Method for removing organic sulfur in flowback fluid of oil and gas field

Abstract

The invention relates to the technical field of oil and gas field water treatment, in particular to a method for removing organic sulfur in oil and gas field flow-back fluid, which comprises the following steps: introducing the oil and gas field flow-back fluid into a treatment tank, and carrying out air flotation treatment on the flow-back fluid; dividing the flowback liquid in the treatment tank into a plurality of layers, and determining an initial depth layer of ventilation according to the variable quantity of foam on the surface of the flowback liquid after ventilation of each layer; determining bubble introduction parameters according to the surface floating value of the flowback fluid; determining the addition amount of the coagulant according to the bubble floating speed from the ventilation position to the liquid surface when the ventilation treatment is judged to be unqualified according to the foam proportion area on the surface of the flowback liquid after ventilation for a second preset duration; when the ventilation treatment is judged to be qualified, judging the qualification of the coagulant feeding mode according to the variable quantity of foam on the surface of the flowback liquid after coagulating sedimentation; after no pollutant is generated on the surface of the flow-back liquid, the ventilation position is moved downwards by the preset depth for continuous treatment, and the problem that the flow-back liquid of the oil and gas field pollutes the environment is effectively avoided.

Description

Technical Field

[0001] The invention relates to the technical field, and in particular to a method for removing organic sulfur from oil and gas field flowback fluid. Background Art

[0002] Oil and gas field flowback fluid is a liquid containing a solid phase produced during the development of oil and gas fields, especially during hydraulic fracturing operations. After the fracturing operation is completed, a portion of the liquid will return to the ground as the oil and gas are produced. This portion of the liquid contains a portion of the original fracturing fluid, as well as minerals and organic matter dissolved or carried out in the formation. If the organic sulfur in the flowback fluid is discharged directly into the environment without treatment, it will seriously pollute the water source. These pollutants may enter the water body through surface runoff, groundwater infiltration, etc., causing water quality deterioration. Therefore, it is necessary to provide a method for treating the flowback fluid to remove organic sulfur, thereby avoiding environmental pollution caused by the flowback fluid.

[0003] In the prior art, some chemical methods, when treating organic sulfur, fail to completely react due to improper control of reaction conditions, resulting in failure to effectively remove the organic sulfur. Other impurities may also be introduced, thus affecting the overall treatment effect. At the same time, the reaction process is complicated and there is a problem of high cost. Summary of the invention

[0004] To this end, the present invention provides a method for removing organic sulfur from oil and gas field flowback fluid, so as to overcome the problem of complex and high cost of removing organic sulfur from oil and gas field flowback fluid in the prior art.

[0005] To achieve the above object, the present invention provides a method for removing organic sulfur from oil and gas field flowback fluid, comprising:

[0006] After the oil and gas field flowback fluid is passed into the treatment pool, the flowback fluid is subjected to flotation treatment;

[0007] Divide the flowback liquid in the treatment pool into several layers, perform ventilation for a first preset time at the bottom of each layer, and determine the initial depth layer of ventilation according to the change in the foam on the surface of the flowback liquid after each layer is ventilated;

[0008] Carry out pre-ventilation treatment to the initial depth layer and determine the parameters for bubble introduction according to the surface floating value of the return fluid;

[0009] When the ventilation treatment is judged to be unqualified according to the proportion of foam on the surface of the return liquid after the second preset ventilation time, the amount of coagulant added is determined according to the floating speed of bubbles from the ventilation position to the liquid surface;

[0010] When the ventilation treatment is judged to be qualified based on the proportion of foam on the surface of the return liquid after the second preset ventilation time, the qualification of the coagulant injection method is judged according to the change in the foam on the surface of the return liquid after coagulation and sedimentation;

[0011] If the change in foam volume is less than the preset change, the coagulant input method is judged to be unqualified, and the coagulant input density is adjusted according to the bubble-free area ratio on the backflow liquid surface;

[0012] The coagulant input method is determined to be qualified when the change in foam is greater than or equal to the preset change, and the ventilation position is moved down to a preset depth to continue processing after no pollutants are generated on the surface of the return liquid.

[0013] Further, the process of determining the initial depth layer of ventilation according to the change in the amount of foam on the surface of the return fluid includes:

[0014] Divide the flowback liquid in the treatment tank vertically into several layers of equal depth;

[0015] The first preset duration of ventilation from top to bottom for each layer of different depth layers of the return fluid;

[0016] Determine the amount of foam change on the surface of the flowback fluid after each layer of ventilation;

[0017] Compare the foam change amount of each layer with the preset foam change amount;

[0018] Under the condition that the foam change amount is less than a preset foam change amount, a layer above the layer is determined as an initial depth layer.

[0019] Further, the process of determining the parameters of bubble introduction according to the surface floating value of the return fluid includes:

[0020] Under the condition that the surface floating value is less than the preset floating value, the parameters for the bubble introduction are determined to be the first bubble size and the first bubble quantity;

[0021] Under the condition that the surface floating value is greater than or equal to the preset floating value, the parameters for determining the bubble introduction are a second bubble size and a second bubble quantity.

[0022] Furthermore, the eligibility of the ventilation treatment is determined based on the proportion of foam area on the surface of the return liquid after the second preset ventilation period. The ventilation treatment is determined to be unqualified when the foam area proportion is less than the preset area proportion, and the amount of coagulant added is determined based on the rising speed of bubbles from the ventilation position to the liquid surface.

[0023] Furthermore, the eligibility of the ventilation treatment is determined based on the area ratio of foam on the surface of the return liquid after the second preset ventilation period, and the ventilation treatment is determined to be qualified when the foam area ratio is greater than or equal to the preset area ratio, and the foam on the surface of the return liquid is scraped off.

[0024] Furthermore, the amount of coagulant added is determined according to the rising velocity of bubbles from the ventilation position to the liquid surface, and under the condition that the rising velocity of bubbles is less than a preset rising velocity, the amount of coagulant added is determined to be the first amount.

[0025] Furthermore, the amount of coagulant added is determined according to the bubble floating speed from the ventilation position to the liquid surface, and under the condition that the bubble floating speed is greater than or equal to the preset floating speed, the amount of coagulant added is determined to be the second amount.

[0026] Furthermore, the eligibility of the coagulant addition method is determined based on the change in foam on the surface of the return liquid after coagulation and sedimentation. When the change in foam is less than a preset change, the coagulant addition method is determined to be unqualified, and the coagulant addition density is adjusted based on the proportion of bubble-free area on the return liquid surface.

[0027] Furthermore, the input density of the coagulant is adjusted according to the bubble-free area ratio of the backflow liquid surface, and under the condition that the bubble-free area ratio is less than the preset bubble-free area ratio, the input density of the coagulant is determined to be the first input density.

[0028] Furthermore, the input density of the coagulant is adjusted according to the bubble-free area ratio of the backflow liquid surface, and under the condition that the bubble-free area ratio is greater than or equal to the preset bubble-free area ratio, the input density of the coagulant is determined to be the second input density.

[0029] Compared with the prior art, the beneficial effect of the present invention lies in that, after ventilating different depth layers of the return fluid for the same preset time, the present invention determines the initial depth layer of ventilation according to the change in the foam on the surface of the return fluid, and determines the upper layer of the layer as the initial depth layer based on the condition that the foam change is less than the preset foam change. By determining the initial depth layer of ventilation, the problem of poor flotation effect caused by the ventilation position being too deep can be avoided, and the optimal treatment position can also be determined to improve the treatment efficiency. The initial depth layer is then pre-ventilated, and the parameters for bubble introduction are determined according to the surface floating value of the return fluid, the optimal parameters for treatment are determined, the treatment efficiency is improved, and the eligibility of the ventilation treatment is determined according to the area occupied by the foam on the surface of the return fluid after the second preset ventilation time, and the eligibility of the coagulant input method is determined according to the change in the foam on the surface of the return fluid after coagulation and sedimentation. Through the combined treatment of flotation and chemical precipitation, the efficient removal effect of organic sulfur in the return fluid of the oil and gas field is guaranteed.

[0030] Furthermore, the present invention determines the initial depth layer of ventilation according to the change in the amount of foam on the surface of the return liquid, divides the return liquid in the treatment pool into several layers vertically, ventilates different depth layers of the return liquid from top to bottom for the same preset time, determines the change in the amount of foam on the surface of the return liquid after each layer is ventilated, and then compares the foam change in each layer with the preset foam change. Based on the condition that the foam change is less than the preset foam change, the layer above the layer is determined as the initial depth layer, which can shorten the processing time and improve efficiency.

[0031] Furthermore, the present invention determines the parameters of bubble introduction according to the surface floating value of the return liquid. Based on the condition that the surface floating value is less than a preset floating value, the parameters of bubble introduction are determined to be a first bubble size and a first bubble quantity. Based on the condition that the surface floating value is greater than or equal to the preset floating value, the parameters of bubble introduction are determined to be a second bubble size and a second bubble quantity. By flexibly adjusting the size and quantity of the bubbles, it is possible to adapt to the treatment of different pollutant concentrations and improve the treatment quality.

[0032] Furthermore, the present invention determines the eligibility of the ventilation treatment based on the proportion of foam area on the surface of the return liquid after the second preset ventilation time, determines the unqualified ventilation treatment based on the condition that the foam area proportion is less than the preset area proportion, and determines the amount of coagulant added based on the rising speed of the bubbles from the ventilation position to the liquid surface, determines the eligibility of the ventilation treatment based on the condition that the foam area proportion is greater than or equal to the preset area proportion, and scrapes the foam on the surface of the return liquid. By determining the eligibility of the ventilation treatment, different treatment methods are determined, thereby improving the flexibility of the treatment.

[0033] Furthermore, the present invention determines the amount of coagulant added according to the bubble floating speed from the ventilation position to the liquid surface, and based on the condition that the bubble floating speed is less than the preset floating speed, determines the amount of coagulant added as the first amount, and based on the condition that the bubble floating speed is greater than or equal to the preset floating speed, determines the amount of coagulant added as the second amount. By dynamically adjusting the use of ventilation and coagulant according to parameters such as the bubble floating speed, it is possible to optimize resource utilization and reduce processing costs.

[0034] Furthermore, the present invention determines the eligibility of the coagulant input method according to the change in foam on the surface of the return liquid after coagulation and sedimentation, determines that the coagulant input method is unqualified based on the condition that the change in foam is less than a preset change, and adjusts the coagulant input density according to the bubble-free area ratio on the return liquid surface, determines the coagulant input density as the first input density based on the condition that the bubble-free area ratio is less than the preset bubble-free area ratio, and determines the coagulant input density as the second input density based on the condition that the bubble-free area ratio is greater than or equal to the preset bubble-free area ratio, and by adjusting the parameters of the chemical precipitation method according to the results of the flotation method, not only the processing efficiency and quality are improved, but also the resource utilization is optimized and the energy consumption is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a flow chart of a method for removing organic sulfur from oil and gas field flowback fluid according to an embodiment of the present invention;

[0036] Figure 2 A flow chart of determining parameters for bubble introduction according to an embodiment of the present invention;

[0037] Figure 3 A flow chart for determining the eligibility of ventilation treatment according to an embodiment of the present invention;

[0038] Figure 4 The present invention is a flowchart for determining the eligibility of a coagulant input method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0039] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0040] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0041] It should be pointed out that the data in this embodiment are obtained by comprehensive analysis and evaluation of the historical test data and the corresponding historical test results of the present invention in the three months before this test. It can be understood by those skilled in the art that the present invention can determine the above parameters for a single item by selecting the highest proportion of values ​​as the preset standard parameters according to the data distribution, using weighted summation to use the obtained values ​​as the preset standard parameters, substituting each historical data into a specific formula and using the values ​​obtained by the formula as the preset standard parameters or other selection methods, as long as the present invention can clearly define different specific situations in the single determination process through the obtained values.

[0042] See also Figure 1 , Figure 2 , Figure 3 as well as Figure 4 As shown, Figure 1 This is a flow chart of a method for removing organic sulfur from oil and gas field flowback fluid according to an embodiment of the present invention; Figure 2 A flow chart of determining parameters for bubble introduction according to an embodiment of the present invention; Figure 3 A flow chart for determining the eligibility of ventilation treatment according to an embodiment of the present invention; Figure 4 The present invention is a flowchart for determining the eligibility of a coagulant input method according to an embodiment of the present invention.

[0043] The embodiment of the present invention provides a method for removing organic sulfur from oil and gas field flowback fluid, comprising:

[0044] After the oil and gas field flowback fluid is passed into the treatment pool, the flowback fluid is subjected to flotation treatment;

[0045] Divide the flowback liquid in the treatment pool into several layers, perform ventilation for a first preset time at the bottom of each layer, and determine the initial depth layer of ventilation according to the change in the foam on the surface of the flowback liquid after each layer is ventilated;

[0046] Carry out pre-ventilation treatment to the initial depth layer and determine the parameters for bubble introduction according to the surface floating value of the return fluid;

[0047] When the ventilation treatment is judged to be unqualified according to the proportion of foam on the surface of the return liquid after the second preset ventilation time, the amount of coagulant added is determined according to the floating speed of bubbles from the ventilation position to the liquid surface;

[0048] When the ventilation treatment is judged to be qualified based on the proportion of foam on the surface of the return liquid after the second preset ventilation time, the qualification of the coagulant injection method is judged according to the change in the foam on the surface of the return liquid after coagulation and sedimentation;

[0049] If the change in foam volume is less than the preset change, the coagulant input method is judged to be unqualified, and the coagulant input density is adjusted according to the bubble-free area ratio on the backflow liquid surface;

[0050] The coagulant input method is determined to be qualified when the change in foam is greater than or equal to the preset change, and the ventilation position is moved down to a preset depth to continue processing after no pollutants are generated on the surface of the return liquid.

[0051] In the embodiment of the present invention, the preset depth is set to 2 m, but the above value is not limited thereto, and those skilled in the art may also adjust the value according to actual needs.

[0052] Specifically, the process of determining the initial depth layer of ventilation based on the change in the amount of foam on the surface of the return fluid includes:

[0053] Divide the flowback liquid in the treatment tank into several layers vertically;

[0054] The first preset time for ventilation from top to bottom to different depth layers of the return fluid is 5 minutes;

[0055] Determine the amount of foam change on the surface of the flowback fluid after each layer of ventilation;

[0056] Compare the foam change amount of each layer with the preset foam change amount;

[0057] Based on the foam change amount being less than the preset foam change amount of 0.1m 3 The condition determines the previous layer of this layer as the initial depth layer.

[0058] In the embodiment of the present invention, the backflow liquid in the treatment pool is divided into a layer every 1m vertically, the first preset time length is 5min, and the preset foam change amount is 0.1m 3 , but the above value is not limited thereto, and those skilled in the art can also adjust the value according to actual needs.

[0059] Specifically, the foam change is measured by an intelligent camera installed on the side wall of the treatment pool at the upper end of the liquid surface. By monitoring the change in the foam on the liquid surface before and after each layer of ventilation, the maximum depth layer suitable for treating the return liquid can be determined, thereby improving the treatment efficiency.

[0060] Specifically, the process of determining the parameters of bubble introduction according to the surface floating value of the return fluid includes:

[0061] Based on the condition that the surface floating value is less than the preset floating value of 0.005m, the parameters for bubble introduction are determined to be the first bubble size and the first bubble quantity;

[0062] Based on the condition that the surface floating value is greater than or equal to the preset floating value, the parameters for bubble introduction are determined to be a second bubble size and a second bubble quantity.

[0063] In the embodiment of the present invention, the preset floating value is 0.005m, but the above value is not limited thereto, and those skilled in the art may also adjust the value according to actual needs.

[0064] Specifically, the surface floating value is measured by a liquid level sensor. By measuring the surface floating value, the effect of bubbles on pollutants can be determined. A small floating value may be due to excessive pollutants, making it difficult for bubbles to float up. Therefore, small-sized and large-volume bubbles are required to increase the contact area with pollutants. A large floating value may be due to large bubble size or excessive number of bubbles, resulting in a fast floating speed, which quickly drives up the liquid level. Therefore, it is necessary to determine the appropriate size and number of bubbles before processing the return fluid.

[0065] In an embodiment of the present invention, the first bubble size is 20 μm, the first bubble number is 2000 / s, the second bubble size is 30 μm, and the second bubble number is 1800 / s, but the above values ​​are not limited to this, and technical personnel in this field can also adjust the values ​​according to actual needs.

[0066] Specifically, the bubble size is controlled by adjusting the size of the air outlet, and the bubble quantity is controlled by adjusting the air intake speed.

[0067] Specifically, the compliance of the ventilation treatment is determined based on the area ratio of foam on the surface of the return liquid after the second preset ventilation time of 30 minutes. The unqualified ventilation treatment is determined based on the condition that the foam area ratio is less than 90% of the preset area ratio, and the amount of coagulant added is determined based on the rising speed of bubbles from the ventilation position to the liquid surface.

[0068] In the embodiment of the present invention, the second preset time length is 30 minutes, and the preset area ratio is 90%, but the above values ​​are not limited thereto, and those skilled in the art may also adjust the values ​​according to actual needs.

[0069] Specifically, the foam area ratio is the ratio of the foam area on the liquid surface to the entire liquid surface, which is determined by intelligent camera analysis.

[0070] Specifically, the eligibility of the ventilation treatment is determined based on the area ratio of foam on the surface of the return liquid after the second preset ventilation time, and the eligibility of the ventilation treatment is determined based on the condition that the foam area ratio is greater than or equal to the preset area ratio, and the foam on the surface of the return liquid is scraped off.

[0071] Specifically, the amount of coagulant added is determined according to the bubble floating speed from the ventilation position to the liquid surface, and based on the condition that the bubble floating speed is less than the preset floating speed of 0.3 m / s, the amount of coagulant added is determined to be the first amount of 60 mg / L.

[0072] In the embodiment of the present invention, the preset floating speed is 0.3 m / s, and the first addition amount is 60 mg / L, but the above values ​​are not limited thereto, and those skilled in the art may also adjust the values ​​according to actual needs.

[0073] Specifically, the amount of coagulant added is determined according to the bubble floating speed from the ventilation position to the liquid surface, and based on the condition that the bubble floating speed is greater than or equal to the preset floating speed, the amount of coagulant added is determined to be the second amount of 50 mg / L.

[0074] In the embodiment of the present invention, the second addition amount is 50 mg / L, but the above value is not limited thereto, and those skilled in the art may also adjust the value according to actual needs.

[0075] Specifically, by determining the rising speed of bubbles, the viscosity of the return fluid in the area where the bubbles pass can be inferred, thereby determining the content of pollutants in the return fluid. Therefore, by adding coagulants to precipitate some organic matter, the viscosity of the area where the bubbles pass can be reduced, so that the rising of bubbles is not affected by excessive pollutants.

[0076] Specifically, the eligibility of the coagulant injection method is determined based on the change in the amount of foam on the surface of the return liquid after coagulation and sedimentation. 3 The coagulant input method is judged as unqualified based on the conditions, and the coagulant input density is adjusted according to the proportion of bubble-free area on the backflow liquid surface.

[0077] In the embodiment of the present invention, the preset change amount is 0.05m 3 , but the above value is not limited thereto, and those skilled in the art can also adjust the value according to actual needs.

[0078] Specifically, after coagulation and sedimentation, the viscosity of the area above the ventilation position decreases, which is conducive to the floating of bubbles. If the increase in foam on the liquid surface under this condition does not meet the preset standard, the coagulant addition method is judged to be unqualified.

[0079] Specifically, the coagulant input density is adjusted according to the bubble-free area ratio of the backflow liquid surface, and the coagulant input density is determined to be the first input density of 65 g / m based on the condition that the bubble-free area ratio is less than 5% of the preset bubble-free area ratio. 2 .

[0080] In the embodiment of the present invention, the preset bubble-free area ratio is 5%, and the first input density is 65g / m 2 , but the above value is not limited thereto, and those skilled in the art can also adjust the value according to actual needs.

[0081] Optionally, the optional types of coagulants include ferric chloride, polyferric sulfate, aluminum sulfate and polyaluminum chloride. In the embodiment of the present invention, the preferred coagulant is aluminum sulfate, which is used to separate the pollutants in the return liquid by sedimentation.

[0082] Specifically, the input density of the coagulant is adjusted according to the bubble-free area ratio of the backflow liquid surface, and the input density of the coagulant is determined to be the second input density of 70 g / m based on the condition that the bubble-free area ratio is greater than or equal to the preset bubble-free area ratio. 2 .

[0083] In the embodiment of the present invention, the second input density is 70g / m 2, but the above value is not limited thereto, and those skilled in the art can also adjust the value according to actual needs.

[0084] Specifically, by adjusting the input density of the coagulant, the contact area between the coagulant and the pollutants can be increased, thereby improving the treatment efficiency.

[0085] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

[0086] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for removing organic sulfur from oil and gas field flowback fluid, characterized in that: include: After the oil and gas field flowback fluid is passed into the treatment pool, the flowback fluid is subjected to flotation treatment; Divide the flowback liquid in the treatment pool into several layers, perform ventilation for a first preset time at the bottom of each layer, and determine the initial depth layer of ventilation according to the change in the foam on the surface of the flowback liquid after each layer is ventilated; Carry out pre-ventilation treatment to the initial depth layer and determine the parameters for bubble introduction according to the surface floating value of the return fluid; When the ventilation treatment is judged to be unqualified according to the proportion of foam on the surface of the return liquid after the second preset ventilation time, the amount of coagulant added is determined according to the floating speed of bubbles from the ventilation position to the liquid surface; When the ventilation treatment is judged to be qualified based on the proportion of foam on the surface of the return liquid after the second preset ventilation time, the qualification of the coagulant injection method is judged according to the change in the foam on the surface of the return liquid after coagulation and sedimentation; If the change in foam volume is less than the preset change, the coagulant input method is judged to be unqualified, and the coagulant input density is adjusted according to the bubble-free area ratio on the backflow liquid surface; The coagulant input method is determined to be qualified when the change in foam is greater than or equal to the preset change, and the ventilation position is moved down to a preset depth to continue processing after no pollutants are generated on the surface of the return liquid.

2. The method for removing organic sulfur from oil and gas field flowback fluid according to claim 1, characterized in that: The process of determining the initial depth layer of ventilation based on the change in the amount of foam on the backflow fluid surface includes: Divide the flowback liquid in the treatment tank vertically into several layers of equal depth; The first preset duration of ventilation from top to bottom for each layer of different depth layers of the return fluid; Determine the amount of foam change on the surface of the flowback fluid after each layer of ventilation; Compare the foam change amount of each layer with the preset foam change amount; Under the condition that the foam change amount is less than a preset foam change amount, a layer above the layer is determined as an initial depth layer.

3. The method for removing organic sulfur from oil and gas field flowback fluid according to claim 1, characterized in that: The process of determining the parameters of bubble introduction based on the surface float value of the return fluid includes: Under the condition that the surface floating value is less than the preset floating value, the parameters for the bubble introduction are determined to be the first bubble size and the first bubble quantity; Under the condition that the surface floating value is greater than or equal to the preset floating value, the parameters for determining the bubble introduction are a second bubble size and a second bubble quantity.

4. The method for removing organic sulfur from oil and gas field flowback fluid according to claim 1, characterized in that: The compliance of the ventilation treatment is determined based on the area ratio of foam on the surface of the return liquid after the second preset ventilation period. The ventilation treatment is judged to be unqualified when the foam area ratio is less than the preset area ratio, and the amount of coagulant added is determined based on the rising speed of bubbles from the ventilation position to the liquid surface.

5. The method for removing organic sulfur from oil and gas field flowback fluid according to claim 4, characterized in that: The eligibility of the ventilation treatment is determined based on the area ratio of the foam on the surface of the return liquid after the second preset ventilation time. The ventilation treatment is determined to be eligibility when the foam area ratio is greater than or equal to the preset area ratio, and the foam on the surface of the return liquid is scraped off.

6. The method for removing organic sulfur from oil and gas field flowback fluid according to claim 4, characterized in that: The amount of coagulant added is determined according to the bubble floating speed from the ventilation position to the liquid surface. Under the condition that the bubble floating speed is less than the preset floating speed, the amount of coagulant added is determined to be the first amount.

7. The method for removing organic sulfur from oil and gas field flowback fluid according to claim 6, characterized in that: The amount of coagulant added is determined according to the bubble floating speed from the ventilation position to the liquid surface, and under the condition that the bubble floating speed is greater than or equal to the preset floating speed, the amount of coagulant added is determined to be the second amount.

8. The method for removing organic sulfur from oil and gas field flowback fluid according to claim 1, characterized in that: The eligibility of the coagulant addition method is determined based on the change in foam on the surface of the return liquid after coagulation and sedimentation. If the change in foam is less than the preset change, the coagulant addition method is determined to be unqualified, and the coagulant addition density is adjusted based on the proportion of bubble-free area on the return liquid surface.

9. The method for removing organic sulfur from oil and gas field flowback fluid according to claim 8, characterized in that: The input density of the coagulant is adjusted according to the proportion of the bubble-free area on the surface of the return liquid. Under the condition that the proportion of the bubble-free area is less than the preset proportion of the bubble-free area, the input density of the coagulant is determined to be the first input density.

10. The method for removing organic sulfur from oil and gas field flowback fluid according to claim 9, characterized in that: The input density of the coagulant is adjusted according to the bubble-free area ratio of the backflow liquid surface, and the input density of the coagulant is determined to be the second input density under the condition that the bubble-free area ratio is greater than or equal to the preset bubble-free area ratio.

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