CN-118222318-B - Crude oil stable gas recovery system and recovery treatment process

CN118222318BCN 118222318 BCN118222318 BCN 118222318BCN-118222318-B

Abstract

The invention discloses a crude oil stable gas recovery system and a recovery treatment process, wherein 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 boosting separation unit and a mixed hydrocarbon stabilizing unit, purified oil is connected to an inlet of the crude oil normal temperature negative pressure cold drawing unit, a liquid phase outlet of the crude oil normal temperature negative pressure cold drawing unit is connected with a stable oil storage and transportation unit, a gas phase outlet is connected with an inlet of the stable gas air cooler, an outlet of the stable gas air cooler is connected with an inlet of the stable gas separator, a mixed hydrocarbon outlet of the stable gas separator is connected with an inlet of the mixed hydrocarbon separator, a gas phase outlet of the stable gas booster separation unit is divided into two paths, a gas phase outlet of the mixed hydrocarbon separator is connected with an inlet of an original stable gas separator, a sewage outlet is connected with a sewage treatment unit, and a mixed hydrocarbon outlet is connected with the mixed hydrocarbon stabilizing unit. The invention solves the problem of oil and gas diffusion risk in the oil field storage and transportation area and improves the production safety of the oil field.

Inventors

ZHAO YUJUN
XIAO JINGFENG
XIAO XUE
ZHU GUOCHENG
HUO FUYONG
LIANG XUANJI
YANG DONGNING
BAI HONGSHENG
WANG MENG
SUN HUI

Assignees

长庆工程设计有限公司
中国石油天然气集团有限公司

Dates

Publication Date: 20260508
Application Date: 20221219

Claims (8)

1. The crude oil stable gas recovery treatment process is characterized by comprising the following steps of: s1, enabling station purified oil (18) to enter a crude oil stabilizing tower (1), after light components are flashed out of the tower, obtaining stabilized oil with the temperature less than or equal to 50 ℃ and the saturated vapor pressure of-60 kPa, after the stabilized oil stays in a buffer tank for 10-15 min, pressurizing by a stabilized oil pump (2), and then conveying the stabilized oil to a stabilized oil storage and transportation unit (20) through a pipeline; S2, forming a mixed phase by stable gas generated at the top of the crude oil stabilizer (1) and spraying sewage from the stable gas separator (5), and then entering an inlet of the air extraction compressor (3); S3, pressurizing the mixed phase generated in the step S2 to 0.3-0.5 MPa at 75-80 ℃ through an air extraction compressor (3), cooling to 40 ℃ through a stable gas cooler (4), then entering a stable gas separator (5), returning part of sewage separated by the stable gas separator (5) to a spray water inlet of the air extraction compressor (3) as spray water, connecting part of sewage to a sewage treatment unit (21) through a pipeline, connecting mixed hydrocarbon separated by the stable gas separator (5) to an inlet of a mixed hydrocarbon booster pump (6) through a pipeline, connecting gas separated by the stable gas separator (5) to a stable gas pressurizing separation unit through a pipeline, dividing gas separated by the stable gas pressurizing separation unit into two paths, connecting one path serving as gas stripping gas to a bottom inlet of a crude oil normal temperature negative pressure cold drawing unit through a pipeline, and connecting the other path serving as fuel gas to a downstream fuel gas storage and transportation unit (22), and the method specifically comprises the following steps: Step a. After the stable gas generated by the stable gas separator (5) is pressurized by the first-stage booster (8), and then is cooled to 40 ℃ by the first-stage gas cooler (9), the stable gas is 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, so that the re-separation of the liquid-phase dissolved gas is realized, and 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, after the stable gas generated in the step a is pressurized by a secondary booster (11), and then is cooled to 40 ℃ by a secondary gas cooler (12), the stable gas is connected to a secondary gas inlet of a heat exchanger (13) through a pipeline, a secondary gas outlet of the heat exchanger (13) is connected to an inlet of a secondary gas separator (14) through a pipeline, a gas phase separated by the secondary gas separator (14) is divided into two paths, one path is connected to the bottom of a crude oil stabilizer (1) body through a pipeline as stripping gas, the other path is connected to a downstream fuel gas storage and transportation unit through a pipeline as fuel gas, and a liquid phase separated by the secondary gas separator (14) is connected to a low-temperature liquid inlet of the heat exchanger (13) through a pipeline; step c, the low-temperature liquid generated in the step b is depressurized through a throttle valve (24) to provide cold energy for the secondary gas, and the warmed low-temperature liquid enters a hydrocarbon-mixing separator (7) to carry out gas-oil-water three-phase separation again; S4, pressurizing the mixed hydrocarbon generated in the step S3 by a mixed hydrocarbon booster pump (6), and connecting the pressurized mixed hydrocarbon to an inlet of a mixed hydrocarbon separator (7) through a pipeline; S5, connecting a gas phase separated by the hydrocarbon mixing separator (7) to an inlet of the stabilizing gas separator (5) through a pipeline, connecting sewage separated by the hydrocarbon mixing separator (7) to the sewage treatment unit (21) through a pipeline, and connecting hydrocarbon mixing separated by the hydrocarbon mixing separator (7) to an inlet of the hydrocarbon mixing stabilizing tower (15) through a pipeline; S6, the mixed hydrocarbon generated in the step S5 enters the upper part of a mixed hydrocarbon stabilizing tower (15), light component distillation in the mixed hydrocarbon escapes from the top of the tower through a heat source provided by a stabilizing tower bottom reboiler (16), the escaping gas is connected to the inlet of a stabilizing gas separator (5) through a pipeline, and the mixed hydrocarbon at the bottom of the stabilizing tower bottom reboiler (16) is cooled to 40 ℃ through a mixed hydrocarbon cooler (17) and then connected to a mixed hydrocarbon storage and transportation unit (23) through a pipeline.
2. The process for recovering and treating crude oil stabilized gas according to claim 1, wherein in the step S2, the amount of the sprayed sewage is controlled based on the outlet temperature of the air extraction compressor (3) being less than or equal to 82 ℃.
3. The process for recovering and treating the crude oil stabilized gas according to claim 1, wherein in the step a, the stabilized gas is pressurized to 0.8-1.0 MPa by a primary booster (8), and then cooled to 40 ℃ by a primary gas cooler (9), and the mixed hydrocarbon with the mass percent of 20% -25% is recovered.
4. The process for recovering and treating the crude oil stable gas according to claim 1, wherein in the step b, the stable gas is pressurized to 2-2.5 MPa by a secondary booster (11), cooled to 10 ℃ by water cooling and low-temperature liquid cooling, and mixed hydrocarbon with the mass percent of 65% -70% is recovered.
5. The process for recovering and treating crude oil stable gas according to claim 1, wherein the throttle valve (24) in the step C reduces the pressure of the liquid phase separated by the secondary gas separator (14) from 2-2.5 MPa to 1-1.5 MPa to form a low-temperature liquid with the temperature of 1-2 ℃ as cold energy for secondary gas supply, and the judgment of the reduced pressure is based on the temperature of the low-temperature liquid being more than 0 ℃.
6. A crude oil stable gas recovery system for implementing the crude oil stable gas recovery treatment process according to any one of claims 1 to 5, which is characterized by comprising a crude oil normal 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 stabilizing unit; The purified oil (18) is connected to the top inlet of a crude oil normal temperature negative pressure cold drawing unit through a purified oil conveying pipeline, the liquid phase outlet of the crude oil normal temperature negative pressure cold drawing unit is connected to a downstream stable oil storage and transportation unit (20) through a pipeline, the gas phase outlet of the crude oil normal temperature negative pressure cold drawing unit is connected with the inlet of a stable gas cooler (4) through a pipeline, the outlet of the stable gas cooler (4) is connected with the inlet of a stable gas separator (5) through a pipeline, the mixed hydrocarbon outlet of the stable gas separator (5) is connected with the inlet of a mixed hydrocarbon booster pump (6) through a pipeline, the outlet of the mixed hydrocarbon booster pump (6) is connected with the inlet of a mixed hydrocarbon separator (7) through a pipeline, the sewage outlet of the stable gas separator (5) is divided into two pipelines, one pipeline is used as spray water and connected to the spray water inlet of the crude oil normal temperature negative pressure cold drawing unit, the other pipeline is connected to a sewage main pipe and is connected to a sewage treatment unit (21), the normal temperature negative pressure cold drawing unit comprises a crude oil stabilizer (1), a stable oil pump (2) and a stable compressor (3), the purified oil (18) is connected to the inlet of the crude oil stabilizer (1) through the purified oil conveying pipeline, the bottom of the crude oil stabilizer (1) is connected to the inlet of the stable oil pump through the stable gas pump, the pipeline is separated into the stable oil pump (2) and the stable oil pump (20), 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 stabilizer (1) is connected to the gas phase inlet of the pumping compressor (3) through a pipeline, and the outlet of the pumping compressor (3) is connected to the inlet of the stabilizer gas cooler (4) through a pipeline; The gas phase outlet of the hydrocarbon mixing separator (7) is connected with the inlet of the stable gas separator (5) through a pipeline, the sewage outlet of the hydrocarbon mixing separator (7) is connected with the sewage treatment unit (21) through a pipeline, the hydrocarbon mixing outlet of the hydrocarbon mixing separator (7) is connected with the hydrocarbon mixing stabilizing unit through a pipeline, the gas phase outlet at the top of the hydrocarbon mixing stabilizing unit is connected with the inlet of the stable gas separator (5) through a pipeline, and the liquid phase outlet of the hydrocarbon mixing stabilizing unit is connected with the hydrocarbon mixing storage and transportation unit (23) through a pipeline; The stable gas pressurizing and separating unit comprises a first-stage supercharger (8), a first-stage gas cooler (9), a first-stage gas separator (10), a second-stage supercharger (11), a second-stage gas cooler (12), a heat exchanger (13) and a second-stage gas separator (14); The inlet of the primary booster (8) is connected with the gas phase outlet of the stable gas separator (5) through a pipeline, the outlet of the primary booster (8) is connected to the inlet of the primary gas cooler (9) through a pipeline, the outlet of the primary gas cooler (9) is connected with the inlet of the primary gas separator (10) through a pipeline, the liquid phase outlet of the primary gas separator (10) is connected with the inlet of the stable gas separator (5) through a pipeline, the gas phase outlet of the primary gas separator (10) is connected with the inlet of the secondary booster (11) through a pipeline, the outlet of the secondary booster (11) is connected with the inlet of the secondary gas cooler (12) through a pipeline, the outlet of the secondary gas cooler (12) is connected with the inlet of the secondary gas cooler (13) through a pipeline, the outlet of the secondary gas of the heat exchanger (13) is connected with the inlet of the secondary gas separator (14) through a pipeline, the gas phase outlet of the secondary gas separator (14) is divided into two pipelines, one pipeline is connected to the bottom of the tower body of the crude oil stabilizer (1) through a pipeline, the other pipeline is connected to the downstream fuel gas storage and transport unit (22), the liquid phase outlet of the secondary gas separator (14) is connected with the low-temperature liquid phase separator (24) through the low-temperature pipeline, and the low-temperature liquid separator (13) is connected with the low-temperature liquid separator (7) through the low-temperature valve.
7. The crude oil stabilized gas recovery system as set forth in claim 6, wherein the hydrocarbon mixing stabilization unit comprises a hydrocarbon mixing stabilization tower (15), a stabilizing bottom reboiler (16) and a hydrocarbon mixing cooler (17), wherein the inlet of the hydrocarbon mixing stabilization tower (15) is connected, the bottom of the hydrocarbon mixing stabilization tower (15) is connected with the gas phase discharging and feeding of the stabilizing bottom reboiler (16) through a pipeline, the gas phase outlet at the top of the hydrocarbon mixing stabilization tower (15) is connected with the inlet of the stabilizing bottom reboiler (16) through a pipeline, the gas phase discharging of the stabilizing bottom reboiler (16) is connected with the bottom feeding of the hydrocarbon mixing stabilization tower (15) through a pipeline, the liquid phase discharging of the stabilizing bottom reboiler (16) is connected with the inlet of the hydrocarbon mixing cooler (17) through a pipeline, and the outlet of the hydrocarbon mixing cooler (17) is connected with the hydrocarbon mixing storage and transportation unit (23) through a pipeline.
8. The crude oil stabilized gas recovery system as set forth in claim 6, wherein the spray water inlet of said air extraction compressor (3) is connected to the sewage outlet of the stabilizing gas separator (5) via a spray water delivery pipe, and fresh water (19) is further connected to the spray water delivery pipe.

Description

Crude oil stable gas recovery system and recovery treatment process Technical Field The invention belongs to the technical field of recovery and utilization of oilfield associated gas, and particularly relates to a crude oil stable gas recovery system and a recovery treatment process. Background The dehydrated purified crude oil contains a large amount of dissolved gas (C1-C4) which is in a gaseous state at normal temperature and normal pressure, so that the vapor pressure of the crude oil is high, and a large amount of oil vapor is generated in the storage and transportation process and discharged into the atmosphere, thereby wasting energy and polluting the environment. The common crude oil stabilization process at home and abroad is negative pressure flash evaporation, the negative pressure flash evaporation pressure is mainly limited by the negative pressure degree which can be achieved by a compressor, the suction pressure of the domestic production negative pressure compressor is generally about-40 kPa, and the saturated vapor pressure of stabilized oil with the output temperature of 50 ℃ can be ensured to be lower than 0.7 times of the local atmospheric pressure only when the corresponding operation temperature is about 55 ℃. However, the temperature of the on-site purified oil is generally 35-45 ℃, the feed crude oil needs to be heated in order to ensure that the stabilized oil reaches the standard, if the stabilized oil is not heated, the pressure of a corresponding stabilizing tower at the lowest temperature of the purified oil of 35 ℃ needs to be minus 60kPa to meet the standard, and only the imported negative pressure compressor can reach minus 60kPa at present, but the problems of long acquisition period and high price exist, so that a low-cost and low-energy-consumption crude oil stabilizing process needs to be formed to meet the requirements of closed gathering and transportation of crude oil which is increased year by year. The methane content of the crude oil stable gas component is less than or equal to 15% (mol), the ethane content is about 25%, and the propane content and the above content are more than or equal to 55% (mol). Recently, for the purposes of saving energy, reducing consumption, improving the yield of liquid hydrocarbon and reducing investment at home and abroad, a series of improvements are made on the process method of the NGL recovery device, mainly including an oil absorption method, a refrigerant refrigeration process technology, a direct heat exchange (DHX) method, an expansion mechanism refrigeration process technology and the like, and the improvement of the process enables the C3+ yield of associated gas to reach about 95%, but a large amount of heavy hydrocarbon in the recovery of pure crude oil stable gas NGL is firstly separated out in a crude oil stable unit in actual operation on site, and the power consumption of a refrigerant compressor in stable gas treatment is maximum, so that a crude oil stable gas treatment process with low cost and low energy consumption needs to be formed, and the problems of carbon emission, safety and environmental protection in production are eliminated. Disclosure of Invention The invention provides a crude oil stable gas recovery system and a recovery treatment process, and aims to solve the problems of high energy consumption, high cost and environmental pollution caused by changing waste into valuables in the recovery treatment process of pure crude oil stable gas. In order to achieve the above purpose, the technical scheme adopted by the invention is as follows: A crude oil stable gas recovery 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 stable gas booster separation unit and a mixed hydrocarbon stabilizing unit; The method comprises the steps of connecting purified oil to the top inlet of a crude oil normal temperature negative pressure cold drawing unit through a purified oil conveying pipeline, connecting a liquid phase outlet of the crude oil normal temperature negative pressure cold drawing unit to a downstream stable oil storage and transportation unit through a pipeline, connecting a gas phase outlet of the crude oil normal temperature negative pressure cold drawing unit to an inlet of a stable gas air cooler through a pipeline, connecting a mixed hydrocarbon outlet of the stable gas air cooler to an inlet of the stable gas separator through a pipeline, connecting a mixed hydrocarbon outlet of the mixed hydrocarbon separator to an inlet of a mixed hydrocarbon separator through a pipeline, connecting a sewage outlet of the mixed hydrocarbon separator to a spray water inlet of the crude oil normal temperature negative pressure cold drawing unit through a pipeline, connecting one pipeline to a sewage outlet of the mixed hydrocarbon separator to a sewage treatment unit, conne