Modified barite powder for oil and gas field drilling fluids
By modifying barite powder with epoxidized polyisoprene, the problem of easy sedimentation of barite powder in drilling fluid is solved, achieving excellent sedimentation stability and dispersibility, which is suitable for oil and gas field drilling fluids.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ANHUI LUHAI PETROLEUM AUX TECH
- Filing Date
- 2026-02-10
- Publication Date
- 2026-06-23
AI Technical Summary
Barite powder tends to settle in drilling fluids, which reduces its rheological properties and settling stability. Existing chemical modification methods are complex and costly.
Epoxidized polyisoprene was used to graft and modify barite powder. Stable chemical bonds were formed by the reaction of silane coupling agent with the surface of barite powder, introducing hydrophobic and oleophilic chains to improve dispersibility.
Modified barite powder exhibits excellent settling stability and dispersibility in drilling fluids, reducing flocculation and sedimentation and viscosity increase, making it suitable for oil and gas field drilling fluids.
Smart Images
Figure SMS_1
Abstract
Description
Technical Field
[0001] This invention belongs to the technical field of inorganic fillers for oil and gas field drilling fluids, specifically relating to a modified barite powder for oil and gas field drilling fluids. Background Technology
[0002] Drilling fluid is a general term for the circulating fluids used in the drilling process to meet operational needs. In the early days of drilling technology, clean water was sufficient for all drilling requirements. However, with advancements in drilling technology and changes in the drilling environment, more functional drilling fluids are needed. During drilling, drilling fluid primarily plays the following roles: cleaning the wellbore and circulating broken rock cuttings to the surface, improving drilling efficiency; cooling the drill bit, reducing its temperature, and extending its lifespan; balancing wellbore pressure and stabilizing it to prevent collapse; balancing pressure to prevent blowouts and lost circulation; and providing auxiliary support during drilling by breaking rocks under high water pressure. Therefore, the quality requirements for drilling fluids are increasingly stringent. The most direct way to achieve these functions is to add weighting agents to the drilling fluid to increase its density, thereby facilitating smooth drilling operations at the wellbore.
[0003] Barite is one of the most common weighting materials in drilling fluids. Due to its superior properties compared to other weighting materials (high density, low environmental impact, and low production cost), it has become a candidate material for drilling. However, due to factors such as gravity, heavy particulate matter tends to settle from the suspension, leading to reduced rheological properties and settling stability of the drilling fluid system, potentially causing various drilling problems.
[0004] To improve the suspension capacity of barite in drilling fluids, hydrophilic barite can be modified to be hydrophobic. A common chemical method is to form an adsorption layer on the barite surface with surfactants, reducing surface energy and surface polarity, thereby improving its dispersibility and compatibility with organic matter. However, this method is complex, the reaction process is difficult to control, and most surfactants are expensive and have a certain degree of toxicity and pollution.
[0005] Therefore, solving the problem of the difficulty in dispersing and easy sedimentation of inorganic barite weighting agents is a technical problem that still needs to be solved in this field. Summary of the Invention
[0006] To address the aforementioned issues, this invention employs epoxidized polyisoprene to graft-modify barite powder. It has been found that the resulting modified barite powder is particularly suitable for oil and gas field drilling fluids, exhibiting excellent settling stability and dispersibility, thereby reducing flocculation, settling, and viscosity increases in the drilling fluid system.
[0007] The reaction mechanism of epoxidized polyisoprene-modified barite in this invention is as follows: Under alcohol solvent and weak acid conditions, the hydrolyzable groups in the silane coupling agent hydrolyze to form a reactive silanol structure. This silanol structure can undergo a condensation reaction with the hydroxyl groups or adsorbed water present on the surface of the barite powder particles, allowing the silane coupling agent to be stably bound to the surface of the barite powder. Simultaneously, the amino functional groups in the silane coupling agent molecule do not participate in the condensation reaction but are distributed outwardly on the surface of the barite powder, thereby introducing amino active sites on the surface of the barite powder. Subsequently, the amino active sites can undergo a ring-opening reaction with the epoxy groups in the epoxidized polyisoprene molecule, forming a stable chemical bond between the barite powder and the organic polymer, thus fixing the epoxidized polyisoprene to the surface of the barite powder by chemical grafting, and covalently grafting the hydrophobic and oleophilic epoxidized polyisoprene polymer chain onto the barite surface.
[0008] Specifically, the present invention provides a modified barite powder for oil and gas field drilling fluid, which is prepared by grafting barite powder with epoxidized polyisoprene.
[0009] Further, the modified barite powder is prepared by a method including the following steps: (1) surface treatment of barite powder with an aminosilane coupling agent to obtain aminated barite powder; (2) reaction of epoxidized polyisoprene with aminated barite powder in an organic solvent under heating to obtain modified barite powder.
[0010] Further, step (1) includes: mixing aminosilane coupling agent, acid and ethanol solution, adding barite powder, mixing, ultrasonic treatment for 2-4 hours, then centrifuging to collect solid powder, vacuum drying to obtain amino-modified barite powder.
[0011] Furthermore, the aminosilane coupling agent is selected from silane coupling agent KH-550.
[0012] Furthermore, the mass ratio of the aminosilane coupling agent to barite powder is 1:5-10.
[0013] Furthermore, the ultrasonic frequency of the ultrasonic treatment is 20-50KHz, the ultrasonic power is 400-600W, and the ultrasonic treatment operates in a pulse mode of 1-2s on / 0.2-0.6s off.
[0014] Further, step (2) includes: dissolving epoxidized polyisoprene in an organic solvent, then adding aminated barite powder, stirring and mixing, controlling the reaction temperature at 50-80℃, reacting under ultrasonic treatment for 3-5 hours, stopping heating and cooling naturally, collecting the solid by centrifugation, and obtaining modified barite powder by washing, drying, grinding and sieving.
[0015] Furthermore, the degree of epoxidation of the epoxidized polyisoprene is 80-90 mol%. Furthermore, the organic solvent is selected from N,N-dimethylformamide.
[0016] Furthermore, the mass ratio of epoxidized polyisoprene to aminated barite powder is 1:1-5.
[0017] Furthermore, the ultrasonic frequency of the ultrasonic treatment is 20-50KHz, the ultrasonic power is 400-600W, and the ultrasonic treatment operates in a pulse mode of 1-2s on / 0.2-0.6s off.
[0018] In other respects, the present invention provides a method for preparing modified barite powder as described herein, comprising the following steps: (1) surface-treating barite powder with an aminosilane coupling agent to obtain aminated barite powder; and (2) reacting epoxidized polyisoprene with aminated barite powder in an organic solvent under heating to obtain modified barite powder.
[0019] Further, in the method, step (1) includes: mixing aminosilane coupling agent, acid and ethanol solution, adding barite powder, stirring and mixing, ultrasonic treatment for 2-4 hours, then centrifuging to collect solid powder, vacuum drying to obtain amino-modified barite powder.
[0020] Furthermore, in the method, the aminosilane coupling agent is selected from silane coupling agent KH-550.
[0021] Furthermore, in the method, the mass ratio of the aminosilane coupling agent to barite powder is 1:5-10.
[0022] Furthermore, in the method, the ultrasonic frequency of the ultrasonic treatment is 20-50KHz, the ultrasonic power is 400-600W, and the ultrasonic treatment operates in a pulse mode of 1-2s on / 0.2-0.6s off.
[0023] Further, in the method, step (2) includes: dissolving epoxidized polyisoprene in an organic solvent, then adding aminated barite powder, stirring and mixing, controlling the reaction temperature at 50-80℃, reacting under ultrasonic treatment for 3-5 hours, stopping heating and cooling naturally, collecting the solid by centrifugation, and obtaining modified barite powder by washing, drying, grinding and sieving.
[0024] Furthermore, in the method, the degree of epoxidation of the epoxidized polyisoprene is 80-90 mol%.
[0025] Furthermore, in the method, the organic solvent is selected from N,N-dimethylformamide.
[0026] Furthermore, in the method, the mass ratio of epoxidized polyisoprene to aminated barite powder is 1:1-5.
[0027] Furthermore, in the method, the ultrasonic frequency of the ultrasonic treatment is 20-50KHz, the ultrasonic power is 400-600W, and the ultrasonic treatment operates in a pulse mode of 1-2s on / 0.2-0.6s off.
[0028] The beneficial effects of this invention are as follows: In the process of developing a new type of modified barite to solve the problem of its difficulty in dispersion and easy sedimentation as a weighting agent, the inventors unexpectedly discovered that when barite powder is grafted with high-epoxy polyisoprene, a polyisoprene coating layer can be formed on the barite powder. Due to the hydrophobicity and oleophilicity of polyisoprene, the modified barite powder has excellent dispersibility in drilling fluid, and at the same time, it does not significantly change the viscosity of the drilling fluid. Currently, no reports in this field have described the applicability of polyisoprene-modified barite powder to drilling fluids. In fact, simply modifying barite powder with polyisoprene does not make it more suitable for use in drilling fluids. As demonstrated in this invention, when barite powder is grafted with polyisoprene that has a low epoxy content or only has end-group epoxidation, the viscosity of the drilling fluid increases significantly, making it unusable. High epoxy content is crucial for the successful application of polyisoprene-modified barite powder in drilling fluids, which is an unexpected finding. Detailed Implementation
[0029] The present invention will be further illustrated below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in this technical field.
[0030] Example 1
[0031] This embodiment provides a modified barite powder for oil and gas field drilling fluid, which is prepared as follows.
[0032] (1) By weight, 100 parts of ethanol solution (ethanol concentration 90wt%), 0.6 parts of acetic acid, and 5 parts of silane coupling agent KH-550 were stirred and mixed, and 30 parts of barite powder were added. After stirring and mixing, the mixture was ultrasonically treated for 4 hours (ultrasonic frequency of 20KHz, ultrasonic power of 400W, and ultrasonic treatment was carried out in a pulse mode of 2s on / 0.6s off). Then, the solid powder was collected by centrifugation and vacuum dried to obtain aminated barite powder.
[0033] (2) By weight, 10 parts of epoxidized polyisoprene (purchased from Polymer Source, product ID: P7055A-EIP, epoxidation degree of 89mol%) were dissolved in 100 parts of N,N-dimethylformamide, and then 20 parts of aminated barite powder were added. After stirring and mixing, the reaction temperature was controlled at 60℃ and the reaction was carried out under ultrasonic treatment for 3 hours (ultrasonic frequency of 50KHz, ultrasonic power of 600W, and ultrasonic treatment was carried out in a pulse mode of 1s on / 0.2s off). Heating was stopped and the mixture was allowed to cool naturally. The solid was collected by centrifugation, washed three times with ethanol and purified water, vacuum dried, ground and sieved to obtain modified barite powder.
[0034] Example 2
[0035] This embodiment provides a modified barite powder for oil and gas field drilling fluid, which is prepared as follows.
[0036] (1) By weight, 100 parts of ethanol solution (ethanol concentration 90wt%), 0.6 parts of acetic acid, and 5 parts of silane coupling agent KH-550 were stirred and mixed, and 50 parts of barite powder were added. After stirring and mixing, the mixture was ultrasonically treated for 2 hours (ultrasonic frequency of 30KHz, ultrasonic power of 500W, and ultrasonic treatment was carried out in a pulse mode of 2s on / 0.6s off). Then, the solid powder was collected by centrifugation and vacuum dried to obtain aminated barite powder.
[0037] (2) By weight, 10 parts of epoxidized polyisoprene (purchased from Polymer Source, product ID: P7055A-EIP, epoxidation degree of 89mol%) were dissolved in 100 parts of N,N-dimethylformamide, and then 50 parts of aminated barite powder were added. After stirring and mixing, the reaction temperature was controlled at 70℃ and the reaction was carried out under ultrasonic treatment for 5 hours (ultrasonic frequency of 40KHz, ultrasonic power of 500W, and ultrasonic treatment was carried out in a pulse mode of 1s on / 0.2s off). Heating was stopped and the mixture was allowed to cool naturally. The solid was collected by centrifugation, washed three times with ethanol and purified water, vacuum dried, ground and sieved to obtain modified barite powder.
[0038] Comparative Example 1
[0039] This comparative example provides a modified barite powder, which is prepared as follows.
[0040] (1) Same as Example 1;
[0041] (2) By weight, 10 parts of epoxidized polyisoprene (purchased from Polymer Source, product ID: P10962-EIP, epoxidation degree of 8 mol%) were dissolved in 100 parts of N,N-dimethylformamide, and then 20 parts of aminated barite powder were added. After stirring and mixing, the reaction temperature was controlled at 60℃ and the reaction was carried out under ultrasonic treatment for 3 hours (ultrasonic frequency of 50KHz, ultrasonic power of 600W, and ultrasonic treatment was carried out in a pulse mode of 1s on / 0.2s off). Heating was stopped and the mixture was allowed to cool naturally. The solid was collected by centrifugation, washed three times with ethanol and purified water, dried under vacuum, ground and sieved to obtain modified barite powder.
[0042] Comparative Example 2
[0043] This comparative example provides a modified barite powder, which is prepared as follows.
[0044] (1) Same as Example 1;
[0045] (2) By weight, 10 parts of double-epoxy polyisoprene (preparation method refers to Example 3 of CN110563861A, epoxy value is 58.36) were dissolved in 100 parts of N,N-dimethylformamide, and then 20 parts of aminated barite powder were added. After stirring and mixing, the reaction temperature was controlled at 60℃ and the reaction was carried out under ultrasonic treatment for 3 hours (ultrasonic frequency is 50KHz, ultrasonic power is 600W, and ultrasonic treatment is carried out in a pulse mode of 1s on / 0.2s off). Heating was stopped and the mixture was allowed to cool naturally. The solid was collected by centrifugation, washed three times with ethanol and purified water in sequence, dried under vacuum, ground and sieved to obtain modified barite powder.
[0046] Comparative Example 3
[0047] (1) Same as Example 1;
[0048] (2) By weight, 10 parts of epoxidized polybutadiene (prepared by the method of CN105693887A with an epoxidation degree of 85 mol%) was dissolved in 100 parts of N,N-dimethylformamide, and then 20 parts of aminated barite powder were added. After stirring and mixing, the reaction temperature was controlled at 60℃ and the reaction was carried out under ultrasonic treatment for 3 hours (ultrasonic frequency of 50KHz, ultrasonic power of 600W, and ultrasonic treatment was carried out in a pulse mode of 1s on / 0.2s off). Heating was stopped and the mixture was allowed to cool naturally. The solid was collected by centrifugation, washed three times with ethanol and purified water, dried under vacuum, ground and sieved to obtain modified barite powder.
[0049] Test case
[0050] The modified barite powder and unmodified barite powder prepared in Examples 1-2 and Comparative Examples 1-3 were added to a white oil-based drilling fluid (the drilling fluid consisted of 240 mL white oil, 6 g oleic acid amide as the main emulsifier, 2 g oleic acid diethanolamide as the co-emulsifier, 60 mL 20 wt% CaCl2 aqueous solution, 0.5 g organic clay, 5 g calcium oxide, 4 g oxidized bitumen as a filtration loss reducer, and modified / unmodified barite powder), forming a density of 2.5 g / cm³. 3 Five drilling fluid systems with an oil-water ratio of 80:20 were tested, and the performance of the obtained drilling fluid systems was then evaluated.
[0051] The drilling fluid temperature was stabilized at 50±1℃, its rheological properties were tested, and then it was placed in an aging kettle and hot-rolled at 200℃ for 16 hours.
[0052] Cool the aging vessel, open the tank for observation, stir at high speed for 20 minutes, maintain the drilling fluid temperature at about 50±1℃, test the rheology and demulsification voltage, and conduct dynamic sedimentation density difference test.
[0053] The drilling fluid is then loaded into an aging kettle and placed in a roller furnace. After standing at 190°C for 16 hours, the aging kettle is cooled to room temperature. The density of the upper and lower layers of the drilling fluid is measured, and the static settling density difference is calculated.
[0054] Following the above testing methods, the modified barite powders prepared in Examples 1-2 and Comparative Examples 1-3 were subjected to oil-based drilling fluid performance tests and settling stability tests. The test results are shown in Table 1.
[0055] Table 1: Test Results
[0056]
[0057] Note:Gel 10s For initial tangential force, Gel 10min ΔV is the final shear force, AV is the apparent viscosity, PV is the plastic viscosity, and YP is the dynamic shear force.
[0058] As shown in Table 1, the modified barite powder prepared in Examples 1 and 2 significantly improved the settling stability of oil-based drilling fluid compared to unmodified barite powder. This indicates that the modified barite powder of the present invention can be well dispersed in oil-based drilling fluid, and the modification with epoxy-based polyisoprene can significantly improve the drilling fluid's ability to retain barite powder. Table 1 also shows that the modified barite powder prepared in Examples 1 and 2 has little effect on the viscosity of oil-based drilling fluid. However, when using polyisoprene with a lower epoxy degree for modification (Comparative Example 1) or using polyisoprene with two-terminated epoxy groups for modification (Comparative Example 2), although the settling stability of the drilling fluid remains good, the viscosity increases significantly. This may be because polyisoprene with a lower epoxy degree is difficult to form a stable coating layer on the barite surface, while polyisoprene with two-terminated epoxy groups may not be able to form a coating layer at all, resulting in a complex surface structure of the modified barite, which increases the viscosity and shear stress of the drilling fluid. When using epoxidized polybutadiene (Comparative Example 3), although the drilling fluid viscosity decreased, the settling stability was significantly worse than that of epoxidized polyisoprene, which is not theoretically constrained. It is believed that this may be due to the structural differences between polybutadiene and polyisoprene. Polybutadiene has no side chains, the hydrophobicity of the coating layer formed on the barite surface is not as high as that of polyisoprene, and its compatibility with oil-based drilling fluids is not as good as that of polyisoprene.
[0059] It should be noted that while the preferred embodiments of the present invention are provided in this specification, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are not intended to impose additional limitations on the content of the present invention; their purpose is to provide a more thorough and comprehensive understanding of the disclosure of the present invention. Furthermore, the above-described technical features can be combined with each other to form various embodiments not listed above, all of which are considered to be within the scope of the present invention. Moreover, those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.
Claims
1. A modified barite powder for oil and gas field drilling fluid, characterized in that, The modified barite powder was prepared by grafting barite powder with epoxidized polyisoprene. The modified barite powder is prepared by a method comprising the following steps: (1) Mix aminosilane coupling agent, acid and ethanol solution, add barite powder, stir and mix, sonicate for 2-4 hours, then centrifuge to collect solid powder, vacuum dry to obtain amino-modified barite powder; The aminosilane coupling agent is selected from silane coupling agent KH-550; the mass ratio of aminosilane coupling agent to barite powder is 1:5-10; (2) Dissolve epoxidized polyisoprene in an organic solvent, then add aminated barite powder, stir and mix, control the reaction temperature at 50-80℃, react under ultrasonic treatment for 3-5 hours, stop heating and allow to cool naturally, collect the solid by centrifugation, and obtain modified barite powder by washing, drying, grinding and sieving; The mass ratio of epoxidized polyisoprene to aminated barite powder is 1:1-5; The degree of epoxidation of the epoxidized polyisoprene is 80-90 mol.
2. The modified barite powder according to claim 1, characterized in that, The organic solvent is selected from N,N-dimethylformamide or tetrahydrofuran.
3. The modified barite powder according to claim 1, characterized in that, The ultrasonic treatment operates at a frequency of 20-50 kHz and a power of 400-600 W, and operates in a pulse mode of 1-2 s on / 0.2-0.6 s off.