A non-triazine desulfurizing agent and its preparation method

Abstract

This invention relates to the field of oil and gas field development and discloses a non-triazine desulfurizer and its preparation method. The preparation method includes the following steps: adding quaternary ammonium salt, hexamethylenetetramine, sodium nitrite, and deionized water into a reaction vessel; heating the reaction vessel and maintaining a constant temperature while stirring until completely dissolved; adding monoethanolamine to the reaction vessel and continuing stirring to form a mixed solution; adding aminotrimethylenephosphonic acid to the reaction vessel; stirring evenly under constant temperature conditions; and cooling and discharging. The non-triazine desulfurizer of this invention has the characteristics of rapid desulfurization and high sulfur capacity, and can effectively remove hydrogen sulfide in a short time; the desulfurization products are environmentally degradable, have no adverse effects on the quality of crude oil or natural gas, and will not cause scaling in the produced water system; it can be applied to various scenarios such as drilling mud, acid fracturing processes, completion fluids, and production gathering and transportation sites; the dosage can be flexibly adjusted according to the hydrogen sulfide concentration and construction process, and the operation is simple.

Description

Technical Field

[0001] This invention relates to the field of oil and gas field development, specifically to a non-triazine desulfurizing agent and its preparation method. Background Technology

[0002] Hydrogen sulfide, a highly toxic gas, is often generated during oil and gas field development, posing a significant hazard to both personnel and equipment. Effective prevention and control of hydrogen sulfide is crucial for the safe development of oil and gas fields. To ensure personal safety, prevent hydrogen sulfide poisoning incidents, reduce the harm of hydrogen sulfide to production equipment, and minimize its environmental pollution, it is essential to strengthen preventative and control measures for hydrogen sulfide. The mechanism of hydrogen sulfide generation mainly includes the following three aspects: (1) Deep within oil and gas reservoirs, there are usually large amounts of sulfate-reducing bacteria. Formation temperature and abundant ammonium and nitrate ions provide favorable conditions for their growth. The metabolic products of sulfate-reducing bacteria contain large amounts of hydrogen sulfide. Furthermore, during oil and gas field development, water injection wells are frequently used to inject water into the oil layer to protect its pressure. Some untreated wastewater often contains sulfate-reducing bacteria. (2) Hydrogen sulfide is often generated along with the metabolic and degradation products of organisms. (3) Thermochemical reduction of sulfates leads to the generation of high-abundance hydrogen sulfide from natural gas. Since hydrogen sulfide is an acidic gas, various alkaline compounds can be used as conventional desulfurizing agents, belonging to the category of non-triazine desulfurizing agents. For example, calcium-based desulfurization uses limestone, slaked lime, etc., as desulfurizing agents, utilizing the chemical and physical stability of calcium sulfate to achieve desulfurization; sodium-based desulfurization uses caustic soda and soda ash as desulfurizing agents. Patent publication number CN102485323A discloses a rapid calcium-based flue gas desulfurization method, using limestone (calcium carbonate) or calcium carbide sludge (calcium hydroxide) as absorbent and sulfate as process absorbent. The flue gas enters the middle of the absorption tower and contacts the absorbent liquid in a countercurrent manner for mass transfer, leaving from the top of the tower. Most of the slurry at the bottom of the tower circulates in the absorption tower, while a small portion of the slurry is sent for separation and dehydration. The liquid phase process water is returned to the absorption system and / or used as calcium slurry, while the solid phase is sent for post-treatment. However, these non-triazine conventional desulfurizers do not achieve ideal desulfurization efficiency in practical applications. Furthermore, because these non-triazine conventional desulfurizers are alkaline, they cause some environmental pollution and are prone to forming scale with calcium and magnesium ions in water, which can then clog pipes. Summary of the Invention

[0003] To overcome the shortcomings of the prior art, the present invention provides a non-triazine desulfurizing agent and its preparation method, the technical solution of which is as follows:

[0004] A method for preparing a non-triazine desulfurizing agent, comprising the following steps:

[0005] (1) Preliminary batching: Add 8-15 parts by weight of quaternary ammonium salt, 8-12 parts by weight of hexamethylenetetramine, 20-30 parts by weight of sodium nitrite, and 40-45 parts by weight of deionized water into the reactor respectively; the quaternary ammonium salt is dodecyl quaternary ammonium salt or tetradecyl quaternary ammonium salt;

[0006] (2) Heating and stirring: Heat the reactor to 55-60°C and keep it at a constant temperature while stirring until completely dissolved;

[0007] (3) Add ingredients again: Add 5-10 parts by weight of monoethanolamine to the reactor and continue stirring to form a mixed solution;

[0008] (4) Compound preparation: Add aminotrimethylenephosphonic acid to the reaction vessel, the amount of which is 1% to 2% of the mass of the mixed solution in step (3);

[0009] (5) Stirring at a constant temperature: Stir for 3 to 4 hours at a constant temperature of 55 to 60°C;

[0010] (6) Cool down and discharge the material.

[0011] Furthermore, in step (1), there are 8 parts by weight of quaternary ammonium salt, 12 parts by weight of hexamethylenetetramine, 30 parts by weight of sodium nitrite, and 40 parts by weight of deionized water.

[0012] Furthermore, in step (1), 13 parts by weight of quaternary ammonium salt, 10 parts by weight of hexamethylenetetramine, 20 parts by weight of sodium nitrite, and 45 parts by weight of deionized water are used.

[0013] Furthermore, in step (1), 15 parts by weight of quaternary ammonium salt, 8 parts by weight of hexamethylenetetramine, 27 parts by weight of sodium nitrite, and 42 parts by weight of deionized water are used.

[0014] Furthermore, the reactor is equipped with an alarm device that will sound an alarm when the temperature inside the reactor deviates from the range of 55-60°C.

[0015] Furthermore, the constant temperature stirring time in step (2) is 1 to 2 hours.

[0016] A non-triazine desulfurizing agent is prepared by the method described above.

[0017] Compared with the prior art, the present invention has the following main advantages:

[0018] 1. High-efficiency desulfurization: Non-triazine desulfurizers have the characteristics of rapid desulfurization and high sulfur capacity, and can effectively remove hydrogen sulfide in a short time;

[0019] 2. Environmentally friendly and pollution-free: Desulfurization products are environmentally degradable, have no adverse effects on the quality of crude oil or natural gas, and will not cause scaling in the produced water system;

[0020] 3. Wide range of applications: It can be applied to various scenarios such as drilling mud, acid fracturing process, completion fluid and production gathering and transportation site;

[0021] 4. Easy to use: The dosage can be flexibly adjusted according to the hydrogen sulfide concentration and construction process, and the operation is simple. Attached Figure Description

[0022] Figure 1 This is a graph showing the hydrogen sulfide monitoring data at the wellhead of pile 59-45 in Experiment Example 2;

[0023] Figure 2 The graph shows the changes in calcium and magnesium ions at different drug concentrations in Experiment Example 4;

[0024] Figure 3 This is a comparison chart of the conventional desulfurizing agent before and after the test in Experiment Example 4;

[0025] Figure 4 The image shows a comparison of the non-triazine desulfurizer prepared in Example 1 of Experiment 4 before and after the test. Detailed Implementation

[0026] The present invention will now be described in detail with reference to the embodiments and accompanying drawings. Example 1

[0027] A method for preparing a non-triazine desulfurizing agent, comprising the following steps:

[0028] (1) Mixing: Add 8 parts by mass of dodecyl quaternary ammonium salt, 12 parts by mass of hexamethylenetetramine, 30 parts by mass of sodium nitrite and 40 parts by mass of deionized water into the reactor respectively; heat to 55°C and stir at a constant temperature for 1 hour until completely dissolved; then add 10 parts by mass of monoethanolamine and continue stirring to form a mixed solution;

[0029] (2) Compound preparation: Add aminotrimethylene phosphonic acid to the above mixture at a dosage of 1%, keep at a constant temperature of 55°C, and stir for 3 hours;

[0030] (3) Discharge: After mixing evenly, cool down and discharge the material. Example 2

[0031] A method for preparing a non-triazine desulfurizing agent, comprising the following steps:

[0032] (1) Mixing: Add 13 parts by mass of tetradecyl quaternary ammonium salt, 10 parts by mass of hexamethylenetetramine, 20 parts by mass of sodium nitrite and 45 parts by mass of deionized water into the reactor respectively; heat to 58°C and stir at a constant temperature for 1.5 hours until completely dissolved; then add 5 parts by mass of monoethanolamine and continue stirring to form a mixed solution;

[0033] (2) Compound preparation: Add aminotrimethylenephosphonic acid to the above mixed solution at a dosage of 1%, keep at a constant temperature of 58°C, and stir for 3.5 hours;

[0034] (3) Discharge: After mixing evenly, cool down and discharge the material. Example 3

[0035] A method for preparing a non-triazine desulfurizing agent, comprising the following steps:

[0036] (1) Mixing: Add 15 parts by mass of tetradecyl quaternary ammonium salt, 8 parts by mass of hexamethylenetetramine, 27 parts by mass of sodium nitrite and 42 parts by mass of deionized water into the reaction vessel respectively; heat to 60°C and stir at a constant temperature for 2 hours until completely dissolved; then add 8 parts by mass of monoethanolamine and continue stirring to form a mixed solution;

[0037] (2) Compound preparation: Add aminotrimethylenephosphonic acid to the above mixed solution at a dosage of 2%, keep the temperature at 60℃, and stir for 4 hours;

[0038] (3) Discharge: After mixing evenly, cool down and discharge the material.

[0039] Experimental Example 1

[0040] In July 2024, our company selected eleven wells in the Xinyuan Management Area of ​​Dongsheng Company for experimental testing. The highest hydrogen sulfide content at the wellheads in the Xinyuan Management Area exceeded 350 mg / m³, mainly distributed in the He 122-1 block. The Xinyuan Management Area is primarily a low-permeability reservoir, mainly developed using waterflooding. In recent years, the number of wells containing hydrogen sulfide and the hydrogen sulfide content have shown a gradual increase, indicating that the hydrogen sulfide formation is secondary to waterflooding. The He 122-1 block is the largest development unit in Xinyuan, with a relatively closed reservoir, no edge or bottom water, and a good injection-production relationship. Furthermore, the injection-production system pipeline in this block is well-developed. Therefore, this block was selected for analysis of the formation mechanism and remediation of hydrogen sulfide in waterflooding. The number of wells containing hydrogen sulfide in this unit has shown a year-on-year upward trend since 2022. After treatment using a novel non-triazine desulfurizing agent, the average hydrogen sulfide content has stabilized. Currently, the average single-well hydrogen sulfide concentration in the He 122-1 block is below 20.0 mg / m³.

[0041] Starting July 5, 2024, based on an average of 100 mg / m³ per well. 3 The hydrogen sulfide content was calculated by gradually adding the non-triazine desulfurizer prepared according to Example 1, with a daily addition of approximately 20 kg. The table below shows the monitoring data of hydrogen sulfide content at the wellhead after continuous addition of the non-triazine desulfurizer prepared in Example 1 (see Table 1).

[0042] Table 1. Chemical dosing in eleven wells in the Xinyuan pipeline area (non-triazine desulfurizer prepared in Example 1)

[0043] Hydrogen sulfide content in one month

[0044] .

[0045] Experiment Example 2

[0046] From July to October 2024, our company conducted a single-well treatment test, selecting the single well "Zhuang 59-45" in the Zhuangxi Oil Production Plant Management Area. Ten days after the agent was added, the hydrogen sulfide content dropped to 30 mg / m³. After three months of continuous addition, the hydrogen sulfide gas produced by SRB bacteria was suppressed.

[0047] Starting July 5, 2024, based on an average of 100 mg / m³ per well. 3 The hydrogen sulfide content was calculated, and the non-triazine desulfurizing agent prepared according to Example 2 was gradually added dropwise for desulfurization, with a daily dosage of about 20 kg. Figure 1 To continuously desulfurize for three months using the non-triazine desulfurizer prepared in Example 2, the hydrogen sulfide content at the wellhead was monitored. Figure 1 The data shows that the hydrogen sulfide concentration has decreased significantly and meets the technical requirements of the relevant authorities.

[0048] Experimental Example 3

[0049] In November 2024, our company selected 6 wells in the current Hezhuang Management Area for experiments. Table 2 shows the basic production situation and hydrogen sulfide content at the wellhead of the six wells.

[0050] Starting November 1, 2024, based on an average of 100 mg / m³ per well. 3 The hydrogen sulfide content was calculated by gradually adding the non-triazine desulfurizer prepared according to Example 3, with a daily addition of approximately 20 kg. The table below shows the hydrogen sulfide content data at the wellhead after one month of continuous addition of the non-triazine desulfurizer prepared in Example 3 (see Table 3).

[0051] Table 2 Production Overview of Six Wells in Xianhezhuang Management Area

[0052] .

[0053] Table 3. Results of continuous chemical dosing (using the non-triazine desulfurizer prepared in Example 3) at six wells in the Xianhezhuang Management Area

[0054] Hydrogen sulfide content at the wellhead

[0055] .

[0056] As can be seen from the above Experiment Example 3, for the Guan 114 well with a large inflow of fluid, the non-triazine desulfurizer prepared in Example 3 has a better effect on removing hydrogen sulfide.

[0057] Experiment Example 4

[0058] A comparative experiment was conducted using a conventional desulfurizing agent and the non-triazine desulfurizing agent prepared in Example 1.

[0059] Since conventional desulfurizing agents have a pH of about 9, well jamming often occurred during the early stages of wellbore addition. Analysis showed that conventional desulfurizing agents are alkaline, which reacts with calcium and magnesium ions in the on-site water to form scale, causing well jamming.

[0060] The non-triazine desulfurizer prepared in Example 1 was used to conduct the following scaling test.

[0061] On October 30, 2024, a scaling test was conducted on well No. Guan 114-X17 in the current Hezhuang management area.

[0062] (a) Basic on-site production situation, see Table 4.

[0063] Table 4 Basic Production Status on Site

[0064] .

[0065] (ii) Water analysis results, see Table 5(1) and Table 5(2).

[0066] Table 5 (1) Water analysis results (water sample taken on October 30, 2024)

[0067] .

[0068] Table 5 (2) Water analysis results (water sample taken on October 30, 2024)

[0069] .

[0070] (III) Test Methods

[0071] 1. Test conditions

[0072] Test medium: Free water separated from produced fluid from on-site oil wells

[0073] Scaling tests were conducted according to standard GB 7477 "Determination of Total Calcium and Magnesium in Water by EDTA Titration".

[0074] 2. Test Procedure

[0075] (1) Separate the free water from the produced fluid from the oil well on site and filter it;

[0076] (2) Based on the on-site liquid volume of 8.4m 3 The maximum dosage is 30 kg / day, so the following six dosage concentrations were selected for testing: 10 kg / day, 20 kg / day, 30 kg / day, 40 kg / day, 60 kg / day, and 100 kg / day. The calcium and magnesium content of the non-triazine desulfurizer prepared in Example 1 at different dosage concentrations compared to conventional desulfurizers is shown in Table 6. Figure 2 .

[0077] Table 6. Calcium and magnesium content at different dosage concentrations

[0078] ;

[0079] Note: The EDTA concentration is 0.0015 mol / L, and the water sample volume is 20 mL.

[0080] Based on the above experimental data, when titrating with the non-triazine desulfurizer prepared in Example 1, the total amount of calcium and magnesium ions in the produced water did not change significantly with the increase of the dosage concentration; when using conventional desulfurizer, the concentration of calcium and magnesium ions in the produced water decreased accordingly, and scaling tended to occur.

[0081] The research results recorded in the article "The Influence of Solution pH on Calcium Carbonate Scaling" published in Volume 33, Issue 5 (September 2004) of *Petrochemical Equipment* indicate that, for a given total calcium concentration, the higher the pH value, the greater the scaling index and the stronger the scaling tendency. Measurements show that the pH of the non-triazine desulfurizer prepared in Example 1 is approximately 7, while the pH of the conventional non-triazine desulfurizer is approximately 9. This experiment demonstrates that the conventional non-triazine desulfurizer exhibits a significantly stronger scaling tendency than the non-triazine desulfurizer prepared in Example 1, which is consistent with the aforementioned research results from *Petrochemical Equipment*.

[0082] 3. Simulated salt water laboratory scaling test

[0083] 3% calcium chloride and 5% desulfurizing agent were added to a test tube at a 1:1 ratio. After 24 hours in an 85℃ oven, precipitation occurred when using conventional desulfurizing agents. (See [link to relevant documentation]). Figure 3 The solution prepared using the non-triazine desulfurizer in Example 1 was clear, without layering or precipitation. (See [reference]). Figure 4 .

[0084] The above experiments show that the non-triazine desulfurizer prepared in Example 1 does not have a significant tendency to scale in the wellbore, thus preventing well jamming.

Claims

1. A method for preparing a non-triazine desulfurizing agent, characterized in that, Includes the following steps: (1) Preliminary batching: Add 8-15 parts by weight of quaternary ammonium salt, 8-12 parts by weight of hexamethylenetetramine, 20-30 parts by weight of sodium nitrite, and 40-45 parts by weight of deionized water into the reactor respectively; the quaternary ammonium salt is dodecyl quaternary ammonium salt or tetradecyl quaternary ammonium salt; (2) Heating and stirring: Heat the reactor to 55-60°C and keep it at a constant temperature while stirring until completely dissolved; (3) Add ingredients again: Add 5-10 parts by weight of monoethanolamine to the reactor and continue stirring to form a mixed solution; (4) Compound preparation: Add aminotrimethylenephosphonic acid to the reaction vessel, the amount of which is 1% to 2% of the mass of the mixed solution in step (3); (5) Stirring at a constant temperature: Stir for 3 to 4 hours at a constant temperature of 55 to 60°C; (6) Cooling down and discharging; The reactor is equipped with an alarm device that will alert the user when the temperature inside the reactor deviates from the range of 55-60°C.

2. The method for preparing a non-triazine desulfurizer according to claim 1, characterized in that, The step (1) consists of 8 parts by weight of quaternary ammonium salt, 12 parts by weight of hexamethylenetetramine, 30 parts by weight of sodium nitrite, and 40 parts by weight of deionized water.

3. The method for preparing a non-triazine desulfurizer according to claim 1, characterized in that, The step (1) consists of 13 parts by weight of quaternary ammonium salt, 10 parts by weight of hexamethylenetetramine, 20 parts by weight of sodium nitrite, and 45 parts by weight of deionized water.

4. The method for preparing a non-triazine desulfurizer according to claim 1, characterized in that, The step (1) consists of 15 parts by weight of quaternary ammonium salt, 8 parts by weight of hexamethylenetetramine, 27 parts by weight of sodium nitrite, and 42 parts by weight of deionized water.

5. The method for preparing a non-triazine desulfurizing agent according to claim 1, characterized in that, The constant temperature stirring time in step (2) is 1 to 2 hours.

6. A non-triazine desulfurizer, characterized in that, It is prepared by the method described in any one of claims 1-5 for a non-triazine desulfurizing agent.

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