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CN-121988143-A - Wellhead carbon dioxide capturing system and method

CN121988143ACN 121988143 ACN121988143 ACN 121988143ACN-121988143-A

Abstract

The invention discloses a wellhead carbon dioxide capturing system and method, comprising a raw material gas buffer tank, a filter, a heater and a gas membrane separator which are sequentially connected, wherein the low-pressure output end of the gas membrane separator is connected with the input end of a CO 2 storage tank, and the high-pressure output end of the gas membrane separator is connected with a product gas ground pipeline. The coalbed methane with high CO 2 is subjected to primary gas-liquid separation by a gas buffer tank and then enters a filter for fine separation, liquid drops and solid particles entrained in the gas are removed through filtration, the residual oil/liquid component is ensured to be smaller than a set value, the coalbed methane treated by the filter enters a heater and then enters a gas membrane separator for separation after temperature rising, the coalbed methane rich in CO 2 enters the gas membrane separator, high-pressure product gas after gas membrane separation enters a downstream ground pipeline, and low-pressure permeate gas after gas membrane separation enters a CO 2 storage tank. The CO 2 trapping rate is ensured, the ground corrosion protection investment is reduced, and the recycling in different well sites is realized.

Inventors

  • LIU JUN
  • LI DAN
  • LIU JING
  • LI XIAOFEI
  • LIU YINCHUN
  • LI SHUHUA
  • ZHANG XIANGGUANG
  • DUAN YUCHEN
  • BAI BINGYANG
  • AN WEIJIE
  • FENG BO
  • WU KE

Assignees

  • 长庆工程设计有限公司
  • 中国石油天然气股份有限公司

Dates

Publication Date
20260508
Application Date
20241106

Claims (10)

  1. 1. The wellhead carbon dioxide capturing system is characterized by comprising a raw material gas buffer tank (1), a filter (2), a heater (3) and a gas membrane separator (4) which are connected in sequence; The low-pressure output end of the gas membrane separator (4) is connected with the input end of the CO 2 storage tank (6), and the high-pressure output end of the gas membrane separator (4) is connected with a product gas ground pipeline.
  2. 2. The wellhead carbon dioxide capture system of claim 1, wherein a glassy polymer membrane is disposed within the gas membrane separator (4).
  3. 3. Wellhead carbon dioxide capture system according to claim 1, characterized in that a booster pump (5) is arranged between the gas membrane separator (4) and the CO 2 storage tank (6).
  4. 4. A method of wellhead carbon dioxide capture based on the system of any of claims 1-3, comprising the steps of: S1, primarily separating gas from liquid of coal bed gas raw gas with high content of CO 2 by a raw gas buffer tank (1), then enabling the gas to enter a filter (2) for fine separation, and filtering to remove liquid drops and solid particles entrained in the gas, so as to ensure that the residual oil/liquid content is smaller than a set value; s2, the coalbed methane treated by the filter (2) enters a heater (3), and enters a gas membrane separator (4) for separation after being heated; S3, the coalbed methane rich in CO 2 enters a gas membrane separator (4), high-pressure product gas separated by a gas membrane enters a downstream ground pipeline, and low-pressure permeate gas separated by the gas membrane enters a CO 2 storage tank (6).
  5. 5. The method for capturing carbon dioxide at wellhead according to claim 4, wherein in S3, the low pressure permeate gas after gas membrane separation enters a booster pump (5), and CO 2 is pressurized to a supercritical state and then is sent to a CO 2 storage tank (6).
  6. 6. The wellhead carbon dioxide capturing method according to claim 4, wherein the concentration of CO 2 in the coalbed methane raw gas containing high CO 2 is 20% -60%, and the temperature of the raw gas is 20-30 ℃.
  7. 7. The wellhead carbon dioxide capturing method according to claim 4, wherein the liquid phase outlets of the raw gas buffer tank (1) and the filter (2) are respectively outputted to a product gas surface pipeline, and are transported to a downstream site together with the product gas through the surface pipeline.
  8. 8. The wellhead carbon dioxide capturing method according to claim 4, wherein in S2, the temperature of the coalbed methane is 36-42 ℃ after being raised by the heater (3).
  9. 9. The wellhead carbon dioxide capture process of claim 4, wherein the residual oil/liquid content is less than 0.01mg/m 3 .
  10. 10. The method for capturing carbon dioxide at a wellhead according to claim 4, wherein after the treatment by a gas membrane separator (4), the concentration of CO 2 in the product gas is reduced to below 5%, the pressure is 3.4-3.9MPa, the concentration of CO 2 in the low-pressure permeation gas is 85-90%, and the pressure is 115-120 kPa.

Description

Wellhead carbon dioxide capturing system and method Technical Field The invention belongs to the field of natural gas separation treatment, and relates to a wellhead carbon dioxide capturing system and method. Background The development of deep coal bed gas in China gradually applies with the large-scale volume fracturing technology, the productivity of the deep coal bed gas is gradually released, and the deep coal bed gas becomes an important strategic alternative resource, but the large-scale liquid consumption also causes that the benefit development of the deep coal bed gas is difficult to realize. Coalbed methane (CBM, coalbed Methane) is a natural gas produced from coal seams and the main component is methane (CH 4). However, coalbed methane often contains a relatively high proportion of carbon dioxide (CO 2), especially at the beginning of production, where the CO 2 concentration may vary from 20% to 60%. The CO 2 not only reduces the calorific value of the coalbed methane, but also can corrode gas conveying equipment and pipeline systems, so that separation treatment is required. In the traditional coal bed gas development process, the coal bed gas rich in CO 2 is usually subjected to simple emission or combustion treatment, however, precious CO 2 resources are wasted, and emission of greenhouse gases is increased. The method solves the problems of lack of water resources, high water treatment cost and the like in mining areas of the Changqing oilfield, and gradually popularizes and applies a CO 2 fracturing process to reduce the scale of the deep coal bed gas, so that the single-well ground entering liquid amount is greatly reduced, and the method has a good application prospect. With the application of CO 2 fracturing technology in coalbed methane development, the demand for CO 2 has increased substantially. CO 2 fracturing is a stimulation means for increasing the permeability of a coal-bed gas well by injecting CO 2, and is particularly suitable for deep coal-bed gas wells. By injecting CO 2 into the coal seam, the microcrack structure of the coal seam can be improved, thereby improving gas permeability and yield. However, in the coal-bed gas well adopting CO 2 fracturing, the concentration of CO 2 in the initial production stage is up to more than 50%, high-concentration CO 2 is dissolved in water and then severely corrodes metal components such as pipelines and equipment, so that the gas well cannot be connected into an established ground system in the initial production stage (3-6 months), the deep coal-bed gas well is in a high gas production stage in the initial stage, the loss of natural gas at the wellhead is high, the safety and environmental protection risks are high, the CO 2 is discharged, the carbon source is wasted, and development difficulties such as high wellhead emptying and drainage loss and high environmental protection risks exist. The method adopts a wellhead blowout mode at the initial stage of CO 2 fracturing deep coal-bed gas well production, the concentration of CO 2 in the discharged gas is higher, the direct discharge is not contrary to the carbon discharge treatment requirements of the current country and enterprises, and a large amount of natural gas emptying loss causes great waste of energy. Therefore, capturing and purifying the deep coal bed gas wellhead CO 2 is important to carbon emission reduction and guarantee of deep coal bed gas benefit development, and is a technical bottleneck problem of important key point of deep coal bed gas large-scale popularization CO 2 fracturing. At present, the domestic well head carbon dioxide trapping, liquefying and reliable technology for deep coal bed gas is provided. Disclosure of Invention The invention aims to overcome the defects of the prior art, and provides a wellhead carbon dioxide capturing system and a wellhead carbon dioxide capturing method, which can not only ensure the CO 2 capturing rate, but also reduce the ground corrosion protection investment and realize the recycling in different well sites. In order to achieve the purpose, the invention is realized by adopting the following technical scheme: A wellhead carbon dioxide capturing system comprises a raw material gas buffer tank, a filter, a heater and a gas membrane separator which are connected in sequence; The low-pressure output end of the gas membrane separator is connected with the input end of the CO 2 storage tank, and the high-pressure output end of the gas membrane separator is connected with a product gas ground pipeline. Preferably, a glassy polymer membrane is arranged in the gas membrane separator. Preferably, a booster pump is arranged between the gas membrane separator and the CO 2 storage tank. A wellhead carbon dioxide capture method comprising the following steps: S1, performing primary gas-liquid separation on coalbed methane raw gas containing high CO 2 through a raw gas buffer tank, and then enabling the coalbed methane raw gas to enter