. The liquid phase outlet of secondary gas separator 14 is connected to the cryogenic liquid inlet of heat exchanger 13 via a cryogenic liquid transportation pipeline. The cryogenic liquid outlet of heat exchanger 13 is connected to the inlet of mixed hydrocarbon separator 7 via a pipeline.

[0049] Furthermore, the mixed hydrocarbon stabilization unit includes a mixed hydrocarbon stabilization tower 15, a bottom reboiler 16, and a mixed hydrocarbon cooler 17. The inlet of the mixed hydrocarbon stabilization tower 15 is connected to the gas phase outlet and feed of the bottom reboiler 16 via a pipeline. The gas phase outlet of the top of the mixed hydrocarbon stabilization tower 15 is connected to the inlet of the stabilized gas separator 5 via a pipeline. The bottom outlet of the mixed hydrocarbon stabilization tower 15 is connected to the feed inlet of the bottom reboiler 16 via a pipeline. The gas phase outlet of the bottom reboiler 16 is connected to the bottom feed inlet of the mixed hydrocarbon stabilization tower 15 via a pipeline. The liquid phase outlet of the bottom reboiler 16 is connected to the inlet of the mixed hydrocarbon cooler 17 via a pipeline. The outlet of the mixed hydrocarbon cooler 17 is connected to the mixed hydrocarbon storage and transportation unit 23 via a pipeline.

[0050] As a further improvement to the above-mentioned technical solution of the present invention, a throttle valve 24 is connected to the cryogenic liquid delivery pipeline.

[0051] It is worth mentioning that the stabilized gas separator 5 and the mixed hydrocarbon separator 7 of the present invention are preferably horizontal three-phase separators. The separator cavity has an independent mixing chamber, oil chamber and water chamber structure. The horizontal three-phase separator has the characteristics of high separation efficiency and high dehydration rate. The water content in the mixed hydrocarbons separated by the three-phase separator is between 0.07% and 0.08%.

[0052] The stabilized gas cooler 4 of the present invention preferably adopts a water-cooled shell-and-tube cooler, which recovers n-butane and higher hydrocarbon condensates when cooled to 40°C.

[0053] The stable gas of this invention employs a two-stage pressurization process. The first-stage pressurizer 8 and the second-stage pressurizer 11 are reciprocating compressors, pressurizing to 0.9 MPa and 2.1 MPa respectively. A water-cooled shell-and-tube cooler and separator are connected between the stages. At the end of each stage, a water-cooled shell-and-tube cooler is used, and the cryogenic liquid separated by the second-stage gas separator 14 is cooled to ensure that C3+ is liquefied and separated as much as possible. The cryogenic liquid separated by the second-stage gas separator 14 is formed by a throttling pressure reduction valve, reducing the pressure from 2.075 MPa to 1.25 MPa, thus forming a cryogenic liquid at 1.063°C to provide cooling for the second-stage gas. The pressure reduction is determined based on the cryogenic liquid temperature being >0°C. The gas phase separated by the second-stage gas separator 14 meets the Class II gas quality requirements of GB17820-2018 "Natural Gas".

[0054] The heat exchanger 13 of the present invention adopts a plate-fin heat exchanger, which has the characteristics of small size and high heat exchange efficiency.

[0055] The mixed hydrocarbon stabilization tower 15 of the present invention is a packed tower, and the bottom reboiler 16 of the stabilization tower is a kettle-type reboiler with electricity as the heat source. The mixed hydrocarbon stabilization tower 15 and the bottom reboiler 16 of the stabilization tower complete the stabilization of the mixed hydrocarbons, so that the stabilized mixed hydrocarbons meet the index requirements of "Industrial Mixed Hydrocarbon Raw Materials" Q / SYCQ002-2021. After being cooled to 40°C by the mixed hydrocarbon cooler 17, the mixed hydrocarbons enter the storage and transportation unit.

[0056] Example 2

[0057] This invention also provides a crude oil stabilized gas recovery and treatment process, comprising the following steps:

[0058] S1. The station purification oil 18 enters the crude oil stabilization tower 1. After the light components are flashed out in the tower, the stabilized oil with a temperature ≤50℃ and a saturated vapor pressure of -60kPa is obtained. After the stabilized oil stays in the buffer tank for 10 to 15 minutes, it is pressurized by the stabilized oil pump 2 and then transported to the stabilized oil storage and transportation unit 20 through the pipeline.

[0059] S2. The light components generated at the top of the crude oil stabilizer tower 1, namely stabilized gas and spray wastewater from stabilized gas separator 5, form a mixed phase and then enter the inlet of the vacuum compressor 3.

[0060] S3. The mixed phase generated in step S2 is pressurized to 0.3-0.5 MPa and 75-80°C by the vacuum compressor 3, and then cooled to 40°C by the stabilizer gas cooler 4 before entering the stabilizer gas separator 5. Part of the wastewater separated by the stabilizer gas separator 5 is returned to the spray water inlet of the vacuum compressor 3 as spray water, and part of the wastewater is connected to the wastewater treatment unit 21 through a pipeline. The mixed hydrocarbons separated by the stabilizer gas separator 5 are connected to the inlet of the mixed hydrocarbon booster pump 6 through a pipeline. The gas phase separated by the stabilizer gas separator 5 is connected to the stabilizer gas booster separation unit through a pipeline. The gas phase separated by the stabilizer gas booster separation unit is divided into two paths. One path is used as stripping gas and connected to the bottom inlet of the crude oil ambient temperature negative pressure cold drawing unit through a pipeline. The other path is used as fuel gas and connected to the downstream fuel gas storage and transportation unit 22 through a pipeline.

[0061] S4. The mixed hydrocarbons generated in step S3 are pressurized by the mixed hydrocarbon booster pump 6 and then connected to the inlet of the mixed hydrocarbon separator 7 via a pipeline.

[0062] S5. The gas phase separated by the mixed hydrocarbon separator 7 is connected to the inlet of the stabilized gas separator 5 via a pipeline. The wastewater separated by the mixed hydrocarbon separator 7 is connected to the wastewater treatment unit 21 via a pipeline. The gas phase separated by the mixed hydrocarbon separator 7 is connected to the inlet of the mixed hydrocarbon stabilizer tower 15 via a pipeline.

[0063] S6. The mixed hydrocarbons generated in step S5 enter the upper part of the mixed hydrocarbon stabilization tower 15. The heat source provided by the bottom reboiler 16 of the stabilization tower distills the ethane, propane and other components in the mixed hydrocarbons and they escape from the top of the tower. The escaped gas is connected to the inlet of the stabilizer gas separator 5 through a pipeline. The mixed hydrocarbons at the bottom of the bottom reboiler 16 are cooled to 40°C by the mixed hydrocarbon cooler 17 and then connected to the mixed hydrocarbon storage and transportation unit 23 through a pipeline.

[0064] As a further improvement of the present invention, the gas phase separated by the stabilized gas separator 5 is connected to the stabilized gas pressurization and separation unit via a pipeline, specifically including the following steps:

[0065] a. The stable gas generated by the stable gas separator 5 is pressurized by the first-stage booster 8, then cooled to 40°C by the first-stage gas cooler 9, and then connected to the first-stage gas separator 10 through a pipeline. The liquid phase separated in the first-stage gas separator 10 is connected to the inlet of the stable gas separator 5 through a pipeline to achieve further separation of the liquid phase dissolved gas. The gas phase separated by the first-stage gas separator 10 is connected to the inlet of the second-stage booster 11 through a pipeline.

[0066] b. The stabilized gas generated in step a is pressurized by the secondary booster 11 and then cooled to 40°C by the secondary gas cooler 12. It is then connected to the secondary gas inlet of the heat exchanger 13 via a pipeline. The secondary gas outlet of the heat exchanger 13 is connected to the inlet of the secondary gas separator 14 via a pipeline. The gas phase separated by the secondary gas separator 14 is divided into two paths. One path is used as stripping gas and connected to the bottom of the crude oil stabilization tower 1 via a pipeline. The other path is used as fuel gas and connected to the downstream fuel gas storage and transportation unit via a pipeline. The liquid phase separated by the secondary gas separator 14 is connected to the cryogenic liquid inlet of the heat exchanger 13 via a pipeline.

[0067] c. The cryogenic liquid produced in step b is depressurized by the throttle valve 24 to provide cooling for the secondary gas. After being heated, the cryogenic liquid enters the mixed hydrocarbon separator 7 for another gas-oil-water three-phase separation.

[0068] It is worth mentioning that the crude oil stabilization process described in step S1 adopts a negative pressure (-60kPa) and room temperature (35℃) cold drawing process to ensure that the saturated vapor pressure of the stabilized oil after stabilization is lower than 0.7 times the local atmospheric pressure. At the same time, if necessary, part of the gas separated by the secondary gas separator 14 can be used as stripping gas and introduced into the bottom of the crude oil stabilization tower 1 to increase the production of stabilized gas, thereby eliminating the need for the construction of crude oil heaters and supporting heating facilities, reducing the one-time investment and operating costs of the unit.

[0069] Preferably, the crude oil stabilization tower adopts a tank-back tower type to ensure that the crude oil residence time is about 10 minutes, so as to improve the crude oil stabilization efficiency; the internal components of the crude oil stabilization tower 1 adopt a sieve plate + herringbone plate type, and the stabilization tower pressure reaches -60kPa after the auxiliary suction compressor is used for suction, which basically reaches the negative pressure level of the imported screw compressor.

[0070] Furthermore, the suction compressor in step S2 is a water-spray screw compressor. Except for a small amount of fresh water required during the initial start-up, the wastewater separated by the subsequent stabilizing gas separator 5 is used as spray water during normal operation, saving the initial investment and replenishment costs of lubricating oil for oil-injected screw compressors. It should be noted that the amount of spray wastewater is based on controlling the outlet temperature of the suction compressor 3 to ≤82℃.

[0071] The stabilizer in step S3 is a water-cooled cooler, which cools the gas to 40°C and recovers about 10% of the mixed hydrocarbon production.

[0072] Furthermore, in step a, the stabilized gas is pressurized to 0.8–1.0 MPa by a primary booster 8, and then cooled to 40°C by a primary gas cooler 9, which can recover a mixed hydrocarbon yield of 20%–25% by mass.

[0073] Furthermore, in step b, the stabilized gas is pressurized to 2-2.5 MPa by a secondary booster 11, and then cooled to 10°C by water cooling and cryogenic liquid cooling, which can recover mixed hydrocarbons with a mass percentage of 65%-70%.

[0074] Further, in step c, the throttle valve 24 reduces the pressure of the liquid phase separated by the secondary separator 14 from 2 to 2.5 MPa to 1 to 1.5 MPa to form a cryogenic liquid at 1 to 2°C to provide cooling for the secondary gas. The criterion for reducing the pressure is that the cryogenic liquid temperature is >0°C.

[0075] In step b above, the gases separated by the secondary gas separator, namely CH4: 44.46% (mol), C2H6: 35.44% (mol), C3+: 18.63% (mol), and CO2: 0.32% (mol), meet the Class II gas quality requirements of GB17820-2018 Natural Gas, and are then used as dry gas in the downstream unit.

[0076] Furthermore, in step S6, the mixed hydrocarbon stabilization tower adopts a packed tower and the bottom reboiler of the stabilization tower adopts a kettle reboiler. The mixed hydrocarbon stabilization tower and the bottom reboiler complete the stabilization of the mixed hydrocarbons, so that the stabilized mixed hydrocarbons meet the index requirements of "Industrial Mixed Hydrocarbon Raw Materials" Q / SYCQ002-2021.

[0077] In summary, this invention achieves crude oil stabilization and treatment through ambient temperature cold drawing, gas extraction and pressurization, cooling, stabilization gas pressurization, cooling, separation, and throttling heat exchange. This addresses the risk of oil and gas diffusion in oilfield storage and transportation areas, improving oilfield production safety. The recovery of dissolved gases from crude oil meets the overall requirements of energy conservation, emission reduction, and clean production. The recovered dissolved gases form mixed hydrocarbons, fuel gas, and other products that meet regulatory requirements, with a C3+ yield exceeding 95%, resulting in significant economic benefits.

[0078] Compared with conventional crude oil stabilization and processing technology, this invention eliminates the need for crude oil heaters and supporting heating facilities, gas-phase or liquid-phase molecular sieve dehydration facilities, and external refrigerant refrigeration facilities, thereby reducing the initial investment and operating costs of the equipment and achieving significant energy-saving and environmental protection effects.

[0079] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A crude oil stabilized gas recovery and treatment process, characterized in that, Includes the following steps: S1. The station purification oil (18) enters the crude oil stabilization tower (1). After the light components are flashed out in the tower, the stabilization oil with a temperature ≤50℃ and a saturated vapor pressure of -60kPa is obtained. After the stabilization oil stays in the buffer tank for 10~15min, it is pressurized by the stabilization oil pump (2) and then transported to the stabilization oil storage and transportation unit (20) through the pipeline. S2, The stabilized gas generated at the top of the crude oil stabilizer (1) and the sprayed wastewater from the stabilized gas separator (5) form a mixed phase and then enter the inlet of the suction compressor (3); S3. The mixed phase generated in step S2 is pressurized to 0.3~0.5MPa and 75~80℃ by the vacuum compressor (3), and then cooled to 40℃ by the stabilizer cooler (4) before entering the stabilizer separator (5). Part of the wastewater separated by the stabilizer separator (5) is returned to the inlet of the vacuum compressor (3) as spray water, and part of the wastewater is connected to the wastewater treatment unit (21) through a pipeline. The mixed hydrocarbons separated by the stabilizer separator (5) are connected to the inlet of the mixed hydrocarbon booster pump (6) through a pipeline. The gas phase separated by the stabilizer separator (5) is connected to the stabilizer booster separation unit through a pipeline. The gas phase separated by the stabilizer booster separation unit is divided into two paths. One path is used as stripping gas and connected to the bottom inlet of the crude oil ambient temperature negative pressure cold drawing unit through a pipeline. The other path is used as fuel gas and connected to the downstream fuel gas storage and transportation unit (22) through a pipeline. Specifically, the following steps are included: Step a. The stable gas generated by the stabilized gas separator (5) is pressurized by the first-stage booster (8), then cooled to 40°C by the first-stage gas cooler (9), and then connected to the first-stage gas separator (10) through a pipeline. The liquid phase separated in the first-stage gas separator (10) is connected to the inlet of the stabilized gas separator (5) through a pipeline to achieve the further separation of the liquid phase dissolved gas. The gas phase separated by the first-stage gas separator (10) is connected to the inlet of the second-stage booster (11) through a pipeline. Step b. The stabilized gas generated in step a is pressurized by the secondary booster (11), then cooled to 40°C by the secondary gas cooler (12), and then connected to the secondary gas inlet of the heat exchanger (13) via a pipeline. The secondary gas outlet of the heat exchanger (13) is connected to the inlet of the secondary gas separator (14) via a pipeline. The gas phase separated by the secondary gas separator (14) is divided into two paths. One path is used as stripping gas and connected to the bottom of the crude oil stabilizer tower (1) via a pipeline. The other path is used as fuel gas and connected to the downstream fuel gas storage and transportation unit via a pipeline. The liquid phase separated by the secondary gas separator (14) is connected to the cryogenic liquid inlet of the heat exchanger (13) via a pipeline. Step c. The cryogenic liquid produced in step b is depressurized by the throttle valve (24) to provide cooling for the secondary gas. After being heated, the cryogenic liquid enters the mixed hydrocarbon separator (7) for another gas-oil-water three-phase separation. S4. The mixed hydrocarbons generated in step S3 are pressurized by the mixed hydrocarbon booster pump (6) and then connected to the inlet of the mixed hydrocarbon separator (7) through a pipeline. S5. The gas phase separated by the mixed hydrocarbon separator (7) is connected to the inlet of the stabilized gas separator (5) via a pipeline. The wastewater separated by the mixed hydrocarbon separator (7) is connected to the wastewater treatment unit (21) via a pipeline. The mixed hydrocarbon separated by the mixed hydrocarbon separator (7) is connected to the inlet of the mixed hydrocarbon stabilizer tower (15) via a pipeline. S6. The mixed hydrocarbons generated in step S5 enter the upper part of the mixed hydrocarbon stabilization tower (15). The light components in the mixed hydrocarbons are distilled out from the top of the tower by the heat source provided by the bottom reboiler (16). The escaping gas is connected to the inlet of the stabilizer gas separator (5) through a pipeline. The mixed hydrocarbons at the bottom of the bottom reboiler (16) are cooled to 40°C by the mixed hydrocarbon cooler (17) and then connected to the mixed hydrocarbon storage and transportation unit (23) through a pipeline.

2. The crude oil stabilized gas recovery and treatment process as described in claim 1, characterized in that: In step S2, the amount of sprayed wastewater is based on controlling the outlet temperature of the vacuum compressor (3) to be ≤82℃.

3. The crude oil stabilized gas recovery and treatment process as described in claim 1, characterized in that: In step a, the stabilized gas is pressurized to 0.8~1.0MPa by a first-stage booster (8), and then cooled to 40°C by a first-stage gas cooler (9), recovering mixed hydrocarbons with a mass percentage of 20%~25%.

4. The crude oil stabilized gas recovery and treatment process as described in claim 1, characterized in that: In step b, the stabilized gas is pressurized to 2~2.5MPa by a two-stage booster (11), and then cooled to 10°C by water cooling and cryogenic liquid cooling to recover mixed hydrocarbons with a mass percentage of 65%~70%.

5. The crude oil stabilized gas recovery and treatment process as described in claim 1, characterized in that: In step c, the throttle valve (24) reduces the pressure of the liquid phase separated by the secondary gas separator (14) from 2~2.5MPa to 1~1.5MPa to form a low-temperature liquid at 1~2℃ to provide cooling for the secondary gas. The criterion for reducing the pressure is that the temperature of the low-temperature liquid is >0℃.

6. A crude oil stabilized gas recovery system implementing the crude oil stabilized gas recovery and treatment process according to any one of claims 1-5, characterized in that: It includes a crude oil ambient temperature negative pressure cold drawing unit, a stable gas cooler (4), a stable gas separator (5), a mixed hydrocarbon booster pump (6), a mixed hydrocarbon separator (7), a stable gas booster separation unit, and a mixed hydrocarbon stabilization unit; Purified oil (18) is connected to the top inlet of the crude oil ambient temperature negative pressure cold drawing unit through the purified oil delivery pipeline. The liquid phase outlet of the crude oil ambient temperature negative pressure cold drawing unit is connected to the downstream stabilized oil storage and transportation unit (20) through a pipeline. The gas phase outlet of the crude oil ambient temperature negative pressure cold drawing unit is connected to the inlet of the stabilized gas cooler (4) through a pipeline. The outlet of the stabilized gas cooler (4) is connected to the inlet of the stabilized gas separator (5) through a pipeline. The mixed hydrocarbon outlet of the stabilized gas separator (5) is connected to the inlet of the mixed hydrocarbon booster pump (6) through a pipeline. The outlet of the mixed hydrocarbon booster pump (6) is connected to the inlet of the mixed hydrocarbon separator (7) through a pipeline. The wastewater outlet of the stabilized gas separator (5) is divided into two paths. One path is used as spray water and is connected to the spray water inlet of the crude oil ambient temperature negative pressure cold drawing unit through a pipeline. The other path is... Connect to the main sewage pipe and connect to the sewage treatment unit (21); the crude oil ambient temperature negative pressure cold drawing unit includes a crude oil stabilization tower (1), a stabilization oil pump (2) and a vacuum compressor (3). The purified oil (18) is connected to the inlet of the crude oil stabilization tower (1) through the purified oil delivery pipeline. A buffer tank is set at the bottom of the crude oil stabilization tower (1). The outlet of the buffer tank is connected to the inlet of the stabilization oil pump (2) through a pipeline. The outlet of the stabilization oil pump (2) is divided into two paths. One path is connected to the downstream stabilization oil storage and transportation unit (20) through a pipeline, and the other path is connected to the inlet of the buffer tank through a pipeline. The gas phase at the top of the crude oil stabilization tower (1) is connected to the gas phase inlet of the vacuum compressor (3) through a pipeline. The outlet of the vacuum compressor (3) is connected to the inlet of the stabilized gas cooler (4) through a pipeline. The gas phase outlet of the stabilized gas separator (5) is connected to the inlet of the stabilized gas pressurization separation unit via a pipeline. The gas phase outlet of the stabilized gas pressurization separation unit is divided into two paths. One path is used as stripping gas and is connected to the bottom inlet of the crude oil ambient temperature negative pressure cold drawing unit via a pipeline. The other path is used as fuel gas and is connected to the downstream fuel gas storage and transportation unit (22) via a pipeline. The gas phase outlet of the mixed hydrocarbon separator (7) is connected to the inlet of the stabilized gas separator (5) via a pipeline. The wastewater outlet of the mixed hydrocarbon separator (7) is connected to the wastewater treatment unit (21) via a pipeline. The mixed hydrocarbon outlet of the mixed hydrocarbon separator (7) is connected to the mixed hydrocarbon stabilization unit via a pipeline. The top gas phase outlet of the mixed hydrocarbon stabilization unit is connected to the inlet of the stabilized gas separator (5) via a pipeline. The liquid phase outlet of the mixed hydrocarbon stabilization unit is connected to the mixed hydrocarbon storage and transportation unit (23) via a pipeline. The stable gas booster and separation unit includes a first-stage booster (8), a first-stage gas cooler (9), a first-stage gas separator (10), a second-stage booster (11), a second-stage gas cooler (12), a heat exchanger (13), and a second-stage gas separator (14). The inlet of the first-stage booster (8) is connected to the gas phase outlet of the stabilized gas separator (5) via a pipeline. The outlet of the first-stage booster (8) is connected to the inlet of the first-stage gas cooler (9) via a pipeline. The outlet of the first-stage gas cooler (9) is connected to the inlet of the first-stage gas separator (10) via a pipeline. The liquid phase outlet of the first-stage gas separator (10) is connected to the inlet of the stabilized gas separator (5) via a pipeline. The gas phase outlet of the first-stage gas separator (10) is connected to the inlet of the second-stage booster (11) via a pipeline. The outlet of the second-stage booster (11) is connected to the inlet of the second-stage gas cooler (12) via a pipeline. The outlet of the second-stage gas cooler (12) is connected to the secondary gas inlet of the heat exchanger (13) via a pipeline. The secondary gas outlet of the heat exchanger (13) is connected to the inlet of the second-stage gas separator (14) via a pipeline. The gas phase outlet of the secondary gas separator (14) is divided into two paths. One path is used as stripped gas and connected to the bottom of the crude oil stabilization tower (1) via a pipeline. The other path is used as fuel gas and connected to the downstream fuel gas storage and transportation unit (22) via a pipeline. The liquid phase outlet of the secondary gas separator (14) is connected to the cryogenic liquid inlet of the heat exchanger (13) via a cryogenic liquid delivery pipeline. A throttle valve (24) is connected to the cryogenic liquid delivery pipeline. The cryogenic liquid outlet of the heat exchanger (13) is connected to the inlet of the mixed hydrocarbon separator (7) via a pipeline.

7. The crude oil stabilization gas recovery system as described in claim 6, characterized in that: The mixed hydrocarbon stabilization unit includes a mixed hydrocarbon stabilization tower (15), a bottom reboiler (16), and a mixed hydrocarbon cooler (17). The inlet of the mixed hydrocarbon stabilization tower (15) is connected to the gas phase outlet and feed of the bottom reboiler (16) via a pipeline. The gas phase outlet of the top of the mixed hydrocarbon stabilization tower (15) is connected to the inlet of the stabilized gas separator (5) via a pipeline. The outlet of the bottom of the mixed hydrocarbon stabilization tower (15) is connected to the feed inlet of the bottom reboiler (16) via a pipeline. The gas phase outlet of the bottom reboiler (16) is connected to the bottom feed inlet of the mixed hydrocarbon stabilization tower (15) via a pipeline. The liquid phase outlet of the bottom reboiler (16) is connected to the inlet of the mixed hydrocarbon cooler (17) via a pipeline. The outlet of the mixed hydrocarbon cooler (17) is connected to the mixed hydrocarbon storage and transportation unit (23) via a pipeline.

8. The crude oil stabilization gas recovery system as described in claim 6, characterized in that: The spray water inlet of the vacuum compressor (3) is connected to the sewage outlet of the spray water conveying pipe and the stable gas separator (5), and fresh water (19) is also connected to the spray water conveying pipe.

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