Selective high-efficiency inorganic composite plugging agent and preparation method thereof

Abstract

The invention discloses a selective high-efficiency inorganic composite plugging agent and a preparation method thereof in the field of oilfield exploitation. The selective high-efficiency inorganic composite plugging agent comprises the following components in parts by weight: 10-20 parts of modified sludge, 5-15 parts of inorganic gel, 4-8 parts of a tackifier, 0.5-0.7 part of sodium citrate and 0.1-0.3 part of sulfamate. Through the synergistic effect of the modified sludge and the inorganic gel, the plugging agent can accurately plug a water flow channel without too much influence on an oil layer, and the stability of the plugging agent in an underground oil field is ensured by adding the inorganic gel. The gel can form a firm blocking layer in a short time, so that a water flow channel is effectively blocked, further flowing of water is prevented, meanwhile, the tackifier and the modified sludge in the profile control agent enhance the lasting stability of the profile control agent in a high-temperature and high-pressure environment, and the long-term effectiveness of the blocking effect is guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of oilfield exploitation, and specifically refers to a selective and efficient inorganic composite plugging agent and a preparation method thereof. Background Art

[0002] Plugging technology is a very critical technical means in oil production. It is mainly used to plug high permeability channels or water drive channels in underground oil and gas reservoirs to improve the recovery rate of oil fields and extend the production life of oil fields. With the deepening of oil field exploitation, traditional water plugging and plugging technology can no longer meet the needs, especially in the face of complex underground environments, low oil recovery efficiency and growing environmental protection pressure. There is an urgent need to develop more efficient, more environmentally friendly and more selective plugging materials.

[0003] Traditional plugging agents mainly include two categories: organic and inorganic. Inorganic plugging agents are widely used in cement plugging, well wall stabilization and other fields in oil fields due to their advantages such as good high temperature resistance, salt and alkali resistance and relatively low price. However, traditional inorganic plugging agents also have some shortcomings. First, the effect of inorganic plugging agents in selective water plugging is limited, and it is often difficult to achieve precise control, resulting in poor plugging effect on the oil layer, and may even affect the exploitation of the oil-producing layer. Secondly, inorganic plugging agents may lose stability under extreme conditions such as certain temperature and pressure, resulting in difficulty in maintaining the plugging effect, affecting the long-term effect of plugging. Furthermore, traditional inorganic plugging agents often have the problem of being difficult to degrade, which may cause secondary pollution.

[0004] In response to these problems, the traditional inorganic plugging agent is modified to improve its plugging performance and selectivity, so that it can better meet the exploitation needs of complex oil and gas reservoirs. The main advantage of inorganic composite plugging agent is that by adding different additives and modified materials, its physical and chemical properties are adjusted to improve the selective plugging ability of different permeability layers, while maintaining high stability and durability. Summary of the invention

[0005] In view of the above situation, in order to overcome the defects of the prior art, the present invention provides a selective and efficient inorganic composite plugging agent and a preparation method thereof. The plugging agent can accurately block the water flow channel without causing too much impact on the oil layer through the synergistic effect of modified sludge and inorganic gel. The addition of inorganic gel ensures the stability of the plugging agent in the underground oil field. The gel can form a solid plugging layer in a short time, thereby effectively blocking the water flow channel and preventing further flow of water. At the same time, the viscosity enhancer and modified sludge in the plugging agent enhance the long-term stability of the plugging agent in high temperature and high pressure environments, ensuring the long-term effectiveness of the plugging effect.

[0006] In order to achieve the above-mentioned object, the technical solution adopted by the present invention is as follows: the present invention proposes a selective and efficient inorganic composite plugging agent, the inorganic composite plugging agent comprises the following components in parts by weight: 10-20 parts of modified sludge, 5-15 parts of inorganic gel, 4-8 parts of thickener, 0.5-0.7 parts of sodium citrate, and 0.1-0.3 parts of aminosulfonate;

[0007] Preferably, the method for preparing the inorganic gel comprises the following steps:

[0008] P1. Dissolve (3-mercaptopropyl)trimethoxysilane and tetraethoxysilane in anhydrous methanol, add DMF and mix well, stir at 180-220 rpm for 10-15 min, add ammonia solution, increase the stirring speed to 300-350 rpm, react for 30 min, and obtain SiO2 wet gel;

[0009] Preferably, in step S1, the mass ratio between the (3-mercaptopropyl)trimethoxysilane and tetraethoxysilane is 1:3-4;

[0010] Preferably, in step S1, the mass concentration of tetraethoxysilane in anhydrous methanol is 0.1-0.2 g / mL;

[0011] Preferably, in step S1, the volume ratio between anhydrous methanol and DMF is 1:3-4;

[0012] Preferably, in step S1, the ammonia solution is obtained by mixing concentrated ammonia water and deionized water, and the mass fraction of the ammonia solution is 10%-15%; the added volume of the ammonia solution is 10%-20% of the volume of anhydrous methanol;

[0013] P2, dissolving aluminum sec-butoxide in anhydrous ethanol, mixing with the SiO2 wet gel prepared in step S1, stirring at 100-120 rpm for 20-30 min, adding an ammonia solution, continuing to stir and react for 2-3 h, centrifuging at 2000-3000 rpm for 5-10 min, removing the supernatant, and obtaining an inorganic gel;

[0014] Preferably, in step S2, the mass volume ratio between tetraethoxysilane and aluminum sec-butoxide is 4-5 g / mL;

[0015] Preferably, in step S2, the volume fraction of the aluminum sec-butoxide in anhydrous ethanol is 1.3-2.0%;

[0016] Preferably, in step S2, the ammonia solution is obtained by mixing concentrated ammonia water and deionized water, and the mass fraction of the ammonia solution is 10%-15%; the added volume of the ammonia solution is 20%-30% of the volume of anhydrous ethanol;

[0017] Preferably, the method for preparing the modified sludge specifically comprises the following steps:

[0018] P3. Place the oily sludge in a constant temperature drying oven, dry it at 100-110°C for 6-8h, grind it, pass it through a 20-40 mesh sieve, add it to petroleum ether, stir it at 150-180rpm, react it for 1-2h, filter it, collect the solid, place it in a 1mol / L hydrochloric acid solution, raise the temperature to 60-80°C, stir it at 200-300rpm, react it for 1-2h, filter it, collect the solid, wash it repeatedly with acetone and deionized water, and dry it to obtain deoiled sludge;

[0019] Preferably, in step P3, the mass volume ratio between the oily sludge and petroleum ether is 0.05-0.1 g / mL;

[0020] P4, dissolving the silane coupling reagent KH550 in anhydrous ethanol, adding the deoiled sludge prepared in step P3, raising the temperature to 60-80°C, stirring at a speed of 150-180rpm, reacting for 2-4h, cooling, filtering, washing with anhydrous ethanol and deionized water, and drying to obtain pretreated sludge;

[0021] Preferably, in step P4, the mass concentration of the silane coupling reagent KH550 in anhydrous ethanol is 10-50 g / L;

[0022] Preferably, in step P4, the mass ratio between the silane coupling agent KH550 and the deoiled sludge is 1:3-5;

[0023] P5, dissolving cysteine ​​in an ethanol aqueous solution, adding EDC and NHS, stirring at 120-150 rpm for 20-40 min, adjusting the pH to 2-3, adding the pretreated sludge prepared in step P4 to the reaction system, introducing nitrogen, heating to 40-60°C under a nitrogen atmosphere, stirring at 200-250 rpm for 4-6 h, cooling, washing with anhydrous ethanol and deionized water, and drying to obtain modified sludge;

[0024] Preferably, in step P5, the mass concentration of cysteine ​​in the ethanol aqueous solution is 20-30 g / L;

[0025] Preferably, in step P5, the mass ratio of cysteine, EDC and NHS is 1-1.2:1.5-1.8:1.8-2.1;

[0026] Preferably, in step P5, the mass ratio between the pretreated sludge and cysteine ​​is 4-6:1;

[0027] Preferably, the preparation method of the tackifier comprises the following steps:

[0028] P6. Dissolve lipoic acid in DMAC, add CDI, mix well, introduce nitrogen, raise the temperature to 40-50° C. in a nitrogen atmosphere, activate the reaction for 8-10 hours, add N-(2-hydroxyethyl) acrylamide, continue stirring at 150-180 rpm, raise the reaction temperature to 80-90° C., react for 12-16 hours, cool, concentrate under reduced pressure to remove the reaction solvent, add deionized water for washing, and freeze-dry to obtain acrylamide-lipoic acid ester;

[0029] Preferably, in step P6, the mass concentration of lipoic acid in DMAC is 20-40 g / L;

[0030] Preferably, in step P6, the mass ratio between CDI and lipoic acid is 1:1.2-1.5;

[0031] Preferably, in step P6, the mass ratio between the N-(2-hydroxyethyl)acrylamide and lipoic acid is 0.5-0.7:1;

[0032] P7, dissolving the acrylamide-lipoic acid ester and methacrylamide prepared in step P6 in DMAC, placing under a nitrogen atmosphere, adding azobisisobutyronitrile, raising the temperature to 80-90° C., reacting for 2-3 hours, removing excess reaction solvent, and drying to obtain a tackifier;

[0033] Preferably, in step P7, the mass ratio between the acrylamide-lipoic acid ester and methacrylamide is 1:4-6;

[0034] Preferably, in step P7, the mass concentration of methacrylamide in DMAC is 0.12-0.2 g / mL;

[0035] Preferably, in step P7, the mass of azobisisobutyronitrile added is 0.5%-1% of the mass of methacrylamide.

[0036] The present invention also provides a method for preparing a selective and efficient inorganic composite plugging agent, which specifically comprises the following steps:

[0037] S1, dissolving the inorganic gel in deionized water, stirring at a speed of 500-700 rpm, adding a tackifier, and continuing to stir and mix for 1-2 hours, and mixing evenly to obtain a mixture;

[0038] Preferably, in step S1, the mass concentration of the inorganic gel in deionized water is 80-100 g / L;

[0039] S2. Add the modified sludge to the mixture prepared in step S2, stir until the reaction system is in a uniform state, add sodium citrate and aminosulfonate, increase the temperature to 40-50° C., use a high-speed stirrer to stir at a speed of 10000-12000 rpm, and after cooling and drying, obtain an inorganic plugging agent.

[0040] The beneficial effects achieved by the present invention are as follows:

[0041] The present invention provides a selective and efficient inorganic composite plugging agent. Through the synergistic effect of modified sludge and inorganic gel, the plugging agent can accurately block the water flow channel without causing too much impact on the oil layer. The addition of inorganic gel ensures the stability of the plugging agent in the underground oil field. The gel can form a solid plugging layer in a short time, thereby effectively blocking the water flow channel and preventing the further flow of water. At the same time, the thickener and modified sludge in the plugging agent enhance the long-term stability of the plugging agent under high temperature and high pressure environment, ensuring the long-term effectiveness of the plugging effect; the modified sludge, as one of the key components in the present invention, is mainly derived from oily sludge. After multi-step modification treatment, it has good physical and chemical stability and strong selective plugging ability. Through acid washing, oil removal, surface modification (such as silane coupling agent KH550 treatment, cysteine ​​modification, etc.) of the sludge, the modified sludge can significantly improve its compatibility with the inorganic gel and enhance its plugging effect in the high permeability layer. Through these treatments, the modified sludge can not only effectively improve the adhesion of the plugging agent, but also continue to play a plugging role in the complex underground environment of the oil field, reducing the formation of water drive layers; the inorganic gel can quickly form a stable gel structure in the high permeability channel through the gelation reaction, block the water flow channel, prevent water from entering the oil layer, and maintain the crude oil production of the oil field. Specifically, the preparation process described in steps P1 and P2 generates SiO2 wet gel through the reaction of (3-mercaptopropyl)trimethoxysilane and tetraethoxysilane, which is then mixed with aluminum sec-butoxide and treated with ammonia water to form an inorganic gel, ensuring that it has good gel strength and stability. When the inorganic gel is mixed with other components, it can quickly solidify in the underground environment and form a solid plugging layer. The high stability of the inorganic gel ensures that it will not fail under high temperature and high pressure environments and can maintain the plugging effect for a long time; the addition of the viscosity enhancer to the plugging agent is to enhance its rheology and adhesion so that it can be more evenly distributed in the complex underground oil reservoirs. The thickener (copolymer of acrylamide-lipoic acid ester and methacrylamide) described in steps P6 and P7 can increase the viscosity of the plugging agent, ensure the stability of the plugging agent during the injection process of the oil field, and is not prone to stratification or sedimentation. This enhanced rheological property enables the plugging agent to accurately block the water flow channel in the underground oil layer, while maintaining good permeability to the oil layer, avoiding negative impact on crude oil production; the selective and efficient inorganic composite plugging agent prepared by the present invention can effectively improve the plugging efficiency in oil field exploitation, prolong the plugging effect, reduce the impact of water drive on the oil layer, and ultimately improve the oil field recovery rate. In addition, the use of a combination of various raw materials such as modified sludge and inorganic gel not only enhances the performance of the plugging agent, but also reduces the cost, and has good economy and environmental protection. These technical advantages make the present invention have broad application prospects and practical value in the process of oil field development. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1The figure is a result diagram of the suspension performance of the inorganic composite profile control agent prepared in Examples 1-3 of the present invention and Comparative Examples 1-3;

[0043] Figure 2 The results of the consolidated mud properties of the inorganic composite profile control agents prepared in Examples 1-3 and Comparative Examples 1-3 of the present invention are shown;

[0044] Figure 3 This is a graph showing the erosion resistance performance of the inorganic composite profile control agent prepared in Examples 1-3 of the present invention and Comparative Examples 1-3.

[0045] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention. DETAILED DESCRIPTION

[0046] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0047] Unless otherwise defined, all professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to those described herein may be applied to the present invention. The preferred implementation methods and materials described herein are for demonstration purposes only and are not intended to limit the content of this application.

[0048] The experimental methods in the following examples are conventional methods unless otherwise specified; the experimental materials and test strains used in the following examples are purchased from commercial channels unless otherwise specified.

[0049] Example 1

[0050] This embodiment provides a selective and efficient inorganic composite plugging agent, which includes the following components in parts by weight: 10 parts of modified sludge, 15 parts of inorganic gel, 4 parts of viscosity enhancer, 0.7 parts of sodium citrate, and 0.3 parts of aminosulfonate;

[0051] The preparation method of the inorganic gel specifically comprises the following steps:

[0052] P1. Accurately weigh 1 g of (3-mercaptopropyl)trimethoxysilane and 4 g of tetraethoxysilane into a flask, add 40 mL of anhydrous methanol to dissolve the reactants, add 120 mL of DMF to mix well, place on a magnetic stirrer and stir at 200 rpm for 10 min, prepare a 15 wt% ammonia solution with concentrated ammonia water and deionized water, take 4 mL and add to the reaction system, increase the stirring speed to 300 rpm, stir and react for 30 min to obtain SiO2 wet gel;

[0053] P2, add 0.8 mL of aluminum sec-butoxide to 40 mL of anhydrous ethanol, mix until the reaction system is uniform, transfer to the SiO2 wet gel prepared in step S1 for mixing, stir at 100 rpm for 20 min, take 10 mL of the ammonia solution prepared in step S1, continue stirring for 2 h, centrifuge at 3000 rpm for 5 min, remove the supernatant, wash the precipitate repeatedly with deionized water until neutral, and obtain an organogel;

[0054] The method for preparing modified sludge specifically comprises the following steps:

[0055] P3. Place 20g of oily sludge in a constant temperature drying oven, dry at 100°C for 8h, grind, pass through a 40-mesh sieve, add to 400mL of petroleum ether, stir at 180rpm, react for 1h, filter, collect solids, place in 1mol / L hydrochloric acid solution, raise the temperature to 80°C, stir at 200rpm, react for 2h, filter, collect solids, wash repeatedly with acetone and deionized water, and dry to obtain deoiled sludge;

[0056] P4, dissolve 3 g of silane coupling reagent KH550 in 100 mL of anhydrous ethanol, add 15 g of the deoiled sludge prepared in step P3, raise the temperature to 80°C, stir and react at a speed of 150 rpm, react for 2 h, cool, filter, react and wash with anhydrous ethanol and deionized water, and dry to obtain pretreated sludge;

[0057] P5, dissolve 3g of cysteine ​​in 100mL of 75vol% ethanol aqueous solution, add 4.5g of EDC and 5.25g of NHS, stir at 150rpm for 20min, adjust the pH to 3, add 12g of the pretreated sludge prepared in step P4 to the reaction system, introduce nitrogen, heat to 50°C under a nitrogen atmosphere, stir at 220rpm for 5h, cool, wash with anhydrous ethanol and deionized water, and dry to obtain modified sludge;

[0058] The preparation method of the tackifier specifically comprises the following steps:

[0059] P6, 3.0g lipoic acid was dissolved in 100mL DMAC, 2.5g CDI was added, and the mixture was uniformly mixed. After nitrogen was introduced, the temperature was raised to 40°C under a nitrogen atmosphere, and the activation reaction was performed for 10h. Then, 1.8g N-(2-hydroxyethyl) acrylamide was added, and the mixture was stirred at 180rpm, the reaction temperature was raised to 80°C, and the reaction was performed for 16h. The mixture was cooled, concentrated under reduced pressure to remove the reaction solution, and deionized water was added for washing. After freeze-drying, acrylamide-lipoic acid ester was obtained;

[0060] P7, dissolving 3.5 g of acrylamide-lipoic acid ester and 14 g of methacrylamide prepared in step P6 in 100 mL of DMAC, placing under a nitrogen atmosphere, adding 70 mg of azobisisobutyronitrile, raising the temperature to 80° C., reacting for 3 h, removing excess reaction solvent, and drying to obtain a tackifier;

[0061] This embodiment also provides a method for preparing a selective and efficient inorganic composite plugging agent, which specifically comprises the following steps:

[0062] S1. Dissolve the inorganic gel in deionized water at a mass concentration of 90 g / L, stir at a speed of 700 rpm, add a tackifier, continue stirring and mixing for 1.5 hours, and mix evenly to obtain a mixture;

[0063] S2. Add the modified sludge to the mixture prepared in step S2, stir until the reaction system is in a uniform state, add sodium citrate and aminosulfonate, raise the temperature to 45° C., use a high-speed stirrer, stir at a speed of 11000 rpm, cool and dry, and obtain an inorganic plugging agent.

[0064] Example 2

[0065] This embodiment provides a selective and efficient inorganic composite plugging agent, which includes the following components in parts by weight: 20 parts of modified sludge, 10 parts of inorganic gel, 8 parts of viscosity enhancer, 0.5 parts of sodium citrate, and 0.1 parts of aminosulfonate;

[0066] The preparation method of the inorganic gel specifically comprises the following steps:

[0067] P1. Accurately weigh 1 g of (3-mercaptopropyl)trimethoxysilane and 3 g of tetraethoxysilane into a flask, add 15 mL of anhydrous methanol to dissolve the reactants, add 60 mL of DMF to mix well, place on a magnetic stirrer and stir at 220 rpm for 15 min, prepare a 10 wt% ammonia solution with concentrated ammonia water and deionized water, take 3 mL and add to the reaction system, increase the stirring speed to 300 rpm, stir and react for 30 min to obtain SiO2 wet gel;

[0068] P2, take 0.65mL of aluminum sec-butoxide and add it to 50mL of anhydrous ethanol, mix until the reaction system is in a uniform state, transfer to the SiO2 wet gel prepared in step S1 for mixing, stir and react at 120rpm for 30min, take 15mL of the ammonia solution prepared in step S1, continue stirring and reacting for 3h, centrifuge at 2000rpm for 10min, remove the supernatant, and repeatedly wash the precipitate with deionized water until it is neutral to obtain an inorganic gel;

[0069] The method for preparing modified sludge specifically comprises the following steps:

[0070] P3. Place 50g of oily sludge in a constant temperature drying oven, dry it at 110°C for 6h, grind it, pass it through a 40-mesh sieve, add it to 500mL of petroleum ether, stir it at 180rpm, react it for 2h, filter it, collect the solid, place it in a 1mol / L hydrochloric acid solution, raise the temperature to 60°C, stir it at 300rpm, react it for 1h, filter it, collect the solid, wash it repeatedly with acetone and deionized water, and dry it to obtain deoiled sludge;

[0071] P4, take 5g of silane coupling reagent KH550 and dissolve it in 100mL of anhydrous ethanol, add 15g of the deoiled sludge prepared in step P3, raise the temperature to 80°C, stir and react at a speed of 180rpm, react for 3h, cool, filter, react and wash with anhydrous ethanol and deionized water, and dry to obtain pretreated sludge;

[0072] P5, dissolve 2g of cysteine ​​in 100mL of 75vol% ethanol aqueous solution, add 3g of EDC and 3.6g of NHS, stir at 150rpm for 40min, adjust the pH to 2, add 10g of the pretreated sludge prepared in step P4 to the reaction system, introduce nitrogen, heat to 40°C under a nitrogen atmosphere, stir at 250rpm for 4h, cool, wash with anhydrous ethanol and deionized water, and dry to obtain modified sludge;

[0073] The preparation method of the tackifier specifically comprises the following steps:

[0074] P6, 4.0g lipoic acid was dissolved in 100mL DMAC, 3.0g CDI was added, and the mixture was uniformly mixed. After nitrogen was introduced, the temperature was raised to 60°C under a nitrogen atmosphere, and the activation reaction was performed for 8h. Then, 2.8g N-(2-hydroxyethyl) acrylamide was added, and the mixture was stirred at 160rpm. The reaction temperature was raised to 85°C, and the mixture was reacted for 14h. The mixture was cooled, concentrated under reduced pressure to remove the reaction solution, and deionized water was added for washing. After freeze-drying, acrylamide-lipoic acid ester was obtained;

[0075] P7, dissolving 4 g of acrylamide-lipoic acid ester and 20 g of methacrylamide prepared in step P6 in 100 mL of DMAC, placing under a nitrogen atmosphere, adding 0.16 g of azobisisobutyronitrile, raising the temperature to 90° C., reacting for 2 h, removing excess reaction solvent, and drying to obtain a tackifier;

[0076] This embodiment also provides a method for preparing a selective and efficient inorganic composite plugging agent, which specifically comprises the following steps:

[0077] S1. Dissolve the inorganic gel in deionized water at a mass concentration of 80 g / L, stir at a speed of 600 rpm, add a tackifier, continue stirring and mixing for 2 hours, and mix evenly to obtain a mixture;

[0078] S2. Add the modified sludge to the mixture prepared in step S2, stir until the reaction system is in a uniform state, add sodium citrate and aminosulfonate, raise the temperature to 40° C., use a high-speed stirrer, stir at a speed of 12000 rpm, cool and dry, and obtain an inorganic plugging agent.

[0079] Example 3

[0080] This embodiment provides a selective and efficient inorganic composite plugging agent, which includes the following components in parts by weight: 15 parts of modified sludge, 5 parts of inorganic gel, 6 parts of viscosity enhancer, 0.6 parts of sodium citrate, and 0.2 parts of aminosulfonate;

[0081] The preparation method of the inorganic gel specifically comprises the following steps:

[0082] P1. Accurately weigh 1 g of (3-mercaptopropyl)trimethoxysilane and 4 g of tetraethoxysilane into a flask, add 20 mL of anhydrous methanol to dissolve the reactants, add 60 mL of DMF to mix well, place on a magnetic stirrer and stir at 180 rpm for 10 min, prepare a 15 wt% ammonia solution with concentrated ammonia water and deionized water, take 2 mL and add to the reaction system, increase the stirring speed to 300 rpm, stir and react for 30 min to obtain SiO2 wet gel;

[0083] P2, add 1 mL of aluminum sec-butoxide to 50 mL of anhydrous ethanol, mix until the reaction system is uniform, transfer to the SiO2 wet gel prepared in step S1 for mixing, stir at 120 rpm for 20 min, take 10 mL of the ammonia solution prepared in step S1, continue stirring for 2 h, centrifuge at 2500 rpm for 5 min, remove the supernatant, and repeatedly wash the precipitate with deionized water until it is neutral to obtain an inorganic gel;

[0084] The method for preparing modified sludge specifically comprises the following steps:

[0085] P3. Place 20g of oily sludge in a constant temperature drying oven, dry it at 100°C for 7h, grind it, pass it through a 30-mesh sieve, add it to 250mL of petroleum ether, stir it at 150rpm, react it for 1.5h, filter it, collect the solid, place it in a 1mol / L hydrochloric acid solution, raise the temperature to 70°C, stir it at 250rpm, react it for 1.5h, filter it, collect the solid, wash it repeatedly with acetone and deionized water, and dry it to obtain deoiled sludge;

[0086] P4, take 3g of silane coupling reagent KH550 and dissolve it in 300mL of anhydrous ethanol, add 12g of the deoiled sludge prepared in step P3, raise the temperature to 70°C, stir and react at a speed of 150rpm, react for 3h, cool, filter, react and wash with anhydrous ethanol and deionized water, and dry to obtain pretreated sludge;

[0087] P5, dissolve 2.5g of cysteine ​​in 100mL of 75vol% ethanol aqueous solution, add 3.8g of EDC and 4.5g of NHS, stir at 150rpm for 20min, adjust the pH to 2.5, add 12.5g of the pretreated sludge prepared in step P4 to the reaction system, introduce nitrogen, heat to 50°C under a nitrogen atmosphere, stir at 220rpm for 5h, cool, wash with anhydrous ethanol and deionized water, and dry to obtain modified sludge;

[0088] The preparation method of the tackifier specifically comprises the following steps:

[0089] P6, 2.0g lipoic acid was dissolved in 100mL DMAC, 1.3g CDI was added, and the mixture was uniformly mixed. After nitrogen was introduced, the temperature was raised to 50°C under a nitrogen atmosphere, and the activation reaction was performed for 9h. Then, 1.0g N-(2-hydroxyethyl) acrylamide was added, and the mixture was stirred at 150rpm. The reaction temperature was raised to 90°C, and the mixture was reacted for 12h. The mixture was cooled, concentrated under reduced pressure to remove the reaction solution, and deionized water was added for washing. After freeze-drying, acrylamide-lipoic acid ester was obtained;

[0090] P7, dissolving 2 g of acrylamide-lipoic acid ester and 12 g of methacrylamide prepared in step P6 in 100 mL of DMAC, placing under a nitrogen atmosphere, adding 0.12 g of azobisisobutyronitrile, raising the temperature to 85° C., reacting for 2.5 h, removing excess reaction solvent, and drying to obtain a tackifier;

[0091] This embodiment also provides a method for preparing a selective and efficient inorganic composite plugging agent, which specifically comprises the following steps:

[0092] S1. Dissolve the inorganic gel in deionized water at a mass concentration of 100 g / L, stir at a speed of 500 rpm, add a tackifier, continue stirring and mixing for 1 hour, and mix evenly to obtain a mixture;

[0093] S2. Add the modified sludge to the mixture prepared in step S2, stir until the reaction system is in a uniform state, add sodium citrate and aminosulfonate, raise the temperature to 50° C., use a high-speed stirrer, stir at a speed of 10,000 rpm, cool and dry, and obtain an inorganic plugging agent.

[0094] Comparative Example 1

[0095] This comparative example provides an inorganic profile control agent and a preparation method thereof, which is different from Example 1 only in that the modified sludge is replaced with the oil-containing sludge of the same weight, and the other components and component contents are the same as those in Example 1.

[0096] Comparative Example 2

[0097] This comparative example provides an inorganic profile control agent and a preparation method thereof, which differs from Example 1 only in that in step P1 of the preparation method of the inorganic gel, tetraethoxysilane is used instead of (3-mercaptopropyl)trimethoxysilane in the same weight fraction, and the remaining components and component contents are the same as those in Example 1.

[0098] Comparative Example 3

[0099] This comparative example provides an inorganic profile control agent and a preparation method thereof, which differs from Example 1 only in that the preparation method of the tackifier does not include P6, that is, N-(2-hydroxyethyl)acrylamide is not modified by lipoic acid, and the remaining components and component contents are the same as those in the example.

[0100] Experimental Example 1

[0101] In this experimental example, the suspension performance of the inorganic profile control agent prepared in Example 1-3 and Comparative Example 1-3 was measured. The inorganic composite profile control agent prepared in Example 1-3 and Comparative Example 1-3 was diluted with deionized water at 30 wt %, stirred and mixed at a speed of 2000 rpm, placed in a measuring cylinder, and allowed to stand at room temperature. The sedimentation was observed and the water separation rate was calculated according to the following formula:

[0102] Water separation rate (%) = (Vs-Vg) / Vs×100%;

[0103] Wherein, Vs is the total volume of the inorganic composite plugging agent dilution liquid before sedimentation, mL; Vg is the volume of the inorganic composite plugging agent after sedimentation, mL.

[0104] Figure 1The suspension performance result graph of the inorganic composite profile controlling agent prepared by Examples 1-3 of the present invention and Comparative Examples 1-3 is as shown in the figure. The water separation rates of the inorganic composite profile controlling agent prepared by Examples 1-3 within 10 minutes are 2.6%, 3.5% and 3.2%, and the water separation rates within 1 hour are 25.0%, 23.1% and 22.7%. Compared with the comparative example, the present invention removes oil and modifies the oily sludge, selects silane containing mercapto groups, and enhances the cross-linking ability of the inorganic composite profile controlling agent in the oil displacement system through the active effect of disulfide bonds. In the tackifier, the oil-containing thioctic acid side chain also enhances the stability of the inorganic composite profile controlling agent in the oil displacement system through the regulating performance of the disulfide bonds.

[0105] Experimental Example 2

[0106] In this experimental example, the consolidation mud properties of the inorganic composite profile control agent prepared in Examples 1-3 and Comparative Examples 1-3 were tested. The inorganic composite profile control agent prepared in Examples 1-3 and Comparative Examples 1-3 was diluted with deionized water at 30wt%, and a certain amount of mudstone sample was taken. After grinding and passing through a 40-mesh sieve, the mudstone sample was fully dried to remove moisture, and then added to a high-temperature and high-pressure consolidation device. The mudstone sample was added, and the temperature was usually set to 80°C, the pressure was set to 30 MPa, and 100 mL of the inorganic plugging agent was injected. After consolidation for 48 hours, the compressive strength was measured to represent the consolidated mud properties;

[0107] Figure 2 The consolidated mud performance result diagram of the inorganic composite profile controlling agent prepared by Examples 1-3 of the present invention and Comparative Examples 1-3 is shown in the figure. As shown in the figure, the compressive strength of the inorganic composite profile controlling agent reaches 11.4 MPa under mud-free conditions. As the mud ratio increases, the compressive strength after consolidation decreases. When the mud ratio reaches 90% of the inorganic composite profile controlling agent, the compressive strength of Examples 1-3 can reach more than 5.0 MPa, while the compressive strength of the inorganic composite profile controlling agent prepared by Comparative Example 1 is close to 1 MPa. The compressive strength of the inorganic composite profile controlling agent prepared by Comparative Example 2 is higher at the beginning, and the compressive strength decreases significantly with the increase of the mud ratio.

[0108] Experimental Example 3

[0109] In this experimental example, the scour resistance of the inorganic composite profile control agent prepared in Examples 1-3 and Comparative Examples 1-3 was measured, and the single-tube experimental model was used for measurement. The experimental steps included filling a sand filling tube, diluting the inorganic composite profile control agent prepared in Examples 1-3 and Comparative Examples 1-3 with deionized water at 30wt%, injecting it into a 1 / 2PV oil displacement system, placing it in a constant temperature box at the experimental temperature to achieve gelation, switching to water displacement, the pressure is 2PV, and observing the injection pressure.

[0110] Figure 3The results of the scour resistance of the inorganic composite profile control agent prepared in Examples 1-3 of the present invention and Comparative Examples 1-3 are shown in the figure. As shown in the figure, when switching to water drive, the subsequent displacement pressure gradually increases and stabilizes at 8.4 MPa, indicating that the plugging agent has formed an effective plugging on the core, and there is no obvious change in the subsequent water drive 2PV pressure, and the scour resistance is good.

[0111] While the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that many changes, modifications, substitutions and variations can be made to the embodiments without departing from the principles and spirit of the invention.

[0112] The present invention and its implementation methods are described above, which is not restrictive. The drawings are only one of the implementation methods of the present invention, and the actual application is not limited thereto. In short, if ordinary technicians in the field are inspired by it and design methods and embodiments similar to the technical solution without creativity without departing from the purpose of the invention, they should all fall within the protection scope of the present invention.

Claims

1. A selective and efficient inorganic composite plugging agent, characterized in that: The inorganic composite plugging agent comprises the following components in parts by weight: 10-20 parts of modified sludge, 5-15 parts of inorganic gel, 4-8 parts of viscosity enhancer, 0.5-0.7 parts of sodium citrate, and 0.1-0.3 parts of aminosulfonate.

2. A selective and efficient inorganic composite plugging agent according to claim 1, characterized in that: The method for preparing the inorganic gel specifically comprises the following steps: P1. Dissolve (3-mercaptopropyl)trimethoxysilane and tetraethoxysilane in anhydrous methanol, add DMF and mix well, stir at 180-220 rpm for 10-15 min, add ammonia solution, increase the stirring speed to 300-350 rpm, react for 30 min, and obtain SiO2 wet gel; P2. Dissolve aluminum sec-butoxide in anhydrous ethanol, mix with the SiO2 wet gel prepared in step S1, stir at 100-120 rpm for 20-30 min, add ammonia solution, continue stirring and react for 2-3 h, centrifuge at 2000-3000 rpm for 5-10 min, remove the supernatant, and obtain an inorganic gel.

3. A selective and efficient inorganic composite plugging agent according to claim 2, characterized in that: In step P1, the mass ratio of (3-mercaptopropyl)trimethoxysilane to tetraethoxysilane is 1:3-4; the mass concentration of tetraethoxysilane in anhydrous methanol is 0.1-0.2 g / mL; the volume ratio of anhydrous methanol to DMF is 1:3-4; the ammonia solution is obtained by mixing concentrated ammonia water and deionized water, and the mass fraction of the ammonia solution is 10%-15%; the added volume of the ammonia solution is 10%-20% of the volume of anhydrous methanol.

4. A selective and efficient inorganic composite plugging agent according to claim 3, characterized in that: In step P2, the mass volume ratio of tetraethoxysilane to aluminum sec-butoxide is 4-5 g / mL; the volume fraction of aluminum sec-butoxide in anhydrous ethanol is 1.3-2.0%; the ammonia solution is obtained by mixing concentrated ammonia water and deionized water, and the mass fraction of the ammonia solution is 10%-15%; the added volume of the ammonia solution is 20%-30% of the volume of anhydrous ethanol.

5. A selective and efficient inorganic composite plugging agent according to claim 4, characterized in that: The method for preparing the modified oily sludge specifically comprises the following steps: P3. Place the oily sludge in a constant temperature drying oven, dry it at 100-110°C for 6-8h, grind it, pass it through a 20-40 mesh sieve, add it to petroleum ether, stir it at 150-180rpm, react it for 1-2h, filter it, collect the solid, place it in a 1mol / L hydrochloric acid solution, raise the temperature to 60-80°C, stir it at 200-300rpm, react it for 1-2h, filter it, collect the solid, wash it repeatedly with acetone and deionized water, and dry it to obtain deoiled sludge; P4, dissolving the silane coupling reagent KH550 in anhydrous ethanol, adding the deoiled sludge prepared in step P3, raising the temperature to 60-80°C, stirring at a speed of 150-180rpm, reacting for 2-4h, cooling, filtering, washing with anhydrous ethanol and deionized water, and drying to obtain pretreated sludge; P5. Dissolve cysteine ​​in an ethanol aqueous solution, add EDC and NHS, stir at 120-150 rpm for 20-40 min, adjust the pH to 2-3, add the pretreated sludge prepared in step P4 to the reaction system, introduce nitrogen, heat to 40-60° C. under a nitrogen atmosphere, stir at 200-250 rpm for 4-6 h, cool, wash with anhydrous ethanol and deionized water, and dry to obtain modified sludge.

6. A selective and efficient inorganic composite plugging agent according to claim 5, characterized in that: In step P3, the mass volume ratio between the oily sludge and petroleum ether is 0.05-0.1 g / mL; in step P4, the mass concentration of the silane coupling reagent KH550 in anhydrous ethanol is 10-50 g / L; in step P4, the mass ratio between the silane coupling reagent KH550 and the deoiled sludge is 1:3-5; in step P5, the mass concentration of cysteine ​​in ethanol aqueous solution is 20-30 g / L; in step P5, the mass ratio of cysteine, EDC and NHS is 1-1.2:1.5-1.8:1.8-2.1; in step P5, the mass ratio between the pretreated sludge and cysteine ​​is 4-6:

1.

7. A selective and efficient inorganic composite plugging agent according to claim 6, characterized in that: The preparation method of the tackifier specifically comprises the following steps: P6. Dissolve lipoic acid in DMAC, add CDI, mix well, introduce nitrogen, raise the temperature to 40-50° C. in a nitrogen atmosphere, activate the reaction for 8-10 hours, add N-(2-hydroxyethyl) acrylamide, continue stirring at 150-180 rpm, raise the reaction temperature to 80-90° C., react for 12-16 hours, cool, concentrate under reduced pressure to remove the reaction solution, add deionized water for washing, and freeze-dry to obtain acrylamide-lipoic acid ester; P7. Dissolve the acrylamide-lipoic acid ester and methacrylamide prepared in step P6 in DMAC, place under nitrogen atmosphere, add azobisisobutyronitrile, raise the temperature to 80-90° C., react for 2-3 hours, remove excess reaction solvent, dry, and obtain a tackifier.

8. A selective and efficient inorganic composite plugging agent according to claim 7, characterized in that: In step P6, the mass concentration of lipoic acid in DMAC is 20-40 g / L; the mass ratio of CDI to lipoic acid is 1:1.2-1.5; and the mass ratio of N-(2-hydroxyethyl)acrylamide to lipoic acid is 1-1.2:

2.

9. A selective and efficient inorganic composite plugging agent according to claim 8, characterized in that: In step P7, the mass ratio of acrylamide-lipoic acid ester to methacrylamide is 1:4-6; the mass concentration of methacrylamide in DMAC is 0.12-0.2 g / mL; and the added mass of azobisisobutyronitrile is 0.5%-1% of the mass of methacrylamide.

10. A method for preparing a selective and efficient inorganic composite plugging agent according to any one of claims 1 to 9, characterized in that: The specific steps include: S1, dissolving the inorganic gel in deionized water, stirring at a speed of 500-700 rpm, adding a tackifier, and continuing to stir and mix for 1-2 hours, and mixing evenly to obtain a mixture; In step S1, the mass concentration of the inorganic gel in deionized water is 80-100 g / L; S2. Add the modified sludge to the mixture prepared in step S2, stir until the reaction system is in a uniform state, add sodium citrate and aminosulfonate, increase the temperature to 40-50° C., use a high-speed stirrer to stir at a speed of 10000-12000 rpm, and after cooling and drying, obtain an inorganic plugging agent.

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