An emulsified plugging agent, a preparation method and application thereof

Abstract

The application provides an emulsified plugging agent and a preparation method and application thereof. The emulsified plugging agent is lecithin hydrophobically modified nano-silicon dioxide, and the particle size is 15-100 nm. The preparation raw materials of the emulsified plugging agent include nano-silicon dioxide, soybean lecithin, an epoxy material and a catalyst; and the mass ratio of the nano-silicon dioxide, the soybean lecithin, the epoxy material and the catalyst is 100:(20-50):(5-30):(0.5-10), preferably 100:(25-38):(10-22):(1-4). The emulsified plugging agent can be applied to oil-based drilling fluid and synthetic-based drilling fluid, has emulsifying and plugging properties, has good dispersion effect in oil-based and synthetic-based base oil, prevents aggregation, helps to plug microcracks of nano level, and improves the stability of W / O emulsion. The emulsified plugging agent can effectively reduce the high-temperature and high-pressure filtration loss of oil-based drilling fluid, improve the compactness of a mud cake, slow down the deep penetration of drilling fluid base filtrate into a formation, effectively plug micro-nano pores, and improve the wellbore stability of a shale formation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of drilling fluid, and particularly relates to an emulsified plugging agent and a preparation method and application thereof. BACKGROUND

[0002] Compared with water-based drilling fluid, oil-based drilling fluid has the advantages of strong inhibition, good well wall stability, good lubricity, strong anti-pollution ability, and small reservoir damage, and has become an important drilling fluid system for drilling shale formations and strong water-sensitive formations. Generally, an emulsifier is added to the oil-based drilling fluid to form a stable W / O emulsion. For the oil-based drilling fluid, improving the stability of the oil-based drilling fluid emulsion is helpful for fast and safe drilling.

[0003] According to the Pickering emulsion theory of nanomaterials and surfactant synergistic stabilization, the addition of nanoparticles to the oil-based drilling fluid helps to improve the stability of the oil-based drilling fluid. The technology has been successfully applied to oil-based drilling fluid abroad, but there are few reports on this aspect in China. There are few nanometer plugging agents suitable for oil-based drilling fluid and synthetic-based drilling fluid, and there is no report on treatment agents with dual functions of emulsification and plugging, which puts forward higher requirements for nanometer plugging agents.

[0004] DSW-S Nanoparticles for Stabilizing Oil-Based Drilling Fluid discloses a hydrophobic modified silica nanoparticle material, and indicates that DSW-S can improve the viscosity and shear force of the oil-based drilling fluid, help to improve the sand carrying and suspension capacity of the oil-based drilling fluid, and greatly improve the emulsion stability of the drilling fluid. The plugging performance and environmental protection performance of the nanoparticles are not indicated.

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

[0006] Preparation and Structure Characterization of Oil-Soluble Nanometer TiO2 Particles discloses a method for preparing oil-soluble nanometer TiO2 particles modified by DTMS by using liquid deposition method. The particles have low friction and wear resistance, and are used as water-based drilling fluid lubricating oil additives. They are not suitable for oil-based drilling fluid and synthetic-based drilling fluid.

[0007] Preparation and Action Mechanism of Hydrophobic Association Polymer Nanometer Silica Filtration Reducer discloses a hydrophobic association polymer nanometer silica micro-nano filtration reducer with a core-shell structure. The particle size D50 value is 284 nm, and the reducer is applied to water-based drilling fluid. It is not suitable for oil-based drilling fluid and synthetic-based drilling fluid.

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

[0009] The present application is directed to the problem of micro-fracture leakage and the electrical stability of W / O emulsion in the construction of oil-based drilling fluid and synthetic-based drilling fluid, which requires a material with a nano-scale particle size to be dispersed in base oil to fill and block the micro-fractures of the formation through small particle size, reduce the leakage of drilling fluid in the formation, and reduce the pressure transmission of drilling fluid, and improve the rock strength of the formation.

[0010] In a first aspect, the present application provides an emulsion plugging agent, which is lecithin hydrophobically modified nano-silica emulsion plugging agent with a particle size of 15-100 nm.

[0011] As a specific embodiment of the present application, the preparation raw materials of the emulsion plugging agent include nano-silica, soy lecithin, epoxy material, catalyst.

[0012] As a specific embodiment of the present application, the mass ratio of the nano-silica, soy 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 application, the nano-silica is selected from unmodified nano-silica with a particle size of 15-100 nm.

[0014] As a specific embodiment of the present application, 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 application, the catalyst is selected from one or more of boron trifluoride etherate, p-toluenesulfonic acid monohydrate, zinc triflate, dodecylbenzenesulfonic acid, and p-nitrobenzoic acid.

[0016] As a specific embodiment of the present application, the CAS number of soy lecithin is 8002-43-5, which can be obtained from the market; the CAS number of epichlorohydrin is 106-89-8, which can be obtained from the market; the CAS number of ethylene glycol diglycidyl ether is 2224-15-9, which can be obtained from the market; the CAS number of diethylene glycol diglycidyl ether is 4206-61-5, which can be obtained from the market; and the CAS number of polyethylene glycol diglycidyl ether is 39443-66-8, which can be obtained from the market.

[0017] As a specific embodiment of the present application, the CAS number of boron trifluoride etherate is 109-63-7, the content is 46.8-47.8%, which can be obtained from the market; the CAS number of p-toluenesulfonic acid monohydrate is 6192-52-5, which can be obtained from the market; the CAS number of zinc triflate is 123334-05-4, which can be obtained from the market; the CAS number of dodecylbenzenesulfonic acid is 27176-87-0, which can be obtained from the market; the CAS number of p-nitrobenzoic acid is 200-526-2, which can be obtained from the market.

[0018] In a second aspect, the present application provides a preparation method of the emulsified plugging agent of the first aspect, comprising the following steps:

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

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

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

[0022] As a specific embodiment of the present application, 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 application, in step S1, the catalyst is selected from one or more of boron trifluoride etherate, p-toluenesulfonic acid monohydrate and zinc triflate.

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

[0025] As a specific embodiment of the present application, in step S1, the conditions of the first reaction include: the temperature is 60-100℃; and / or, the time is 2-5h.

[0026] According to the present application, the first reaction is based on the activation and modification of the polyhydroxy and amino groups in the lecithin structure by the epoxy compound, which improves the polarity of the material.

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

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

[0029] As a specific embodiment of the present application, in step S2, the conditions of the second reaction include: temperature of 80-120℃; and / or, time of 3-6h.

[0030] According to the present application, the second reaction utilizes the low size, strong adsorption and Lewis acid characteristics of the nanosilica to strongly adsorb the high-polarity material in the ingredient, and the modified lecithin as a whole presents high charge and large polarity performance, which is difficult to desorb, thereby improving the modification effect.

[0031] As a specific embodiment of the present application, the mass ratio of the nanosilica, 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 application, in step S3, the concentration treatment method includes recovering the excess solvent by distillation under reduced pressure.

[0033] In the present application, the preparation method can be completed using a round-bottom flask with a reflux condenser. Both the first reaction and the second reaction of the present application can be refluxed.

[0034] In a third aspect, the present application provides the use of the emulsified plugging agent prepared by the preparation method of the second aspect in the field of drilling fluids.

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

[0036] The above raw materials in the present application can be self-made or commercially available, and the present application does not particularly limit this.

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

[0038] 1. The prepared plugging agent can be applied to oil-based drilling fluids and synthetic-based drilling fluids, has emulsification and plugging performance, can have good dispersion effect in oil-based and synthetic-based base oil, prevent aggregation, help to plug microcracks at the nanoscale, improve the stability of W / O emulsion, effectively reduce the high-temperature and high-pressure filtration loss of oil-based drilling fluids, improve the compactness of the mud cake, slow down the penetration of drilling fluid base filtrate into the formation, effectively plug micro-nano pores, and improve the wellbore stability of shale formations.

[0039] 2、The plugging agent is rich in sources, low in cost and naturally degradable. DETAILED DESCRIPTION

[0040] The application will be further described in conjunction with specific examples, but it does not constitute any limitation to the application.

[0041] The specific information of the reagents in the embodiments of the application is as follows:

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

[0043] The CAS number of epichlorohydrin is 106-89-8, which is commercially available as an analytical pure reagent;

[0044] The CAS number of ethylene glycol diglycidyl ether is 2224-15-9, which is commercially available as an analytical pure reagent;

[0045] The CAS number of diethylene glycol diglycidyl ether is 4206-61-5, which is commercially available as an analytical pure reagent;

[0046] The CAS number of polyethylene glycol diglycidyl ether is 39443-66-8, which is commercially available as an analytical pure reagent.

[0047] The CAS number of boron trifluoride etherate is 109-63-7, which is commercially available with a content of 46.8-47.8%;

[0048] The CAS number of p-toluenesulfonic acid monohydrate is 6192-52-5, which is commercially available as an analytical pure reagent;

[0049] The CAS number of zinc triflate is 123334-05-4, which is commercially available as an analytical pure reagent;

[0050] The CAS number of dodecylbenzenesulfonic acid is 27176-87-0, which is commercially available as an analytical pure reagent;

[0051] The CAS number of p-nitrobenzoic acid is 200-526-2, which is commercially available as an analytical pure reagent.

[0052] Example 1

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

[0054] S1: 30 g of soybean lecithin, 15 g of ethylene glycol diglycidyl ether and 1.5 g of zinc triflate were mixed in 600 mL of tetrahydrofuran solvent, and reflux stirring reaction was carried out at 66℃ for 5 h to obtain a corresponding epoxidized modified soybean lecithin solution.

[0055] S2: To the activated modified soybean lecithin solution described in step S1, add 100 g of nano-silica, mix and stir at 66°C under reflux for 5 h to obtain the corresponding soybean lecithin modified nano-silica emulsion plugging agent solution.

[0056] S3: Perform vacuum distillation treatment on the soybean lecithin modified nano-silica emulsion plugging agent solution described in step S2, distill out the residual solvent to obtain the final product of the lecithin hydrophobically modified nano-silica emulsion plugging agent.

[0057] Example 2

[0058] This example provides an emulsion plugging agent and a preparation method thereof, and the specific details are as follows:

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

[0060] S2: To the activated modified soybean lecithin solution described in step S1, add 100 g of nano-silica, mix and stir at 83°C under reflux for 5 h to obtain the corresponding soybean lecithin modified nano-silica emulsion plugging agent solution.

[0061] S3: Perform vacuum distillation treatment on the soybean lecithin modified nano-silica emulsion plugging agent solution described in step S2, distill out the residual solvent to obtain the final product of the lecithin hydrophobically modified nano-silica emulsion plugging agent.

[0062] Example 3

[0063] This example provides an emulsion plugging agent and a preparation method thereof, and the specific details are as follows:

[0064] S1: Mix 30 g of soybean lecithin, 26 g of diethylene glycol diglycidyl ether, and 1.8 g of p-toluenesulfonic acid monohydrate in 500 mL of ethylene glycol dimethyl ether solvent, and reflux stir at 83°C for 4 h to obtain the corresponding epoxidized modified soybean lecithin solution.

[0065] S2: To the activated modified soybean lecithin solution described in step S1, add 100 g of nano-silica, mix and stir at 83°C under reflux for 5 h to obtain the corresponding soybean lecithin modified nano-silica emulsion plugging agent solution.

[0066] S3: Perform vacuum distillation treatment on the soybean lecithin modified nano-silica emulsion plugging agent solution described in step S2, distill out the residual solvent to obtain the final product of the lecithin hydrophobically modified nano-silica emulsion plugging agent.

[0067] Application Example 1

[0068] In a high-speed blender, add base oil 240 g, water bath heating to 50℃, high-speed blender at 10000 r / min under the condition of high-speed stirring, add self-made emulsifier 12 g, wetting agent 3 g, filtrate reducer 6 g, organic clay 12 g, barite, water phase 60 mL, continuous stirring for 2 h, prepare oil-based drilling fluid with density of 1.5 / cm 3 .

[0069] Application Example 2

[0070] In a high-speed blender, add base oil 240 g, slowly add the emulsion plugging agent prepared in Example 1 6 g, water bath heating to 50℃, high-speed blender at 10000 r / min under the condition of high-speed stirring, add emulsifier 12 g, wetting agent 3 g, filtrate reducer 6 g, organic clay 12 g, barite, water phase 60 mL, continuous stirring for 2 h, prepare oil-based drilling fluid with density of 1.5 / cm 3 .

[0071] Application Example 3

[0072] In a high-speed blender, add base oil 240 g, slowly add the emulsion plugging agent prepared in Example 2 6 g, water bath heating to 50℃, high-speed blender at 10000 r / min under the condition of high-speed stirring, add emulsifier 12 g, wetting agent 3 g, filtrate reducer 6 g, organic clay 12 g, barite, water phase 60 mL, continuous stirring for 2 h, prepare oil-based drilling fluid with density of 1.5 / cm 3 .

[0073] Application Example 4

[0074] In a high-speed blender, add base oil 240 g, slowly add the emulsion plugging agent prepared in Example 3 6 g, water bath heating to 50℃, high-speed blender at 10000 r / min under the condition of high-speed stirring, add emulsifier 12 g, wetting agent 3 g, filtrate reducer 6 g, organic clay 12 g, barite, water phase 60 mL, continuous stirring for 2 h, prepare oil-based drilling fluid with density of 1.5 / cm 3 .

[0075] Application Example 5

[0076] In a high-speed blender, add base oil 240 g, slowly add the emulsion plugging agent prepared in Example 1 6 g, water bath heating to 50℃, high-speed blender at 10000 r / min under the condition of high-speed stirring, add emulsifier 12 g, wetting agent 3 g, filtrate reducer 6 g, organic clay 12 g, barite, water phase 60 mL, calcium carbonate 800 mesh 6 g, 1500 mesh 2 g, 3000 mesh 10 g, continuous stirring for 2 h, prepare oil-based drilling fluid with density of 1.5 / cm3 Oil-based drilling fluid.

[0077] Test Example 1

[0078] The rheological properties of the nano-plugging agents obtained in Examples 1-5 were tested on oil-based drilling fluids. The test results are shown in Table 1.

[0079] Table 1. Effects of nano-plugging agents on the rheology of oil-based drilling fluids.

[0080]

[0081] As can be seen from the table above, all five application examples have good rheological properties, electrical stability, and dynamic-plastic ratio, indicating that the nano-silica emulsion plugging agent prepared in this invention has little impact on the rheological properties of drilling fluids and will not affect the rheological properties and electrical stability of oil-based drilling fluids.

[0082] Test Example 2

[0083] The nano-plugging agents obtained in 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 agents on the permeability of oil-based drilling fluid mud cake.

[0085]

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

[0087] In summary, the emulsifying plugging agent of this invention can be applied to oil-based and synthetic-based drilling fluids, possessing both emulsifying and plugging properties. It exhibits good dispersion in both oil-based and synthetic-based base oils, preventing aggregation and aiding in the plugging of nanoscale micro-fractures, while simultaneously improving the stability of W / O emulsions. It effectively reduces the filtrate loss of oil-based drilling fluids under high temperature and pressure, improves the compactness of the mud cake, slows the penetration of drilling fluid-based filtrate into the formation, effectively plugs micro- and nano-pores, and enhances wellbore stability in shale formations.

[0088] Any numerical values recited herein include all values from the lower value and up to the upper value. Values that are recited herein also include values that are "framed" by the recited values. For example, if a concentration range is stated as 1% to 50%, it is intended that values such as 25%, 30%, and 35% are expressly enumerated. All integer values are used "open ended" such that "50%" really means "50% to 50%". The same principle applies to ranges recited as being "between" two values. Discrete, non-integer values can be assumed within the stated ranges. These are only a few of the specific examples that are given. In the application, all possible combinations of numerical values between the lowest value and the highest value enumerated, are to be considered to be expressly stated in this application.

[0089] It should be noted that the foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present application. While the application has been described with reference to exemplary embodiments, it is understood that the words that have been used herein are words of description, and that they are being used under the descriptive and explanatory privilege intended to aid in the understanding of the application. Modifications can be made to the application in light of the teachings herein, and other steps can be added or deleted thereof without departing from the intended scope of the application. Although the application has been described with reference to particular means, materials and embodiments, from the foregoing description, one skilled in the art can effect a wide variety of modifications to the preferred embodiments of the application without departing from the scope of the intended application. While the preferred embodiments of the application have been made this description is illustrative and not restrictive. Various modifications can become apparent to those skilled in the art, and the present application is to be limited only by the scope of the appended claims.

Claims

1. An emulsified plugging agent, characterized in that, The emulsified plugging agent is a lecithin-modified nano-silica emulsified plugging agent with a particle size of 15-100 nm; the raw materials for preparing the emulsified plugging agent include nano-silica, soybean lecithin, epoxy materials, and catalysts; the mass ratio of the nano-silica, soybean lecithin, epoxy materials, and catalysts is 100:(20-50):(5-30):(0.5-10); The preparation method of the emulsified plugging agent includes the following steps: S1: Soybean lecithin, epoxy material, catalyst and solvent are mixed and subjected to a first reaction to obtain a first intermediate; S2: The first intermediate obtained in step S1 is mixed with nano-silica to carry out a second reaction to obtain the second intermediate; S3: The second intermediate obtained in step S2 is concentrated to obtain the lecithin hydrophobic modified nano silica emulsion blocker.

2. The emulsified plugging agent according to claim 1, characterized in that, The mass ratio of the nano-silica, soybean lecithin, epoxy material, and catalyst is 100:(25-38):(10-22):(1-4).

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

4. The emulsified plugging agent according to any one of claims 1-3, 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 1-3, characterized in that, The epoxy material is bisphenol A diglycidyl ether.

6. The emulsified plugging agent according to any one of claims 1-3, characterized in that, The catalyst is selected from one or more of boron trifluoride ether, p-toluenesulfonic acid monohydrate, zinc trifluoromethanesulfonate, dodecylbenzenesulfonic acid, and p-nitrobenzoic acid.

7. A method for preparing the emulsified plugging agent according to any one of claims 1-6, characterized in that, Includes the following steps: S1: Soybean lecithin, epoxy material, catalyst and solvent are mixed and subjected to a first reaction to obtain a first intermediate; S2: The first intermediate obtained in step S1 is mixed with nano-silica to carry out a second reaction to obtain the second intermediate; S3: The second intermediate obtained in step S2 is concentrated to obtain the lecithin hydrophobic modified nano silica emulsion blocker.

8. The preparation method according to claim 7, characterized in that, In step S1, the solvent is selected from ethylene glycol dimethyl ether, tetrahydrofuran, and dichloroethane; and / or, The conditions for the first reaction include: a temperature of 60~100℃; and / or a time of 2~5 h.

9. The preparation method according to claim 7, characterized in that, In step S2, the nano-silica particles have a diameter of 15-100 nm; and / or, The mass-to-volume ratio of the nano-silica to the solvent is 100 g: 400-800 mL; and / or, The conditions for the second reaction include: a temperature of 80~120℃; and / or a time of 3~6 h.

10. The preparation method according to claim 9, characterized in that, The mass-to-volume ratio of the nano-silica to the solvent is 100 g: 450-650 mL.

11. The application of the emulsified plugging agent according to any one of claims 1-6 or the emulsified plugging agent prepared by the preparation method according to any one of claims 7-10 in the field of drilling fluids with mineral oil or synthetic base oil as the continuous phase.

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