Emulsified plugging agent as well as preparation method and application thereof

Abstract

The invention provides an emulsified plugging agent as well as a preparation method and application thereof. The emulsifying blocking agent is nano silicon dioxide hydrophobically modified by lecithin, and the particle size of the emulsifying blocking agent is 15-100nm. The emulsifying blocking agent is prepared from the following raw materials: nano silicon dioxide, soya bean lecithin, an epoxy material and a catalyst, the mass ratio of the nano silicon dioxide to the soybean lecithin to the epoxy material to the catalyst is 100: (20-50): (5-30): (0.5-10), preferably 100: (25-38): (10-22): (1-4). The emulsifying and blocking agent can be applied to oil-based drilling fluid and synthetic-based drilling fluid, has emulsifying and blocking performance, can have a good dispersion effect in oil-based and synthetic-based base oil, prevents aggregation, facilitates blocking of nano-scale micro-cracks, and improves the stability of W / O emulsion at the same time. The high-temperature and high-pressure filter loss of the oil-based drilling fluid is effectively reduced, the compactness of a mud cake is improved, drilling fluid-based filtrate is prevented from going deep into a stratum, micro-nano apertures are effectively blocked, and the well wall stability of a shale stratum is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of drilling fluid, and in particular relates to an emulsified plugging agent and a preparation method and application thereof. Background Art

[0002] Compared with water-based drilling fluid, oil-based drilling fluid has many advantages such as strong inhibition, good well wall stability, good lubricity, strong anti-pollution ability, and little damage to reservoirs. It has become an important drilling fluid system for drilling shale formations and highly water-sensitive formations. Generally, emulsifiers are added to oil-based drilling fluids to form stable W / O emulsions. For oil-based drilling fluids, improving the stability of oil-based drilling fluid emulsions is helpful for rapid and safe drilling.

[0003] According to the Pickering emulsion theory of synergistic stabilization of nanomaterials and surfactants, adding nanoparticles to oil-based drilling fluids can help improve the stability of oil-based drilling fluids. This technology has been successfully applied in oil-based drilling fluids abroad, but there are few reports on this in China. There are few nano-plugging agents suitable for oil-based drilling fluids and synthetic-based drilling fluids, and there are no reports on treatment agents with dual emulsification and plugging effects, which puts higher requirements on nano-level plugging agents.

[0004] "The Stabilizing Effect of DSW-S Nanoparticles on Oil-Based Drilling Fluids" discloses a hydrophobically modified silica nanoparticle material and points out that DSW-S can increase the viscosity and shear force of oil-based drilling fluids, help improve the sand-carrying and suspension capacity of oil-based drilling fluids, and significantly improve the emulsification stability of drilling fluids. The plugging performance and environmental performance of nanoparticles are not mentioned.

[0005] "Preparation and Performance Evaluation of Nano-Silica Plugging Agent for Drilling Fluid" discloses a modified nano-silica with a core-shell structure, which is applied to water-based drilling fluids with a particle size of 11-72nm. It is not suitable for oil-based and synthetic drilling fluids.

[0006] "Preparation of Oil-Soluble Nano-TiO2 Particles and Their Structural Characterization" discloses a method for preparing DTMS-modified oil-soluble nano-TiO2 particles using a liquid phase deposition method. The particles have low friction and wear resistance and are used as lubricant additives for water-based drilling fluids. They are not suitable for oil-based drilling fluids and synthetic-based drilling fluids.

[0007] "Development and Mechanism of Hydrophobic Associating Polymer Nano-Silica Fluid Loss Reducer" discloses a hydrophobic associating polymer nano-silica micro-nano fluid loss reducer with a core-shell structure. The particle size D50 value is 284nm, and it is used in water-based drilling fluids, but not in oil-based drilling fluids and synthetic-based drilling fluids.

[0008] Therefore, there is an urgent need for a nano-scale emulsified plugging agent to fill and plug the micro-cracks in the formation and reduce the loss of drilling fluid in the formation. Summary of the invention

[0009] The present invention aims at the problems of formation micro-crack leakage and electrical stability of W / O emulsion encountered in the construction of oil-based drilling fluid and synthetic-based drilling fluid. It is necessary to disperse materials with nano-scale particle size in the base oil, fill and seal the micro-cracks of the formation through small particle size, reduce the leakage of drilling fluid in the formation, reduce the pressure transmission of drilling fluid, and improve the rock strength of the formation.

[0010] In a first aspect, the present invention provides an emulsified plugging agent, which is a lecithin hydrophobically modified nano-silicon dioxide emulsified plugging agent with a particle size of 15 to 100 nm.

[0011] As a specific embodiment of the present invention, the raw materials for preparing the emulsified plugging agent include nano-silicon dioxide, soybean lecithin, epoxy material, and catalyst.

[0012] As a specific embodiment of the present invention, the mass ratio of the nano-silicon dioxide, soybean lecithin, epoxy material and catalyst is 100:(20-50):(5-30):(0.5-10), preferably 100:(25-38):(10-22):(1-4).

[0013] As a specific embodiment of the present invention, the nano-silicon dioxide is selected from unmodified nano-silicon dioxide with a particle size of 15-100 nm.

[0014] As a specific embodiment of the present invention, the epoxy material is selected from one or more of epichlorohydrin, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, and polyethylene glycol diglycidyl ether.

[0015] As a specific embodiment of the present invention, the catalyst is selected from one or more of boron trifluoride etherate, p-toluenesulfonic acid monohydrate, zinc trifluoromethanesulfonate, dodecylbenzenesulfonic acid, and p-nitrobenzoic acid.

[0016] As a specific embodiment of the present invention, the CAS number of soybean lecithin is 8002-43-5, which can be commercially available; the CAS number of epichlorohydrin is 106-89-8, which can be commercially available analytically pure reagents; the CAS number of ethylene glycol diglycidyl ether is 2224-15-9, which can be commercially available analytically pure reagents; the CAS number of diethylene glycol diglycidyl ether is 4206-61-5, which can be commercially available analytically pure reagents; the CAS number of polyethylene glycol diglycidyl ether is 39443-66-8, which can be commercially available analytically pure reagents.

[0017] As a specific embodiment of the present invention, the CAS number of boron trifluoride ethyl ether is 109-63-7, the content is 46.8-47.8%, and it can be commercially available; the CAS number of p-toluenesulfonic acid monohydrate is 6192-52-5, which can be obtained from a commercially available analytically pure reagent; the CAS number of zinc trifluoromethanesulfonate is 123334-05-4, which can be obtained from a commercially available analytically pure reagent; the CAS number of dodecylbenzenesulfonic acid is 27176-87-0, which can be obtained from a commercially available analytically pure reagent; and the CAS number of p-nitrobenzoic acid is 200-526-2, which can be obtained from a commercially available analytically pure reagent.

[0018] In a second aspect, the present invention provides a method for preparing the emulsified plugging agent according to the first aspect, comprising the following steps:

[0019] S1: mixing soybean lecithin, epoxy material, catalyst and solvent to carry out a first reaction to obtain a first intermediate;

[0020] S2: mixing the first intermediate obtained in step S1 with nano-silicon dioxide to perform a second reaction to obtain a second intermediate;

[0021] S3: The second intermediate obtained in step S2 is concentrated to obtain the emulsified plugging agent of the lecithin hydrophobically modified nano-silica.

[0022] As a specific embodiment of the present invention, in step S1, the epoxy material is selected from one or more of ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, and bisphenol A diglycidyl ether.

[0023] As a specific embodiment of the present invention, in step S1, the catalyst is selected from one or more of boron trifluoride etherate, p-toluenesulfonic acid monohydrate, and zinc trifluoromethanesulfonate.

[0024] As a specific embodiment of the present invention, in step S1, the solvent is selected from ethylene glycol dimethyl ether, tetrahydrofuran, and ethylene dichloride.

[0025] As a specific embodiment of the present invention, in step S1, the conditions of the first reaction include: a temperature of 60 to 100° C.; and / or a time of 2 to 5 hours.

[0026] According to the present invention, the first reaction is based on the activation and modification of the polyhydroxyl and amino groups in the lecithin structure by epoxides to enhance the polarity of the material.

[0027] As a specific embodiment of the present invention, in step S2, the particle size of the nano-silicon dioxide is 15-100 nm.

[0028] As a specific embodiment of the present invention, in step S2, the mass volume ratio of the nano-silicon dioxide and the solvent is 100g:400-800mL, preferably 100g:450-650mL.

[0029] As a specific embodiment of the present invention, in step S2, the conditions of the second reaction include: a temperature of 80 to 120° C.; and / or a time of 3 to 6 hours.

[0030] According to the present invention, the second reaction utilizes the low size, strong adsorption and Lewis acid characteristics of nano-silicon dioxide to strongly adsorb high polar materials in the components. The modified lecithin generally exhibits high charge and high polarity properties. This adsorption is difficult to desorb, thereby improving the modification effect.

[0031] As a specific embodiment of the present invention, the mass ratio of the nano-silicon dioxide, soybean lecithin, epoxy material and catalyst is 100:(20-50):(5-30):(0.5-10), preferably 100:(25-38):(10-22):(1-4).

[0032] As a specific embodiment of the present invention, in step S3, the concentration treatment method includes distilling the second intermediate under reduced pressure to recover excess solvent.

[0033] In the present invention, a round bottom flask with a reflux condenser can be used to complete the preparation method. Both the first reaction and the second reaction of the present invention can be reflux reactions.

[0034] In a third aspect, the present invention provides use of the emulsified plugging agent described in the first aspect or the emulsified plugging agent prepared by the preparation method described in the second aspect in the field of drilling fluid.

[0035] As a specific embodiment of the present invention, the emulsified plugging agent can be used in drilling fluids with mineral oil or synthetic base oil as a continuous phase, and is not limited to oil-based drilling fluids and synthetic-based drilling fluids.

[0036] The above raw materials in the present invention can be prepared in-house or commercially available, and the present invention is not particularly limited thereto.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] 1. The plugging agent prepared by the present invention can be applied to oil-based drilling fluid and synthetic-based drilling fluid, has emulsification and plugging properties, can have a good dispersion effect in oil-based and synthetic-based base oils, prevent aggregation, help plug nano-scale micro-cracks, and improve the stability of W / O emulsions. It effectively reduces the high-temperature and high-pressure filtration loss of oil-based drilling fluid, improves the compactness of mud cakes, slows down the penetration of drilling fluid-based filtrate into the formation, effectively plugs micro-nano pores, and improves the stability of the well wall of shale formations.

[0039] 2. The plugging agent of the present invention is abundant in source, low in cost and can be naturally degraded. DETAILED DESCRIPTION

[0040] The present invention will be further described below in conjunction with specific embodiments, but they do not constitute any limitation to the present invention.

[0041] The specific information of the reagents in each embodiment of the present invention is as follows:

[0042] The CAS number of soybean lecithin is 8002-43-5 and is commercially available;

[0043] The CAS number of epichlorohydrin is 106-89-8, and it is a commercially available analytical grade reagent;

[0044] Ethylene glycol diglycidyl ether, CAS number 2224-15-9, commercially available analytical grade reagent;

[0045] The CAS number of diethylene glycol diglycidyl ether is 4206-61-5, and it is a commercially available analytical grade reagent;

[0046] The CAS number of polyethylene glycol diglycidyl ether is 39443-66-8, and it is a commercially available analytical grade reagent.

[0047] The CAS number of boron trifluoride ethyl ether is 109-63-7, content: 46.8-47.8%, commercially available;

[0048] The CAS number of p-toluenesulfonic acid monohydrate is 6192-52-5, and it is a commercially available analytical grade reagent;

[0049] The CAS number of zinc trifluoromethanesulfonate is 123334-05-4, and it is a commercially available analytical grade reagent;

[0050] The CAS number of dodecylbenzenesulfonic acid is 27176-87-0, and it is a commercially available analytical grade reagent;

[0051] The CAS number of p-nitrobenzoic acid is 200-526-2, and it is a commercially available analytical grade reagent.

[0052] Example 1

[0053] This embodiment provides an emulsified plugging agent and a preparation method thereof, the specific details of which are as follows:

[0054] S1: 30 g of soybean lecithin, 15 g of ethylene glycol diglycidyl ether, and 1.5 g of zinc trifluoromethanesulfonate were mixed in 600 mL of tetrahydrofuran solvent, and the mixture was refluxed at 66° C. and stirred for 5 h to obtain the corresponding epoxidized modified soybean lecithin solution.

[0055] S2: Add 100 g of nano-silicon dioxide to the activated modified soybean lecithin solution described in step S1, mix and stir, reflux and react at 66° C. for 5 h to obtain the corresponding soybean lecithin-modified nano-silicon dioxide emulsified plugging agent solution.

[0056] S3: subjecting the soybean lecithin-modified nano-silica emulsified plugging agent solution described in step S2 to reduced pressure distillation to distill out the residual solvent to obtain the final product, a lecithin hydrophobically modified nano-silica emulsified plugging agent.

[0057] Example 2

[0058] This embodiment provides an emulsified plugging agent and a preparation method thereof, the specific details of which are as follows:

[0059] S1: 30 g of soybean lecithin, 26 g of diethylene glycol diglycidyl ether, and 1.8 g of p-toluenesulfonic acid monohydrate were mixed in 500 mL of ethylene glycol dimethyl ether solvent, and the mixture was refluxed at 83° C. and stirred for 4 h to obtain the corresponding epoxidized modified soybean lecithin solution.

[0060] S2: Add 100 g of nano-silicon dioxide to the activated modified soybean lecithin solution described in step S1, mix and stir, reflux and react at 83° C. for 5 h to obtain the corresponding soybean lecithin-modified nano-silicon dioxide emulsified plugging agent solution.

[0061] S3: subjecting the soybean lecithin-modified nano-silica emulsified plugging agent solution described in step S2 to reduced pressure distillation to distill out the residual solvent to obtain the final product, a lecithin hydrophobically modified nano-silica emulsified plugging agent.

[0062] Example 3

[0063] This embodiment provides an emulsified plugging agent and a preparation method thereof, the specific details of which are as follows:

[0064] S1: 30 g of soybean lecithin, 30 g of bisphenol A diglycidyl ether, and 3.4 g of boron trifluoride ether were mixed in 650 mL of dichloroethane solvent, and refluxed at 83° C. with stirring for 4 h to obtain the corresponding epoxidized modified soybean lecithin solution.

[0065] S2: Add 100 g of nano-silicon dioxide to the activated modified soybean lecithin solution described in step S1, mix and stir, reflux and react at 83° C. for 5 h to obtain the corresponding soybean lecithin-modified nano-silicon dioxide emulsified plugging agent solution.

[0066] S3: subjecting the soybean lecithin-modified nano-silica emulsified plugging agent solution described in step S2 to reduced pressure distillation to distill out the residual solvent to obtain the final product, a lecithin hydrophobically modified nano-silica emulsified plugging agent.

[0067] Application Example 1

[0068] Add 240g of base oil to a high-speed stirrer, heat the water bath to 50°C, stir at 10000r / min, add 12g of homemade emulsifier, 3g of wetting agent, 6g of filtrate reducer, 12g of organic soil, barite, and 60mL of water phase in sequence, stir continuously for 2h, and prepare a density of 1.5 / cm 3 Oil-based drilling fluid.

[0069] Application Example 2

[0070] Add 240g of base oil to a high-speed stirrer, slowly add 6g of the emulsified plugging agent prepared in Example 1, heat the water bath to 50°C, stir at a high speed of 10000r / min, add 12g of emulsifier, 3g of wetting agent, 6g of filtrate reducer, 12g of organic soil, barite, and 60mL of water phase in sequence, stir continuously for 2h, and prepare a density of 1.5 / cm 3 Oil-based drilling fluid.

[0071] Application Example 3

[0072] Add 240 g of base oil to a high-speed stirrer, slowly add 6 g of the emulsified plugging agent prepared in Example 2, heat the water bath to 50 ° C, stir at a high speed of 10000 r / min, add 12 g of emulsifier, 3 g of wetting agent, 6 g of filtrate reducer, 12 g of organic soil, barite, and 60 mL of water phase in sequence, stir continuously for 2 h, and prepare a density of 1.5 / cm 3 Oil-based drilling fluid.

[0073] Application Example 4

[0074] Add 240g of base oil to a high-speed stirrer, slowly add 6g of the emulsified plugging agent prepared in Example 3, heat the water bath to 50°C, stir at a high speed of 10000r / min, add 12g of emulsifier, 3g of wetting agent, 6g of filtrate reducer, 12g of organic soil, barite, and 60mL of water phase in sequence, stir continuously for 2h, and prepare a density of 1.5 / cm 3 Oil-based drilling fluid.

[0075] Application Example 5

[0076] Add 240g of base oil to the high-speed stirrer, slowly add 6g of the emulsified plugging agent prepared in Example 1, heat the water bath to 50°C, stir at a high speed of 10000r / min, add 12g of emulsifier, 3g of wetting agent, 6g of filtrate reducer, 12g of organic soil, barite, 60mL of water phase, 6g of 800 mesh calcium carbonate, 2g of 1500 mesh, and 10g of 3000 mesh calcium carbonate in turn, stir continuously for 2h, and the prepared density is 1.5 / cm3 Oil-based drilling fluid.

[0077] Test Example 1

[0078] The nano plugging agent obtained in Application Examples 1-5 was used to test the rheological properties of oil-based drilling fluid. The test results are shown in Table 1:

[0079] Table 1 Effect of nano plugging agent on rheological properties of oil-based drilling fluid

[0080]

[0081] It can be seen from the above table that the five application examples all have good rheological properties, electrical stability and dynamic-plastic ratio, indicating that the nano-silica emulsified plugging agent prepared by the present invention has little effect on the rheological properties of the drilling fluid and will not affect the rheological properties and electrical stability of the oil-based drilling fluid.

[0082] Test Example 2

[0083] The nano plugging agents obtained in Application Examples 1, 2, and 5 were used to test the permeability of oil-based drilling fluids. The test results are shown in Table 2:

[0084] Table 2 Effect of nano plugging agent on permeability of oil-based drilling fluid mud cake

[0085]

[0086] It can be seen from the above table that after adding the emulsified plugging agent of the present invention, a nano-particle water-blocking layer is formed on the oil-based drilling fluid mud cake, which effectively reduces the filtration loss and the permeability of the mud cake, indicating that the plugging effect is excellent.

[0087] In summary, the emulsified plugging agent of the present invention can be applied to oil-based drilling fluids and synthetic-based drilling fluids, has the performance of emulsification and plugging, can have a good dispersion effect in oil-based and synthetic-based base oils, prevent aggregation, help plug nano-scale micro-cracks, and improve the stability of W / O emulsions. It effectively reduces the high-temperature and high-pressure filtration loss of oil-based drilling fluids, improves the compactness of mud cakes, slows down the penetration of drilling fluid-based filtrate into the formation, effectively plugs micro-nano pores, and improves the stability of the well wall of shale formations.

[0088] Any numerical value mentioned in the present invention, if there is only an interval of two units between any minimum value and any maximum value, includes all values ​​from the minimum value to the maximum value each time increasing by one unit. For example, if the amount of a component, or the value of a process variable such as temperature, pressure, time, etc. is declared to be 50-90, in this specification it means that 51-89, 52-88... and 69-71 and 70-71 are specifically listed. For non-integer values, 0.1, 0.01, 0.001 or 0.0001 can be appropriately considered as a unit. These are just some specially specified examples. In this application, in a similar manner, all possible combinations of numerical values ​​between the listed minimum and maximum values ​​are considered to have been disclosed.

[0089] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. An emulsified plugging agent, characterized in that: The emulsified plugging agent is a lecithin hydrophobically modified nano-silicon dioxide emulsified plugging agent with a particle size of 15-100 nm.

2. The emulsified plugging agent according to claim 1, characterized in that: The raw materials for preparing the emulsified plugging agent include nano-silicon dioxide, soybean lecithin, epoxy material and catalyst; the mass ratio of the nano-silicon dioxide, soybean lecithin, epoxy material and catalyst is 100:(20-50):(5-30):(0.5-10), preferably 100:(25-38):(10-22):(1-4).

3. The emulsified plugging agent according to claim 1 or 2, characterized in that: The particle size of the nano silicon dioxide is 15-100 nm.

4. The emulsified plugging agent according to any one of claims 1 to 3, characterized in that: The epoxy material is selected from one or more of epichlorohydrin, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, and polyethylene glycol diglycidyl ether.

5. The emulsified plugging agent according to any one of claims 1 to 4, characterized in that: The catalyst is selected from one or more of boron trifluoride etherate, p-toluenesulfonic acid monohydrate, zinc trifluoromethanesulfonate, dodecylbenzenesulfonic acid, and p-nitrobenzoic acid.

6. A method for preparing the emulsified plugging agent according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1: mixing soybean lecithin, epoxy material, catalyst and solvent to carry out a first reaction to obtain a first intermediate; S2: mixing the first intermediate obtained in step S1 with nano-silicon dioxide to perform a second reaction to obtain a second intermediate; S3: The second intermediate obtained in step S2 is concentrated to obtain the emulsified plugging agent of the lecithin hydrophobically modified nano-silica.

7. The preparation method according to claim 6, characterized in that: In step S1, the epoxy material is selected from one or more of ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, and bisphenol A diglycidyl ether; and / or, The catalyst is selected from one or more of boron trifluoride ethyl etherate, p-toluenesulfonic acid monohydrate, and zinc trifluoromethanesulfonate; and / or, The solvent is selected from ethylene glycol dimethyl ether, tetrahydrofuran, ethylene dichloride; and / or, The conditions of the first reaction include: a temperature of 60 to 100° C.; and / or a time of 2 to 5 hours.

8. The preparation method according to claim 6 or 7, characterized in that: In step S2, the nano-silicon dioxide particle size is 15-100 nm; and / or, The mass volume ratio of the nano-silicon dioxide to the solvent is 100 g:400-800 mL, preferably 100 g:450-650 mL; and / or, The conditions of the second reaction include: a temperature of 80 to 120° C.; and / or a time of 3 to 6 hours.

9. The preparation method according to any one of claims 6 to 8, characterized in that: The mass ratio of the nano-silicon dioxide, soybean lecithin, epoxy material and catalyst is 100:(20-50):(5-30):(0.5-10), preferably 100:(25-38):(10-22):(1-4).

10. Use of the emulsified plugging agent according to any one of claims 1 to 5 or the emulsified plugging agent prepared by the preparation method according to any one of claims 6 to 9 in the field of drilling fluids with mineral oil or synthetic base oil as a continuous phase.

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