A high-temperature high-density drilling fluid thinner and a preparation method thereof

Abstract

The application provides a diluent for high-temperature and high-density drilling fluid and a preparation method thereof, and the preparation method comprises the following steps: S1, mixing monomers, a chain transfer agent and a solvent, stirring and dissolving, then introducing N2 to remove oxygen, then adding an initiator to perform a polymerization reaction, cooling to room temperature after the reaction is completed, and obtaining a first mixed solution; S2, adding 3,4-dihydroxybenzaldehyde and p-toluenesulfonic acid to the first mixed solution, introducing N2 to remove oxygen, then performing a reaction at a first temperature, cooling to room temperature after the reaction is completed, and obtaining a second mixed solution; S3, adding 3-chloro-2-hydroxypropanesulfonic acid sodium and 4-dimethylaminopyridine to the second mixed solution, introducing N2 to remove oxygen, then performing a reaction at a second temperature, cooling to room temperature after the reaction is completed, then freezing and recrystallizing, and obtaining the powder-shaped diluent; the prepared diluent can adjust the rheological property of the drilling fluid at high temperature and maintain various performances of the drilling fluid.

Description

Technical Field

[0001] This invention relates to the field of oilfield chemical technology, and more specifically, to a high-temperature, high-density drilling fluid diluent and its preparation method. Background Technology

[0002] With the continuous deepening of oil and gas exploration and development, the number of deep and ultra-deep wells is increasing year by year. These deep wells generally have extreme conditions such as high temperature, high pressure, and high salinity, which poses a severe challenge to drilling fluids. The control of drilling fluid rheology is a major problem in the drilling process.

[0003] In the drilling process of deep and ultra-deep wells, high-density or even ultra-high-density water-based drilling fluids are typically required to balance formation pressure. The extremely high solids content further increases the difficulty of rheological control of the drilling fluid under high temperature and high salinity conditions. In addition, clay particles are prone to agglomeration and flocculation under high temperature and high salinity conditions. Complex and variable formation environments, such as salt and calcium intrusion and drill cuttings intrusion, can also lead to the failure of treatment agents, ultimately causing drilling fluid thickening, deterioration of rheological properties, and accidents such as stuck pipe and wellbore instability.

[0004] Drilling fluid diluents play a crucial role in reducing drilling fluid viscosity parameters and are one of the key agents for effectively controlling drilling fluid rheology. The importance of high-quality diluent products for safe and efficient drilling is self-evident. Currently, diluents can be divided into dispersible diluents and low-molecular-weight polymer diluents. Polymer diluents not only reduce the plastic viscosity and dynamic shear force of drilling fluids but also improve their ability to inhibit formation mud formation, making them particularly advantageous in high-temperature deep well drilling and a long-standing research hotspot in drilling fluids.

[0005] Based on the above background, the inventors have developed a high-temperature, high-density drilling fluid diluent and its preparation method to achieve the purpose of adjusting the rheological properties of drilling fluid at high temperatures and maintaining various properties of drilling fluid. Summary of the Invention

[0006] The purpose of this invention is to address at least one of the aforementioned deficiencies in the prior art. For example, one objective of this invention is to provide a high-temperature, high-density drilling fluid diluent and its preparation method, thereby solving the problem that under high-temperature, salt-impregnated, or calcium-impregnated conditions, the drilling fluid clay disperses, leading to an enhanced network structure and increased viscosity and shear stress.

[0007] To achieve the above objectives, the present invention provides a diluent for high-temperature, high-density drilling fluids, wherein the diluent comprises the following structural units:

[0008]

[0009] Another aspect of the present invention provides a method for preparing a diluent for high-temperature, high-density drilling fluid, comprising the following steps:

[0010] S1. Mix the monomer, chain transfer agent and solvent, stir until completely dissolved, then introduce N2 to remove oxygen, then add the initiator to carry out the polymerization reaction, and cool to room temperature after the reaction is completed to obtain the first mixture.

[0011] S2. Add 3,4-dihydroxybenzaldehyde and p-toluenesulfonic acid to the first mixture obtained in step S1, and pass N2 through to remove oxygen. Then, carry out the reaction at the first temperature. After the reaction is completed, cool to room temperature to obtain the second mixture.

[0012] S3. Add sodium 3-chloro-2-hydroxypropanesulfonate and 4-dimethylaminopyridine to the second mixture obtained in step S2, and pass N2 through to remove oxygen. Then, carry out the reaction at the second temperature. After the reaction is completed, cool to room temperature, then freeze and recrystallize to obtain a powdered diluent.

[0013] The diluent has the following structural unit:

[0014]

[0015] In a preferred embodiment of this solution, the monomer is a combination of acrylamide, propyl 3-(dimethylamino)methacrylate, and allyl alcohol.

[0016] Furthermore, in a preferred embodiment of this solution, the mass ratio of acrylamide, propyl 3-(dimethylamino)methacrylate, and allyl alcohol is 20-35:10-20:5-10.

[0017] In a preferred embodiment of this solution, the amount of p-toluenesulfonic acid added is 0.2 to 0.4% of the monomer mass.

[0018] In a preferred embodiment of this solution, the molar ratio of 3,4-dihydroxybenzaldehyde to allyl alcohol is 1.2 to 1.4:1.

[0019] In a preferred embodiment of this scheme, the amount of 4-dimethylaminopyridine added is 0.1 to 0.2% of the monomer mass.

[0020] In a preferred embodiment of this solution, the molar ratio of sodium 3-chloro-2-hydroxypropanesulfonate to propyl 3-(dimethylamino)methacrylate is 1.2 to 1.4:1.

[0021] In a preferred embodiment of this scheme, the chain transfer agent is sodium hypophosphite; and / or the amount of the chain transfer agent added is 4 to 8% of the monomer mass.

[0022] In a preferred embodiment of this scheme, the initiator is any one of azobisisobutyrazoline hydrochloride (VO44), azobisisobutyramidine hydrochloride (V50), benzoyl peroxide (BPO), and azobisisobutyronitrile (AIBN); and / or the amount of the initiator added is 0.1 to 0.2% of the monomer mass.

[0023] In a preferred embodiment of this solution, the solvent is N,N-dimethylformamide.

[0024] In a preferred embodiment of this solution, in step S1, the polymerization reaction temperature is 50–60°C and the reaction time is 6–8 hours.

[0025] In a preferred embodiment of this solution, in step S2, the first temperature is 85-90°C, and the reaction time at the first temperature is 20-24 hours.

[0026] In a preferred embodiment of this solution, in step S3, the second temperature is 80-85°C, and the reaction time at the second temperature is 70-72 hours.

[0027] Compared with the prior art, the beneficial effects of the present invention include at least one of the following:

[0028] (1) The present invention provides a high-temperature and high-density drilling fluid diluent and its preparation method. By designing the molecular structure, cationic groups are introduced on the side chain of the polymer. The cationic groups can be adsorbed on the surface of charged clay particles, reducing the friction between particles and improving the salt resistance of the drilling fluid.

[0029] (2) The present invention provides a high-temperature and high-density drilling fluid diluent and its preparation method, which introduces sulfonic acid groups on the polymer side chain through quaternization reaction. The sulfonic acid groups have strong hydration ability and can form a strong solvation layer, thereby improving the drilling fluid's temperature and salt resistance.

[0030] (3) In this invention, the amino and hydroxyl groups in the diluent have a hydration effect, which can increase the thickness of the hydration layer, increase the zeta potential, increase the repulsive force, and inhibit clay aggregation and flocculation.

[0031] (4) In this invention, the polymer side chain of the diluent has a phenolic hydroxyl structure, and the phenolic hydroxyl group is adsorbed onto the Al at the edge of the clay particle end face through a coordination bond. 3+ This further weakens clay aggregation and flocculation, releases free water, and through their combined effects, achieves the purpose of reducing the viscosity and shear stress of the system at high temperatures and adjusting the rheological properties of the drilling fluid.

[0032] (5) The raw materials used in the preparation method of the present invention are available on the market and can be prepared using conventional methods. The raw materials are simple and easy to obtain, the preparation process is simple, and the cost is low. Attached Figure Description

[0033] The above and other objects and / or features of the present invention will become clearer from the following description taken in conjunction with the accompanying drawings, in which:

[0034] Figure 1 The infrared spectrum of an exemplary embodiment of a high-temperature, high-density drilling fluid diluent and its preparation method according to the present invention is shown.

[0035] Figure 2 The diagram shows a Zeta potential diagram of an exemplary embodiment of a high-temperature, high-density drilling fluid diluent and its preparation method according to the present invention. Detailed Implementation

[0036] In the following, a high-temperature, high-density drilling fluid diluent and its preparation method will be described in detail with reference to exemplary embodiments.

[0037] Exemplary Example 1

[0038] A high-temperature, high-density drilling fluid diluent, wherein the diluent comprises the following structural units:

[0039]

[0040] Exemplary Example 2

[0041] A method for preparing a diluent for high-temperature, high-density drilling fluid includes the following steps:

[0042] S1. Mix the monomer, chain transfer agent and solvent, stir until completely dissolved, then introduce N2 to remove oxygen, then add the initiator to carry out the polymerization reaction, and cool to room temperature after the reaction is completed to obtain the first mixture.

[0043] The monomer is a combination of three substances: acrylamide, propyl 3-(dimethylamino)methacrylate, and allyl alcohol.

[0044] S2. Add 3,4-dihydroxybenzaldehyde and p-toluenesulfonic acid to the first mixture obtained in step S1, and pass N2 through to remove oxygen. Then react at 85-90℃ for 20-24 hours. After the reaction is completed, cool to room temperature to obtain the second mixture.

[0045] The polymerization reaction temperature is 50–60℃, and the reaction time is 6–8 hours.

[0046] S3. Add sodium 3-chloro-2-hydroxypropanesulfonate and 4-dimethylaminopyridine to the second mixture obtained in step S2, and then pass N2 through to remove oxygen. Then react at 80-85°C for 70-72 hours. After the reaction is completed, cool to room temperature, then freeze and recrystallize to obtain a powdered diluent.

[0047] The diluent has the following structural unit:

[0048]

[0049] In this exemplary embodiment, the mass ratio of acrylamide, propyl 3-(dimethylamino)methacrylate, and allyl alcohol is (20-35):(10-20):(5-10), for example, 25:13:7, or 28:15:8, or 33:19:9.

[0050] In this exemplary embodiment, the amount of p-toluenesulfonic acid added is 0.2 to 0.4% of the monomer mass.

[0051] In this exemplary embodiment, the molar ratio of 3,4-dihydroxybenzaldehyde to allyl alcohol is 1.2 to 1.4:1.

[0052] In this exemplary embodiment, the amount of 4-dimethylaminopyridine added is 0.1 to 0.2% of the monomer mass.

[0053] In this exemplary embodiment, the molar ratio of sodium 3-chloro-2-hydroxypropanesulfonate to propyl 3-(dimethylamino)methacrylate is 1.2 to 1.4:1.

[0054] In this exemplary embodiment, the chain transfer agent is sodium hypophosphite, and the amount of chain transfer agent added is 4 to 8% of the monomer mass.

[0055] In this exemplary embodiment, the initiator is any one of azobisisobutyrazoline hydrochloride (VO44), azobisisobutyramidine hydrochloride (V50), benzoyl peroxide (BPO), and azobisisobutyronitrile (AIBN); and / or the amount of the initiator added is 0.1 to 0.2% of the monomer mass.

[0056] In this exemplary embodiment, the solvent is N,N-dimethylformamide. The N,N-dimethylformamide monomer concentration is prepared to be 35% to 45%.

[0057] To better understand the exemplary embodiments described above, further explanation will be provided below with reference to specific examples.

[0058] Example 1

[0059] A high-temperature, high-density drilling fluid diluent and its preparation method, wherein the preparation method specifically includes the following steps:

[0060] S1. Take acrylamide, propyl 3-(dimethylamino)methacrylate, allyl alcohol, chain transfer agent, solvent and other raw materials according to the required raw materials and proportions. Place the raw materials in a container and stir until completely dissolved. Then, introduce N2 into the solution to purge air for 30 minutes. Then, add the initiator to the solution and react at 55°C for 8 hours. After the reaction is completed, cool to room temperature for later use.

[0061] The solvent is N,N-dimethylformamide, and the N,N-dimethylformamide monomer concentration is prepared to be 35% to 45%, preferably 40%.

[0062] S2. Add 3,4-dihydroxybenzaldehyde and p-toluenesulfonic acid to S1 according to the raw material ratio, and purge the air into the solution with N2 for 30 min. React at 90℃ for 24 h. After the reaction is completed, cool to room temperature.

[0063] S3. Add sodium 3-chloro-2-hydroxypropanesulfonate and 4-dimethylaminopyridine to S2 according to the raw material ratio, and purge the air into the solution with N2 for 30 min. React at 85℃ for 72 h. After the reaction is completed, cool to room temperature, freeze, and recrystallize to obtain a powdered filtration loss reducer.

[0064] The structural formula of the obtained diluent product includes structural unit (Ⅰ):

[0065]

[0066] The raw materials and components of the diluent prepared in this embodiment are shown in Table 1 below. The diluent obtained in this embodiment is denoted as high-temperature resistant diluent L1.

[0067] Table 1

[0068] reagents Increase Acrylamide 20 3-(dimethylamino)methacrylate 10 Acrylic alcohol 5 AIBN 0.1 Sodium hypophosphite 4 3,4-Dihydroxybenzaldehyde 1.2 p-Toluenesulfonic acid 0.2 Sodium 3-chloro-2-hydroxypropanesulfonate 1.2 4-Dimethylaminopyridine 0.1

[0069] Example 2

[0070] A high-temperature, high-density drilling fluid diluent and its preparation method are disclosed, the preparation method being the same as that described in Example 1.

[0071] The raw materials and components of the diluent prepared in this embodiment are shown in Table 2 below. The diluent obtained in this embodiment is denoted as high-temperature resistant diluent L2.

[0072] Table 2

[0073] reagents Increase Acrylamide 25 3-(dimethylamino)methacrylate 15 Acrylic alcohol 5 AIBN 0.1 Sodium hypophosphite 4 3,4-Dihydroxybenzaldehyde 1.2 p-Toluenesulfonic acid 0.2 Sodium 3-chloro-2-hydroxypropanesulfonate 1.2 4-Dimethylaminopyridine 0.1

[0074] Example 3

[0075] A high-temperature, high-density drilling fluid diluent and its preparation method are disclosed, the preparation method being the same as that described in Example 1.

[0076] The raw materials and components of the diluent prepared in this embodiment are shown in Table 3 below. The diluent obtained in this embodiment is denoted as high-temperature resistant diluent L3.

[0077] Table 3

[0078] reagents Increase Acrylamide 30 3-(dimethylamino)methacrylate 10 Acrylic alcohol 5 AIBN 0.1 Sodium hypophosphite 4 3,4-Dihydroxybenzaldehyde 1.2 p-Toluenesulfonic acid 0.2 Sodium 3-chloro-2-hydroxypropanesulfonate 1.2 4-Dimethylaminopyridine 0.1

[0079] Example 4

[0080] A high-temperature, high-density drilling fluid diluent and its preparation method are disclosed, the preparation method being the same as that described in Example 1.

[0081] The raw materials and components of the diluent prepared in this embodiment are shown in Table 4 below. The diluent obtained in this embodiment is denoted as high-temperature resistant diluent L4.

[0082] Table 4

[0083] reagents Increase Acrylamide 40 3-(dimethylamino)methacrylate 10 Acrylic alcohol 5 AIBN 0.1 Sodium hypophosphite 6 3,4-Dihydroxybenzaldehyde 1.4 p-Toluenesulfonic acid 0.2 Sodium 3-chloro-2-hydroxypropanesulfonate 1.2 4-Dimethylaminopyridine 0.1

[0084] Example 5

[0085] A high-temperature, high-density drilling fluid diluent and its preparation method are disclosed, the preparation method being the same as that described in Example 1.

[0086] The raw materials and components of the diluent prepared in this embodiment are shown in Table 5 below. The diluent obtained in this embodiment is denoted as high-temperature resistant diluent L5.

[0087] Table 5

[0088] reagents Increase Acrylamide 20 3-(dimethylamino)methacrylate 15 Acrylic alcohol 5 AIBN 0.1 Sodium hypophosphite 4 3,4-Dihydroxybenzaldehyde 1.2 p-Toluenesulfonic acid 0.2 Sodium 3-chloro-2-hydroxypropanesulfonate 1.3 4-Dimethylaminopyridine 0.1

[0089] Example 6

[0090] A high-temperature, high-density drilling fluid diluent and its preparation method are disclosed, the preparation method being the same as that described in Example 1.

[0091] The raw materials and components of the diluent prepared in this embodiment are shown in Table 6 below. The diluent obtained in this embodiment is denoted as high-temperature resistant diluent L6.

[0092] Table 6

[0093] reagents Increase Acrylamide 35 3-(dimethylamino)methacrylate 20 Acrylic alcohol 5 AIBN 0.1 Sodium hypophosphite 4 3,4-Dihydroxybenzaldehyde 1.2 p-Toluenesulfonic acid 0.2 Sodium 3-chloro-2-hydroxypropanesulfonate 1.4 4-Dimethylaminopyridine 0.1

[0094] Example 7

[0095] A high-temperature, high-density drilling fluid diluent and its preparation method are disclosed, the preparation method being the same as that described in Example 1.

[0096] The raw materials and components of the diluent prepared in this embodiment are shown in Table 7 below. The diluent obtained in this embodiment is denoted as high-temperature resistant diluent L7.

[0097] Table 7

[0098] reagents Increase Acrylamide 20 3-(dimethylamino)methacrylate 10 Acrylic alcohol 10 AIBN 0.1 Sodium hypophosphite 4 3,4-Dihydroxybenzaldehyde 1.4 p-Toluenesulfonic acid 0.4 Sodium 3-chloro-2-hydroxypropanesulfonate 1.2 4-Dimethylaminopyridine 0.1

[0099] Figure 1 The infrared spectrum of the diluent prepared in Example 1 is shown below: The signal peak at 3400 cm⁻¹ is a characteristic peak of -OH and -NH₂. The signal peak at 2800–2900 cm⁻¹ is the stretching vibration peak of CH in the methyl and methylene groups, which is generated by the stretching vibration of the methyl and methylene groups in the polymer backbone and propyl 3-(dimethylamino)methacrylate. The signal peak at 1680 cm⁻¹ is generated by the C=O stretching vibration. The signal peaks appearing at 1400–1600 cm⁻¹ are characteristic absorption peaks of the C=C stretching vibration in the aromatic ring. The signal peaks at 1200 cm⁻¹ and 1050 cm⁻¹ are -SO₃ signal peaks. The infrared spectral data indicate that the target product was successfully obtained.

[0100] Figure 2 The graph shows the change in Zeta potential after the diluents prepared in Examples 1 and 2 were added to the base slurry. Figure 2 It can be seen that after adding L1 and L2, the absolute value of ζ of clay particles increases significantly, with L2 showing a better effect than L1. This indicates that the amino, hydroxyl, sulfonic acid, and cationic groups in the diluent molecules of this invention can generate electrostatic adsorption with the clay surface, increasing the thickness of the clay hydration film, thereby enhancing the repulsive force between clay particles and reducing the viscosity of the drilling fluid.

[0101] Table 8 shows the effect of the diluent prepared in Example 7 on the performance of drilling fluid. As can be seen from Table 8, the viscosity of the drilling fluid system gradually decreases with the increase of diluent content. This is mainly because the diluent molecules can be effectively adsorbed on the surface of clay particles and barite, reducing the friction between solid particles and maintaining good rheological properties of the drilling fluid. This indicates that the diluent has good compatibility with the drilling fluid used.

[0102] Table 8. Effects of diluents on drilling fluid properties

[0103]

[0104] The reagents used in the above embodiments are as follows:

[0105] 3-(dimethylamino)methacrylate and acrylamide are both industrial-grade products produced by Chengdu Kesheng.

[0106] 3,4-Dihydroxybenzaldehyde and allyl alcohol are analytical grade products produced by Aladdin Reagents.

[0107] Sodium hypophosphite, initiator, p-toluenesulfonic acid, sodium 3-chloro-2-hydroxypropanesulfonate, 4-dimethylaminopyridine, and N,N-dimethylformamide are all analytical grade products produced by Chengdu Kesheng.

[0108] Although the present invention has been described above in conjunction with exemplary embodiments and accompanying drawings, those skilled in the art should understand that various modifications can be made to the above embodiments without departing from the spirit and scope of the claims.

Claims

1. A diluent for high-temperature, high-density drilling fluid, characterized in that, The diluent has the following structural unit:

2. A method for preparing a diluent for high-temperature, high-density drilling fluid, characterized in that, Includes the following steps: S1. Mix the monomer, chain transfer agent and solvent, stir until completely dissolved, then introduce N2 to remove oxygen, then add the initiator to carry out the polymerization reaction, and cool to room temperature after the reaction is completed to obtain the first mixture. S2. Add 3,4-dihydroxybenzaldehyde and p-toluenesulfonic acid to the first mixture obtained in step S1, and pass N2 through to remove oxygen. Then, carry out the reaction at the first temperature. After the reaction is completed, cool to room temperature to obtain the second mixture. S3. Add sodium 3-chloro-2-hydroxypropanesulfonate and 4-dimethylaminopyridine to the second mixture obtained in step S2, and pass N2 through to remove oxygen. Then, carry out the reaction at the second temperature. After the reaction is completed, cool to room temperature, then freeze and recrystallize to obtain a powdered diluent. The diluent has the following structural unit:

3. The preparation method according to claim 2, characterized in that, The monomer is a combination of three substances: acrylamide, propyl 3-(dimethylamino)methacrylate, and allyl alcohol.

4. The preparation method according to claim 3, characterized in that, The mass ratio of acrylamide, propyl 3-(dimethylamino)methacrylate, and allyl alcohol is 20-35:10-20:5-10.

5. The preparation method according to claim 2, characterized in that, The amount of p-toluenesulfonic acid added is 0.2 to 0.4% of the monomer mass.

6. The preparation method according to claim 3, characterized in that, The molar ratio of 3,4-dihydroxybenzaldehyde to allyl alcohol is 1.2 to 1.4:

1.

7. The preparation method according to claim 3, characterized in that, The amount of 4-dimethylaminopyridine added is 0.1 to 0.2% of the monomer mass.

8. The preparation method according to claim 3, characterized in that, The molar ratio of sodium 3-chloro-2-hydroxypropanesulfonate to propyl 3-(dimethylamino)methacrylate is 1.2 to 1.4:

1.

9. The preparation method according to claim 2, characterized in that, The chain transfer agent is sodium hypophosphite; and / or The amount of chain transfer agent added is 4 to 8% of the monomer mass.

10. The preparation method according to claim 2, characterized in that, The initiator is any one of azobisisobutyrazoline hydrochloride, azobisisobutyramidine hydrochloride, benzoyl peroxide, and azobisisobutyronitrile; and / or The amount of initiator added is 0.1 to 0.2% of the monomer mass.

11. The preparation method according to claim 2, characterized in that, The solvent is N,N-dimethylformamide.

12. The preparation method according to claim 2, characterized in that, In step S1, the polymerization reaction temperature is 50–60°C and the reaction time is 6–8 hours.

13. The preparation method according to claim 2, characterized in that, In step S2, the first temperature is 85-90°C, and the reaction time at the first temperature is 20-24 hours.

14. The preparation method according to claim 2, characterized in that, In step S3, the second temperature is 80-85°C, and the reaction time at the second temperature is 70-72 hours.

Images