A powdered anti-wear friction reducer for drilling fluids and a method of making the same

Abstract

The application discloses a powder anti-wear and drag-reducing agent for drilling fluid and a preparation method thereof, and the preparation method comprises the following steps: S1, uniformly mixing styrene, a catalyst and a crosslinking agent to obtain a mixture A; adding modified graphite powder and rubber powder into the mixture A and uniformly dispersing to obtain a mixture B; S2, adding the mixture B into a polyvinyl alcohol aqueous solution to perform a suspension polymerization reaction; and S3, after the suspension polymerization reaction is completed, performing post-treatment on the product to obtain the powder anti-wear and drag-reducing agent for drilling fluid. The surface active component in the anti-wear and drag-reducing agent can be adsorbed on the casing wall, so that the frictional resistance of the drilling tool and the casing is reduced, and the corresponding ball forming component can change the sliding friction between the drilling tool and the casing into rolling friction, so that the frictional resistance is greatly reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of drilling, in particular to a powder anti-wear friction reducer for drilling fluid and a preparation method thereof. BACKGROUND

[0002] Under the influence of conditions such as shallow burial and high clay content in the target layer, it is easy to cause large drilling and tripping friction and large torque during drilling, especially during horizontal section drilling; in view of this problem, a treating agent capable of reducing drilling friction is urgently needed.

[0003] In the past, when encountering large friction and torque during drilling, a surfactant (liquid lubricant) or a solid lubricant (graphite, glass beads or plastic beads) is added, but the horizontal section drilling of shallow burial is an oil-based drilling fluid system, most of which is oil, so the lubricity is good, and the effect of the liquid lubricant is not good; the solid glass beads and the like not only have low strength and are easy to break during use, resulting in greater friction, and because the size is large, they can only be used for one week in the downhole, and will be screened out from the shaker after one week, and cannot be used while drilling; the plastic beads are affected by the oil-based drilling fluid system during use due to the oil-wet surface of the plastic beads, and the particles are too coarse to continuously take effect; therefore, so far there is no special anti-wear friction reducer suitable for oil-based drilling fluid and capable of improving downhole friction and torque. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a powder anti-wear friction reducer for drilling fluid and a preparation method thereof, which can be used in oil-based drilling fluid and effectively reduce drilling friction and torque.

[0005] The technical solution adopted by the present application to solve the technical problem is: a preparation method of a powder anti-wear friction reducer for drilling fluid, comprising the following steps:

[0006] S1, uniformly mixing styrene, a catalyst and a crosslinking agent to obtain a mixture A; adding modified graphite powder and rubber powder to the mixture A and uniformly dispersing to obtain a mixture B;

[0007] S2, adding the mixture B to a polyvinyl alcohol aqueous solution to perform a suspension polymerization reaction;

[0008] S3, after the suspension polymerization reaction is completed, the product is post-treated to obtain a powder anti-wear friction reducer for drilling fluid;

[0009] The weight ratio of the styrene, the modified graphite powder, the rubber powder and the polyvinyl alcohol is (30-50) :(30-40) :(20-40) :(1.2-1.6).

[0010] According to the above scheme, in the step S1, the catalyst is benzoyl peroxide or azobisisobutyronitrile, and the crosslinking agent is divinylbenzene.

[0011] According to the above scheme, in the step S1, the weight ratio of styrene, catalyst and crosslinking agent is (30-50):(1-3):(2-4).

[0012] According to the above scheme, in the step S1, the modified graphite powder is obtained by adding graphite powder into a surface modifier GS aqueous solution, ultrasonic treatment and drying and grinding; the mass concentration of the surface modifier GS aqueous solution is 8-12%; and the mesh number of the graphite powder is 300-400.

[0013] According to the above scheme, the surface modifier GS aqueous solution is obtained by adding triethanolamine into an organic acid and reacting at a temperature of 145-155℃ for 2.5-3.5h; and the organic acid is trioleic acid, and the weight ratio of trioleic acid and triethanolamine is (40-50):(50-60).

[0014] According to the above scheme, in the step S1, the rubber powder is hydrogenated nitrile rubber powder or butyl rubber powder, and the mesh number is 250-300.

[0015] According to the above scheme, in the step S2, the mass fraction of the polyvinyl alcohol aqueous solution is 1%.

[0016] According to the above scheme, in the step S2, the suspension polymerization reaction is divided into two steps, the first step of suspension polymerization reaction is carried out at a temperature of 75-85℃ for 3.5-4.5h, and the second step of suspension polymerization reaction is carried out at a temperature of 90-100℃ for 1.5-2.5h.

[0017] According to the above scheme, in the step S3, the post-treatment includes cooling to 50℃, filtration, washing, drying and ball milling.

[0018] The application further provides a powdery anti-wear and drag-reducing agent for drilling fluid.

[0019] The powdery anti-wear and drag-reducing agent for drilling fluid and the preparation method thereof have the following beneficial effects:

[0020] 1. The anti-wear and drag-reducing agent obtained by the application can adsorb on the casing wall to reduce the frictional resistance of the drilling tool and the casing, and the corresponding ball-forming component can change the sliding friction between the drilling tool and the casing into rolling friction, thereby greatly reducing the frictional resistance.

[0021] 2. The anti-wear and drag-reducing agent obtained by the present invention is a composite particle of resin, graphite and rubber. Such a composition can not only withstand higher pressure without causing the spherical shape to be destroyed, but also restore the spherical state when the pressure is released, thereby separating the drill string from the well wall and preventing the drill string from sticking to the well wall, thereby reducing drilling and tripping friction.

[0022] 3. In this invention, due to the special structure of the composite particles containing graphite, rubber and polystyrene, it will not affect the performance of the drilling fluid in oil-based drilling fluid.

[0023] 4. In this invention, the final mesh size of the product is maintained between 260 and 320 mesh, so it can pass through the screen of the vibrating screen on site, and can play a long-term role in drilling fluid. It is also simple to use.

[0024] 5. Due to its unique composite properties, this invention exhibits better temperature resistance, stronger friction reduction, and greater durability compared to conventional graphite and spherical resin. Detailed Implementation

[0025] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, the specific embodiments of the present invention are now described in detail.

[0026] This invention provides a method for preparing a powdered anti-wear and drag-reducing agent for drilling fluids, solving the problems of high friction and torque in drilling fluids, comprising the following steps:

[0027] S1. Synthesis of surface modifier: 40-50 parts by weight of organic acid are injected into a reactor, the stirrer is turned on and the temperature is raised to 150℃±5℃, while stirring, 50-60 parts by weight of triethanolamine are injected into the reactor, and the reaction is carried out at this temperature for 3 hours. After cooling to below 50℃, the surface modifier GS is obtained. Preferably, the organic acid is trioleic acid.

[0028] S2. Treatment of graphite powder: Graphite powder is added to a surface modifier GS aqueous solution and ultrasonically treated for a period of time (preferably 15-25 min), then filtered, dried, and ground to obtain surface-modified graphite powder. Preferably, the graphite powder has a mesh size of 300-400 mesh and should not be molded after being pressed at 3.5 MPa for 2 min and then released. Preferably, the concentration of the surface modifier GS aqueous solution is 10%; the mass-volume ratio of graphite powder to GS aqueous solution is 1 g:(1.5-2.5) mL, preferably 1 g:2 mL.

[0029] S3, 30-50 parts by weight of styrene without inhibitor is added into the reactor, and a certain amount of catalyst and crosslinking agent is added into the reactor, after mixing uniformly, 30-40 parts by weight of the surface modified graphite powder and 20-40 parts by weight of rubber powder are added into the reactor in turn, after stirring for 30 min, ultrasonic dispersion is performed for 20 min. Preferably, the catalyst is benzoyl peroxide or azobisisobutyronitrile; the crosslinking agent is divinylbenzene. Preferably, the rubber powder is hydrogenated nitrile rubber powder or butyl rubber powder, and the mesh number is 250-300.

[0030] S4, then the styrene solution containing graphite powder and rubber powder is added into 120-160 parts by weight of polyvinyl alcohol aqueous solution (the mass fraction of polyvinyl alcohol is 1%), and the first step of suspension polymerization is performed under strong stirring and heating to 80℃±5℃, after reaction for 3.5-4.5 h, the temperature is increased to 95℃±5℃, and the second step of suspension polymerization is performed for 1.5-2.5 h. Preferably, the stirring speed is greater than 1000 rpm; the first step of suspension polymerization is preferably performed at 80℃±3℃ for 4 h; the second step of suspension polymerization is preferably performed at 95℃±3℃ for 2 h.

[0031] S5, cooling to 50℃, filtering, washing, drying, and then crushing, to obtain the desired anti-wear and friction-reducing agent product. Preferably, the ball milling method is used for crushing, so as to ensure that the product is spherical, and the mesh number of the anti-wear and friction-reducing agent product after crushing is controlled to be 260-320.

[0032] Example 1

[0033] 1) Synthesis of surface modifier: 50 parts by weight of organic acid is injected into the reactor, the stirrer is started and the temperature is increased to 150℃±5℃, 50 parts by weight of triethanolamine is injected into the reactor while stirring, and the reaction is performed at this temperature for 3 hours, and then the temperature is decreased to below 50℃ to obtain the surface modifier GS.

[0034] 2) Treatment of graphite powder: the graphite powder is added into the aqueous solution of surface modifier GS and treated by ultrasonic wave for a period of time, then filtered, dried, and ground to obtain the surface modified graphite powder.

[0035] 3) 30 g of styrene without inhibitor is added into the reactor, and 2 g of azobisisobutyronitrile and 3 g of divinylbenzene are added into the reactor, after mixing uniformly, 40 g of surface modified graphite powder and 20 g of rubber powder are added into the reactor in turn, after stirring for 30 min, ultrasonic dispersion is performed for 20 min.

[0036] 4) Then the styrene solution containing graphite powder and rubber powder is added into 120g polyvinyl alcohol aqueous solution (polyvinyl alcohol mass fraction is 1%), and suspension solution polymerization is carried out under strong stirring and temperature rising to 80℃±3℃, and after reaction for 4h, the temperature is raised to 95℃±3℃, and reaction is carried out for another 2h.

[0037] 5) Temperature is lowered to 50℃, and filtration, washing, drying and ball milling are carried out, and the anti-wear and drag-reducing agent product is obtained.

[0038] Example 2

[0039] 1) Synthesis of surface modifier: 40 parts by weight of organic acid is injected into a reactor, a stirrer is started and temperature is raised to 150℃±5℃, and 60 parts by weight of triethanolamine is injected into the reactor while stirring, and reaction is carried out at the temperature for 3h, and the surface modifier GS is obtained after temperature lowering to below 50℃.

[0040] 2) Treatment of graphite powder: graphite powder is added into the surface modifier GS aqueous solution, and ultrasonic treatment is carried out for a period of time, and then filtration, drying and grinding are carried out, and the surface-modified graphite powder is obtained.

[0041] 3) 40g styrene without polymerization inhibitor is added into a reactor, and 2g of dibenzoyl peroxide and 3g of divinylbenzene are added into the reactor, and after mixing, 35g of surface-modified graphite powder and 30g of rubber powder are added into the reactor in sequence, and stirring is carried out for 30min, and then ultrasonic dispersion is carried out for 20min.

[0042] 4) Then the styrene solution containing graphite powder and rubber powder is added into 140g polyvinyl alcohol aqueous solution (polyvinyl alcohol mass fraction is 1%), and suspension solution polymerization is carried out under strong stirring and temperature rising to 80℃±3℃, and after reaction for 4h, the temperature is raised to 95℃±3℃, and reaction is carried out for another 2h.

[0043] 5) Temperature is lowered to 50℃, and filtration, washing, drying and ball milling are carried out, and the anti-wear and drag-reducing agent product is obtained.

[0044] Example 3

[0045] 1) Synthesis of surface modifier: 45 parts by weight of organic acid is injected into a reactor, a stirrer is started and temperature is raised to 150℃±5℃, and 55 parts by weight of triethanolamine is injected into the reactor while stirring, and reaction is carried out at the temperature for 3h, and the surface modifier GS is obtained after temperature lowering to below 50℃.

[0046] 2) Treatment of graphite powder: graphite powder is added into the surface modifier GS aqueous solution, and ultrasonic treatment is carried out for a period of time, and then filtration, drying and grinding are carried out, and the surface-modified graphite powder is obtained.

[0047] 3) In the reactor, 50 g of styrene without inhibitor was added, and 2 g of azobisisobutyronitrile and 3 g of divinylbenzene were added to the reactor. After mixing, 30 g of surface-modified graphite powder and 20 g of rubber powder were sequentially added to the reactor. After stirring for 30 min, ultrasonic dispersion was performed for 20 min.

[0048] 4) Then, the styrene solution containing graphite powder and rubber powder was added to 160 g of polyvinyl alcohol aqueous solution (polyvinyl alcohol mass fraction of 1%), and suspension solution polymerization was performed under strong stirring and heating to 80℃±3℃. After 4 h of reaction, the temperature was raised to 95℃±3℃, and the reaction was continued for another 2 h.

[0049] 5) The temperature was lowered to 50℃, and filtration, washing, and drying were performed, followed by ball milling to obtain the desired anti-wear and friction-reducing agent product.

[0050] Example 4

[0051] 1) Synthesis of surface modifier: 50 parts by weight of organic acid was added to the reactor, the stirrer was turned on, and the temperature was raised to 150℃±5℃. While stirring, 50 parts by weight of triethanolamine was added. The reaction was continued at this temperature for 3 h, and the temperature was then lowered to below 50℃ to obtain the surface modifier GS.

[0052] 2) Treatment of graphite powder: The graphite powder was added to an aqueous solution of the surface modifier GS and treated with ultrasonic waves for a period of time, then filtered, dried, and ground to obtain surface-modified graphite powder.

[0053] 3) In the reactor, 40 g of styrene without inhibitor was added, and 2 g of dibenzoyl peroxide and 3 g of divinylbenzene were added to the reactor. After mixing, 35 g of surface-modified graphite powder and 40 g of rubber powder were sequentially added to the reactor. After stirring for 30 min, ultrasonic dispersion was performed for 20 min.

[0054] 4) Then, the styrene solution containing graphite powder and rubber powder was added to 140 g of polyvinyl alcohol aqueous solution (polyvinyl alcohol mass fraction of 1%), and suspension solution polymerization was performed under strong stirring and heating to 80℃±3℃. After 4 h of reaction, the temperature was raised to 95℃±3℃, and the reaction was continued for another 2 h.

[0055] 5) The temperature was lowered to 50℃, and filtration, washing, and drying were performed, followed by ball milling to obtain the desired anti-wear and friction-reducing agent product.

[0056] Comparative Example 1

[0057] The graphite modification step was omitted, and unmodified graphite was directly added to the polyvinyl alcohol aqueous solution. The other conditions were the same as in Example 1.

[0058] Comparative Example 2

[0059] Commercially available triethanolamine oleate was used as the surface modifier, replacing the surface modifier GS prepared in this invention. Other conditions were the same as in Example 1.

[0060] Comparative Example 3

[0061] The same 40g of surface-modified graphite powder and 20g of rubber powder as in Example 1 were directly mixed.

[0062] Application examples

[0063] The Xingye Block is a new shale gas development block located by Sinopec in Zhongxian County, Fuling District, Chongqing. The target formation is the Dongyuemiao Section 1 of the Ziliujing Formation, with lithology consisting of gray (black) mudstone interbedded with (dark) gray fine sandstone and siltstone. Due to its shallow burial depth and high clay content (over 50%), coupled with unique geological structures, drilling in this area, especially in horizontal sections, experiences high drilling friction and torque. The first batch of exploratory wells in the Xingye Block failed to reach their designed depths due to friction issues, all being completed prematurely. Therefore, given the specific conditions in this area, there is an urgent need for a treatment agent that can reduce downhole drilling friction.

[0064] The following compares the performance of the powdered anti-wear and drag-reducing agent for drilling fluid synthesized in this invention with graphite lubricant (Yanxing Chemical Co., Ltd.), liquid lubricant (Rongsheng Chemical Co., Ltd.), and plastic ball lubricant (Rongsheng Chemical Co., Ltd.). The experimental steps are as follows: Take the oil-based drilling fluid from Xingye 1 well, add 2vt% of the sample, and measure the friction coefficient reduction rate (relative to the oil-based drilling fluid slurry reduction rate), demulsification voltage, and six-speed value of the drilling fluid after adding the sample according to standard GB / T16783.2.

[0065] The specific steps are as follows: Take 400mL of Xingye 1 well oil-based drilling fluid (site slurry, density 1.83g / cm³). 3 Add 8g of sample and stir at high speed for 20 minutes to prepare a sample slurry. Pour the slurry into an aging tank and roll it at 120℃ for 16 hours. Then stir at high speed for 20 minutes and measure the reduction rate of the friction coefficient of the drilling fluid (relative to the reduction rate of the oil-based drilling fluid slurry), demulsification voltage, and six-speed value.

[0066] Specific groups:

[0067] Blank group: On-site slurry;

[0068] Sample group 1: field slurry + 2% anti-wear and drag-reducing agent obtained in Example 1;

[0069] Sample group 2: field slurry + 2% of Example 2;

[0070] Sample group 3: field slurry + 2% of Example 3;

[0071] Sample group 4: field slurry + 2% of Example 4;

[0072] Sample group 5: field slurry + 2% comparative example 1;

[0073] Sample group 6: field slurry + 2% comparative example 2;

[0074] Sample group 7: field slurry + 2% comparative example 3;

[0075] Reference Group A: On-site slurry + 2% graphite lubricant;

[0076] Reference Group B: On-site slurry + 2% liquid lubricant;

[0077] Reference group C: On-site slurry + 2% plastic balls.

[0078] Table 1 Comparison of the performance of the anti-wear and drag-reducing agent of this invention with other substances added to field slurry.

[0079]

[0080] As can be seen from Table 1, the powdered anti-wear and drag-reducing agent synthesized in this invention can not only significantly reduce the friction coefficient of the drilling fluid in the field (by 90-96%), but also has no significant effect on the viscosity and demulsification voltage of the oil-based drilling fluid. When added to the oil-based drilling fluid, it also has a certain effect on reducing water loss (HTHP decreases from 2.4 to around 2.0). While graphite lubricant has no significant effect on the performance of the drilling fluid system, its friction coefficient reduction is relatively low. The addition of liquid lubricant not only reduces the demulsification voltage of the oil-based drilling fluid in the field (ES decreases from 1552 to 1257), but also has a certain thickening effect. However, its addition only reduces the friction coefficient of the drilling fluid by 10%, showing no significant effect. The addition of plastic balls thickens the oil-based drilling fluid system, and the lubrication effect is not as good as that of the anti-wear and drag-reducing agent synthesized in this invention.

[0081] The products obtained by Comparative Examples 1, 2, and 3, which changed the reaction conditions, raw materials, or proportions, did not have the same lubricity as those in Example 1, indicating that the reaction system of the present invention has a synergistic effect.

[0082] The treatment agent of this invention has been applied in a well drilled by a certain company, and the effect is significant. When drilling reached 4028 meters, the drilling friction and torque were too high, frequently causing the top drive to stall. After adding 2% anti-wear and drag-reducing agent on site, the friction was reduced from 40 tons to below 26 tons, and the torque was also significantly reduced, showing a good friction-reducing and drag-reducing effect. Continuous supplementation was carried out in the later stages, and the friction and torque did not completely decrease to the normal range in the later stages, ultimately enabling the well to be successfully completed.

[0083] This invention discloses a method for preparing a powdered anti-wear and drag-reducing agent for drilling fluids. The method involves surface-modifying graphite powder and rubber powder, then performing suspension polymerization with styrene and other materials to form a ternary composite particle of graphite, rubber, and polystyrene. The particle size is then controlled by stirring, and finally, the product is ground to a particle size range of 300-350 mesh using a special pulverizing device, resulting in a powdered anti-wear and drag-reducing agent for drilling fluids. This method for preparing the powdered anti-wear and drag-reducing agent for drilling fluids is simple, produces a stable product with good anti-wear and drag-reducing effects, has no adverse effects on the drilling fluid system, and can be used during drilling, providing a long-lasting anti-wear and drag-reducing effect. It has achieved good results in the Xingye block application.

[0084] The embodiments of the present invention have been described above, but the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims, and these forms are all within the protection scope of the present invention.

Claims

1. A method for preparing a powdered anti-wear and drag-reducing agent for drilling fluids, characterized in that, Includes the following steps: S1. Styrene, catalyst and crosslinking agent are mixed evenly to obtain mixture A; modified graphite powder and rubber powder are added to mixture A and dispersed evenly to obtain mixture B; S2. Add mixture B to the polyvinyl alcohol aqueous solution to carry out a suspension polymerization reaction; S3. After the suspension polymerization reaction is completed, the product is post-processed to obtain a powdered anti-wear and drag-reducing agent for drilling fluid. The weight ratio of styrene, modified graphite powder, rubber powder and polyvinyl alcohol is (30-50):(30-40):(20-40):(1.2-1.6). In step S1, the modified graphite powder is obtained by adding graphite powder to an aqueous solution of a surface modifier, ultrasonically treating it, and then drying and grinding it; the mass concentration of the aqueous solution of the surface modifier is 8-12%; and the mesh size of the graphite powder is 300-400 mesh. The surface modifier is obtained by adding triethanolamine to an organic acid and reacting at a temperature of 145-155°C for 2.5-3.5 hours; the organic acid is trioleic acid, and the weight ratio of trioleic acid to triethanolamine is (40-50):(50-60). The mesh size of the anti-wear and drag-reducing agent is 260 mesh to 320 mesh.

2. The method for preparing the powdered anti-wear and drag-reducing agent for drilling fluid according to claim 1, characterized in that, In step S1, the catalyst is benzoyl peroxide or azobisisobutyronitrile, and the crosslinking agent is divinylbenzene.

3. The method for preparing the powdered anti-wear and drag-reducing agent for drilling fluid according to claim 1, characterized in that, In step S1, the weight ratio of styrene, catalyst and crosslinking agent is (30-50):(1-3):(2-4).

4. The method for preparing the powdered anti-wear and drag-reducing agent for drilling fluid according to claim 1, characterized in that, In step S1, the rubber powder is hydrogenated nitrile rubber powder or butyl rubber powder, and the mesh size is 250 mesh to 300 mesh.

5. The method for preparing the powdered anti-wear and drag-reducing agent for drilling fluid according to claim 1, characterized in that, In step S2, the mass fraction of the polyvinyl alcohol aqueous solution is 1%.

6. The method for preparing the powdered anti-wear and drag-reducing agent for drilling fluid according to claim 1, characterized in that, In step S2, the suspension polymerization reaction is divided into two steps. The first step of the suspension polymerization reaction is carried out at a temperature of 75-85℃ for a reaction time of 3.5-4.5h. The second step of the suspension polymerization reaction is carried out at a temperature of 90-100℃ for a reaction time of 1.5-2.5h.

7. The method for preparing the powdered anti-wear and drag-reducing agent for drilling fluid according to claim 1, characterized in that, In step S3, the post-processing includes cooling to 50°C, filtering, washing, drying, and ball milling.

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