Nanosilicon emulsion and its application in environment-friendly water-based drilling fluid

Abstract

This application provides a nano-silicone emulsion, its preparation method, and its application. The nano-silicone emulsion provided in this application comprises: 5-15 parts by weight of polyol; 1-10 parts by weight of nano-SiO2; 1-10 parts by weight of silane coupling agent; 5-20 parts by weight of silicate; and 100 parts by weight of water. Using polyol, silane coupling agent, nano-SiO2, silicate, and water as raw materials, this application obtains the nano-silicone emulsion through physical blending and chemical grafting modification. It can effectively inhibit bentonite hydration and dispersion, seal formation micro-fractures, and simultaneously form a strongly adsorbed hydrophobic semi-permeable membrane on the wellbore, achieving both physical sealing and chemical wellbore strengthening. For formations with well-developed bedding or fractures, the nano-silicone emulsion provided in this application can enhance the drilling fluid's ability to inhibit collapse and seal wellbore, reduce hydration stress, decrease the interaction between water-based filtrate and formation rocks, and improve mud cake quality, thereby achieving wellbore strengthening.

Description

Technical Field

[0001] This invention relates to the field of oil and gas drilling technology, and in particular to a nano-silica emulsion and its application in environmentally friendly water-based drilling fluids. Background Technology

[0002] Wellbore instability is a common and serious problem in shale oil and gas exploration and development. The main shale reservoirs in Southwest China are the marine Longmaxi and Wufeng Formations, and the continental Qianfoya Formation. The reservoir minerals are primarily illite, with minor amounts of montmorillonite and illite / montmorillonite mixed layers. Illite particles exhibit extremely high physicochemical activity, with expansion stresses similar to montmorillonite and expansion rates several times greater. Simultaneously, shale formations contain numerous nano- to micro-nano-sized micropores. Under the influence of hydraulic pressure differentials, chemical potential differences, and capillary forces, drilling fluid filtrate enters the formation along these microfractures, causing rapid expansion of the illite / montmorillonite mixed layers. This leads to changes in pore pressure and rock stress, easily resulting in wellbore instability.

[0003] The main reason for wellbore instability in the Southwest region is that the continental Qianfoya Formation shale reservoir has a high clay mineral content, illite accounts for 36% to 50%, illite / montmorillonite mixed layer content is 10% to 20%, and it does not contain montmorillonite with strong hydration and expansion properties. The gray-black shale has strong bedding, obvious micro-fracture characteristics, well-developed organic matter, and weak structural planes. Working fluids can easily invade along weak structural planes such as bedding fractures, reduce effective stress and destroy the integrity of the rock structure, resulting in a significant reduction in the mechanical parameters of weak structural planes of bedding fractures, causing collapse.

[0004] Currently used inorganic salt-based clay hydration inhibitors are effective in inhibiting hydration swelling in montmorillonite-bearing formations, but their effect is not significant in formations containing illite or illite / montmorillonite mixed layers. Drilling fluids struggle to form a dense filter cake on low-permeability shale surfaces. The main challenge for environmentally friendly water-based drilling fluids in drilling mudstone and shale formations is how to effectively inhibit clay mineral hydration dispersion, construct a hydrophobic and dense film structure on the rock surface, simultaneously seal the internal pores and throats of the shale, improve the cohesive strength of the shale, and achieve both physical sealing and chemical wall-forming effects. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a nano-silica emulsion and its application in environmentally friendly water-based drilling fluid. The nano-silica emulsion provided by the present invention has a strong ability to inhibit the hydration and dispersion of bentonite, and can enhance the ability of environmentally friendly water-based drilling fluid to inhibit collapse and seal the wall.

[0006] This application provides a nano-silicone emulsion, comprising:

[0007] 5 to 15 parts by weight of polyol;

[0008] 1 to 10 parts by weight of nano-SiO2;

[0009] 1 to 10 parts by weight of silane coupling agent;

[0010] 5 to 20 parts by weight of silicate;

[0011] And 100 parts by weight of water.

[0012] In some specific implementations, the polyol is selected from one or more of ethylene glycol or polyethylene glycol.

[0013] In some specific implementations, the particle size of the nano-SiO2 is 1 nm to 100 nm.

[0014] In some specific implementations, the silane coupling agent has the structure of formula (I):

[0015] RSiX3 formula (I)

[0016] In formula (I), R is an organic functional group; X is an alkoxy group.

[0017] In some specific implementations, the silane coupling agent is selected from one or more of γ-methacryloxypropyltrimethoxysilane, 3-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and vinyltriethoxysilane.

[0018] In some specific implementations, the silicate is selected from one or more of potassium methylsilicate, sodium methylsilicate, potassium silicate, or sodium silicate.

[0019] This application also provides a method for preparing the nano-silicone emulsion described in the above technical solution, comprising the following steps:

[0020] Water and polyol are mixed, magnetically stirred and heated, and then mixed with silane coupling agent, nano-SiO2 and silicate to obtain nano-silicone emulsion.

[0021] In some specific implementations, the temperature for heating is 40℃ to 90℃.

[0022] This application also provides an application of the nano-silicone emulsion described in the above technical solution or the nano-silicone emulsion prepared by the method described in the above technical solution in environmentally friendly water-based drilling fluid.

[0023] This application also provides an environmentally friendly water-based drilling fluid, including the nano-silicone emulsion described in the above technical solution or the nano-silicone emulsion prepared by the method described in the above technical solution;

[0024] The mass concentration of the nano-silicone emulsion is 1% to 15%.

[0025] The nano-silicone emulsion provided in this application comprises: 5-15 parts by weight of polyol; 1-10 parts by weight of nano-SiO2; 1-10 parts by weight of silane coupling agent; 5-20 parts by weight of silicate; and 100 parts by weight of water. This application uses polyol, silane coupling agent, nano-SiO2, silicate, and water as raw materials, and obtains the nano-silicone emulsion through physical blending and chemical grafting modification. The polyol can reduce the activity of water, achieving the purpose of shale dehydration and improving shale stability; the silane coupling agent can convert the hydrophilic surface formed by SiO2 into a hydrophobic surface, reducing the free energy of the rock surface; the synergistic effect of polyol and silane coupling agent can effectively prevent the aggregation between nano-SiO2 molecules, improving the dispersion stability of the emulsion; silicate can form colloids and nano-sized particles of different sizes in drilling fluid, which have a film-forming and sealing effect on the rock surface. Therefore, the nano-silicone emulsion provided in this application can be applied to environmentally friendly water-based drilling fluid systems, with an applicable density of 1.15 g / cm³. 3 ~2.55g / cm 3 The applicable temperature range is 100℃~185℃.

[0026] The nano-silica emulsion provided in this application can effectively inhibit the hydration and dispersion of bentonite, seal formation microfractures, and simultaneously form a strongly adsorbed, hydrophobic, and semi-permeable membrane on the wellbore, achieving both physical sealing and chemical wellbore strengthening. Specifically designed for well-behaved or fractured formations, the nano-silica emulsion can enhance the drilling fluid's ability to inhibit collapse and seal wellbore, reduce hydration stress, decrease the interaction between water-based filtrate and formation rock, and improve mud cake quality, thereby achieving wellbore strengthening.

[0027] Moreover, all components in the preparation process of the nano-silicone emulsion described in this application can be converted into the final product, which conforms to the principle of atom economy in green chemistry; its raw materials are widely available, the preparation process is simple and safe, the conditions are mild, and it is easy to promote and apply. Attached Figure Description

[0028] Figure 1 These are photographs of the core samples from the test cases in this application, showing the immersion process. Detailed Implementation

[0029] This invention provides nano-silicone emulsions and their application in environmentally friendly water-based drilling fluids. Those skilled in the art can refer to the content of this document and appropriately modify the process parameters to achieve the desired results. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The methods and applications of this invention have been described through preferred embodiments. Those skilled in the art can clearly modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this invention to realize and apply the technology of this invention.

[0030] This application provides a nano-silicone emulsion, comprising:

[0031] 5 to 15 parts by weight of polyol;

[0032] 1 to 10 parts by weight of nano-SiO2;

[0033] 1 to 10 parts by weight of silane coupling agent;

[0034] 5 to 20 parts by weight of silicate;

[0035] And 100 parts by weight of water.

[0036] This application uses polyols, silane coupling agents, nano-SiO2, silicates and water as raw materials to obtain nano-silica emulsions through physical blending and chemical grafting modification. It can inhibit clay hydration and dispersion, seal formation micro-fractures, and form a strongly adsorbed hydrophobic semi-permeable membrane on the well wall, thus achieving the effects of physical sealing and chemical wall consolidation.

[0037] The nano-silicone emulsion provided in this application includes 100 parts by weight of water. This application does not have any special restrictions on the water; tap water is acceptable.

[0038] The nano-silicone emulsion provided in this application comprises 5 to 15 parts by weight of a polyol, wherein the polyol has the structure of formula (1):

[0039] C n H 2n+2-x (OH) x Equation (1)

[0040] In formula (1), n ​​is the number of carbon atoms in the polyol, which can be 2 to 20, such as 2, 4, 5, 6, 7, 10, 12, 15, etc., and x is the number of hydroxyl groups, which can be 2 to 5, such as 2, 3, 4, 5, etc.

[0041] In some specific implementations, the polyol is selected from diols, such as ethylene glycol or polyethylene glycol, or one or more of them. In some specific implementations, the molecular weight of the polyethylene glycol is preferably 100 to 2000, more preferably 400 to 1000.

[0042] Polyols can reduce water activity, thereby achieving shale dehydration and improving shale stability. In some specific implementations, the nano-silicone emulsion preferably includes 8 to 13 parts by weight of polyol, more preferably 9 to 11 parts by weight of polyol.

[0043] The nano-silica emulsion provided in this application comprises 1 to 10 parts by weight of nano-SiO2. Nano-SiO2 can effectively seal micropores and fractures in shale. The use of nanoparticles in drilling fluids can reduce formation damage, improve lubricity, and enhance rheological properties. In some specific implementations, the particle size of the nano-SiO2 is 1 nm to 100 nm, preferably 10 nm to 100 nm, more preferably 15 nm to 80 nm, and most preferably 20 nm. In some specific implementations, the nano-silica emulsion preferably comprises 3 to 7 parts by weight of nano-SiO2.

[0044] The nano-silicone emulsion provided in this application includes 1-10 parts by weight of a silane coupling agent. The silane coupling agent can convert the hydrophilic surface formed by SiO2 into a hydrophobic surface, reducing the surface free energy of the rock. The silane coupling agent, in synergy with the polyol, can effectively prevent the aggregation between nano-SiO2 molecules, improving the dispersion stability of the emulsion. In some specific implementations, the silane coupling agent has the structure of formula (I):

[0045] RSiX3 formula (I)

[0046] In formula (I), R is an organic functional group, such as aminoalkyl, vinyl, epoxyalkyl, etc.; X is an alkoxy group, such as methoxy, ethoxy, etc. In some specific implementations, the silane coupling agent includes, but is not limited to, γ-methacryloxypropyltrimethoxysilane, 3-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriethoxysilane, etc., and can be one or more of them. When the silane coupling agent is a combination of multiple substances, this application does not have any special restrictions on the specific proportion of each substance. In some specific implementations, the nano-silicone emulsion preferably includes 3 to 9 parts by weight of silane coupling agent, more preferably 6 to 8 parts by weight of silane coupling agent.

[0047] The nano-silicone emulsion provided in this application also includes 5-20 parts by weight of silicate. Silicate can form colloids and nanoparticles of different sizes in drilling fluid, exhibiting a film-forming and sealing effect on the rock surface. In some specific implementations, the silicate includes, but is not limited to, potassium methylsilicate, sodium methylsilicate, potassium silicate, or sodium silicate, and may be one or more of these. When the silicate is a combination of multiple substances, this application does not impose any special restrictions on the specific proportions of each substance. In some specific implementations, the nano-silicone emulsion preferably includes 10-15 parts by weight of silicate.

[0048] This application also provides a method for preparing the nano-silicone emulsion described in the above technical solution, comprising the following steps:

[0049] Water and polyol are mixed, magnetically stirred and heated, and then mixed with silane coupling agent, nano-SiO2 and silicate to obtain nano-silicone emulsion.

[0050] This application first mixes water and a polyol, preferably adding the polyol to the water, and then heats the mixture under magnetic stirring. The heated solution is then mixed with a silane coupling agent, nano-SiO2, and silicate, and stirred until homogeneous to obtain a nano-silicone emulsion. In some specific implementations, the heating temperature is 40℃ to 90℃, preferably 50℃ to 80℃, and most preferably 60℃.

[0051] The nano-silicone emulsion provided in this application can be applied to environmentally friendly water-based drilling fluid systems. Based on this, this application also provides an application of the nano-silicone emulsion described in the above technical solution or the nano-silicone emulsion prepared by the method described in the above technical solution in environmentally friendly water-based drilling fluids, with a suitable density of 1.15 g / cm³. 3 ~2.55g / cm 3 The applicable temperature range is 100℃~185℃.

[0052] This application also provides an environmentally friendly water-based drilling fluid, including the nano-silicone emulsion described in the above technical solution or the nano-silicone emulsion prepared by the method described in the above technical solution;

[0053] The mass concentration of the nano-silicone emulsion is 1% to 15%, preferably 3% to 10%.

[0054] In some specific implementations, the environmentally friendly water-based drilling fluid also includes water, bentonite, thickening and shearing agents, filtration loss reducers, anti-collapse agents, weighting agents, etc.

[0055] In this application, the mass of the bentonite is preferably 2% to 4% of the mass of the water-based drilling fluid, more preferably 2%.

[0056] In this application, the viscosity-enhancing and shearing agent is preferably a natural plant gum modified type (such as high-viscosity polyanionic cellulose, hydroxyethyl cellulose, etc.) or an organic polysaccharide modified derivative type (such as xanthan gum, etc.), and may be one or more of these. When the viscosity-enhancing and shearing agent is a combination of multiple substances, this application does not impose any special restrictions on the specific proportions of each substance. The viscosity-enhancing and shearing agent is more preferably an organic polysaccharide modified derivative type (such as xanthan gum). In some specific implementations, the mass of the viscosity-enhancing and shearing agent is preferably 0.05% to 0.2% of the mass of the water-based drilling fluid, more preferably 0.1%.

[0057] In this application, the filtration loss reducing agent is preferably a modified natural material-based filtration loss reducing agent, such as modified cellulose like hydroxyethyl cellulose, polyanionic cellulose, modified starch, modified humic acids, etc., and may be one or more of these, more preferably polyanionic cellulose. In some specific implementations, the mass of the filtration loss reducing agent is preferably 1% to 2% of the mass of the water-based drilling fluid.

[0058] In this application, the anti-collapse agent is preferably a polyether aminoalkyl glycoside. In some specific implementations, the mass of the anti-collapse agent is preferably 10% to 20% of the mass of the water-based drilling fluid.

[0059] In this application, the weighting agent is preferably barite.

[0060] The environmentally friendly water-based drilling fluid comprising nano-silicone emulsion provided by this invention has an applicable density of 1.15–2.55 g / cm³. 3 The applicable temperature range is 100–185℃. Compared with potassium chloride water-based drilling fluid, the drilling fluid provided in this application exhibits less change in rheological properties, reduced filtration loss under high temperature and high pressure, and stronger ability to inhibit collapse and seal the drilling wall.

[0061] The following examples further illustrate the nano-silicone emulsion provided in this application and its application in environmentally friendly water-based drilling fluids.

[0062] The polyethylene glycol, potassium silicate, sodium silicate, and potassium chloride used in the following examples were of analytical grade.

[0063] γ-Methacryloxypropyltrimethoxysilane, 3-aminopropyltriethoxysilane, γ-glycidyl etheroxypropyltrimethoxysilane, vinyltriethoxysilane, manufactured by Dongguan Kangjin New Materials;

[0064] Potassium methylsilicate powder and sodium methylsilicate powder are produced by Jinan Xingchi Chemical Co., Ltd.

[0065] Nano-SiO2, with a particle size of 20nm, produced by Suzhou Youyan New Materials.

[0066] Bentonite, xanthan gum XC, polyanionic cellulose sodium salt PAC-LV, and polyether aminoalkyl glycoside NAPG are all products sold by Sinopec Zhongyuan Petroleum Engineering Company.

[0067] Example 1

[0068] Take 100mL of water, add 15g of ethylene glycol, stir magnetically and heat to 60℃, then add 10g of γ-methacryloyloxypropyltrimethoxysilane, 10g of nano-SiO2 and 20g of potassium methylsilicate in sequence, and stir evenly to obtain nano-silicone emulsion 1.

[0069] Example 2

[0070] Take 100mL of water, add 10g of polyethylene glycol 400, stir magnetically and heat to 60℃, then add 10g of 3-aminopropyltriethoxysilane, 10g of nano-SiO2 and 20g of sodium methylsilicate in sequence, and stir evenly to obtain nano-silicone emulsion 2.

[0071] Example 3

[0072] Take 100mL of water, add 10g of polyethylene glycol 800, stir magnetically and heat to 60℃, then add 10g of γ-glycidyl etheroxypropyltrimethoxysilane, 10g of nano-SiO2 and 20g of sodium methylsilicate in sequence, and stir evenly to obtain nano-silicone emulsion 3.

[0073] Example 4

[0074] Take 100mL of water, add 10g of polyethylene glycol 800, stir magnetically and heat to 60℃, then add 10g of vinyltriethoxysilane, 10g of nano SiO2 and 20g of sodium silicate in sequence, and stir evenly to obtain nano-silicone emulsion 4.

[0075] Example 5

[0076] Take 100mL of water, add 10g of polyethylene glycol 600, stir magnetically and heat to 60℃, then add 8g of vinyltriethoxysilane, 7g of nano SiO2 and 10g of potassium methylsilicate in sequence, and stir evenly to obtain nano-silicone emulsion 5.

[0077] Comparative Example 1

[0078] 7% potassium chloride aqueous solution.

[0079] Comparative Example 2

[0080] A 7% potassium chloride + 2% sodium silicate + 2% potassium methylsilicate aqueous solution.

[0081] Performance testing

[0082] (1) Evaluation of suppression performance

[0083] The inhibition performance was evaluated using a core immersion test. 25g of bentonite was mixed with 3.5g of water and pressed under 10MPa pressure for 5 minutes to obtain the experimental core. First, a 7% aqueous solution was prepared using the example, and then the core was immersed in it. Simultaneously, the core was immersed in the comparative example, placed in an aging vessel, and then placed in a roller furnace. After rolling at 180℃ for 16 hours, the core immersion was observed at room temperature. The results are shown below. Figure 1 And Table 1, Figure 1 These are photographs of the core samples from the test examples of this application. As shown in Table 1, the nano-silica emulsion obtained by this invention can effectively inhibit the hydration and dispersion of bentonite, while also exhibiting a significant wall-consolidation effect.

[0084] Table 1 Evaluation of Suppression Performance

[0085] Core diameter / cm Core height / cm Description of the state of the core after soaking Original rock core 2.5 2.8 / Example 1 2.71 3.22 The shape is relatively intact, but the cracks are obvious. Example 2 / / The shape is incomplete and the edges are severely worn. Example 3 2.58 2.85 It is in good condition with slight wear on the edges. Example 4 / / The shape is incomplete and the edges are severely worn. Example 5 2.54 2.81 It has a complete shape and clear edges. Comparative Example 1 / / The core sample was dispersed, and the bentonite was completely hydrated. Comparative Example 2 / / The core was broken, containing a few tiny fragments.

[0086] (2) Drilling fluid compatibility evaluation

[0087] Based on 400ml of 2% bentonite-based drilling fluid, under high-speed stirring, add 0.4g of XC, 8g of PAC-LV, and 48g of NAPG sequentially, and then use barite to weigh the fluid to a density of 1.40g / cm³. 3 To obtain environmentally friendly water-based drilling fluid slurry.

[0088] The nano-silica emulsion obtained in the example reaction and the solution prepared in the comparative example were added to the base slurry, respectively. After aging at 120℃ for 16 hours, the comprehensive performance of the drilling fluid was measured at 50℃. The measurement method was carried out according to GB / T 16783.2-2012 "Field Testing of Drilling Fluids for Petroleum and Natural Gas Industry - Part 1: Water-based Drilling Fluids". The results are shown in Table 2. As can be seen from Table 2, the addition of the product of this invention to the environmentally friendly water-based drilling fluid did not significantly change the rheological properties of the drilling fluid system; the high-temperature and high-pressure filtration loss decreased. This indicates that the nano-silica emulsion has good compatibility with the environmentally friendly water-based drilling fluid and has good filtration loss reduction performance.

[0089] Table 2 Drilling Fluid Compatibility Evaluation

[0090]

[0091] Experimental results show that the nano-silica emulsion prepared by the method described in this invention has strong ability to inhibit bentonite hydration and dispersion, and good compatibility with environmentally friendly water-based drilling fluids. For formations with well-developed bedding or fractured structures, it can enhance the drilling fluid's ability to inhibit collapse and seal the wellbore, reduce hydration stress, decrease the interaction between water-based filtrate and formation rocks, improve mud cake quality, and achieve wellbore strengthening.

[0092] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A nanosilicon emulsion characterized in that, include: 5 to 15 parts by weight of polyol; 1 to 10 parts by weight of nano-SiO2; 1 to 10 parts by weight of silane coupling agent; 5 to 20 parts by weight of silicate; And 100 parts by weight of water.

2. The nanosilicon emulsion of claim 1, wherein, The polyol is selected from one or more of ethylene glycol or polyethylene glycol.

3. The nanosilicon emulsion of claim 1, wherein, The particle size of the nano-SiO2 is 1 nm to 100 nm.

4. The nanosilicon emulsion of claim 1, wherein, The silane coupling agent has the structure of formula (I): RSiX3 formula (I) In formula (I), R is an organic functional group; X is an alkoxy group.

5. The nanosilicon emulsion of claim 4, wherein The silane coupling agent is selected from one or more of γ-methacryloxypropyltrimethoxysilane, 3-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and vinyltriethoxysilane.

6. The nanosilicon emulsion of claim 1, wherein, The silicate is selected from one or more of potassium methylsilicate, sodium methylsilicate, potassium silicate, or sodium silicate.

7. A method for preparing the nano-silicone emulsion according to any one of claims 1 to 6, comprising the following steps: Water and polyol are mixed, magnetically stirred and heated, and then mixed with silane coupling agent, nano-SiO2 and silicate to obtain nano-silicone emulsion.

8. The production method according to claim 7, characterized by, The temperature for the heating is 40℃~90℃.

9. The application of the nano-silicone emulsion according to any one of claims 1 to 6 or the nano-silicone emulsion prepared by the method according to any one of claims 7 to 8 in environmentally friendly water-based drilling fluids.

10. An environmentally friendly water-based drilling fluid, comprising the nano-silicone emulsion as described in any one of claims 1 to 6 or the nano-silicone emulsion prepared by the method described in any one of claims 7 to 8; The mass concentration of the nano-silicone emulsion is 1% to 15%.

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