A water quality stabilizer for oilfield reinjection water and its preparation method

Abstract

This invention provides an oilfield reinjection water quality stabilizer and its preparation method, belonging to the field of oil well water treatment technology. The water quality stabilizer comprises nitrogen-doped nano-carbon quantum dots; one preparation method includes the following steps: dissolving citric acid and organic amine in water to prepare a reaction solution; heating the reaction solution to 180-280℃, followed by centrifugal filtration; concentrating and drying the filtrate to obtain nitrogen-doped nano-carbon quantum dots. The oilfield reinjection water quality stabilizer provided by this invention uses nitrogen-doped nano-carbon quantum dots as the water quality stabilizer. Its composition is simple, the dosage is small, and it exhibits significant bactericidal, corrosion-inhibiting, and scale-inhibiting effects, making it suitable for stabilizing reinjection water quality during oil and gas field development.

Description

Technical Field

[0001] This invention relates to the field of oil well water treatment technology, specifically to an oilfield reinjection water quality stabilizer and its preparation method. Background Technology

[0002] In the mid-to-late stages of oilfield development, to maintain reservoir pressure and prolong the flow period of oil wells, the main method currently used is to inject water into the formation. This replenishes the void volume occupied by the extracted crude oil in the reservoir, stabilizing or increasing the reservoir pressure, thereby achieving high and stable oil production and improving the ultimate recovery rate. Most oilfields in my country currently employ water injection for oil recovery, and to improve subsequent extraction efficiency, water injection begins during the peak oilfield development period. However, during water injection, the water injected underground to replenish formation pressure is produced along with the crude oil. After oil-water separation, a large amount of oilfield wastewater is generated. This requires careful treatment before reinjection.

[0003] Oilfield reinjection water, produced along with crude oil, typically carries a large amount of contaminants, including minerals, organic matter, hydrogen sulfide, and numerous bacteria from the formation and crude oil. This reinjection water is prone to corrosion and scaling during treatment, leading to corrosion or blockage of subsequent water blending / injection systems and injection wells, thus affecting normal production. To address the pollution and corrosion caused by oilfield reinjection water, water quality stabilizers are currently the most common method used in oilfields to reduce corrosion and kill bacteria.

[0004] Patent CN107117722A discloses a water quality stabilizer for oilfield polyurethane-containing wastewater and its preparation method. The water quality stabilizer for oilfield polyurethane-containing wastewater is made of dodecyl dimethyl benzyl ammonium chloride, rosin amine polyoxyethylene ether, imidazoline derivative, water, and polyquaternary ammonium salt in a ratio of 15:10:5:62:8. The preparation method includes: adding dodecyl tertiary amine and water to a reaction vessel, raising the temperature inside the reaction vessel to 90-110℃, then adding benzyl chloride dropwise while maintaining the temperature inside the reaction vessel; after the addition of benzyl chloride, maintaining the temperature for 2-3 hours to generate dodecyl dimethyl benzyl ammonium chloride in the vessel; adding rosin amine to another reaction vessel, raising the temperature to 120℃ and starting to add ethylene oxide dropwise, maintaining the temperature inside the vessel at 120℃±5℃ and the pressure at 2-3 kPa during the dropwise addition, maintaining the temperature for 4-6 hours after the dropwise addition is completed; cooling to below 80℃, adding the above-mentioned dodecyl dimethyl benzyl ammonium chloride, water, imidazoline derivative, and polyquaternary ammonium salt to the reaction vessel, maintaining the temperature and stirring for 0.5 hours; lowering the temperature to below 50℃, and discharging to obtain the product.

[0005] Patent CN1357497A discloses a water quality stabilizer for circulating cooling water, which is composed of: 100 parts of phosphonocarboxylic acid derivatives (as a reference); 80-150 parts of sulfonate / carboxylic acid copolymers; 80-100 parts of zinc salts; 5-10 parts of copper corrosion inhibitors; and 10-20 parts of organic bromine bactericides (all by weight). This water quality stabilizer is suitable for circulating cooling water treatment in industries such as oil refining, chemical, fertilizer, pharmaceutical, and brewing, as well as for oilfield reinjection water treatment. It is particularly suitable for circulating cooling water treatment in thermal power plants, and is applicable to water with high hardness, high alkalinity, and high temperature. It is highly efficient, non-toxic, and has good thermal stability, effectively preventing corrosion and scaling of cooling equipment, and effectively controlling microorganisms.

[0006] Nitrogen-doped carbon quantum dots, as a novel nanomaterial, have attracted widespread attention in fields such as bioimaging, biolabeling, analytical chemistry, and catalysis due to their advantages including low toxicity, high fluorescence stability, good water solubility, and excellent optical properties. Currently, the applications of nitrogen-doped carbon quantum dots are mainly limited to bioimaging and metal ion detection.

[0007] Related research reports indicate that in order to address the impact of iron ions in wastewater and stabilize them, a series of studies on iron ion stabilization have been conducted. Based on multiple field surveys, sampling, and indoor experiments, a composite iron ion stabilizer has been developed. Through field application to current river wastewater, a good water quality stabilization effect has been achieved (Fan Tao. Research on water quality stabilization technology for oilfield wastewater [J]. Petroleum and Natural Gas Chemical Industry, 2011, 40(2): 214-214.). However, the literature does not use nitrogen-doped nano-carbon quantum dots as an oilfield water stabilizer.

[0008] Other studies have reported on the problem of excessive suspended solids content in produced water from the ternary composite flooding in Daqing Oilfield, which leads to the precipitation of colloidal carbonate particles and increased suspended solids content. These studies have developed a water quality stabilizer based on a chelation mechanism to inhibit the formation of new mineral particles in the produced water. Field application tests of the water quality stabilizer were conducted in the weakly alkaline ternary composite flooding in the North 2 West block and the strong alkaline ternary composite flooding in the Labei East block of Daqing Oilfield. The tests verified that the suspended solids content in the produced water after treatment with the water quality stabilizer reached the control index of 20 mg / L for reinjection into high-permeability reservoirs containing polymeric wastewater (Liu Wenjie. Application of water quality stabilizers in produced water treatment of ternary composite flooding [J]. Fine and Specialty Chemicals, 2013(07):16-19.). The literature mainly involves a water quality stabilizer based on a chelation mechanism, but does not involve the preparation of a novel stabilizer containing nitrogen-doped nano-carbon quantum dots and isopropanolamine.

[0009] In summary, nitrogen-doped carbon quantum dots, as a novel nanomaterial, have attracted widespread attention in fields such as bioimaging, biolabeling, analytical chemistry, and catalysis due to their advantages including low toxicity, high fluorescence stability, good water solubility, and excellent optical properties. Currently, the applications of nitrogen-doped carbon quantum dots are mainly limited to bioimaging and metal ion detection, but their application in oilfield water treatment has not yet been observed. Furthermore, most existing water quality stabilizers are corrosion inhibitors and bactericides formulated with various organic compounds, resulting in complex compositions and requiring large dosages. Therefore, there is an urgent need to develop a water quality stabilizer with simpler components and lower dosage requirements. Summary of the Invention

[0010] In view of the shortcomings of the existing technology, the present invention aims to provide an oilfield reinjection water quality stabilizer. The oilfield reinjection water quality stabilizer uses nitrogen-doped nano carbon quantum dots as the water quality stabilizer. Its composition is simple, and its corrosion inhibition and bactericidal effects are obvious. It also has a certain slow-release effect, a long action time, and reduces the amount of water quality stabilizer used.

[0011] This invention is achieved through the following technical solution:

[0012] On the one hand, the present invention provides an oilfield reinjection water quality stabilizer, which includes nitrogen-doped nano-carbon quantum dots.

[0013] Furthermore, the water quality stabilizer also includes any one of isopropanolamine, diisopropanolamine, or triisopropanolamine.

[0014] On the other hand, the present invention also provides a method for preparing the above-mentioned oilfield reinjection water quality stabilizer, which is simple and easy to promote and apply.

[0015] The preparation method includes the following steps:

[0016] (1) Dissolve citric acid and organic amine in water to prepare a reaction solution;

[0017] (2) After heating the reaction solution to 180-280℃, centrifuge and filter it. After concentrating and drying the filtrate, nitrogen-doped carbon nanotube quantum dots are obtained.

[0018] Furthermore, in some technical solutions, the mass ratio of citric acid to organic amine is 1:0.5-1;

[0019] Preferably, the mass ratio of citric acid to organic amine is 1:0.8-1;

[0020] More preferably, the mass ratio of citric acid to organic amine is 1:1, 1:0.5, or 1:0.8;

[0021] Furthermore, in some technical solutions, the reaction time in step (2) above is 3-8 hours;

[0022] Preferably, the reaction time in step (2) above is 5-6 hours;

[0023] More preferably, the reaction time in step (2) above is 3h, 5h, 6h or 8h.

[0024] Furthermore, in some technical solutions, the organic amine mentioned in step (1) above is one or more of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine and polyethyleneimine;

[0025] Preferably, the organic amine mentioned in step (1) above is one or more of ethylenediamine, diethylenetriamine, and polyethyleneimine;

[0026] More preferably, the organic amine mentioned in step (1) above is ethylenediamine or / and polyethyleneimine.

[0027] As a preferred technical solution, the preparation method of the oilfield reinjection water quality stabilizer specifically includes the following steps:

[0028] S1) Preparation of nitrogen-doped carbon nanotube quantum dots;

[0029] S2) The prepared nitrogen-doped carbon nanotubes are added to isopropanolamine, diisopropanolamine, or triisopropanolamine, water is added, the mixture is stirred, and the mixture is heated for 10-15 minutes to obtain the product.

[0030] Specifically, in step S1), the preparation of nitrogen-doped carbon nanotube quantum dots includes:

[0031] S11) Dissolve citric acid and organic amine in water to prepare a reaction solution;

[0032] S12) After heating the reaction solution to 180-280℃, centrifuge and filter the solution. After concentrating and drying the filtrate, nitrogen-doped carbon nanotube quantum dots are obtained.

[0033] Furthermore, in some technical solutions, the mass ratio of citric acid to organic amine is 1:0.5-1;

[0034] Preferably, the mass ratio of citric acid to organic amine is 1:0.8-1;

[0035] More preferably, the mass ratio of citric acid to organic amine is 1:1, 1:0.5, or 1:0.8;

[0036] Furthermore, in some technical solutions, the reaction time in step (2) above is 3-8 hours;

[0037] Preferably, the reaction time in step (2) above is 5-6 hours;

[0038] More preferably, the reaction time in step (2) above is 3h, 5h, 6h or 8h.

[0039] Furthermore, in some technical solutions, the organic amine mentioned in step (1) above is one or more of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine and polyethyleneimine;

[0040] Preferably, the organic amine mentioned in step (1) above is one or more of ethylenediamine, diethylenetriamine, and polyethyleneimine;

[0041] More preferably, the organic amine mentioned in step (1) above is ethylenediamine or / and polyethyleneimine.

[0042] Furthermore, in some technical solutions, the reaction temperature in step S2) above is 50-80℃;

[0043] Preferably, the reaction temperature in step S2) above is 50-60°C;

[0044] More preferably, the reaction temperature in step S2) above is 50°C, 60°C or 80°C;

[0045] Preferably, the heating reaction in step S2) above lasts for 12-15 minutes;

[0046] More preferably, the heating reaction in step S2) above is 10 min, 12 min, or 15 min.

[0047] In some preferred embodiments, the mass ratio of nitrogen-doped carbon nanotubes to isopropanolamine is 1:0.15-0.3;

[0048] Preferably, the mass ratio of the nitrogen-doped carbon nanotube quantum dots to isopropanolamine is 1:0.2-0.3.

[0049] The mass ratio of the nitrogen-doped carbon nanotubes to diisopropanolamine is 1:0.15-0.3;

[0050] Preferably, the mass ratio of the nitrogen-doped carbon nanotube quantum dots to diisopropanolamine is 1:0.2-0.3.

[0051] The mass ratio of the nitrogen-doped carbon nanotubes to triisopropanolamine is 1:0.15-0.3;

[0052] Preferably, the mass ratio of the nitrogen-doped carbon nanotube quantum dots to triisopropanolamine is 1:0.2-0.3.

[0053] This invention also provides the application of the above-mentioned oilfield reinjection water quality stabilizer in oilfield reinjection water.

[0054] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0055] This invention addresses the problem of large quantities of contaminated oilfield reinjection water generated during oil and gas field development. This reinjection water severely pollutes and corrodes equipment, affecting its service life and hindering oil and gas field development. Therefore, a water quality stabilizer is needed to reduce the corrosion and pollution caused by the contaminated reinjection water. Existing water quality stabilizers are mostly corrosion inhibitors and bactericides formulated with various organic compounds, resulting in complex compositions and requiring large dosages. This invention provides an oilfield reinjection water quality stabilizer and its preparation method, using nitrogen-doped nano-carbon quantum dots as the water quality stabilizer. Its composition is simple, the dosage is small, and it exhibits significant bactericidal, corrosion-inhibiting, and scale-inhibiting effects, making it suitable for stabilizing reinjection water quality during oil and gas field development. Detailed Implementation

[0056] The present invention will be further described below with reference to the embodiments.

[0057] Example 1: A water quality stabilizer for oilfield reinjection water

[0058] Prepared using the following method:

[0059] Citric acid and ethylenediamine in a mass ratio of 1:1 were dissolved in deionized water to prepare a reaction solution with a citric acid mass concentration of 10%. The reaction solution was heated to 180°C and reacted for 8 hours. After centrifugation and filtration, the filtrate was concentrated and dried to obtain nitrogen-doped carbon nanoparticles, which were taken as product A.

[0060] Example 2: A water quality stabilizer for oilfield reinjection water

[0061] Prepared using the following method:

[0062] Citric acid and ethylenediamine in a mass ratio of 1:0.5 were dissolved in deionized water to prepare a reaction solution with a citric acid mass concentration of 10%. The reaction solution was heated to 280℃ and reacted for 3 hours. After centrifugation and filtration, the filtrate was concentrated and dried to obtain nitrogen-doped carbon nanoparticles, which were taken as product B.

[0063] Example 3: A water quality stabilizer for oilfield reinjection water

[0064] Prepared using the following method:

[0065] Citric acid and ethylenediamine in a mass ratio of 1:0.8 were dissolved in deionized water to prepare a reaction solution with a citric acid mass concentration of 10%. The reaction solution was heated to 220℃ and reacted for 5 hours. After centrifugation and filtration, the filtrate was concentrated and dried to obtain nitrogen-doped carbon nanoparticles, which were taken as product C.

[0066] Example 4: A water quality stabilizer for oilfield reinjection water

[0067] Prepared using the following method:

[0068] Citric acid and polyethyleneimine in a mass ratio of 1:1 were dissolved in deionized water to prepare a reaction solution with a citric acid mass concentration of 10%. The reaction solution was heated to 250°C and reacted for 6 hours. After centrifugation and filtration, the filtrate was concentrated and dried to obtain nitrogen-doped carbon nanoparticles, which were taken as product D.

[0069] Example 5: A water quality stabilizer for oilfield reinjection water

[0070] Prepared using the following method:

[0071] S1) Preparation of nitrogen-doped carbon nanotube quantum dots:

[0072] S11) Dissolve citric acid and ethylenediamine in deionized water at a mass ratio of 1:0.8 to prepare a reaction solution with a citric acid mass concentration of 10%.

[0073] S12) After heating the reaction solution to 220℃ and reacting for 5 hours, centrifuge and filter the solution. After concentrating and drying the filtrate, nitrogen-doped carbon nanotube quantum dots are obtained.

[0074] S2) Nitrogen-doped carbon nanotubes and isopropanolamine were weighed in a mass ratio of 1:0.3. The weighed nitrogen-doped carbon nanotubes were added to isopropanolamine, water was added and stirred, and the mixture was heated to 50°C for 15 min to obtain product E.

[0075] Example 6: A water quality stabilizer for oilfield reinjection water

[0076] Prepared using the following method:

[0077] S1) Preparation of nitrogen-doped carbon nanotube quantum dots:

[0078] S11) Dissolve citric acid and ethylenediamine in deionized water at a mass ratio of 1:0.8 to prepare a reaction solution with a citric acid mass concentration of 10%.

[0079] S12) After heating the reaction solution to 220℃ and reacting for 5 hours, centrifuge and filter the solution. After concentrating and drying the filtrate, nitrogen-doped carbon nanotube quantum dots are obtained.

[0080] S2) Nitrogen-doped carbon nanotubes and isopropanolamine were weighed in a mass ratio of 1:0.15. The weighed nitrogen-doped carbon nanotubes were added to isopropanolamine, water was added and stirred, and the mixture was heated to 80°C and reacted for 10 min to obtain product F.

[0081] Example 7: A water quality stabilizer for oilfield reinjection water

[0082] Prepared using the following method:

[0083] S1) Preparation of nitrogen-doped carbon nanotube quantum dots:

[0084] S11) Dissolve citric acid and ethylenediamine in deionized water at a mass ratio of 1:0.8 to prepare a reaction solution with a citric acid mass concentration of 10%.

[0085] S12) After heating the reaction solution to 220℃ and reacting for 5 hours, centrifuge and filter the solution. After concentrating and drying the filtrate, nitrogen-doped carbon nanotube quantum dots are obtained.

[0086] S2) Nitrogen-doped carbon nanotubes and isopropanolamine were weighed in a mass ratio of 1:0.2. The weighed nitrogen-doped carbon nanotubes were added to isopropanolamine, water was added and stirred, and the mixture was heated to 60°C and reacted for 12 minutes to obtain product G.

[0087] Example 8: A water quality stabilizer for oilfield reinjection water

[0088] Prepared using the following method:

[0089] S1) Preparation of nitrogen-doped carbon nanotube quantum dots:

[0090] S11) Dissolve citric acid and polyethyleneimine in deionized water at a mass ratio of 1:1 to prepare a reaction solution with a citric acid mass concentration of 10%.

[0091] S12) After heating the reaction solution to 250℃ and reacting for 6 hours, centrifuge and filter the solution. After concentrating and drying the filtrate, nitrogen-doped carbon nanotube quantum dots are obtained.

[0092] S2) Weigh nitrogen-doped carbon nanotubes and isopropanolamine in a mass ratio of 1:0.2. Add the weighed nitrogen-doped carbon nanotubes to isopropanolamine, add water, stir, and heat to 60°C for 12 min to obtain product H.

[0093] The water quality stabilizer prepared above was diluted with water to a solution of 10 mg / L, and then added to the flowing oilfield reinjection water for dynamic simulation experiments and scale inhibition experiments. The test results are shown in Table 1 below.

[0094] Table 1

[0095]

[0096] As can be seen from the test results in Table 1 above, the water quality stabilizer provided by this invention can significantly reduce the corrosion and pollution of equipment by contaminated reinjection water, thereby significantly reducing the corrosion rate.

[0097] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A water quality stabilizer for oilfield reinjection water, characterized in that: The oilfield reinjection water quality stabilizer includes nitrogen-doped nano-carbon quantum dots and isopropanolamine; The preparation method of the oilfield reinjection water quality stabilizer includes the following steps: S1) Preparation of nitrogen-doped carbon nanotube quantum dots; S2) The prepared nitrogen-doped carbon nanotubes were added to isopropanolamine, water was added and stirred, and the mixture was heated for 10-15 min to obtain the product. Specifically, in step S1), the preparation of nitrogen-doped carbon nanotube quantum dots includes: S11) Dissolve citric acid and organic amine in water to prepare a reaction solution; S12) After heating the reaction solution to 180-280℃, centrifuge and filter the solution. After concentrating and drying the filtrate, nitrogen-doped carbon nanotube quantum dots are obtained. In step S2), the heating reaction temperature is 50-60℃, and the mass ratio of nitrogen-doped carbon nanotube quantum dots to isopropanolamine is 1:0.15-0.

3.

2. A method for preparing the oilfield reinjection water quality stabilizer as described in claim 1, characterized in that: Includes the following steps: S1) Preparation of nitrogen-doped carbon nanotube quantum dots; S2) The prepared nitrogen-doped carbon nanotubes were added to isopropanolamine, water was added and stirred, and the mixture was heated for 10-15 min to obtain the product. Specifically, in step S1), the preparation of nitrogen-doped carbon nanotube quantum dots includes: S11) Dissolve citric acid and organic amine in water to prepare a reaction solution; S12) After heating the reaction solution to 180-280℃, centrifuge and filter the solution. After concentrating and drying the filtrate, nitrogen-doped carbon nanotube quantum dots are obtained. In step S2), the heating reaction temperature is 50-60℃, and the mass ratio of nitrogen-doped carbon nanotube quantum dots to isopropanolamine is 1:0.15-0.

3.

3. The method for preparing the oilfield reinjection water quality stabilizer according to claim 2, characterized in that: In step S11), the mass ratio of citric acid to organic amine is 1:0.5-1.

4. The method for preparing the oilfield reinjection water quality stabilizer according to claim 2, characterized in that: The reaction time in step S12) is 3-8 hours.

5. The method for preparing the oilfield reinjection water quality stabilizer according to claim 2, characterized in that: In step S11), the organic amine is one or more of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and polyethyleneimine.

6. The application of the oilfield reinjection water quality stabilizer prepared by the method of claim 1 or any one of claims 2-5 in oilfield reinjection water.

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