A viscosity reducer, a preparation method and application thereof

Abstract

The application provides a viscosity reducer and a preparation method and application thereof. The application provides a viscosity reducer, which comprises the following raw materials in weight components: 10-50 parts of non-polar component A, 10-60 parts of polar component B and 30-50 parts of surfactant C; the non-polar component A is selected from one or more of octane, petroleum ether, dotriacontane, octacosane, carbon disulfide, carbon tetrachloride, ethane, cyclohexane, liquid paraffin, ethyl acetate and diethylene glycol butyl ether; the polar component B is prepared by the reaction of styrene, maleic anhydride and acrylate; and the surfactant C is prepared by the reaction of the polar component B, an organic acid and a polyamine. The viscosity reducer provided by the application can significantly reduce the viscosity and shear force of the oil-based drilling fluid, improve the flowability of the oil-based drilling fluid, and especially reduce the viscosity and shear force of the oil-based drilling fluid after pollution.

Description

Technical Field

[0001] This invention relates to the field of drilling fluid technology, specifically to a viscosity reducer, its preparation method, and its application. Background Technology

[0002] As exploration conditions for oil-based drilling fluids become increasingly demanding, the required density is constantly rising, leading to increased use of weighting materials and consequently, a continuous increase in the viscosity of the drilling fluid, particularly for fluids with a density greater than 1.8 g / cm³. 3 For oil-based drilling fluids, viscosity reducers are a key treatment agent. During the preparation and use of oil-based drilling fluids, excessive viscosity often occurs, especially as cost-cutting measures lead to repeated reuse of the fluid, resulting in a continuous increase in the content of inferior solid phases and a widespread phenomenon of excessively thickened fluids. Furthermore, during drilling, the intrusion of waxy and asphalt-containing crude oil from the formation contributes to the thickening of oil-based drilling fluids. When the bottom hole temperature is high, wax dissolves in the base oil, while gums and asphaltenes remain suspended and dispersed in the oil, resulting in a relatively acceptable apparent viscosity. However, when the drilling fluid is in a surface tank at a lower temperature, gums and asphaltenes associate, increasing the system viscosity. Wax precipitates from the base oil, forming a network structure that encapsulates the base oil, thus deteriorating the fluid's flowability.

[0003] At this point, adding a certain amount of viscosity reducer becomes a necessary option for on-site treatment. The general principle of the action of oil-based drilling fluid viscosity reducers is that the viscosity reducer itself has surface activity. By improving the oleophilicity of the solid phase, it increases the oil phase's capacity to hold the oil. The viscosity reducer coats the solid phase surface, reducing the interaction between the solid phases. Alternatively, the viscosity reducer molecule may contain negatively charged functional groups that can interact with clay, preventing it from forming a network structure, thereby reducing shear stress and improving rheological properties. However, this type of viscosity reducer has limited effectiveness in addressing the flow pattern deterioration caused by heavy oil contamination.

[0004] However, existing drilling fluid viscosity reducers cannot improve problems such as the continuous increase of inferior solid phases in oil-based drilling fluid due to repeated use, excessive viscosity of drilling fluid, or the intrusion of high wax or asphalt crude oil from the formation into the drilling fluid during drilling, which causes the drilling fluid to thicken and thus exceed the viscosity standard, resulting in deterioration of drilling fluid fluid flowability.

[0005] Patent application CN104152122A describes a viscosity reducer for oil-based drilling fluids, comprising a terpolymer of polyethylene glycol, maleic anhydride, and polyethylene polyamine, with the polyethylene glycol having a molecular weight of 200-2000. Using diesel oil as a solvent, polyethylene glycol and maleic anhydride are reacted to obtain an ester compound; polyethylene polyamine is then added to the ester compound to obtain the terpolymer. The product contains -OH, -COO-, and -CONH- groups, which can form hydrogen bonds with organic groups in clay, thereby effectively breaking the interaction between organic groups in the clay and the oil. However, this viscosity reducer only binds to clay through functional groups and does not solve the thickening problem caused by heavy oil, weighting materials, or poor-quality solid phases. Summary of the Invention

[0006] To address the aforementioned problems in the prior art, this invention proposes a viscosity reducer, its preparation method, and its application.

[0007] In a first aspect, the present invention provides a viscosity reducer comprising the following raw materials by weight: 10-50 parts of nonpolar component A, 10-60 parts of polar component B and 30-50 parts of surfactant C.

[0008] Nonpolar component A is selected from one or more of the following: octane, petroleum ether, dodecane, octacosane, carbon disulfide, carbon tetrachloride, ethane, cyclohexane, liquid paraffin, ethyl acetate, and diethylene glycol butyl ether.

[0009] Polar component B is prepared by reacting styrene, maleic anhydride and acrylate.

[0010] Surfactant C is prepared by reacting polar component B, organic acid and polyamine.

[0011] As a specific embodiment of the present invention, the acrylate is prepared from acrylic acid and long-chain alkanol. The conditions for preparing polar component B include: the mass ratio of acrylic acid, long-chain alkanol, styrene and maleic anhydride is (90-120):(240-300):(20-40):(80-110).

[0012] As a specific embodiment of the present invention, the reaction conditions of acrylic acid and long-chain alkanol include: a temperature of 120-140°C and a time of 2-3 hours.

[0013] As a specific embodiment of the present invention, the reaction conditions for styrene, maleic anhydride and acrylate include: a temperature of 110-120°C and a time of 6-8 hours.

[0014] As a specific embodiment of the present invention, the long-chain alkanol is selected from those with C8-C9 carbon atoms. 22 One or more of the alcohols.

[0015] As a specific embodiment of the present invention, the conditions for preparing surfactant C include: the mass ratio of polar component B, organic acid and polyamine is (40-60):(110-130):(20-40).

[0016] As a specific embodiment of the present invention, in the process of preparing surfactant C, the reaction conditions of polar component B, organic acid and polyamine include: temperature of 160-180°C and time of 2-3 hours.

[0017] As a specific embodiment of the present invention, the organic acid is selected from one or more of tall oil acid, stearic acid, lauric acid, decanoic acid, palmitic acid, rosin acid, dodecylbenzenesulfonic acid, behenic acid, linolenic acid and adipic acid.

[0018] As a specific embodiment of the present invention, the polyamine is selected from one or more of polyethylene polyamine, diethylenetriamine, triethylenetetramine and tetraethylenepentamine.

[0019] In a second aspect, the present invention provides a method for preparing the viscosity reducer provided in the first aspect of the present invention, comprising: mixing a nonpolar component A, a polar component B and a surfactant C to prepare the viscosity reducer.

[0020] As a specific embodiment of the present invention, the preparation method of the viscosity reducer provided in the first aspect of the present invention includes the following steps: mixing non-polar component A, polar component B and surfactant C, heating to 80-100°C, stirring, keeping warm for 1-2 hours, and cooling to room temperature to obtain the viscosity reducer.

[0021] Thirdly, the present invention provides an application of the viscosity reducer provided in the first aspect of the present invention or the viscosity reducer prepared by the preparation method provided in the second aspect of the present invention in drilling fluids. Specifically, its application in oil-based drilling fluids.

[0022] Preferably, the mass ratio of the viscosity reducer to the drilling fluid volume is 3% to 5%.

[0023] Compared with the prior art, the present invention has the following beneficial effects.

[0024] (1) The present invention provides a viscosity reducer for oil-based drilling fluid, which can significantly reduce the viscosity and shear stress of oil-based drilling fluid and improve the fluidity of oil-based drilling fluid, especially reducing the viscosity and shear stress of contaminated oil-based drilling fluid.

[0025] (2) The viscosity reducer provided by the present invention can be used to treat the deterioration of the flow pattern of drilling fluid caused by high-quality solid phase, oil and gas pollution, etc. The poor solid phase has electrical repulsion between layers and end-face attraction to form a network structure. The increased viscosity of the drilling fluid after oil and gas pollution also causes the flow pattern to deteriorate. The viscosity reducer components of the present invention can form a coating on the solid phase, reduce the formation of network structure in the drilling fluid, change the wettability of the solid phase, improve the tolerance of the solid phase in polar terms, and the polar and non-polar components can dissolve some of the invading substances. Combined with solid control treatment of drilling fluid, the optimal flow pattern of oil-based drilling fluid can be achieved.

[0026] (3) The present invention provides a viscosity reducer for oil-based drilling fluid, which can effectively improve the viscosity reduction rate and reduce the circulating pump pressure when applied to oil-based drilling fluid.

[0027] (4) The present invention provides a viscosity reducer for oil-based drilling fluid, which has a simple preparation process, convenient operation, low cost, stable product quality, and high economic value.

[0028] (5) The viscosity reducer for oil-based drilling fluid provided by the present invention can be applied to the reprocessing of old oil-based drilling fluid slurry after well completion, which can effectively improve the fluidity and reuse value of old oil-based drilling fluid slurry. Detailed Implementation

[0029] The present invention will be further described below with reference to specific embodiments, but this does not constitute any limitation on the present invention.

[0030] Example 1

[0031] A viscosity reducer for oil-based drilling fluid comprises 150g of non-polar component A, 140g of polar component B and 170g of surfactant C. The three components are mixed and heated to 80°C, stirred for 5 minutes and kept at that temperature for 1 hour to obtain 460g of composite viscosity reducer.

[0032] Component A is ethyl acetate;

[0033] The preparation process of component B includes: In a three-necked flask reaction apparatus equipped with an electric stirrer, reflux condenser, and water separator, 270g of octadecyl alcohol is added and heated to 70℃ to melt it. Under stirring conditions, 2g of hydroquinone (polymer inhibitor), 3g of p-toluenesulfonic acid (catalyst), 150g of cyclohexane (dehydrating agent), and 90g of methacrylic acid are added sequentially. The temperature is slowly increased to 125℃, and the reaction is carried out for 2 hours. 15.8mL of water is condensed to obtain the reaction product. The reaction product is placed in a separatory funnel and washed with 5% NaOH solution until the aqueous layer is colorless. All 332g of the reaction product is returned to the above reactor, and 34g of styrene, 98g of maleic anhydride, and 50g of toluene (solvent) are added. The mixture is stirred and heated to 110℃, and nitrogen is purged for oxygen removal for 30 minutes. 5g of AIBN initiator is added, and the reaction is maintained at this temperature for 7 hours to obtain component B.

[0034] Preparation process of component C: Using the same reaction apparatus as that used to prepare component B, weigh 40g of component B, 120g of tall oil fatty acid, and 20g of diethylenetriamine. Gradually heat to 170℃ for 2 hours, condense 5.2mL of water under vacuum, and cool to obtain component C.

[0035] Example 2

[0036] A viscosity reducer for oil-based drilling fluid comprises 150g of non-polar component A, 150g of polar component B and 200g of surfactant C. The three components are mixed and heated to 85°C, stirred for 5 minutes and kept at that temperature for 1 hour to obtain 500g of composite viscosity reducer.

[0037] Component A is selected from petroleum ether;

[0038] The preparation process of component B includes: In a three-necked flask reaction apparatus equipped with an electric stirrer, a reflux condenser, and a water separator, 300g of heptane was added and heated to 70°C to melt it. Under stirring conditions, 2g of hydroquinone (polymer inhibitor), 3g of p-toluenesulfonic acid (catalyst), 200g of cyclohexane (dehydrating agent), and 110g of methacrylic acid were added sequentially. The temperature was slowly increased to 130°C, and the reaction was carried out for 2.5 hours. 16mL of water was condensed to obtain the reaction product. The reaction product was placed in a separatory funnel and washed with 5% NaOH solution until the aqueous layer was colorless. All 490g of the reaction product was returned to the above reactor, and 35g of styrene, 100g of maleic anhydride, and 50g of toluene (solvent) were added. The mixture was stirred and heated to 115°C, and nitrogen was purged for oxygen removal for 30 minutes. 5g of AIBN initiator was added, and the reaction was maintained at this temperature for 8 hours to obtain component B.

[0039] The preparation process of component C includes: using the same reaction apparatus as the preparation process of component B, weighing 60g of component B, 130g of palmitic acid and 20g of diethylenetriamine, gradually heating to 175℃ for 2 hours, condensing 8.2mL of water under vacuum, and cooling to obtain component C.

[0040] Example 3

[0041] A viscosity reducer for oil-based drilling fluid comprises 200g of non-polar component A, 100g of polar component B and 180g of surfactant C. The three components are mixed and heated to 85°C, stirred for 5 minutes and kept at that temperature for 1 hour to obtain 480g of composite viscosity reducer.

[0042] Component A is diethylene glycol butyl ether;

[0043] The preparation process of component B includes: In a three-necked flask reaction apparatus equipped with an electric stirrer, a reflux condenser, and a water separator, 240 g of palmitol was added and heated to 55 °C to melt it. Under stirring conditions, 1 g of hydroquinone (polymer inhibitor), 2 g of p-toluenesulfonic acid (catalyst), 100 g of cyclohexane (dehydrating agent), and 100 g of methacrylic acid were added sequentially. The temperature was slowly increased to 130 °C, and the reaction was carried out for 2 hours. 14.8 mL of water was condensed to obtain the reaction product. The reaction product was placed in a separatory funnel and washed with 5% NaOH solution until the aqueous layer was colorless. All 325 g of the reaction product was placed back into the above reactor, and 30 g of styrene, 100 g of maleic anhydride, and 50 g of toluene (solvent) were added. The mixture was stirred and heated to 115 °C, and nitrogen was purged for oxygen removal for 30 min. 3 g of AIBN initiator was added, and the reaction was maintained at this temperature for 8 hours to obtain component B.

[0044] The preparation process of component C includes: using the same apparatus as the preparation process of component B, weighing 40g of component B, 130g of palmitic acid and 30g of diethylenetriamine, gradually heating to 180℃, reacting for 2h, condensing 8.0mL of water under vacuum, and cooling to obtain component C.

[0045] Comparative Example 1

[0046] The specific process is as follows: In a three-necked flask equipped with an electric stirrer, reflux condenser, and water separator, 270g of octadecyl alcohol was added and heated to 70℃ to melt it. Under stirring conditions, 2g of hydroquinone (polymer inhibitor), 3g of p-toluenesulfonic acid (catalyst), 150g of cyclohexane (water-removing agent), and 90g of acrylic acid were added sequentially. The temperature was slowly raised to 125℃, and the reaction was carried out for 2 hours. 15.6mL of water was condensed to obtain the reaction product. The reaction product was placed in a separatory funnel and washed with 5% NaOH solution until the aqueous layer was colorless. All 330g of the reaction product was placed back into the above reactor, and 40g of styrene, 100g of maleic anhydride, and 200g of toluene were added. The mixture was stirred and heated to 110℃, and nitrogen was purged for oxygen removal for 30 minutes. 4g of BPO initiator was added, and the reaction was maintained at this temperature for 6 hours to obtain an oil-based drilling fluid viscosity reducer.

[0047] Performance testing

[0048] First, drilling fluid was prepared. Then, the drilling fluid was contaminated with inferior solid phase and crude oil. The viscosity and shear effects of Examples 1-3 and Comparative Example 1 on the contaminated drilling fluid were then tested.

[0049] Drilling fluid formulation: 240mL white oil + 2.5% primary emulsifier + 1.5% secondary emulsifier + 2% wetting agent + 2.5% organic clay + 3% calcium oxide + 5% oxidized bitumen + 60mL calcium chloride aqueous solution (calcium chloride to water mass-volume ratio of 25%) + 600g barite (to increase the formulation density to 1.90g / cm³). 3The percentages of primary emulsifier, secondary emulsifier, wetting agent, organic clay, calcium oxide, and oxidized bitumen added to the drilling fluid formulation are by mass-to-volume ratios, with the drilling fluid volume based on 300 mL. For example, 2.5% primary emulsifier is the percentage of the emulsifier's mass to the drilling fluid volume (300 mL).

[0050] Inferior solid phase is selected from mudstone and shale fragments, which are crushed and passed through a 120-mesh sieve.

[0051] The crude oil selected is waxy crude oil from a shale well in a certain block.

[0052] The test samples were aged by rolling at 200℃ for 16 hours. Under 65℃ conditions, the electrical stability before and after aging was measured using an electrical stability meter, and the plastic viscosity, dynamic shear force, and static shear force before and after aging were measured using a six-speed viscometer. The sedimentation after aging was measured using a steel ruler sedimentation meter. The test results are shown in Table 1.

[0053] The percentage content in the formulations below refers to the mass ratio of the added substance to the volume of the drilling fluid formulation. The volume of the drilling fluid formulation is based on 300 mL. For example, drilling fluid formulation + 10% inferior solid phase is: drilling fluid formulation + inferior solid phase accounting for 10% of the mass and volume of the drilling fluid formulation, where the volume of the drilling fluid formulation is based on 300 mL.

[0054] Table 1. Test data of the viscosity reducers prepared in the examples and comparative examples.

[0055]

[0056] As shown in Table 1, after being contaminated with inferior solid phases and crude oil, the viscosity and shear rate of oil-based drilling fluids increase after aging. Especially after contamination with inferior solid phases, the fluidity of the oil-based drilling fluid becomes extremely poor after aging. By adding the viscosity reducer of this invention to the contaminated oil-based drilling fluid, the viscosity and shear rate of the contaminated oil-based drilling fluid decrease significantly before and after aging, and the viscosity reduction effect is significantly higher than that of the viscosity reducer in Comparative Example 1, which is ineffective for contaminated drilling fluids. Therefore, the viscosity reducer of this invention can significantly reduce the viscosity and shear rate of contaminated oil-based drilling fluids, improve their fluidity, reduce circulating pump pressure, and enable the recycling of oil-based drilling fluids.

[0057] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on 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 terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A viscosity reducer, characterized in that, It includes the following raw materials by weight: 10-50 parts of nonpolar component A, 10-60 parts of polar component B and 30-50 parts of surfactant C; The nonpolar component A is selected from one or more of the following: octane, petroleum ether, dodecane, octacosane, carbon disulfide, carbon tetrachloride, ethane, cyclohexane, liquid paraffin, ethyl acetate, and diethylene glycol butyl ether. The polar component B is prepared by reacting styrene, maleic anhydride and acrylate; The surfactant C is prepared by reacting the polar component B, an organic acid, and a polyamine. The acrylate is prepared from acrylic acid and long-chain alkanols; The long-chain alkanols are selected from those with carbon numbers C8-C9. 22 One or more of the alcohols; The organic acid is selected from one or more of tall oil acid, stearic acid, lauric acid, decanoic acid, palmitic acid, rosin acid, dodecylbenzenesulfonic acid, behenic acid, linolenic acid and adipic acid; The polyamine is selected from one or more of the polyethylene polyamines.

2. The viscosity reducer according to claim 1, characterized in that, The conditions for preparing polar component B include: the mass ratio of acrylic acid, long-chain alkanol, styrene and maleic anhydride is (90-120):(240-300):(20-40):(80-110); And / or, the polyamine is selected from one or more of diethylenetriamine, triethylenetetramine, and tetraethylenepentamine.

3. The viscosity reducer according to claim 2, characterized in that, The reaction conditions for acrylic acid and long-chain alkanols include: a temperature of 120~140℃ and a time of 2~3h; and / or, the reaction conditions for styrene, maleic anhydride and acrylates include: a temperature of 110~120℃ and a time of 6~8h.

4. The viscosity reducer according to claim 3, characterized in that, The conditions for preparing surfactant C include: the mass ratio of polar component B, organic acid, and polyamine is (40-60):(110-130):(20-40).

5. The viscosity reducer according to claim 4, characterized in that, In the preparation of surfactant C, the reaction conditions of the polar component B, organic acid and polyamine include: temperature of 160~180℃ and time of 2~3h.

6. A method for preparing the viscosity reducer according to any one of claims 1-5, characterized in that, A viscosity reducer was prepared by mixing nonpolar component A, polar component B, and surfactant C.

7. A method for preparing the viscosity reducer according to any one of claims 1-5, characterized in that, The process includes the following steps: mixing non-polar component A, polar component B and surfactant C, heating to 80~100℃, stirring, keeping warm for 1~2 hours, and cooling to room temperature to obtain a viscosity reducer.

8. The application of a viscosity reducer according to any one of claims 1-5 or a viscosity reducer prepared by the preparation method according to claim 6 or 7 in drilling fluid.

9. The application according to claim 8, characterized in that, The mass ratio of the viscosity reducer to the volume of the drilling fluid is 3% to 5%.

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