A graphene oxide-based nanocomposite desulfurizer for drilling fluid and preparation method thereof

Abstract

This patent application discloses a graphene oxide-based nanocomposite desulfurizer for drilling fluid and a preparation method thereof. The nanocomposite desulfurizer is made of graphene oxide and modified nano iron oxide, and the mass ratio of graphene oxide to modified nano iron oxide is 1:4-8. The present invention uses graphene oxide and modified nano iron oxide materials to prepare the nanocomposite desulfurizer. The surface of graphene oxide is rich in oxygen-containing functional groups, such as carboxyl, hydroxyl, etc., which are easy to adsorb inorganic nanoparticles, so the modified nano iron oxide particles are loaded on the graphene oxide. The nanocomposite desulfurizer prepared by the present invention not only relies on the chemical reaction of iron oxide and hydrogen sulfide to generate sulfide to remove hydrogen sulfide, but also improves the desulfurization effect of traditional solid treatment agents with high specific surface area and layered structure, improves the temperature resistance of the desulfurizer, and can reduce the drilling fluid loss, improve the rheology of the drilling fluid, and can be used in both water-based and oil-based drilling fluids to meet the needs of on-site drilling desulfurization construction.

Description

Technical Field

[0001] The invention relates to the field of desulfurization of oil and gas fields, and in particular to a graphene oxide-based nano-composite desulfurizer for drilling fluid and a preparation method thereof. Background Art

[0002] Hydrogen sulfide (H2S) is a highly toxic, flammable gas that is colorless and smells like rotten eggs. It is soluble in water and oil, and its solubility decreases as the temperature of the solution increases. When people are exposed to a concentration of 10ppm, their eyes may be irritated; at a concentration of 100ppm, they will experience coughing, eye irritation, and loss of smell within 3 to 15 minutes; at a concentration of 1000ppm, they will immediately lose consciousness, resulting in permanent brain damage or brain death.

[0003] At present, the Sichuan Basin, Tarim Basin, Ordos Basin and other areas in my country all contain high-sulfur gas reservoirs. During the drilling process of high-sulfur gas reservoirs, hydrogen sulfide intrusion into the drilling fluid will cause the following hazards: ① It will cause the pH value or alkalinity of the drilling fluid to decrease, affecting the performance of the drilling fluid, deteriorating the rheological properties and filtration properties, affecting the carrying of rock cuttings, the stability of the well wall, and causing the pressure of drilling and drilling; ② It will corrode the drill bit, and the metal will be damaged by hydrogen embrittlement, causing the sudden breakage of the downhole pipe string, the failure of the wellhead equipment, the explosion of the ground manifold and instrumentation, and cause a blowout or fire accident. ③ Hydrogen sulfide will spread into the air with the circulation of the drilling fluid, causing poisoning and other personal safety injuries.

[0004] Therefore, when encountering H2S gas invasion during oil and gas drilling, it is crucial to be able to remove H2S in the drilling fluid in a timely manner. At present, the removal efficiency of H2S in water-based or oil-based drilling fluids is mainly improved by adding desulfurizers to the drilling fluids, relying on physical adsorption or chemical reaction. Usually desulfurizers include solid desulfurizers and liquid desulfurizers. Solid desulfurizers include copper-based desulfurizers, iron-based desulfurizers, and zinc-based desulfurizers, but they have problems such as low desulfurization efficiency, flocculation and precipitation, and affecting the rheology and filtration of drilling fluids. Summary of the invention

[0005] In order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide a graphene oxide-based nanocomposite desulfurizer for drilling fluid and a preparation method thereof. The nanocomposite desulfurizer of the present invention not only relies on the chemical reaction of iron oxide and hydrogen sulfide to generate sulfide to remove hydrogen sulfide, but also improves the desulfurization effect of traditional solid treatment agents due to its high specific surface area and layered structure, improves the temperature resistance of the desulfurizer, and can reduce the filtration loss of drilling fluid and improve the rheology of drilling fluid. It can be used in both water-based and oil-based drilling fluids to meet the needs of on-site drilling desulfurization construction.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A graphene oxide-based nanocomposite desulfurizer for drilling fluid is prepared by compounding graphene oxide and modified nano iron oxide, wherein the mass ratio of graphene oxide to modified nano iron oxide is 1:4-8.

[0008] Compared with the prior art, the present invention has the following beneficial effects:

[0009] 1. The present invention utilizes graphene oxide and modified nano iron oxide materials to prepare nano composite desulfurizers. The surface of graphene oxide is rich in oxygen-containing functional groups, such as carboxyl, hydroxyl, etc., which are easy to adsorb inorganic nanoparticles, so modified nano iron oxide particles are loaded on graphene oxide. The nano composite desulfurizer prepared by the present invention not only relies on the chemical reaction of iron oxide and hydrogen sulfide to generate sulfide to remove hydrogen sulfide, but also has a high specific surface area and a layered structure to improve the desulfurization effect of traditional solid treatment agents, improve the temperature resistance of the desulfurizer, and can reduce the drilling fluid loss, improve the rheology of the drilling fluid, and can be used in both water-based and oil-based drilling fluids to meet the needs of on-site drilling desulfurization construction.

[0010] 2. By controlling the mass ratio of graphene oxide and modified nano-iron oxide to 1:4-8, the final prepared nanocomposite desulfurizer can have a "book page"-like multilayer structure with nanoparticle adsorption, and the formed "book page"-like multilayer structure is significant. The nanoparticles with high specific surface area increase the efficiency of hydrogen sulfide adsorption, and at the same time, the "book page"-like multilayer structure increases the adsorption efficiency of hydrogen sulfide on the surface. The desulfurizer formed by the composite of the two can significantly improve the desulfurization effect.

[0011] As a preferred embodiment of the present invention, the graphene oxide is prepared by the following method:

[0012] (1) 150-180 mg of graphite powder was mixed with 18-25 mL of sulfuric acid, stirred at 20-30° C., and 6-10 mL of nitric acid was added. After stirring for 20-25 h, the precipitate was washed at least three times with distilled water and dried;

[0013] (2) taking 35-45 mg of the dried product of step (1), adding 8-12 mL of sulfuric acid and stirring at 12-18° C., adding 100-140 mg of potassium permanganate during the process, stirring for 20-25 h, and adding 25-35 mL of distilled water during the process;

[0014] (3) adding 5 to 8 mL of hydrogen peroxide and centrifuging after 30 to 45 minutes to obtain a precipitate;

[0015] (4) washing the precipitate at least three times with 3-5 mL of chloric acid and then washing at least three times with deionized water;

[0016] (5) Add 35-45 mg NaHCO3 to the obtained mixture, adjust the pH to 7-7.5, centrifuge to obtain a precipitate, and dry the precipitate to obtain graphene oxide.

[0017] The graphene oxide prepared by the above method has a significant "book page" multilayer structure and a large specific surface area. Using it as an adsorbent can disperse the modified nano iron oxide to the greatest extent to form a nano composite structure. The prepared nano composite desulfurizer has better desulfurization performance.

[0018] As a preferred embodiment of the present invention, the modified nano iron oxide is prepared by the following method:

[0019] (1) Add 30-50 mL of anhydrous ethanol and 10-30 mL of deionized water into a reaction container, add 10-20 g of nano-iron oxide, and place the reaction container in an ultrasonic disperser for 40-60 minutes;

[0020] (2) adding a silane coupling agent, the silane coupling agent accounting for 10-20% of the mass fraction of the nano-iron oxide, adjusting the pH to 4-5 with dilute hydrochloric acid, stirring for 5-10 hours, and the temperature during stirring is 60-90° C.;

[0021] (3) After standing and centrifuging, the lower precipitate is removed, washed with anhydrous ethanol and deionized water at least three times respectively, filtered and dried to obtain modified nano-iron oxide.

[0022] Nano iron oxide has a high specific surface area and high specific surface energy, and its surface is covered with many hydroxyl groups. It is a polar substance and is easy to agglomerate, which limits the effect of its ultrafine effect. The modified nano iron oxide prepared by the above method has greatly reduced surface polarity and uniform particle size, which can effectively improve the dispersion ability and affinity of nano iron oxide in the solution and improve the surface properties of nano iron oxide. The modified nano iron oxide can be fully dispersed on the "book page" multilayer structure graphene oxide, and the desulfurization effect is significant.

[0023] The embodiment of the present invention also provides a method for preparing a graphene oxide-based nanocomposite desulfurizer for drilling fluid, comprising the following steps:

[0024] (1) Add 40-160 g of modified nano-iron oxide into 80-100 mL of anhydrous ethanol and disperse in an ultrasonic disperser for 30-40 min;

[0025] (2) adding 10 to 20 g of graphene oxide, controlling the mass ratio of graphene oxide to modified nano-iron oxide to be 1:4 to 8, and stirring in a constant temperature water bath at 75 to 85° C. for 4 h;

[0026] (3) The lower part is allowed to stand and precipitate, filtered, and placed in an oven for drying to prepare a graphene oxide-based nanocomposite desulfurizer for drilling fluid.

[0027] By adopting the above preparation method, by controlling the mass ratio of graphene oxide and modified nano iron oxide, and controlling the preparation at the above reaction temperature and time, the final product can have a "book page"-like multilayer structure with nanoparticle adsorption, and the "book page"-like multilayer structure is significant. The nanoparticles with high specific surface area increase the efficiency of hydrogen sulfide adsorption, and the "book page"-like multilayer structure increases the adsorption efficiency of hydrogen sulfide on the surface. The desulfurizer formed by the combination of the two can significantly improve the desulfurization effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a scanning electron microscope image of the nanocomposite desulfurizer prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0029] Typical embodiments that embody the features and advantages of the present invention will be described in detail in the following description. It should be understood that the present invention can have various changes in different embodiments without departing from the scope of the present invention, and the descriptions and illustrations therein are essentially used for illustration purposes rather than for limiting the present invention.

[0030] Example 1

[0031] This embodiment discloses a graphene oxide-based nanocomposite desulfurizer for drilling fluid, which is composited from graphene oxide and modified nano iron oxide, wherein the mass ratio of graphene oxide to modified nano iron oxide is 1:6.

[0032] Wherein, graphene oxide is prepared by the following method:

[0033] (1) 160 mg of graphite powder was mixed with 20 mL of sulfuric acid, stirred with a magnetic stirrer at 25° C., and 8 mL of nitric acid was added. After stirring for 24 h, the precipitate was washed three times with distilled water and finally dried in an oven at 50° C.;

[0034] (2) Take 40 mg of the dried product of step (1), add 10 mL of sulfuric acid and stir with a magnetic stirrer at 14 ° C. During the process, add 120 mg of potassium permanganate and stir for 24 h. During the process, add 30 mL of distilled water;

[0035] (3) Add 6 mL of hydrogen peroxide, and after 45 min, centrifuge at 4000 rpm / min for 10 min to obtain a precipitate;

[0036] (4) The precipitate was washed three times with 3 mL of chloric acid and then washed three times with deionized water;

[0037] (5) Add 40 mg NaHCO3 to the obtained mixture, adjust the pH to 7-7.5, centrifuge to obtain a precipitate, and dry the precipitate to obtain graphene oxide.

[0038] Among them, the modified nano iron oxide is prepared by the following method:

[0039] (1) Add 30 mL of anhydrous ethanol and 10 mL of deionized water into a reaction container, add 10 g of nano-iron oxide, and place the reaction container in an ultrasonic disperser for 60 min;

[0040] (2) adding 1 g of silane coupling agent, the silane coupling agent accounting for 10% of the mass fraction of nano-iron oxide, adjusting the pH to 4-5 with dilute hydrochloric acid, stirring for 10 hours, and the temperature during stirring is 60°C;

[0041] (3) After standing and centrifuging, the lower precipitate was removed, washed three times with anhydrous ethanol and deionized water respectively, filtered and dried in a 60° C. vacuum oven for 16 h to obtain modified nano-iron oxide.

[0042] This embodiment also provides a method for preparing the above-mentioned graphene oxide-based nanocomposite desulfurizer for drilling fluid, comprising the following steps:

[0043] (1) Add 40 g of modified nano-iron oxide into 100 mL of anhydrous ethanol and disperse in an ultrasonic disperser for 35 min;

[0044] (2) Add 10 g of graphene oxide and stir in a constant temperature water bath at 80 °C for 4 h;

[0045] (3) The lower precipitate is allowed to stand and filtered, placed in an oven to dry, and placed at 80° C. for 16 hours to prepare a graphene oxide-based nanocomposite desulfurizer for drilling fluid.

[0046] like Figure 1 As shown, it is a scanning electron microscope image of the graphene oxide-based nanocomposite desulfurizer for drilling fluid prepared in this embodiment. It can be seen from the figure that the desulfurizer has a "page-like" multilayer structure of nanoparticle adsorption. Both the nanoparticles and the layered structure can increase the adsorption specific surface area and enhance the desulfurization effect.

[0047] Example 2

[0048] This embodiment discloses a graphene oxide-based nanocomposite desulfurizer for drilling fluid, which is composited from graphene oxide and modified nano iron oxide, wherein the mass ratio of graphene oxide to modified nano iron oxide is 1:4.

[0049] In this embodiment, the preparation of modified nano iron oxide and graphene oxide is the same as that in Example 1.

[0050] Example 3

[0051] This embodiment discloses a graphene oxide-based nanocomposite desulfurizer for drilling fluid, which is composited from graphene oxide and modified nano iron oxide, wherein the mass ratio of graphene oxide to modified nano iron oxide is 1:7.

[0052] In this embodiment, the preparation of modified nano iron oxide and graphene oxide is the same as that in Example 1.

[0053] Desulfurization efficiency test of desulfurizer

[0054] The graphene oxide-based nanocomposite desulfurizer for drilling fluid of the invention was added to water-based and oil-based drilling fluids to evaluate its effect on rheology and filtration loss and test the desulfurization rate.

[0055] Water-based drilling fluid formula: 4% bentonite slurry + 0.4% CMC~LV + 0.5% KPAM + 1% NH4HPAN + 3% FT~1 + 2% SPNH + 2% SMP.

[0056] Oil-based drilling fluid formula: white oil + 5% emulsifier HFMO + 20% CaCl2 solution + 3% organic soil HFEL + 5% lime + 5% filtration reducer HFLO + 4% ultrafine calcium carbonate.

[0057] The evaluation test method is as follows:

[0058] Prepare 400mL of drilling fluid, add 2% mass concentration of graphene oxide-based nanocomposite desulfurizer for drilling fluid, pour into a special aging tank to prevent hydrogen sulfide pollution, open the valve stem of the aging tank after sealing, use a 500ppm hydrogen sulfide gas bottle (the rest is nitrogen) to fill the aging tank with 1MPa hydrogen sulfide gas, and then roll age for 16 hours at 150℃. Test the rheology and filtration performance of the drilling fluid before and after adding the desulfurizer, and use a pump-suction hydrogen sulfide detector to test the hydrogen sulfide concentration in the aging tank after aging to evaluate the desulfurization efficiency. The temperature condition for high temperature and high pressure filtration loss test is 150℃.

[0059] Table 1 Basic properties and desulfurization efficiency of water-based drilling fluid

[0060]

[0061] Table 2 Basic properties and desulfurization efficiency of oil-based drilling fluid

[0062]

[0063]

[0064] It can be seen from Table 1 and Table 2 that the graphene oxide-based nanocomposite desulfurizer for drilling fluid prepared by the present invention can be used in both water-based and oil-based drilling fluids, has a temperature resistance of 150°C, and a desulfurization efficiency of >99%. It can improve the rheological properties of the drilling fluid, increase the dynamic-plastic ratio, enhance the rock-carrying effect, and significantly reduce the drilling fluid loss, thus meeting the technical requirements for desulfurization of drilling fluid in high-sulfur formations on site.

[0065] It can be clearly seen from Tables 1 and 2 that the desulfurization rate in water-based and oil-based drilling fluids using the nanocomposite desulfurizer in Examples 1-3 can reach more than 99%, while the desulfurization rate of the existing commonly used solid desulfurizer, basic zinc carbonate, is less than 40%, and the desulfurization rate of the commonly used liquid desulfurizer, alcohol ether amide complex, is less than 60%. It can be seen that the desulfurization rate of the desulfurizer prepared by the present invention is significantly higher.

[0066] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A graphene oxide-based nanocomposite desulfurizer for drilling fluid, characterized in that: It is made of graphene oxide and modified nano iron oxide, and the mass ratio of graphene oxide to modified nano iron oxide is 1:4-8; The graphene oxide is prepared by the following method: (1) Mix 150-180 mg of graphite powder with 18-25 mL of sulfuric acid, stir at 20-30°C, add 6-10 mL of nitric acid, stir for 20-25 hours, wash the precipitate with distilled water at least three times, and dry; (2) Take 35-45 mg of the dried product of step (1), add 8-12 mL of sulfuric acid and stir at 12-18 °C, add 100-140 mg of potassium permanganate, stir for 20-25 h, and add 25-35 mL of distilled water; (3) Add 5 to 8 mL of hydrogen peroxide and centrifuge for 30 to 45 minutes to obtain a precipitate; (4) The precipitate was washed at least three times with 3-5 mL of chloric acid and then washed at least three times with deionized water; (5) adding 35-45 mg NaHCO3 to the obtained mixture, adjusting the pH to 7-7.5, centrifuging to obtain a precipitate, and drying the precipitate to obtain graphene oxide; The modified nano iron oxide is prepared by the following method: (1) Add 30-50 mL of anhydrous ethanol and 10-30 mL of deionized water into a reaction container, add 10-20 g of nano-iron oxide, and place the reaction container in an ultrasonic disperser for 40-60 minutes; (2) Add silane coupling agent, the silane coupling agent accounts for 10-20% of the mass fraction of nano-iron oxide, adjust the pH to 4-5 with dilute hydrochloric acid, stir for 5-10 hours, and the temperature during stirring is 60-90°C; (3) After standing and centrifuging, remove the lower precipitate, wash it with anhydrous ethanol and deionized water at least three times respectively, filter and dry it to obtain modified nano-iron oxide.

2. The graphene oxide-based nanocomposite desulfurizer for drilling fluid according to claim 1, characterized in that: The mass ratio of the graphene oxide to the modified nano iron oxide is 1:6-8.

3. The method for preparing a graphene oxide-based nanocomposite desulfurizer for drilling fluid according to any one of claims 1 to 2, characterized in that: The following steps are involved: (1) Add 40-80 g of modified nano-iron oxide into 80-100 mL of anhydrous ethanol and disperse in an ultrasonic disperser for 30-40 min; (2) Add 10-20 g of graphene oxide and stir in a constant temperature water bath at 75-85 °C for 4 h; (3) The lower part is allowed to stand and precipitate, and then filtered, and then placed in an oven for drying to prepare a graphene oxide-based nanocomposite desulfurizer for drilling fluid.

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