Modified asphalt for drilling fluid and preparation method and application thereof

Abstract

The application discloses modified asphalt for drilling fluid and a preparation method and application thereof. The modified asphalt for drilling fluid comprises base asphalt and a modifier, the softening point of the base asphalt is 120-180 DEG C, and the modifier comprises modifier I and / or modifier II. The modified asphalt for drilling fluid has a high softening point, cation characteristics, high high-temperature resistance and strong adhesion to a well wall by using the modifier containing a specific functional group structure, and can continuously play a role in a high-temperature water-based drilling fluid.

Description

Technical Field

[0001] This invention belongs to the field of modified asphalt, specifically relating to a modified asphalt for drilling fluid, its preparation method, and its application. Background Technology

[0002] Asphalt products have wide applications in oil and gas drilling, serving as a crucial component of drilling fluids and an indispensable agent in modern drilling engineering. They possess comprehensive properties such as anti-collapse, lubrication, reduced filtration loss, and high-temperature stability. With the development of oil exploration and development, drilling depths are continuously increasing, and the formations encountered are becoming more complex, leading to a rise in the number of directional wells, horizontal wells, and other specialized drilling methods. This places higher demands on asphalt products and systems used in drilling fluids. Ordinary softening-point asphalt may soften excessively or even flow, failing to meet the high-temperature requirements of deep well operations. Developing high-softening-point asphalt with good high-temperature performance, excellent sealing properties, and reduced filtration loss to meet the needs of oilfield drilling engineering is of paramount importance.

[0003] To improve the performance of bituminous products used in drilling fluids, numerous methods for modifying bituminous materials have been disclosed. The most common method is sulfonation, as illustrated in standards such as US3485745, CN1239133A, and CN101906311A. After sulfonation, bituminous materials primarily form sulfonates, resulting in a softening point that is almost undetectable, limiting its use to relatively low temperatures. This method is ineffective in sealing and reducing filtration loss. Furthermore, this process is complex and can easily cause environmental pollution.

[0004] High softening point petroleum asphalt is primarily oil-soluble, so it disperses well in oil-based drilling fluids and its application is not a problem. However, in water-based drilling fluids, due to its very low water solubility, it presents difficulties in dispersion and stability. This is a major factor limiting the widespread application of high softening point asphalt in water-based drilling fluids.

[0005] When high softening point asphalt is used in drilling fluids, it is required to be dispersed into the mud system as fine particles. This ensures uniform asphalt dispersion and prevents the agglomeration of large lumps that could clog the vibrating screen and render the fluid unusable. Typically, the particle size of the asphalt should be below 120μm, or even below 100μm, for normal use. Common high softening point asphalts include petroleum asphalt, coal tar pitch, and natural asphalt.

[0006] High softening point bitumen used in deep and ultra-deep wells not only requires a high softening point but also good compatibility and stability with drilling fluid systems, especially water-based drilling fluid systems. Since wellbore rock formations are typically negatively charged, bitumen with cationic properties not only disperses easily and stably in drilling fluid systems but also bonds more firmly to the wellbore, thus better stabilizing the wellbore and providing sealing. Summary of the Invention

[0007] To address the problems of low softening point, poor dispersion, and inadequate performance in drilling fluids by existing asphalt products used in water-based drilling fluids, which fail to meet the performance requirements for sealing, preventing collapse, stabilizing the wellbore, and reducing filtration loss, this invention provides a modified asphalt for drilling fluids, its preparation method, and its application. This invention utilizes a modifier containing specific functional groups, resulting in a modified asphalt with a high softening point, cationic properties, strong high-temperature resistance, and excellent adhesion to the wellbore, enabling it to function continuously in high-temperature water-based drilling fluids.

[0008] The first aspect of this invention provides a modified bitumen for drilling fluid, comprising a base bitumen and a modifier, wherein the base bitumen has a softening point of 120–180°C, and the modifier comprises modifier I and / or modifier II, the general formulas of modifier I and modifier II being as follows:

[0009]

[0010] R1, R2, R3, R4, R5, and R6 represent organic groups.

[0011] Furthermore, R1, R2, R3, R4, R5, and R6 are alkyl groups, preferably C1-C6. 10 Alkyl groups, more preferably C1-C5 alkyl groups.

[0012] Furthermore, the base asphalt is selected from one or more of solvent-decomposed asphalt, oxidized asphalt, and natural asphalt.

[0013] Furthermore, based on the weight of the modified bitumen for drilling fluid, the content of the base bitumen is 90wt% to 99.9wt%, and the content of the modifier is 0.1wt% to 10wt%.

[0014] A second aspect of the present invention provides a method for preparing modified bitumen for drilling fluid, comprising:

[0015] (1) Preparation of modifier;

[0016] (2) The base bitumen is dissolved in an organic solvent, and then the modifier prepared in step (1) is added. The grafting reaction is carried out under stirring, and then halogenated hydrocarbons are added to continue the reaction to obtain modified bitumen for drilling fluid.

[0017] Further, the method for preparing the modifier in step (1) includes: reacting a primary amine compound with a tertiary amine structure with carbon disulfide in an alkaline solution; then adding a desulfurizing agent to carry out a desulfurization reaction to obtain the modifier.

[0018] Furthermore, the primary amine compounds having a tertiary amine structure include, but are not limited to, one or more of N,N-dimethylethylenediamine, 3-(dibutylamino)propylamine, and N,N-bis(3-aminopropyl)methylamine.

[0019] Furthermore, the alkaline solution is an organic alkaline solution and / or an inorganic alkaline solution, including but not limited to one or more of triethylamine solution and K2CO3 solution.

[0020] Furthermore, the mass concentration of the alkaline solution is 5 wt% to 35 wt%. The mass-to-volume ratio of the primary ammonium compound to the alkaline solution is 1:5 to 1:45 g / mL.

[0021] Furthermore, the primary amine compound reacts with carbon disulfide at room temperature, such as 20–30°C, for 1–10 h, wherein the molar ratio of the primary amine compound to carbon disulfide is 1:1 to 1:10.

[0022] Furthermore, the desulfurizing agent is one or more of di-tert-butyl dicarbonate, sodium persulfate, and copper sulfate pentahydrate. The molar ratio of primary amine compound to desulfurizing agent is 1:1 to 1:4.

[0023] Furthermore, the temperature of the desulfurization reaction is 4℃~25℃, and the reaction time is 0.5~2h.

[0024] Furthermore, after the desulfurization reaction is completed, a modifier is obtained through post-processing. The post-processing includes washing, extraction, drying, and rotary evaporation.

[0025] Furthermore, the washing can be performed using a saturated sodium chloride solution or water to remove impurities. The washing can be carried out in a centrifuge tube, with centrifugation for 5–30 minutes followed by washing. The extraction is preferably performed using ethyl acetate 2–4 times. The drying is preferably performed using anhydrous sodium sulfate. The rotary evaporation yields the modifier product.

[0026] Further, in step (2), the organic solvent is selected from one or more of chloroform, dichloromethane, toluene, tetrahydrofuran, and carbon tetrachloride. The mass ratio of the organic solvent to the base asphalt is 1:1 to 1:20.

[0027] Further, in step (2), the stirring speed is 90-2000 rpm, and the grafting reaction conditions are: reaction at 10-120℃ for 1-24 hours, preferably reaction at 30-110℃ for 2-12 hours. After the reaction is completed, excess organic solvent can be removed by rotary evaporation.

[0028] Further, in step (2), the haloalkane is benzyl chloride and / or hexadecane bromo.

[0029] Furthermore, the molar ratio of the modifier to the haloalkane is 1:1 to 1:5.

[0030] Furthermore, in step (2), after adding the haloalkane, the reaction is continued under the following conditions: reaction at 80-120°C for 1-4 hours, preferably reaction at 80-100°C for 2-3 hours.

[0031] A third aspect of the present invention provides the application of the above-mentioned modified bitumen for drilling fluid in drilling fluid.

[0032] Furthermore, when the modified bitumen for drilling fluid is applied to drilling fluid, it can be pulverized using conventional methods in the art, such as freezing the modified bitumen for drilling fluid at -10℃ to -50℃ for 1 to 10 hours, and then pulverizing it with a universal pulverizer for 1 to 60 seconds to obtain modified bitumen particles for drilling fluid with an average particle size of 80 to 120 mesh.

[0033] Furthermore, the amount of modified bitumen particles added to the drilling fluid is 1% to 10% by weight.

[0034] Furthermore, the drilling fluid is preferably a water-based drilling fluid.

[0035] Compared with the prior art, the present invention has the following advantages:

[0036] (1) The modifier used in this invention contains tertiary amine and isothiocyanate groups. Under certain conditions, the tertiary amine group can exhibit positive charge. With isothiocyanate groups, it is easy to react with the active groups in the asphalt and thus graft it into the asphalt, making the base asphalt more active.

[0037] (2) The modified asphalt of this invention has cationic groups grafted onto its surface, which has strong surface activity and is easier to disperse evenly and stably in drilling fluid, especially water-based drilling fluid, thus solving the problem that asphalt-based treatment agents are difficult to disperse stably in water-based drilling fluid.

[0038] (3) The modified asphalt of this invention has cationic groups grafted onto its surface, making it positively charged, while the rock strata of the well wall are usually negatively charged. Therefore, the asphalt with cationic properties will bond more firmly to the well wall and can better play the role of sealing and reducing filtration loss.

[0039] (4) In this invention, a specific modifier is used to modify high softening point asphalt under the condition of solvent. The resulting modified asphalt has a high softening point and strong activity, and can continue to play a role at high temperature when applied to drilling fluid. Attached Figure Description

[0040] Figure 1 The modifier ITC-1 prepared in Example 1 1 H NMR spectrum;

[0041] Figure 2 The mass spectrum of the modifier ITC-1 prepared in Example 1;

[0042] Figure 3 The modifier ITC-2 prepared in Example 2 1 H NMR spectrum;

[0043] Figure 4 The mass spectrum is that of the modifier ITC-2 prepared in Example 2. Detailed Implementation

[0044] The following non-limiting embodiments are intended to enable those skilled in the art to more fully understand the invention, but do not limit the invention in any way.

[0045] Example 1

[0046] Preparation of Modifier ITC-1

[0047] Add 70 mL of water, 5.52 g of K₂CO₃, and 3.72 g of 3-(dibutylamino)propylamine sequentially to a 250 mL flask. Slowly add 4.56 g of CS₂ and stir at 25 °C for 10 h. Cool to 10 °C in an ice-water bath, then slowly add 4.76 g of Na₂S₂O₈ and stir for 1 h. After the desulfurization reaction is complete, wash with 20 mL of saturated sodium chloride solution to remove impurities, then extract four times with 25 mL of ethyl acetate and dry with anhydrous sodium sulfate. Finally, rotary evaporate using a rotary evaporator to obtain ITC-1. 1 The H NMR spectrum is shown in [reference]. Figure 1 Mass spectrum (see) Figure 2 .

[0048]

[0049] Example 2

[0050] Preparation of modifier ITC-2

[0051] Add 100 mL of water, 12.15 g of triethylamine, and 4.36 g of N,N-bis(3-aminopropyl)methylamine to a 250 mL flask, then slowly add 7.59 g of carbon disulfide and stir at 25 °C for 6 h; then slowly add 9.87 g of CuSO4·5H2O at 20 °C and stir for 1.5 h. After the desulfurization reaction is complete, transfer the reaction mixture to a centrifuge tube, centrifuge the mixture for 15 min, add 20 mL of water to wash and remove impurities, then extract twice with 30 mL of ethyl acetate, dry with anhydrous sodium sulfate, and then rotary evaporate using a rotary evaporator to obtain ITC-2. 1 The H NMR spectrum is shown in [reference]. Figure 3 Mass spectrum (see) Figure 4 .

[0052]

[0053] Example 3

[0054] 100g of melt-desorbed bitumen with a softening point of 123.5℃ was placed in 260g of chloroform and fully dissolved. The modifier ITC-1 prepared above was then added and stirred mechanically at 1000rpm for 4h at 100℃. Then, 5.75g of benzyl chloride was slowly added and stirring continued for 1.5h at 80℃. After the reaction was completed, excess organic solvent was removed by rotary evaporation to obtain modified bitumen for drilling fluid containing 5.2wt% of modifier ITC-1.

[0055] The modified bitumen for drilling fluid was frozen at -25°C for 5 hours, then crushed for 60 seconds using a universal pulverizer, and sieved to obtain modified bitumen particles for drilling fluid with an average particle size of 80 mesh.

[0056] Example 4

[0057] 100g of solvent-desorbed bitumen with a softening point of 131.8℃ was placed in 180g of tetrahydrofuran and fully dissolved. The modifier ITC-2 prepared above was then added and stirred mechanically at 1500 rpm at 70℃ for 8 hours. Then, 9.15g of hexadecane bromide was slowly added and stirring continued. The reaction was carried out at 80℃ for 2.5 hours. After the reaction was completed, excess organic solvent was removed by rotary evaporation to obtain modified bitumen for drilling fluid containing 4.6wt% of modifier ITC-2.

[0058] The modified bitumen for drilling fluid was frozen at -35°C for 4 hours, then crushed for 50 seconds using a universal pulverizer, and sieved to obtain modified bitumen particles for drilling fluid with an average particle size of 100 mesh.

[0059] Example 5

[0060] 100g of oxidized asphalt with a softening point of 142.6℃ was placed in 420g of chloroform and dissolved completely. The modifier ITC-1 prepared above was then added and stirred mechanically at 800 rpm for 8 hours at 70℃. Then, 7.98g of benzyl chloride was slowly added and stirring continued for 2 hours at 90℃. After the reaction was completed, excess organic solvents were removed by rotary evaporation to obtain modified asphalt for drilling fluid containing 5.8wt% of modifier ITC-1.

[0061] The modified bitumen for drilling fluid was frozen at -30°C for 8.5 hours, then crushed for 30 seconds using a universal pulverizer, and sieved to obtain modified bitumen particles for drilling fluid with an average particle size of 80 mesh.

[0062] Example 6

[0063] 100g of oxidized asphalt with a softening point of 154.8℃ was placed in 640g of chloroform and fully dissolved. The modifier ITC-2 prepared above was added and stirred mechanically at 1200 rpm for 8 hours at 70℃. Then, 11.59g of benzyl chloride was slowly added and stirring continued for 3 hours at 100℃. After the reaction was completed, excess organic solvent was removed by rotary evaporation to obtain modified asphalt for drilling fluid containing 6.0wt% of modifier ITC-2.

[0064] The modified bitumen for drilling fluid was frozen at -35°C for 7 hours, then crushed for 40 seconds using a universal pulverizer, and sieved to obtain modified bitumen particles for drilling fluid with an average particle size of 100 mesh.

[0065] Comparative Example 1

[0066] 100g of melt-desorbed asphalt with a softening point of 131.8℃ was frozen at -35℃ for 4 hours, then crushed for 50s using a universal pulverizer, and sieved to obtain drilling fluid asphalt particles with an average particle size of 100 mesh.

[0067] Comparative Example 2

[0068] 100g of solvent-desorbed bitumen with a softening point of 131.8℃ was placed in 180g of tetrahydrofuran and the modifier ITC-2 prepared above was added after it was fully dissolved. The mixture was stirred mechanically at 1500 rpm at 70℃ for 8 hours. After the reaction was completed, excess organic solvent was removed by rotary evaporation to obtain modified bitumen for drilling fluid containing 4.6 wt% of modifier ITC-2.

[0069] The modified bitumen for drilling fluid was frozen at -35°C for 4 hours, then crushed for 50 seconds using a universal pulverizer, and sieved to obtain modified bitumen particles for drilling fluid with an average particle size of 100 mesh.

[0070] The properties of the modified bitumen for drilling fluid obtained in Examples 3-6 and Comparative Examples 1-2 are shown in Table 1. The pulverized particles were placed in the prepared base slurry (the amount of modified bitumen added for drilling fluid was 4.8 wt% by weight of drilling fluid), and subjected to high-speed shearing for 20 min to obtain the drilling fluid system. Its drilling fluid performance was tested and is shown in Table 2.

[0071] The preparation process of the base slurry is as follows: 2.75g of anhydrous sodium carbonate is added to every 1000mL of water, followed by 60g of sodium bentonite. The mixture is stirred at high speed for 20min and then cured at room temperature for 24h to obtain the base slurry.

[0072] Table 1. Physicochemical parameters of modified bitumen for drilling fluids obtained from each embodiment and comparative example.

[0073]

[0074] Table 2 Properties of Drilling Fluid

[0075]

[0076] Wherein: AV: apparent viscosity, PV: plastic viscosity; viscosity, low temperature and low pressure (API) and high temperature and high pressure filtration loss are determined according to GB / T16783 method, and the aging conditions are: 160℃, 16 hours.

Claims

1. A modified bitumen for use in drilling fluids, characterized in that, The modified asphalt for drilling fluid comprises a base asphalt and a modifier, the softening point of the base asphalt is 120-180℃, the modifier comprises modifier I and / or modifier II, the general formula of the modifier I and the modifier II is as follows: ； In the formula, R1, R2, R3, R4, R5 and R6 represent organic groups. R1, R2, R3, R4, R5, and R6 are each independently selected from C1 to C2. 10 alkyl.

2. The modified bitumen for drilling fluid according to claim 1, characterized by, The R1, R2, R3, R4, R5 and R6 are each independently selected from C1-C5 alkyl.

3. The modified bitumen for drilling fluids according to claim 1, characterized in that, The base asphalt is selected from one or more of the following: solution-deasphalted asphalt, oxidized asphalt, natural asphalt.

4. The modified bitumen for drilling fluids according to claim 1, characterized in that, The content of the base asphalt is 90wt%-99.9wt% and the content of the modifier is 0.1wt%-10wt% based on the weight of the modified asphalt for drilling fluid.

5. The method of claim 1-4, wherein the modified bitumen for drilling fluid is prepared by the steps of: The method comprises: (1) preparing a modifier; (2) dissolving the base asphalt in an organic solvent, then adding the modifier prepared in step (1) to carry out grafting reaction under stirring, and then adding a halogenated hydrocarbon to continue the reaction to obtain the modified asphalt for drilling fluid.

6. The method of claim 5, wherein, The method for preparing the modifier in step (1) comprises: reacting a primary amine compound with a tertiary amine structure in an alkaline solution with carbon disulfide; then adding a desulfurization agent to carry out desulfurization reaction to obtain the modifier.

7. The method of claim 6, wherein, The primary amine compound with a tertiary amine structure is one or more of the following: N,N-dimethylethylenediamine, 3-(dibutylamino)propylamine and N,N-bis(3-aminopropyl)methylamine.

8. The method of claim 6, wherein, The alkaline solution is an organic alkaline solution and / or an inorganic alkaline solution.

9. The method of claim 8, wherein, The alkaline solution is one or more of the following: triethylamine solution and K2CO3 solution.

10. The method of claim 6, wherein, The temperature for the reaction of the primary amine compound with carbon disulfide is 20-30℃ and the reaction time is 1-10h; the molar ratio of the primary amine compound to carbon disulfide is 1:1-1:

10.

11. The method of claim 6, wherein, The desulfurization agent is one or more of the following: di-tert-butyl dicarbonate, sodium persulfate and copper sulfate pentahydrate; the molar ratio of the primary amine compound to the desulfurization agent is 1:1-1:

4.

12. The method of claim 6, wherein, The temperature for the desulfurization reaction is 4-25℃ and the reaction time is 0.5-2h.

13. The method of claim 5, wherein, In step (2), the organic solvent is selected from one or more of the following: chloroform, dichloromethane, toluene, tetrahydrofuran and carbon tetrachloride; the mass ratio of the organic solvent to the base asphalt is 1:1-1:

20.

14. The method of claim 5, wherein, In step (2), the grafting reaction is carried out at 10-120℃ for 1-24h.

15. The method of claim 14, wherein, In step (2), the grafting reaction is carried out at 30-110℃ for 2-12h.

16. The method of claim 5, wherein, In step (2), the halogenated hydrocarbon is benzyl chloride and / or bromohexadecane; the molar ratio of the modifier to the halogenated hydrocarbon is 1:1-1:

5.

17. The method of claim 5, wherein, In step (2), after the halogenated hydrocarbon is added, the reaction is continued at 80-120℃ for 1-4h.

18. The method of claim 17, wherein, In step (2), after the halogenated hydrocarbon is added, the reaction is continued at 80-100℃ for 2-3h.

19. The modified asphalt for drilling fluid as claimed in any one of claims 1-4 or prepared by the method as claimed in any one of claims 5-18 is applied in a drilling fluid.

20. The use according to claim 19, characterized in that, The drilling fluid is a water-based drilling fluid.

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