High-temperature-resistant and strong-cementation borehole wall stabilizer for drilling fluid as well as preparation method and application of borehole wall stabilizer

Abstract

The invention provides a well wall stabilizer with high temperature resistance and strong cementation for drilling fluid as well as a preparation method and application of the well wall stabilizer. The borehole wall stabilizer for the drilling fluid contains a polymer with the following structure: # imgabs0 #, and a preparation method of the borehole wall stabilizer for the drilling fluid comprises the following steps: reacting an oxygen-containing silafane monomer with halogenated silane in an organic solvent, then adding into a dialkyl diene monomer and N, N-dialkyl alkyl acrylamide, adding an initiator for reaction, and carrying out post-treatment on a product to obtain the borehole wall stabilizer for the drilling fluid. The drilling fluid well wall stabilizer prepared by the invention has good compatibility, can resist high temperature, can seal rock samples and improve the mechanical properties of the rock samples, and a water-based drilling fluid system formed by the drilling fluid well wall stabilizer as a key treating agent has good rheological property, wall fixing property and collapse resistance.

Description

Technical Field

[0001] The present invention relates to the field of oil drilling, and more particularly to a high temperature resistant and strongly cemented well wall stabilizer for drilling fluid and a preparation method and application thereof. Background Art

[0002] In order to solve the problem of wellbore stability, oil-based drilling fluid and high-performance water-based drilling fluid systems are currently mainly used at home and abroad. Although oil-based drilling fluid can effectively stabilize the wellbore, it has problems such as high cost, environmental unfriendliness, and poor cementing quality. At present, the water-based drilling fluid system cannot completely replace the oil-based drilling fluid to meet the needs of drilling in complex geological conditions and unconventional oil and gas reservoirs. Studies have shown that wellbore instability is the result of multiple factors such as physics, mechanics, and chemistry. Conventional drilling fluid treatment agents often focus on chemical factors, so it is difficult to achieve true wellbore stability. In recent years, researchers at home and abroad have successively developed a series of chemical wall-fixing and anti-collapse treatment agents that can improve the pressure-bearing capacity of the wellbore. At present, the commonly used water-based drilling fluid wall-fixing and anti-collapse agents mainly include silicates, silicones, polymer alcohols, aluminum-based, and asphalt products. They use the changes in temperature, pH, mineralization, etc. or turbidity point effects after entering the formation to produce physical and chemical changes to generate precipitation or insoluble substances to block the micropores and microcracks of shale, thereby achieving the purpose of consolidating the wellbore. However, the application of the above-mentioned treatment agents in the system has certain limitations, mainly manifested in the limited actual improvement of the wellbore pressure-bearing capacity, poor compatibility with drilling fluid, weakened effect at high temperature, and unfriendly to the environment. Summary of the invention

[0003] In order to solve the technical problems existing in the prior art, the present invention provides a high temperature resistant and strongly cemented wellbore stabilizer for drilling fluid and its preparation method and application. The wellbore stabilizer can be adsorbed and cemented on the rock surface to improve the rock's pressure bearing capacity, thereby improving the wellbore stability of complex formations from a "mechanical-chemical" perspective.

[0004] The existing wellbore stabilizers are either pure plugging or use silicon, and their application has certain limitations, such as limited actual improvement of the wellbore pressure bearing capacity, poor drilling fluid compatibility, weakened effect at high temperature, and unfriendly to the environment. The present invention prepares a wellbore stabilizer containing a new polymer monomer, and introduces fluorine into the monomer. Since the chemical properties of fluorine are more active than silicon, after using fluorine, the wellbore stabilizer can react with the formation faster and stronger, playing a similar "adhesive" role, and also improves the compatibility problem of drilling fluid caused by the use of silicon.

[0005] The high temperature resistant and strong cementing ability wellbore stabilizer for drilling fluid prepared by the present invention enhances the mechanical properties of the formation rock after the action of the drilling fluid on the basis of the existing conventional anti-collapse technology. On the one hand, the treatment agent can undergo physical or chemical changes in the formation, cement and break the formation rock samples, and improve their mechanical properties; on the other hand, it can form a strong adsorption layer on the rock surface, which helps to weaken the interaction between the rock and the fluid, thereby synergizing in both mechanical and chemical aspects to maintain the stability of the wellbore. Therefore, the development of a drilling fluid treatment agent that can seal and consolidate broken formation rocks and enhance the pressure bearing capacity of the wellbore under high temperature conditions can effectively promote water-based drilling fluids to replace oil-based drilling fluids, and more efficiently maintain the stability of the wellbore, which has great theoretical and practical significance.

[0006] One of the purposes of the present invention is to provide a wellbore stabilizer for drilling fluid.

[0007] The drilling fluid well wall stabilizer contains a polymer having a structure as shown in formula (I):

[0008]

[0009] In formula (I), R 1 C m H 2m-1 , m is 2 to 6; R 2 C n H 2n-1 , n is 1 to 3; R 3 C p H 2p+1 , p is 1 to 4; R 4 C q H 2q , q is 1 to 3; R 5 C r H 2r+1 , r is 1 to 3; a and b are independently selected from integers greater than 1, preferably integers of 1 to 5000; R 6 and R 7 are independently selected from H atoms or X groups, and R 6 and R 7 At least one of them is an X group; the X group is preferably a structure represented by formula (II):

[0010]

[0011] In formula (II), R 8 C s H 2s+1 , s is 1 to 4; R 8 ˊ is C t H 2t , t is 1 to 4; R 9 C uH 2u , u is 1 to 3;

[0012] The weight average molecular weight of the drilling fluid well wall stabilizer is 45000-200000 g / mol, preferably 50000-150000 g / mol, more preferably 55000-100000 g / mol; the molecular weight polydispersity coefficient is 1.0-4.0; preferably 1.3-3.0. If the molecular weight is too high, it may affect the solubility and dispersibility of the treatment agent in the drilling fluid, and may also have a significant impact on the rheology, filtration and other properties of the drilling fluid; if the molecular weight is too low, there will not be enough adsorption strength and cementation effect.

[0013] The high temperature resistant strong bonding well wall stabilizer of the present invention is obtained by grafting a fluorine-containing silicon group (Formula V) onto a main chain formed by copolymerization of a vinyl monomer (Formula III) and an acrylamide monomer (Formula IV).

[0014] The second object of the present invention is to provide a method for preparing a wellbore stabilizer for drilling fluid, comprising:

[0015] The oxygen-containing silyl fluoride monomer reacts with halogenated silane in an organic solvent and then is added to the dialkyl diene monomer and N,N-dialkyl alkylene amide, and then an initiator is added to react. The product is post-treated to obtain the wellbore stabilizer for drilling fluid.

[0016] In a preferred embodiment of the present invention,

[0017] The method comprises the following steps:

[0018] (1) removing water from the dialkyl diene monomer;

[0019] (2) removing water from N,N-dialkyl alkyl enamide;

[0020] (3) dissolving the oxygen-containing siloxane monomer in an organic solvent, stirring, adding a halogenated silane, and reacting to obtain a halogenated oxygen-containing siloxane monomer;

[0021] (4) dissolving the dialkyl diene monomer obtained in step (1) in the N,N-dialkyl alkylene amide obtained in step (2), adding the halogenated oxygen-containing silyl fluoride monomer obtained in step (3) after preheating, adding an initiator to react, and the product is post-treated to obtain the wellbore stabilizer for drilling fluid.

[0022] In a preferred embodiment of the present invention,

[0023] Step (1), after dissolving the dialkyl diene monomer in water, adding Na 2 SO 4, after adding, the hydrolysis reaction of the monomer can be inhibited. If sodium sulfate is not added, the monomer may cause double bond hydrolysis after dissolving in water. After standing, vacuum distillation is performed, and then anhydrous CuSO 4 Powder, repeated vacuum distillation, adding anhydrous CuSO 4 Powder step until anhydrous CuSO 4 Add anhydrous CuSO until it does not change color. 4 This is to further remove the crystal water and ensure that the water removal is complete without discoloration to obtain the treated dialkyl diene monomer;

[0024] Step (2), dissolving N,N-dialkyl alkyl enamide in water, adding MgSO 4 , compete for the crystal water in the molecule, and protect the amide group from hydrolysis. After vacuum distillation, add CaO powder, use calcium oxide to react to remove part of the water, and adjust the pH value at the same time. After sufficient stirring, remove the supernatant, vacuum distill and collect the fractions, and add Al 2 O 3 The powder was further dehydrated and distilled under reduced pressure again, and then anhydrous CuSO 4 Powder, repeated vacuum distillation, and then adding anhydrous CuSO 4 Powder step until anhydrous CuSO 4 Add anhydrous CuSO until it does not change color. 4 Further water removal without discoloration verifies that the water has been completely removed, thereby obtaining the treated N, N-dialkyl alkyl enamide;

[0025] The purpose of the above steps (1) to (2) is to remove the crystal water in the dialkyl diene monomer and N,N-dialkyl alkyl enamide while keeping the monomer structure and double bond structure unchanged, but without destroying its own structure or allowing it to hydrolyze.

[0026] In a preferred embodiment of the present invention,

[0027] Step (1),

[0028] The general formula of the dialkyl diene monomer is shown in formula (III):

[0029]

[0030] In formula (III), R 10 C v H 2v-1 , v is 1 to 3; R 11 C w H 2w+1 , w is 1 to 3; R 12 C x H 2x, x is 1 to 3; the dialkyldiene monomer is preferably at least one of dimethyldivinylammonium chloride, dimethyldiallylammonium chloride, diethyldiallylammonium chloride, dimethyldiallylammonium bromide, and dimethyldiallylammonium n-butylammonium chloride; more preferably dimethyldiallylammonium chloride, the dialkyldiene monomer includes but is not limited to the monomers listed above;

[0031] Step (2),

[0032] The general formula of the N,N-dialkyl alkyl enamide is shown in formula (IV):

[0033]

[0034] In formula (IV), R 13 C y H 2y-1 , y is 1 to 2; R 14 C z H 2z+1 , z is 1 to 4; R 15 C f H 2f , f is 1 to 4; the N,N-dialkyl alkyl enamide is preferably at least one of N,N-dimethyl acrylamide, N,N-diethyl acrylamide, and N,N-diisopropyl acrylamide; more preferably N,N-dimethyl acrylamide, and the N,N-dialkyl alkyl enamide includes but is not limited to the monomers listed above;

[0035] R in formula (IV) 14 Corresponding to R in formula (I) 3 The amide group removes the oxygen atom and the double bond to which it is attached, R 13 and R 15 The double bond of 1 ;

[0036] Step (3),

[0037] The general formula of the oxygen-containing siloxane monomer is shown in (V):

[0038]

[0039] In formula (V), R 16 C g H 2g+1 , g is 1 to 4; R 17 C h H 2h , h is 1 to 3;

[0040] The oxygen-containing silfluoroethane monomer is preferably at least one of trifluoroethylmethylcyclotrisiloxane, trifluoropropylmethylcyclotrisiloxane and trifluoropropylethylcyclotrisiloxane; more preferably trifluoroethylmethylcyclotrisiloxane. The oxygen-containing silfluoroethane monomer includes but is not limited to the monomers listed above.

[0041] The structural formula of the halogenated oxygen-containing siloxane monomer generated in step (3) is:

[0042]

[0043] In formula (VI), R 18 C i H 2i+1 , i is 1 to 4; R 18 ˊ is C j H 2j , j is 1 to 4; R 19 C k H 2k , k is 1 to 3.

[0044] In a preferred embodiment of the present invention,

[0045] Step (1),

[0046] The water is deionized water;

[0047] The mass ratio of the dialkyl diene monomer to water is 1:(10-50);

[0048] The Na 2 SO 4 The mass of the dialkyl diene monomer is 3% to 6%;

[0049] The vacuum distillation can be carried out by a common method in the prior art;

[0050] Each addition of anhydrous CuSO 4 The mass range of the powder is 0.1% to 1% of the mass of the dialkyl diene monomer; the number of repetitions is preferably 2 to 4 times;

[0051] The standing time is 12 to 36 hours;

[0052] Step (2),

[0053] The water is deionized water;

[0054] The mass ratio of the N,N-dialkyl alkyl enamide to deionized water is 1:(20-40);

[0055] The MgSO 4 The mass of is 3% to 6% of the mass of N, N-dialkyl alkyl enamide;

[0056] The mass of CaO is 3% to 6% of the mass of N,N-dialkyl alkyl enamide;

[0057] The vacuum distillation can be carried out by a common method in the prior art;

[0058] The fraction collected is the fraction at 70-80°C;

[0059] The Al 2 O 3 The mass of the powder is 5% to 15% of the mass of the N,N-dialkyl alkyl enamide;

[0060] Each addition of anhydrous CuSO 4 The mass range of the powder is 0.1% to 1% of the mass of the N,N-dialkyl alkyl enamide; the number of repetitions is preferably 2 to 4 times.

[0061] In a preferred embodiment of the present invention,

[0062] Step (3),

[0063] The organic solvent is an organic solvent commonly used in the prior art, preferably at least one of tetrahydrofuran, tert-butanol, acetone, and n-pentane;

[0064] The mass ratio of the oxygen-containing siloxane monomer to the organic solvent is 1:(1-100), preferably 1:(5-20);

[0065] The stirring time is 20min to 2h;

[0066] The stirring rate is 60 to 300 rpm;

[0067] The reaction temperature is room temperature; and / or,

[0068] The reaction time should be 4 to 16 hours, preferably 6 to 12 hours;

[0069] The product after the reaction is post-treated, and the post-treatment includes washing and reduced pressure distillation. The washing can be carried out using a commonly used organic solvent, such as toluene;

[0070] The halogenated silane is at least one of chlorosilanes or their derivatives, preferably at least one of alkyl chlorosilane, alkyl trichlorosilane, and cyanoethyl chlorosilane; for example, the alkyl chlorosilane may be tert-butyl dimethyl chlorosilane, and the cyanoethyl chlorosilane may be 2-cyanoethyl trichlorosilane;

[0071] The molar ratio of the oxygen-containing silyl fluoroalkane monomer to the halogenated element in the halogenated silane is 1:(1-1.5).

[0072] In a preferred embodiment of the present invention,

[0073] Step (4),

[0074] The molar ratio of silicon in the halogenated oxygen-containing siloxane monomer, vinyl in the dialkyl diene monomer, and amide in the N,N-dialkyl alkylene amide is 1.5:(1.5-2.5):(8.0-10.0), preferably 1.5:(2.0-2.5):(9.0-10.0);

[0075] The preheating temperature is 50-100°C, and the preheating time is 10-40 minutes; preferably, the preheating temperature is 70-90°C, and the preheating time is 15-30 minutes;

[0076] After adding the halogenated oxygen-containing silfluoroethane monomer, nitrogen is passed through, preferably for 10 to 60 minutes;

[0077] The initiator is a commonly used initiator in the art, preferably at least one of azobisisobutyronitrile, azobisisobutylamidine hydrochloride, azobisisobutylimidazoline hydrochloride, and azobisisopropylimidazoline, more preferably at least one of azobisisobutyronitrile and azobisisobutylamidine hydrochloride, and most preferably azobisisobutyronitrile;

[0078] The mass ratio of the initiator to the halogenated oxygen-containing siloxane monomer is (0.05% to 0.2%):1, preferably (0.1% to 0.15%):1;

[0079] The reaction is a reflux reaction; preferably,

[0080] The reaction temperature is 50-80°C, preferably 60-75°C;

[0081] The reaction time is 5 to 20 hours, preferably 7 to 12 hours, and more preferably 8 to 10 hours;

[0082] The post-treatment includes washing. The washing may be performed with commonly used solvents in the art, such as acetone, ethanol, etc., or with a mixed solvent, such as an ethanol solution of 50% acetone by mass. The washing may be performed multiple times, such as 2 to 6 times.

[0083] The third object of the present invention is to provide a wellbore stabilizer for drilling fluid obtained by the above preparation method.

[0084] A fourth object of the present invention is to provide a wellbore stabilizer for drilling fluid for use in the field of oil drilling.

[0085] Compared with the prior art, the present invention has the following beneficial effects:

[0086] The invention has good well wall stabilization effect, convenient preparation process control, simple operation, stable product quality, good effect when used under 180°C, and the water-based drilling fluid system composed of it as a key treatment agent has good rheology, wall solidity and anti-collapse properties.

[0087] Compared with the prior art, the wellbore stabilizer of the present invention has good compatibility with the drilling fluid. Experimental results show that the rheological and filtration properties are better after compatibility. After adding the sample of the present invention, the API filtration loss and high-temperature and high-pressure water loss of the drilling fluid are reduced. After adding the wellbore stabilizer of the present invention to the rock sample, the pressure bearing capacity of the rock sample is significantly improved, and the rock sample can be effectively consolidated. BRIEF DESCRIPTION OF THE DRAWINGS

[0088] Figure 1 This is the infrared spectrum of the high temperature resistant and strong bonding well wall stabilizer prepared in Example 1. DETAILED DESCRIPTION

[0089] The present invention is described in detail below in conjunction with specific drawings and embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the content of the present invention still fall within the scope of protection of the present invention.

[0090] Meanwhile, the experimental methods described in the following examples are all conventional methods unless otherwise specified; the reagents and equipment described are all commercially available unless otherwise specified.

[0091] The raw materials used in the examples are all conventional commercially available raw materials.

[0092] Test method:

[0093] Drilling fluid rheology and filtration performance test: GB / T 16783.1-2014 Field test procedures for water-based drilling fluids Part 1: Water-based drilling fluids.

[0094] Rock sample uniaxial compressive strength test: Different commercially available drilling fluid treatment agents with well wall stabilization effect are mixed with the product of the present invention into a solution, and then an artificial sandstone rock sample (gas permeability 100mD) is immersed in the test solution, placed in a high-temperature roller furnace and hot rolled at 180°C for 16 hours, and after cooling to room temperature, a TAW-100 microcomputer-controlled triaxial mechanical testing instrument (Changchun Chaoyang Testing Instrument Co., Ltd.) is used to test the uniaxial compressive strength of the rock sample.

[0095] Method for determining weight average molecular weight and molecular weight distribution: Weight average molecular weight (Mw) and dispersion coefficient (D) are determined by gel permeation chromatography (GPC). The standard and the sample to be tested are dissolved in the mobile phase to prepare 10 mg / mL standard and sample solutions. The standard and the sample to be tested are injected sequentially, and the chromatogram of the standard and the chromatogram of the sample are recorded. The elution time of the standard and the sample is compared, and the data is processed using Angilent GPC software to determine the Mw and D values ​​of the sample.

[0096] Example 1

[0097] Dissolve 200 g of dimethyl divinyl ammonium chloride in 3000 mL of deionized water, then add 10.0 g of Na 2 SO 4 After standing for 24 hours, vacuum distillation was added, and 1.5 g of anhydrous CuSO 4 Powder and mix evenly with a glass rod, repeat the above steps 3 times until anhydrous CuSO 4 Until it doesn't turn blue.

[0098] Dissolve 200 g of N,N-dimethylacrylamide in 5 L of deionized water and add 10.0 g of MgSO 4 After vacuum distillation, 12.0 g of CaO powder was added, and vacuum distillation was performed again to collect the fraction at 76 °C. 10.0 g of Al was added to the obtained fraction. 2 O 3 The powder was distilled under reduced pressure again and 1.50 g of anhydrous CuSO 4 Powder and mix evenly with a glass rod, repeat the above steps 3 times until anhydrous CuSO 4 Until it doesn't turn blue.

[0099] Weigh 23.4 g (0.055 mol) of trifluoroethylmethylcyclotrisiloxane, dissolve it in 200 g of tetrahydrofuran, place it on a magnetic stirrer and stir it at 200 rpm for 30 min, add 10.78 g (0.072 mol) of tert-butyldimethylchlorosilane, react at room temperature for 10.5 h, wash with toluene, and obtain a halogenated oxygen-containing silfluoroethane monomer after reduced pressure distillation.

[0100] Dissolve 17.92g (0.134mol) of purified dimethyl divinyl ammonium chloride and 98.99g (1.0mol) of N, N-dimethyl acrylamide, and preheat at 70°C for 15min. Add halogenated oxygen-containing silyl fluoride monomer under stirring and pass nitrogen for 30min. Mix 0.045g of azobisisobutyronitrile and 5g of tetrahydrofuran, then add them to the reaction system, reflux at 70°C for 9h, take out the product, and wash it 5 times in an ethanol solution of 50% by mass acetone to obtain the product. The sample is freeze-dried, granulated, and stored at 4°C, which is recorded as SMGB-1.

[0101] The molecular structure of the high temperature resistant and strong bonding well wall stabilizer prepared in this embodiment is shown in Formula (VII). The relative molecular mass was tested by the aforementioned method using the British Agilent PL-GPC50 gel chromatograph, and the test results are shown in Table 1.

[0102] Table 1 Relative molecular mass test results

[0103]

[0104]

[0105] Its infrared spectrum is as follows Figure 1 As shown in the figure, the characteristic peak of SMGB-1 near 3377cm-1 is the stretching vibration absorption peak of -OH. The characteristic peak of SMGB-1 near 2924cm-1 is the stretching vibration peak of the CH bond in the alkane. -1 The characteristic peaks on the left and right are the stretching vibration peaks of saturated fatty acid ester CO. -1 The characteristic peaks on the left and right are the bending vibration peaks of the CH bonds in alkanes. -1 Attribution to -CH 2 CH 2 CF 3 Vibration absorption peak, 1026cm -1 The characteristic peaks near 707, 765 and 856 cm-1 were identified as the stretching vibration characteristic peaks of CH connected to Si. -1 The characteristic peaks at were identified as the characteristic peaks of in-plane and out-of-plane bending vibrations of Si-O, proving that the oxygen-containing silfluoroethane monomer, N,N-dimethylacrylamide and dimethyldivinylammonium chloride reacted.

[0106] Example 2

[0107] Dissolve 200 g of dimethyldi-n-butylammonium chloride in 10 L of deionized water, then add 6.0 g of Na 2 SO 4 After standing for 24 hours, vacuum distillation was performed and 2.0 g of anhydrous CuSO 4 Powder and mix evenly with a glass rod, repeat the above steps 4 times until anhydrous CuSO 4 Until it doesn't turn blue.

[0108] Dissolve 200 g of N,N-diisopropylacrylamide in 4 L of deionized water and add 6.0 g of MgSO 4 After vacuum distillation, 6.0 g of CaO powder was added, and vacuum distillation was performed again to collect the fraction at 80 °C. 30.0 g of Al 2 O3 The powder was distilled under reduced pressure again and 1.0 g of anhydrous CuSO 4 Powder and mix evenly with a glass rod, repeat the above steps 2 times until anhydrous CuSO 4 Until it doesn't turn blue.

[0109] 11.71 g (0.025 mol) of trifluoropropylmethylcyclotrisiloxane was weighed and dissolved in 200 g of tetrahydrofuran. The mixture was stirred on a magnetic stirrer at 60 rpm for 20 min. 2.36 g (0.0125 mol) of 2-cyanoethyltrichlorosilane was added. The mixture was reacted at room temperature for 12 h, washed with toluene, and distilled under reduced pressure to obtain a halogenated oxygen-containing silfluoroethane monomer.

[0110] Dissolve 8.08g of purified dimethyldi-n-butylammonium chloride (0.05mol) and 69.75g of N,N-diisopropylacrylamide (0.45mol) and preheat at 90°C for 30min. Add halogenated oxygen-containing silyl fluoride monomer under stirring and pass nitrogen for 30min. Mix 0.017g of azobisisobutylimidazoline hydrochloride and 5g of tetrahydrofuran, then add them to the reaction system, reflux at 60°C for 10h, take out the product, and wash it 5 times in an ethanol solution of 50% acetone by mass to obtain the product. The sample is freeze-dried, granulated, and stored at 4°C, which is recorded as SMGB-2.

[0111] The molecular structure of the high temperature resistant and strong cementing well wall stabilizer prepared in this embodiment is shown in formula (VIII). The relative molecular mass was tested by the aforementioned method using the British Agilent PL-GPC50 gel chromatograph, and the test results are shown in Table 2.

[0112] Table 2 SMGB-2 relative molecular mass test results

[0113]

[0114]

[0115] Embodiment 3:

[0116] Dissolve 200 g of dimethyl divinyl ammonium chloride in 2.0 L of deionized water, then add 6.0 g of Na 2 SO 4 After standing for 24 h, the mixture was evaporated under reduced pressure and 0.2 g of anhydrous CuSO 4 Powder and mix evenly with a glass rod, repeat the above steps 2 times until anhydrous CuSO 4 Until it doesn't turn blue.

[0117] Dissolve 200 g of N,N-diisopropylacrylamide in 8.0 L of deionized water and add 6.0 g of MgSO4 After vacuum distillation, 12.0 g of CaO powder was added, and vacuum distillation was performed again to collect the fraction at 70 °C. 30.0 g of Al 2 O 3 The powder was distilled under reduced pressure again and 2.0 g of anhydrous CuSO 4 Powder and mix evenly with a glass rod, repeat the above steps 4 times until anhydrous CuSO 4 Until it doesn't turn blue.

[0118] Weigh 23.42 g (0.05 mol) of trifluoropropylmethylcyclotrisiloxane, dissolve it in 200 g of tetrahydrofuran, place it on a magnetic stirrer and stir it at 300 rpm for 2 h, add 3.15 g (0.0167 mol) of 2-cyanoethyltrichlorosilane, react at room temperature for 6 h, wash with toluene, and obtain a halogenated oxygen-containing silfluoroethane monomer after reduced pressure distillation.

[0119] Dissolve 16.63g of purified dimethyl divinyl ammonium chloride (0.125mol) and 155.24g of N, N-diisopropyl acrylamide (1.0mol) and preheat at 90°C for 30min. Add halogenated oxygen-containing silyl fluoride monomer under stirring and pass nitrogen for 30min. Mix 0.012g of azobisisobutylimidazoline hydrochloride and 5g of tetrahydrofuran, then add them to the reaction system, reflux at 60°C for 8h, take out the product, and wash it 5 times in an ethanol solution of 50% acetone by mass to obtain the product. The sample is freeze-dried, granulated, and stored at 4°C, which is recorded as SMGB-3.

[0120] The molecular structure of the high temperature resistant and strong bonding well wall stabilizer prepared in this embodiment is shown in formula (IX). The relative molecular mass was tested by the aforementioned method using the British Agilent PL-GPC50 gel chromatograph, and the test results are shown in Table 3.

[0121] Table 3 SMGB-3 relative molecular mass test results

[0122]

[0123]

[0124] Test Example 1

[0125] Compatibility evaluation:

[0126] In order to examine the adaptability of the synthetic product of the present invention in the water-based drilling fluid system, compatibility tests were conducted with sulfonated lignite resin (SPNH), sulfonmethylphenolic resin (SMP-II), aluminum-based polymer (DSP-I) and the like commonly used in the field. Two groups of drilling fluid formulas were designed using the well wall stabilizer obtained in Examples 1 to 3 and the above-mentioned drilling fluid treatment agent to examine the compatibility of the sample in Example 1 with the commonly used treatment agent in the water-based drilling fluid.

[0127] No. 1: 2% bentonite + 0.15% FA367 + 2% sulfonated methylphenolic resin SMP-II + 2% sulfonated lignite resin SPNH + 2% emulsified asphalt;

[0128] No. 2: 2% bentonite + 0.15% FA367 + 1% sample of Example 1 + 2% sulfonated methylphenolic resin SMP-II + 2% sulfonated lignite resin SPNH + 2% emulsified asphalt;

[0129] No. 3: 2% bentonite + 0.15% FA367 + 1% sample of Example 2 + 2% sulfonated methylphenolic resin SMP-II + 2% sulfonated lignite resin SPNH + 2% emulsified asphalt;

[0130] No. 4: 2% bentonite + 0.15% FA367 + 1% sample of Example 3 + 2% sulfonated methylphenolic resin SMP-II + 2% sulfonated lignite resin SPNH + 2% emulsified asphalt.

[0131] The drilling fluid was prepared according to the above formula, and the performance of the slurry was tested before and after hot rolling at 180°C / 16h. The results are shown in Table 4.

[0132] Table 4 Rheological filtration properties of drilling fluids with different formulations

[0133]

[0134] It can be seen from the test results that the four drilling fluid systems all have good rheological and filtration properties. After adding the wellbore stabilizers of Examples 1 to 3, the API filtration loss and high temperature and high pressure water loss of the drilling fluid are reduced. After high temperature, the viscosity increasing effect is still strong and the viscosity retention rate is good, which proves that it has good temperature resistance. The test results show that the product of the present invention has good temperature resistance, compatibility and filtration loss reduction effect.

[0135] Test Example 2

[0136] Uniaxial compressive strength test of rock samples:

[0137] Different commercially available drilling fluid treatment agents with wellbore stabilizing effect and the wellbore stabilizers for drilling fluid prepared in Examples 1 to 3 of the present invention were prepared into solutions, and then an artificial sandstone sample (gas permeability 100 mD) was immersed in the test solution, placed in a high-temperature roller furnace and hot rolled at 180° C. for 16 h, and after cooling to room temperature, a TAW-100 microcomputer-controlled triaxial mechanical testing instrument (Changchun Chaoyang Testing Instrument Co., Ltd.) was used to test the uniaxial compressive strength of the rock sample. The experimental results are shown in Table 5.

[0138] No. 1: untreated;

[0139] No. 2: clean water;

[0140] No. 3: 2% aqueous solution of the wellbore stabilizer for drilling fluid prepared in Example 1;

[0141] No. 4: 2% aqueous solution of the wellbore stabilizer for drilling fluid prepared in Example 2;

[0142] No. 5: 2% aqueous solution of the wellbore stabilizer for drilling fluid prepared in Example 3;

[0143] No. 6: 2% aluminum humate aqueous solution;

[0144] No. 7: 2% sodium silicate aqueous solution;

[0145] No. 8: 1% potassium polyacrylate aqueous solution.

[0146] Table 5 Uniaxial compressive strength test results of rock samples

[0147] Experiment No. Uniaxial compressive strength / MPa 1 12.40 2 5.52 3 7.66 4 8.03 5 7.25 6 6.71 7 5.93 8 5.59

[0148] The uniaxial compressive strength of the dry rock sample is relatively high, at 12.4MPa, and drops to 6.5MPa after being soaked in clean water, a decrease of about 50%. After the drilling fluid prepared in Examples 1 to 3 is treated with a 2% aqueous solution of a wellbore stabilizer, the pressure bearing capacity of the rock sample is significantly improved, reaching 7.66MPa, 8.03MPa and 7.25MPa, respectively, which is nearly 20% higher than that of clean water, and is better than other commonly used drilling fluid treatment agents with wellbore stabilization effects, indicating that the product of the present invention can effectively consolidate the rock sample and effectively improve its pressure bearing capacity. The rock sample can still maintain a relatively high compressive strength after being heated in the solution of the treatment agent of the present invention, which means that the sample of the present invention can still play a good role under harsh high temperature conditions.

[0149] In the prior art, the high temperature resistant materials usually select the temperature resistant monomers containing sulfur elements. The polymers prepared from such monomers will release toxic gases after being exposed to high temperatures, and most of the decomposition products are toxic. The product of the present invention only contains C, H, O, Si, and F elements, and does not contain N, S and other elements, which is more environmentally friendly.

Claims

1. A wellbore stabilizer for drilling fluid, comprising a polymer having a structure as shown in formula (I): In formula (I), R1 is C m H 2m-1 , m is 2 to 6; R2 is C n H 2n-1 , n is 1 to 3; R3 is C p H 2p+1 , p is 1 to 4; R4 is C q H 2q , q is 1 to 3; R5 is C r H 2r+1 , r is 1 to 3; a and b are independently selected from integers greater than 1, preferably integers of 1 to 5000; R6 and R7 are independently selected from H atoms or X groups, and at least one of R6 and R7 is an X group; the X group is preferably a structure represented by formula (II): In formula (II), R8 is C s H 2s+1 , s is 1 to 4; R8ˊ is C t H 2t , t is 1 to 4; R9 is C u H 2u , u is 1 to 3; The weight average molecular weight of the wellbore stabilizer for drilling fluid is 45000-200000 g / mol, preferably 50000-150000 g / mol, more preferably 55000-100000 g / mol; the polydispersity coefficient of the molecular weight is 1.0-4.0, preferably 1.3-3.

0.

2. A method for preparing the wellbore stabilizer for drilling fluid according to claim 1, comprising: The oxygen-containing silyl fluoride monomer reacts with halogenated silane in an organic solvent and then is added to the dialkyl diene monomer and N,N-dialkyl alkylene amide, and then an initiator is added to react. The product is post-treated to obtain the wellbore stabilizer for drilling fluid.

3. The method for preparing a wellbore stabilizer for drilling fluid according to claim 2, characterized in that: The following steps are involved: (1) removing water from the dialkyl diene monomer; (2) removing water from N,N-dialkyl alkyl enamide; (3) dissolving the oxygen-containing siloxane monomer in an organic solvent, adding a halogenated silane after stirring, and obtaining a halogenated oxygen-containing siloxane monomer after reaction; (4) dissolving the dialkyl diene monomer obtained in step (1) in the N,N-dialkyl alkylene amide obtained in step (2), adding the halogenated oxygen-containing silyl fluoride monomer obtained in step (3) after preheating, adding an initiator to react, and the product is post-treated to obtain the wellbore stabilizer for drilling fluid.

4. The method for preparing a wellbore stabilizer for drilling fluid according to claim 3, characterized in that: Step (1), dissolving the dialkyl diene monomer in water, adding Na2SO4, leaving it to stand and then distilling it under reduced pressure, then adding anhydrous CuSO4 powder, repeating the steps of distilling under reduced pressure and adding anhydrous CuSO4 powder until the anhydrous CuSO4 does not change color, to obtain a treated dialkyl diene monomer; and / or, Step (2), dissolving N,N-dialkyl alkyl enamide in water, adding MgSO4, distilling under reduced pressure, adding CaO powder, stirring thoroughly and removing the supernatant, distilling under reduced pressure and collecting the fractions, adding Al2O3 powder to the fractions, distilling under reduced pressure again, and then adding anhydrous CuSO4 powder, repeating the distillation under reduced pressure, and then adding anhydrous CuSO4 powder until the anhydrous CuSO4 does not change color, thereby obtaining the treated N,N-dialkyl alkyl enamide.

5. The method for preparing a wellbore stabilizer for drilling fluid according to claim 3, characterized in that: Step (1), The general formula of the dialkyl diene monomer is shown in formula (III): In formula (III), R 10 C v H 2v-1 , v is 1 to 3; R 11 C w H 2w+1 , w is 1 to 3; R 12 C x H 2x , x is 1 to 3; the dialkyldiene monomer is preferably at least one of dimethyldivinylammonium chloride, dimethyldiallylammonium chloride, diethyldiallylammonium chloride, dimethyldiallylammonium bromide and dimethyldiallylammonium n-butylammonium chloride; and / or, Step (2), The general formula of the N,N-dialkyl alkyl enamide is shown in formula (IV): In formula (IV), R 13 C y H 2y-1 , y is 1 to 2; R 14 C z H 2z+1 , z is 1 to 4; R 15 C f H 2f , f is 1 to 4; the N,N-dialkyl alkyl acrylate is preferably at least one of N,N-dimethyl acrylamide, N,N-diethyl acrylamide, and N,N-diisopropyl acrylamide; and / or, Step (3), The general formula of the oxygen-containing siloxane monomer is shown in (V): In formula (V), R 16 C g H 2g+1 , g is 1 to 4; R 17 C h H 2h , h is 1 to 3; the oxygen-containing silfluoroethane monomer is preferably at least one of trifluoroethylmethylcyclotrisiloxane, trifluoropropylmethylcyclotrisiloxane and trifluoropropylethylcyclotrisiloxane.

6. The method for preparing a wellbore stabilizer for drilling fluid according to claim 4, characterized in that: Step (1), The water is deionized water; and / or, The mass ratio of the dialkyl diene monomer to water is 1:(10-50); and / or, The mass of the Na2SO4 is 3% to 6% of the mass of the dialkyl diene monomer; and / or, The standing time is 12 to 36 hours; and / or, The mass range of the anhydrous CuSO4 powder added each time is 0.1% to 1% of the mass of the dialkyl diene monomer; the number of repetitions is preferably 2 to 4 times; and / or, Step (2), The water is deionized water; and / or, The mass ratio of the N,N-dialkyl alkyl enamide to deionized water is 1:(20-40); and / or, The mass of MgSO4 is 3% to 6% of the mass of N,N-dialkyl alkyl enamide; and / or, The mass of CaO is 3% to 6% of the mass of N,N-dialkyl alkyl enamide; and / or, The collected fraction is the fraction at 70-80°C; and / or, The mass of the Al2O3 powder is 5% to 15% of the mass of the N,N-dialkyl alkyl enamide; and / or, The mass range of the anhydrous CuSO4 powder added each time is 0.1% to 1% of the mass of the N,N-dialkyl alkyl enamide; the number of repetitions is preferably 2 to 4 times.

7. The method for preparing a wellbore stabilizer for drilling fluid according to claim 3, characterized in that: Step (3), The organic solvent is at least one of tetrahydrofuran, tert-butyl alcohol, acetone and n-pentane; and / or, The mass ratio of the oxygen-containing siloxane monomer to the organic solvent is 1:(1-100), preferably 1:(5-20); and / or, The stirring time is 20min to 2h; and / or, The stirring rate is 60 to 300 rpm; and / or, The reaction temperature is room temperature; and / or, The reaction time should be 4 to 16 hours, preferably 6 to 12 hours; and / or, The product after the reaction is subjected to post-treatment, wherein the post-treatment includes washing and reduced pressure distillation; and / or, The halosilane is at least one of chlorosilanes or their derivatives, preferably at least one of alkylchlorosilane, alkyltrichlorosilane and cyanoethylchlorosilane; and / or, The molar ratio of the oxygen-containing silyl fluoroalkane monomer to the halogenated element in the halogenated silane is 1:(1-1.5).

8. The method for preparing a wellbore stabilizer for drilling fluid according to claim 3, characterized in that: Step (4), The molar ratio of silicon in the halogenated oxygen-containing siloxane monomer, vinyl in the dialkyl diene monomer, and amide in the N,N-dialkyl alkylene amide is 1.5:(1.5-2.5):(8.0-10.0), preferably 1.5:(2.0-2.5):(9.0-10.0); and / or, The preheating temperature is 50-100°C, and the preheating time is 10-40 minutes; preferably, the preheating temperature is 70-90°C, and the preheating time is 15-30 minutes; and / or, After adding the halogenated oxygen-containing silfluoroethane monomer, nitrogen is passed through, preferably for 10 to 60 minutes; and / or, The initiator is a commonly used initiator in the art, preferably at least one of azobisisobutyronitrile, azobisisobutylamidine hydrochloride, azobisisobutylimidazoline hydrochloride, and azobisisopropylimidazoline; and / or, The mass ratio of the initiator to the halogenated oxygen-containing siloxane monomer is (0.05% to 0.2%): 1; The reaction is a reflux reaction; preferably, The reaction temperature is 50 to 80°C, preferably 60 to 75°C; and / or, The reaction time is 5 to 20 hours, preferably 7 to 12 hours, more preferably 8 to 10 hours; and / or, The post-treatment includes washing.

9. A wellbore stabilizer for drilling fluid obtained by the preparation method as claimed in any one of claims 2 to 8.

10. Use of the wellbore stabilizer for drilling fluid according to claim 1 or 9 in the field of oil drilling.

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