Preparation method of high-temperature-resistant flow pattern adjusting polymer and application of polymer in high temperature resistance

Abstract

The invention provides a preparation method of a high-temperature-resistant flow pattern adjusting polymer and application of the high-temperature-resistant flow pattern adjusting polymer in high temperature resistance. The preparation method comprises the following steps: 1) dissolving 2-acrylamide-2-methylpropanesulfonic acid in a first solvent, adjusting the pH value to 7-8, and then adding sodium p-styrenesulfonate to obtain a raw material mixture I; 2) dissolving octadecyl dimethyl allyl ammonium chloride and acrylamide in a second solvent to obtain a raw material mixture II; 3) uniformly mixing the raw material mixture I and the raw material mixture II, removing oxygen, then adding a first initiator, dissolving the first initiator, and continuously reacting for 4-6 hours under the protection of nitrogen at 30-50 DEG C to obtain a white gel product; and 4) washing the white gel product with a third solvent, filtering, drying and grinding to obtain the high-temperature-resistant flow pattern adjusting polymer.

Description

Technical Field

[0001] The invention provides a high temperature resistant polymer as a flow pattern regulator. Background Art

[0002] With the gradual increase in the exploration and development of domestic oil and gas fields, the requirements for drilling and completion fluid technology, especially the technology for protecting oil and gas layers, are getting higher and higher. The degree of damage to oil and gas layers will directly affect the production of oil and gas wells, the discovery of new exploration areas and new oil and gas layers. As the working fluid that first contacts the oil and gas layer, drilling fluid is becoming more and more important. Since the solid particles in conventional soil-containing high-solid drilling fluids can cause damage to the reservoir, soil-free, low-solid or even no-solid drilling fluid technology for reservoir protection has emerged. As more and more deep wells and ultra-deep horizontal wells are being developed, the drilling fluids in the existing technology cannot meet the needs of underground construction operations with formation temperatures exceeding 160°C. The temperature resistance problem of drilling and completion fluids is becoming increasingly serious. In order to adapt to more severe high-temperature environments, it is urgent to solve the problem of high temperature resistance difference of clay-free drilling fluids. The main manifestations are: without bentonite as a foundation, ordinary natural viscosity-increasing and filtration-reducing materials have poor temperature resistance, and after high-temperature aging, there will be obvious viscosity reduction and shearing phenomenon, which is not conducive to the suspension and carrying of rock cuttings; and the lack of dense filling of clay particles in the mud cake composition will increase the high-temperature water loss, and excessive liquid phase migration to the deep reservoir is not conducive to the stability of the well wall and reservoir protection. Therefore, it is of great practical significance to develop a clay-free high-temperature resistant drilling fluid that is conducive to well wall stability and reservoir protection. Summary of the invention

[0003] One of the present inventions provides a method for preparing a high temperature resistant flow pattern regulating polymer, which comprises the following steps:

[0004] 1) dissolving 2-acrylamide-2-methylpropanesulfonic acid in a first solvent, adjusting the pH value to 7 to 8, and then adding sodium styrene sulfonate to obtain a raw material mixture I;

[0005] 2) dissolving octadecyl dimethyl allyl ammonium chloride and acrylamide in a second solvent to obtain a raw material mixture II;

[0006] 3) mixing the raw material mixture I and the raw material mixture II uniformly, deoxygenating, then adding the first initiator, dissolving the first initiator, and reacting continuously for 4 to 6 hours at 30 to 50° C. under nitrogen protection to obtain a white gel product;

[0007] 4) washing the white gel product with a third solvent, filtering, drying and grinding to obtain the high temperature resistant flow pattern regulating polymer.

[0008] In a specific embodiment, the first initiator is a mixture of at least one of ammonium persulfate, potassium persulfate and benzoyl peroxide and sodium bisulfite, and the molar ratio of at least one of ammonium persulfate, potassium persulfate and benzoyl peroxide to sodium bisulfite is 1:2 to 2:1.

[0009] In a specific embodiment, in step 1), the mass ratio of the 2-acrylamide-2-methylpropane sulfonic acid to the sodium styrene sulfonate is (3 to 4):1.

[0010] In a specific embodiment, in step 1), based on the mass of the raw material mixture I as 100%, the mass content of the 2-acrylamide-2-methylpropane sulfonic acid is 10.8% to 12.5%, and the mass content of the sodium styrene sulfonate is 2.7% to 4.2%.

[0011] In a specific embodiment, in step 2), the mass ratio of octadecyldimethylallylammonium chloride to acrylamide is 1:(20 to 80).

[0012] In a specific embodiment, in step 2), based on the mass of the raw material mixture II as 100%, the mass content of the octadecyl dimethyl allyl ammonium chloride is 0.19% to 0.8%, and the mass content of the acrylamide is 15.4% to 16%.

[0013] In a specific embodiment, in step 3), the mass ratio of the raw material mixture I to the raw material mixture II is 1:(2.6 to 2.8).

[0014] In a specific embodiment, the first solvent is water; the second solvent is a mixture of water and acetone; and the third solvent is ethanol.

[0015] In a specific embodiment, the volume ratio of water to acetone is 7:3 to 9:1.

[0016] The second aspect of the present invention provides the use of a high temperature resistant flow pattern regulating polymer prepared by the method described in any one of the first aspects of the present invention in high temperature resistance.

[0017] In a specific embodiment, the high temperature is above 180°C.

[0018] In one embodiment, the elevated temperature is 180 to 200°C.

[0019] The third aspect of the present invention provides a drilling fluid, which includes a high temperature resistant flow pattern regulator, a high temperature resistant viscosity increasing and filtration reducing agent, a lubricating defoaming agent, a shielding temporary plugging agent, a weighting agent, a pH regulator and water, wherein the high temperature resistant flow pattern regulator is xanthan gum and a high temperature resistant flow pattern regulating polymer prepared by the method described in any one of the present inventions.

[0020] In a specific embodiment, based on the mass of the water as 100 parts by mass, the anti-high temperature flow pattern regulator is 1 to 2 parts by mass, the anti-high temperature viscosity increasing and filtration reducer is 2 to 3 parts by mass, the lubricating defoaming agent is 1 to 2 parts by mass, the shielding temporary plugging agent is 3 to 7 parts by mass, the weighting agent is 30 to 75 parts by mass, and the pH adjuster is 0.7 to 1.1 parts by mass.

[0021] In a specific embodiment, the mass ratio of the high temperature resistant flow pattern regulating polymer to the xanthan gum is 3:2 to 2:1.

[0022] In a specific embodiment, the high temperature resistant viscosity increasing fluid loss reducing agent is prepared by the following steps:

[0023] 1) mixing corn starch, wheat starch and konjac starch with water to form a paste, gelatinizing at 60 to 80° C. for 1 to 2 hours, and cooling to 40 to 50° C. to obtain a first component;

[0024] II) dissolving 2-acrylamide-2-methylpropanesulfonic acid, acrylamide, diethyldiallylammonium chloride and acryloyloxytrimethylammonium chloride in water, mixing well, and adjusting the pH value to 6 to 8 to obtain a second component;

[0025] III) mixing the first component and the second component uniformly, raising the temperature to 70 to 90° C.; deoxygenating with a deoxidizer, filling with nitrogen, and then adding a second initiator to dissolve it, and sealing and standing at 70 to 90° C. for 2 to 5 hours to obtain a gel product;

[0026] IV) washing the gel product with ethanol, filtering, drying and grinding to obtain the high temperature resistant viscosity increasing fluid loss reducing agent.

[0027] In a specific embodiment, in step I), the mass ratio of corn starch, wheat starch and konjac starch is (30 to 40):(30 to 40):(20 to 40).

[0028] In one specific embodiment, in step I), taking the total mass of corn starch, wheat starch and konjac starch as 100%, the content of corn starch is 33.3% to 37.5%, the content of wheat starch is 33.3% to 37.5%, and the content of konjac starch is 25% to 33.3%.

[0029] In one specific embodiment, in step I), based on the total mass of the first component as 100%, the total content of the corn starch, wheat starch and konjac starch is 10.7 wt% to 16.7 wt%.

[0030] In a specific embodiment, in step II), based on the total mass of 2-acrylamide-2-methylpropane sulfonic acid, acrylamide, diethyldiallyl ammonium chloride and acryloxytrimethylammonium chloride as 100%, the content of 2-acrylamide-2-methylpropane sulfonic acid is 12.5% ​​to 19%, the content of acrylamide is 63.6% to 75%, the content of diethyldiallyl ammonium chloride is 6.25% to 9.5%, and the content of acryloxytrimethylammonium chloride is 4.8% to 9.1%.

[0031] In one specific embodiment, in step II), based on the total mass of the second component as 100%, the total content of 2-acrylamide-2-methylpropanesulfonic acid, acrylamide, diethyldiallylammonium chloride and acryloxytrimethylammonium chloride is 17.4 wt % to 21.1 wt %.

[0032] In a specific embodiment, in step III), the mass ratio of the first component to the second component is (0.99 to 1.84):1.

[0033] In a specific embodiment, the second initiator is at least one of ammonium persulfate, benzoyl peroxide and potassium persulfate.

[0034] In one specific embodiment, the amount of the second initiator used is 0.4% of the total weight of the monomers in step II).

[0035] In a specific embodiment, the lubricating defoaming agent is at least one of polyether polyol (for example, CAS No.: 9003-11-6) and silicone (for example, CAS No.: 9006-65-9); the shielding temporary plugging agent is at least one of 165 mesh, 325 mesh, 600 mesh, and 1250 mesh calcium carbonate, and the weighting agent is sodium formate and optionally potassium chloride.

[0036] In a specific embodiment, based on 100 parts by mass of the water, the amount of potassium chloride in the weighting agent is 0 to 15 parts by mass, and the amount of sodium formate is 30 to 60 parts by mass.

[0037] In a specific embodiment, the pH adjuster is sodium hydroxide and sodium carbonate in a mass ratio of 60:40.

[0038] In a specific embodiment, taking the total mass of the temporary shielding agent as 100%, the mass contents of calcium carbonate with particle sizes of 165 mesh, 325 mesh, 600 mesh and 1250 mesh are 20%, 20%, 30% and 30% respectively.

[0039] In a specific embodiment, the oxygen scavenger is sodium sulfite.

[0040] Beneficial effects of the present invention:

[0041] (1) Good temperature resistance, temperature resistance can reach 180℃;

[0042] (2) Good filtration control performance, low high temperature and high pressure and PPT filtration loss, which can effectively prevent the wellbore instability caused by the increase of pore pressure due to the filtrate entering the formation, and reduce the damage of filtrate invasion to the reservoir, which is beneficial to wellbore stability and reservoir protection;

[0043] (3) The reservoir protection effect is good, and the permeability recovery value can reach more than 95%. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is the nuclear magnetic resonance hydrogen spectrum of the high temperature resistant flow pattern regulating polymer 1#. DETAILED DESCRIPTION

[0045] The present invention will be further described below in conjunction with examples, but the examples of the present invention are only exemplary descriptions, and the implementation methods do not constitute limitations of the present invention under any circumstances.

[0046] High temperature resistant flow pattern regulating polymer

[0047] Example 1

[0048] 1) dissolving 20 parts by mass of 2-acrylamide-2-methylpropanesulfonic acid in 160 parts by mass of water, adjusting the pH value to 7.0, and then adding 5 parts by mass of sodium styrene sulfonate to obtain a raw material mixture I;

[0049] 2) dissolving 1 part by mass of octadecyldimethylallylammonium chloride and 80 parts by mass of acrylamide in a mixture of 440 parts by mass of water and acetone to obtain a raw material mixture II, wherein water and acetone are mixed in a mass ratio of 90:10;

[0050] 3) The raw material mixture I and the raw material mixture II were mixed uniformly at a mass ratio of 185:521 (1:2.8), nitrogen was introduced to deoxygenate, and then 0.16 parts by mass of ammonium persulfate-sodium bisulfite (molar ratio of 1:2) was added as an initiator, and after the initiator was dissolved, the reaction was continued at 30° C. under nitrogen protection for 4 hours to obtain a white gel product;

[0051] 4) The white gel product was washed three times with anhydrous ethanol, filtered, dried at 60° C., ground and passed through an 80-mesh sieve to obtain a high temperature resistant flow pattern regulating polymer 1#.

[0052] The JNM-ECZR NMR spectrometer was used to analyze the high temperature flow regulation polymer 1#. The results are shown in Figure 1 .

[0053] according to Figure 1 From the spectrum, we can see that:

[0054] δ = 0.89 ppm and 1.26 ppm are the chemical shifts of H on the hydrophobic chain CH3 and CH2 of octadecyldimethylallylammonium chloride, respectively, while δ = 3.30 ppm is the chemical shift of H on CH3 attached to the nitrogen atom;

[0055] δ = 1.73 ppm and 2.27 ppm are the chemical shifts of CH2 and H on CH connected to the amide group on the polyacrylamide chain, respectively, while δ = 5.42 ppm is the chemical shift of H on CONH2;

[0056] δ = 1.43ppm and 2.27ppm are the chemical shifts of CH2 and H on CH connected to the amide group on sodium 2-acrylamide-2-methylpropanesulfonate, respectively, while δ = 5.03ppm is the chemical shift of H on NH, δ = 1.47ppm is the chemical shift of H on two CH3 connected to the nitrogen atom, and δ = 3.17ppm is the chemical shift of H on CH2 connected to the sulfur atom;

[0057] δ=7.64ppm and 7.80ppm are the chemical shifts of H at two different positions on the benzene ring in sodium styrene sulfonate.

[0058] From the above results, it can be seen that the four monomers of 2-acrylamide-2-methylpropane sulfonic acid, sodium styrene sulfonate, octadecyl dimethyl allyl ammonium chloride and acrylamide are copolymerized, and the high temperature resistant flow pattern regulating component 1# is the product obtained by the polymerization reaction of the four monomers.

[0059] Example 2

[0060] 1) dissolving 30 parts by mass of 2-acrylamide-2-methylpropanesulfonic acid in 200 parts by mass of water, adjusting the pH value to 8.0, and then adding 10 parts by mass of sodium styrene sulfonate to obtain a raw material mixture I;

[0061] 2) dissolving 5 parts by mass of octadecyldimethylallylammonium chloride and 100 parts by mass of acrylamide in a mixture of 520 parts by mass of water and acetone to obtain a raw material mixture II, wherein water and acetone are mixed in a mass ratio of 70:30;

[0062] 3) mixing the raw material mixture I and the raw material mixture II in a mass ratio of 240:625 (1:2.6), introducing nitrogen to deoxygenate, and then adding 0.58 parts by mass of benzoyl peroxide-sodium bisulfite (molar ratio of 2:1) as an initiator, dissolving the initiator, and reacting continuously at 50° C. under nitrogen protection for 6 hours to obtain a white gel product;

[0063] 4) The white gel product was washed three times with anhydrous ethanol, filtered, dried at 60° C., ground and passed through a 100-mesh sieve to obtain a high temperature resistant flow pattern regulating polymer 2#.

[0064] The anti-high temperature flow pattern regulating polymer 2# was analyzed by nuclear magnetic resonance spectroscopy using a JNM-ECZR nuclear magnetic resonance spectroscopy instrument. The results showed that the four monomers, 2-acrylamide-2-methylpropane sulfonic acid, sodium styrene sulfonate, octadecyl dimethyl allyl ammonium chloride and acrylamide, were copolymerized, and the anti-high temperature flow pattern regulating component 2# was the product of the polymerization reaction of the four monomers.

[0065] Example 3

[0066] 1) dissolving 25 parts by mass of 2-acrylamide-2-methylpropanesulfonic acid in 180 parts by mass of water, adjusting the pH value to 7.5, and then adding 8 parts by mass of sodium styrene sulfonate to obtain a raw material mixture I;

[0067] 2) dissolving 3 parts by mass of octadecyldimethylallylammonium chloride and 90 parts by mass of acrylamide in a mixture of 480 parts by mass of water and acetone to obtain a raw material mixture II, wherein water and acetone are mixed in a mass ratio of 22:3;

[0068] 3) mixing the raw material mixture I and the raw material mixture II in a mass ratio of 213:573 (1:2.7), introducing nitrogen to deoxygenate, and then adding 0.25 parts by mass of potassium persulfate-sodium bisulfite (molar ratio of 1:1) as an initiator, dissolving the initiator, and reacting continuously at 40° C. under nitrogen protection for 5 hours to obtain a white gel product;

[0069] 4) The white gel product was washed three times with ethanol, filtered, dried at 60° C., ground and passed through a 100-mesh sieve to obtain a high temperature resistant flow pattern regulating polymer 3#.

[0070] The anti-high temperature flow pattern regulating polymer 3# was analyzed by nuclear magnetic resonance spectroscopy using a JNM-ECZR nuclear magnetic resonance spectroscopy instrument. The results showed that the four monomers, 2-acrylamide-2-methylpropane sulfonic acid, sodium styrene sulfonate, octadecyl dimethyl allyl ammonium chloride and acrylamide, were copolymerized, and the anti-high temperature flow pattern regulating component 2# was the product of the polymerization reaction of the four monomers.

[0071] High temperature resistant viscosity increasing fluid loss reducer

[0072] Example 4

[0073] Prepared by the following steps:

[0074] 1) 30 parts by mass of corn starch, 30 parts by mass of wheat starch and 20 parts by mass of konjac starch were mixed with 400 parts by mass of water to form a paste, gelatinized at 60° C. for 1 hour, and cooled to 40° C. to obtain a first component;

[0075] II) dissolving 10 parts by mass of 2-acrylamide-2-methylpropanesulfonic acid monomer in 300 parts by mass of water, then adding 60 parts by mass of acrylamide monomer, 5 parts by mass of diethyldiallylammonium chloride monomer, and 5 parts by mass of acryloxytrimethylammonium chloride monomer, mixing well and adjusting the pH value to 6 to obtain a second component;

[0076] III) 480 parts by weight of the first component and 380 parts by weight of the second component were mixed uniformly, and the temperature was raised to 70° C.; 0.0430 parts by weight of deoxidizer sodium sulfite was used for deoxidation, and the viscosity of the mixed solution gradually increased and the solution became transparent, and nitrogen was filled, and then 0.32 parts by weight of initiator ammonium persulfate (the amount of initiator added was 0.4% of the total weight of the monomer) was added to dissolve it, and the mixture was sealed and allowed to stand at 70° C. for 2 hours to obtain a gel product;

[0077] IV) The gel product was washed three times with anhydrous ethanol, filtered, dried at 70° C., ground and passed through an 80-mesh sieve to obtain a high temperature resistant viscosity increasing fluid loss reducer 1#.

[0078] Example 5

[0079] Prepared by the following steps:

[0080] 1) 40 parts by mass of corn starch, 40 parts by mass of wheat starch and 40 parts by mass of konjac starch are mixed with 1000 parts by mass of water to form a paste, gelatinized at 80° C. for 2 hours, and cooled to 50° C. to obtain a first component;

[0081] II) dissolving 20 parts by mass of 2-acrylamide-2-methylpropanesulfonic acid monomer in 500 parts by mass of water, then adding 70 parts by mass of acrylamide monomer, 10 parts by mass of diethyldiallylammonium chloride monomer, and 10 parts by mass of acryloyloxytrimethylammonium chloride monomer, mixing well and adjusting the pH value to 8 to obtain a second component;

[0082] III) 1120 parts by weight of the first component and 610 parts by weight of the second component were mixed uniformly, and the temperature was raised to 90° C.; 0.0865 parts by weight of a deoxidizer, sodium sulfite, was used for deoxidation, and the viscosity of the mixed solution gradually increased and the solution became transparent, nitrogen was filled, and then 0.44 parts by weight of an initiator, benzoyl peroxide (the amount of the initiator added was 0.4% of the total weight of the monomers) was added to dissolve it, and the mixture was sealed and allowed to stand at 90° C. for 5 hours to obtain a gel product;

[0083] IV) The gel product was washed three times with anhydrous ethanol, filtered, dried at 70° C., ground and passed through a 120-mesh sieve to obtain a high temperature resistant viscosity increasing fluid loss reducer 2#.

[0084] Example 6

[0085] Prepared by the following steps:

[0086] 1) 35 parts by mass of corn starch, 35 parts by mass of wheat starch and 30 parts by mass of konjac starch were mixed with 500 parts by mass of water to form a paste, gelatinized at 70° C. for 2 hours, and cooled to 45° C. to obtain a first component;

[0087] II) dissolving 20 parts by mass of 2-acrylamide-2-methylpropanesulfonic acid monomer in 500 parts by mass of water, then adding 70 parts by mass of acrylamide monomer, 10 parts by mass of diethyldiallylammonium chloride monomer, and 5 parts by mass of acryloyloxytrimethylammonium chloride monomer, mixing well and adjusting the pH value to 7 to obtain a second component;

[0088] III) 600 parts by weight of the first component and 605 parts by weight of the second component were mixed uniformly, and the temperature was raised to 80° C.; 0.0603 parts by weight of deoxidizer sodium sulfite was used for deoxidation, and the viscosity of the mixed solution gradually increased and the solution became transparent, and nitrogen was filled, and then 0.42 parts by weight of initiator potassium persulfate (the amount of initiator added was 0.4% of the total weight of the monomer) was added to dissolve it, and the mixture was sealed and allowed to stand at 80° C. for 3 hours to obtain a gel product;

[0089] IV) The gel product was washed three times with anhydrous ethanol, filtered, dried at 70° C., ground and passed through a 100-mesh sieve to obtain a high temperature resistant viscosity increasing fluid loss reducer 3#.

[0090] Drilling Fluid

[0091] Example 7

[0092] The components of the clay-free high-temperature resistant drilling fluid are as follows: 100 parts by weight of water; 0.7 parts by weight of a pH value regulator (the mass ratio of sodium hydroxide to sodium carbonate is 60:40), 1 part by weight of a high-temperature resistant flow pattern regulator (a high-temperature resistant flow pattern regulating polymer 1# and xanthan gum in a mass ratio of 60:40), 2 parts by weight of a high-temperature resistant viscosity increasing and fluid loss reducing agent 1#, 1 part by weight of a polyether polyol (CAS No: 9003-11-6), 3 parts by weight of a shielding temporary plugging agent (a calcium carbonate mixture with a mass content of 20%, 20%, 30% and 30% and a particle size of 165 mesh, 325 mesh, 600 mesh and 1250 mesh), 0 parts by weight of an inorganic salt weighting agent potassium chloride, and 30 parts by weight of an organic salt weighting agent sodium formate.

[0093] The preparation process is as follows:

[0094] Put 300mL of water into a high stirring cup, and add 2.1g of pH value regulator, 6g of high temperature resistant viscosity increasing and fluid loss reducing agent 1#, 3g of polyether polyol, 9g of shielding temporary plugging agent, 0g of potassium chloride, and 90g of sodium formate in sequence while stirring at a stirring rate of 8000rpm. Stir each material for 10 minutes, and finally add 3g of high temperature resistant flow type regulator. After stirring for 40 minutes, the density is 1.17g / cm 3 Clay-free high temperature drilling fluid.

[0095] Example 8

[0096] The components of the clay-free high-temperature resistant drilling fluid are as follows: 100 parts by weight of water; 1.1 parts by weight of a pH value regulator (the mass ratio of sodium hydroxide to sodium carbonate is 60:40), 2 parts by weight of a high-temperature resistant flow pattern regulator (a high-temperature resistant flow pattern regulating polymer 2# and xanthan gum with a mass ratio of 60:30), 3 parts by weight of a high-temperature resistant viscosity increasing and fluid loss reducing agent 2#, 2 parts by weight of a polyether polyol (CAS No: 9003-11-6), 7 parts by weight of a shielding temporary plugging agent (a calcium carbonate mixture with a mass content of 20%, 20%, 30% and 30% and a particle size of 165 mesh, 325 mesh, 600 mesh and 1250 mesh), 15 parts by weight of an inorganic salt weighting agent potassium chloride, and 60 parts by weight of an organic salt weighting agent sodium formate.

[0097] The preparation process is as follows:

[0098] Put 300mL of water into a high stirring cup, and add 3.3g of pH regulator, 9g of high temperature resistant viscosity increasing and filtration reducing agent 2#, 6g of polyether polyol, 21g of shielding temporary plugging agent, 45g of potassium chloride, and 180g of sodium formate in sequence while stirring at a stirring rate of 8000rpm. Stir each material for 10 minutes, and finally add 6g of high temperature resistant flow type regulator. After stirring for 40 minutes, the density is 1.30g / cm 3 Clay-free high temperature drilling fluid.

[0099] Example 9

[0100] The components of the clay-free high-temperature resistant drilling fluid are as follows: 100 parts by weight of water; 1 part by weight of a pH value regulator (the mass ratio of sodium hydroxide to sodium carbonate is 60:40), 1.5 parts by weight of a high-temperature resistant flow pattern regulator (a high-temperature resistant flow pattern regulating polymer 3# and xanthan gum with a mass ratio of 60:30), 2.5 parts by weight of a high-temperature resistant viscosity increasing and fluid loss reducing agent 3#, 1.5 parts by weight of a polyether polyol (CAS No: 9003-11-6), 5 parts by weight of a shielding temporary plugging agent (a calcium carbonate mixture with a mass content of 20%, 20%, 30% and 30% and a particle size of 165 mesh, 325 mesh, 600 mesh and 1250 mesh), 7.5 parts by weight of an inorganic salt weighting agent potassium chloride, and 45 parts by weight of an organic salt weighting agent sodium formate.

[0101] The preparation process is as follows:

[0102] Put 300mL of water into a high stirring cup, and add 3g of pH regulator, 7.5g of high temperature resistant viscosity increasing and fluid loss reducing agent 3#, 4.5g of polyether polyol, 15g of shielding temporary plugging agent, 22.5g of potassium chloride, and 135g of sodium formate in sequence while stirring at a stirring rate of 8000rpm. Stir each material for 10 minutes, and finally add 4.5g of high temperature resistant flow pattern regulator. After stirring for 40 minutes, the density is 1.25g / cm 3 Clay-free high temperature drilling fluid.

[0103] Example 10

[0104] The components of the clay-free high-temperature resistant drilling fluid are as follows: 100 parts by weight of water; 1 part by weight of a pH value regulator (the mass ratio of sodium hydroxide to sodium carbonate is 60:40), 1.75 parts by weight of a high-temperature resistant flow pattern regulator (a high-temperature resistant flow pattern regulating polymer 3# and xanthan gum with a mass ratio of 60:30), 2.5 parts by weight of a high-temperature resistant viscosity increasing and fluid loss reducing agent 1#, 1 part by weight of a polyether polyol (CAS No: 9003-11-6), 5 parts by weight of a shielding temporary plugging agent (a mixture of calcium carbonate with a mass content of 20%, 20%, 30% and 30% and a particle size of 165 mesh, 325 mesh, 600 mesh and 1250 mesh), 15 parts by weight of an inorganic salt weighting agent potassium chloride, and 60 parts by weight of an organic salt weighting agent sodium formate.

[0105] The preparation process is as follows:

[0106] Put 300mL of water into a high stirring cup, and add 3g of pH regulator, 7.5g of high temperature resistant viscosity increasing and fluid loss reducing agent 1#, 3g of polyether polyol, 15g of shielding temporary plugging agent, 45g of potassium chloride, and 180g of sodium formate in sequence while stirring at a stirring rate of 8000rpm. Stir each material for 10 minutes, and finally add 5.25g of high temperature resistant flow pattern regulator. After stirring for 40 minutes, the density is 1.30g / cm 3 Clay-free high temperature drilling fluid.

[0107] Embodiment 11

[0108] The difference from Example 10 is that the high temperature resistant viscosity increasing fluid loss reducing agent is high temperature resistant viscosity increasing fluid loss reducing agent 2#. The obtained density is 1.30 g / cm 3 Clay-free high temperature drilling fluid.

[0109] Example 12

[0110] The difference from Example 10 is that the high temperature resistant flow pattern regulating polymer is the high temperature resistant flow pattern regulating polymer 2#, and the high temperature resistant viscosity increasing fluid loss reducing agent is the high temperature resistant viscosity increasing fluid loss reducing agent 3#. The obtained density is 1.30 g / cm 3 Clay-free high temperature drilling fluid.

[0111] Example 13

[0112] The difference from Example 10 is that the high temperature resistant flow pattern regulating polymer is the high temperature resistant flow pattern regulating polymer 2#, and the high temperature resistant viscosity increasing fluid loss reducing agent is the high temperature resistant viscosity increasing fluid loss reducing agent 1#. The obtained density is 1.30 g / cm 3 Clay-free high temperature drilling fluid.

[0113] Embodiment 14

[0114] The difference from Example 10 is that the high temperature resistant flow pattern regulating polymer is the high temperature resistant flow pattern regulating polymer 1#, and the high temperature resistant viscosity increasing fluid loss reducing agent is the high temperature resistant viscosity increasing fluid loss reducing agent 3#. The obtained density is 1.30 g / cm 3 Clay-free high temperature drilling fluid.

[0115] Embodiment 15

[0116] The difference from Example 10 is that the high temperature resistant flow pattern regulating polymer is the high temperature resistant flow pattern regulating polymer 1#, and the high temperature resistant viscosity increasing fluid loss reducing agent is the high temperature resistant viscosity increasing fluid loss reducing agent 2#. The obtained density is 1.30 g / cm 3 Clay-free high temperature drilling fluid.

[0117] Comparative Example 1

[0118] Carboxymethyl starch was purchased from Renqiu Guangshun Environmental Protection Technology Co., Ltd.

[0119] Xanthan gum was purchased from Hebei Jiuyu Biotechnology Co., Ltd.

[0120] Fenugreek gum and guar gum were purchased from Jiangsu Caiwei Biotechnology Co., Ltd.

[0121] The difference from Example 10 is that the high temperature resistant viscosity increasing and fluid loss reducing agent is 2.5 parts by mass of carboxymethyl starch, and the high temperature resistant flow pattern regulator is 1.75 parts by mass of a biopolymer composition (xanthan gum, fenugreek gum, and guar gum in a mass ratio of 50:45:5).

[0122] The density was 1.30 g / cm 3 of drilling fluid.

[0123] Comparative Example 2

[0124] Xanthan gum was purchased from Hebei Jiuyu Biotechnology Co., Ltd.

[0125] Fenugreek gum and guar gum were purchased from Jiangsu Caiwei Biotechnology Co., Ltd.

[0126] The difference from Example 10 is that the high temperature resistant flow pattern regulator is 1.75 parts by weight of a biopolymer composition (xanthan gum, fennel gum, and guar gum in a mass ratio of 50:45:5).

[0127] The density was 1.30 g / cm 3 of drilling fluid.

[0128] Comparative Example 3

[0129] Carboxymethyl starch was purchased from Renqiu Guangshun Environmental Protection Technology Co., Ltd.

[0130] The difference from Example 10 is that the high temperature resistant viscosity increasing fluid loss reducer is 2.5 parts by mass of carboxymethyl starch.

[0131] The density was 1.30 g / cm 3 of drilling fluid.

[0132] In order to illustrate the temperature resistance, fluid loss control and reservoir protection performance of the clay-free high-temperature resistant drilling fluid of the present invention, experimental measurements were performed on Examples 7 to 15 and Comparative Examples 1 to 3, respectively.

[0133] (1) Evaluation of temperature resistance

[0134] The drilling fluids obtained in Examples 7 to 15 and Comparative Examples 1 to 3 were hot-rolled at 160, 180 and 200° C. for 16 h, respectively, and the basic properties of the drilling fluids after treatment at different temperatures were measured in accordance with GB / T16783.1-2014 "Field Test of Drilling Fluids in Petroleum and Natural Gas Industry Part 1: Water-Based Drilling Fluids". The test results are shown in Table 1.

[0135] Table 1

[0136]

[0137] Note: The temperature for measuring medium pressure filtration loss at room temperature is 25℃ and the pressure is 0.7MPa.

[0138] It can be seen from Table 1 that the clay-free high-temperature drilling fluid provided by the present invention has significant temperature resistance, and still has good adhesion and low API filtration after aging at 180°C and 200°C. Compared with Comparative Examples 1 to 3, the adhesion stability and filtration control performance at high temperature are significantly improved.

[0139] (2) Evaluation of fluid loss control performance

[0140] The drilling fluid systems of Examples 7 to 15 and Comparative Examples 1 to 3 were subjected to high temperature and high pressure filtration loss determination according to GB / T16783.1-2014 "Field Test of Drilling Fluids in Petroleum and Natural Gas Industry Part 1: Water-based Drilling Fluids", wherein the pressure difference was 3.5 MPa and the temperature was 180°C; and the permeability plugging filtration loss determination was performed using a permeability plugging instrument according to "GB / T 29170-2012 Laboratory Test of Drilling Fluids in Petroleum and Natural Gas Industry", wherein the filtration medium used was a sand disk with a permeability of 500 mD, the pressure difference was 6.9 MPa, and the temperature was 180°C. The filtration loss for 30 min of filtration loss is shown in Table 2.

[0141] Table 2

[0142]

[0143] It can be seen from Table 2 that the clay-free high-temperature drilling fluid provided by the present invention has excellent filtration control performance. Compared with Comparative Examples 1 to 3, the high-temperature and high-pressure filtration loss and the permeation plugging filtration loss at 180°C are significantly reduced, which can effectively prevent the wellbore instability caused by the increase in pore pressure due to the filtrate entering the formation, and at the same time reduce the damage to the reservoir caused by the filtrate invasion, which is beneficial to the wellbore stability and reservoir protection.

[0144] (3) Evaluation of reservoir protection performance

[0145] The drilling fluid systems of Examples 7 to 15 and Comparative Examples 1 to 3 were evaluated for reservoir protection effects according to the petroleum and natural gas industry standard SY / T6540-2002 "Indoor Evaluation Method for Damage to Reservoirs by Drilling and Completion Fluids", wherein the temperature was 180° C. The evaluation results are shown in Table 3.

[0146] Table 3

[0147]

[0148] It can be seen from Table 3 that the clay-free high-temperature drilling fluid provided by the present invention has excellent reservoir protection performance. The permeability recovery values ​​of Examples 7 to 15 at 180°C are all over 95.0%, which has better reservoir protection effect than Comparative Examples 1 to 3.

[0149] Although the present invention has been described with reference to specific embodiments, it will be appreciated by those skilled in the art that various changes may be made without departing from the true spirit and scope of the present invention. In addition, the subject matter, spirit and scope of the present invention may be varied to accommodate specific situations, materials, material combinations and methods. All of these changes are included within the scope of the claims of the present invention.

Claims

1. A method for preparing a high temperature resistant flow pattern regulating polymer, comprising the following steps: 1) dissolving 2-acrylamide-2-methylpropanesulfonic acid in a first solvent, adjusting the pH value to 7 to 8, and then adding sodium styrene sulfonate to obtain a raw material mixture I; 2) dissolving octadecyl dimethyl allyl ammonium chloride and acrylamide in a second solvent to obtain a raw material mixture II; 3) mixing the raw material mixture I and the raw material mixture II uniformly, deoxygenating, then adding the first initiator, dissolving the first initiator, and reacting continuously for 4 to 6 hours at 30 to 50° C. under nitrogen protection to obtain a white gel product; 4) washing the white gel product with a third solvent, filtering, drying and grinding to obtain the high temperature resistant flow pattern regulating polymer.

2. The method according to claim 1, It is characterized in that The first initiator is a mixture of at least one of ammonium persulfate, potassium persulfate and benzoyl peroxide and sodium bisulfite, and the molar ratio of at least one of ammonium persulfate, potassium persulfate and benzoyl peroxide to sodium bisulfite is 1:2 to 2:

1.

3. The method according to claim 1 or 2, It is characterized in that In step 1), the mass ratio of the 2-acrylamide-2-methylpropane sulfonic acid to the sodium styrene sulfonate is (3 to 4):1; Preferably, in step 1), based on the mass of the raw material mixture I as 100%, the mass content of the 2-acrylamide-2-methylpropane sulfonic acid is 10.8% to 12.5%, and the mass content of the sodium styrene sulfonate is 2.7% to 4.2%; and / or In step 2), the mass ratio of octadecyl dimethyl allyl ammonium chloride to acrylamide is 1:(20 to 80); Preferably, in step 2), based on the mass of the raw material mixture II as 100%, the mass content of the octadecyl dimethyl allyl ammonium chloride is 0.19% to 0.8%, and the mass content of the acrylamide is 15.4% to 16%; and / or In step 3), the mass ratio of the raw material mixture I to the raw material mixture II is 1:(2.6 to 2.8).

4. The method according to any one of claims 1 to 3, It is characterized in that The first solvent is water; the second solvent is a mixture of water and acetone; the third solvent is ethanol; preferably, the volume ratio of water to acetone is 7:3 to 9:

1.

5. Use of the high temperature resistant flow pattern regulating polymer prepared by the method according to any one of claims 1 to 4 in high temperature resistance.

6. The use according to claim 5, It is characterized in that The high temperature is above 180°C; Preferably, the high temperature is 180 to 200°C.

7. A drilling fluid, comprising a high temperature resistant flow pattern regulator, a high temperature resistant viscosity increasing and fluid loss reducing agent, a lubricating defoaming agent, a shielding temporary plugging agent, a weighting agent, a pH regulator and water, wherein the high temperature resistant flow pattern regulator is xanthan gum and a high temperature resistant flow pattern regulating polymer prepared by the method according to any one of claims 1 to 4.

8. The drilling fluid according to claim 7, It is characterized in that Based on the mass of the water as 100 parts by mass, the anti-high temperature flow pattern regulator is 1 to 2 parts by mass, the anti-high temperature viscosity increasing and fluid loss reducing agent is 2 to 3 parts by mass, the lubricating defoaming agent is 1 to 2 parts by mass, the shielding temporary plugging agent is 3 to 7 parts by mass, the weighting agent is 30 to 75 parts by mass, and the pH regulator is 0.7 to 1.1 parts by mass; Preferably, the mass ratio of the high temperature resistant flow pattern regulating polymer to the xanthan gum is 3:2 to 2:

1.

9. The drilling fluid according to claim 7, It is characterized in that The high temperature resistant viscosity increasing fluid loss reducing agent is prepared by the following steps: 1) mixing corn starch, wheat starch and konjac starch with water to form a paste, gelatinizing at 60 to 80° C. for 1 to 2 hours, and cooling to 40 to 50° C. to obtain a first component; II) dissolving 2-acrylamide-2-methylpropanesulfonic acid, acrylamide, diethyldiallylammonium chloride and acryloyloxytrimethylammonium chloride in water, mixing well, and adjusting the pH value to 6 to 8 to obtain a second component; III) mixing the first component and the second component uniformly, raising the temperature to 70 to 90° C.; deoxygenating with a deoxidizer, filling with nitrogen, and then adding a second initiator to dissolve it, and sealing and standing at 70 to 90° C. for 2 to 5 hours to obtain a gel product; IV) washing the gel product with ethanol, filtering, drying and grinding to obtain the high temperature resistant viscosity increasing fluid loss reducing agent; Preferably, in step I), the mass ratio of corn starch, wheat starch and konjac starch is (30 to 40):(30 to 40):(20 to 40); preferably, taking the total mass of corn starch, wheat starch and konjac starch as 100%, the content of corn starch is 33.3% to 37.5%, the content of wheat starch is 33.3% to 37.5%, and the content of konjac starch is 25% to 33.3%; Preferably, in step I), based on the total mass of the first component as 100%, the total content of the corn starch, wheat starch and konjac starch is 10.7wt% to 16.7wt%; Preferably, in step II), based on the total mass of 2-acrylamide-2-methylpropanesulfonic acid, acrylamide, diethyldiallyl ammonium chloride and acryloxytrimethylammonium chloride as 100%, the content of 2-acrylamide-2-methylpropanesulfonic acid is 12.5% ​​to 19%, the content of acrylamide is 63.6% to 75%, the content of diethyldiallyl ammonium chloride is 6.25% to 9.5%, and the content of acryloxytrimethylammonium chloride is 4.8% to 9.1%; Preferably, in step II), based on the total mass of the second component as 100%, the total content of 2-acrylamide-2-methylpropanesulfonic acid, acrylamide, diethyldiallylammonium chloride and acryloxytrimethylammonium chloride is 17.4wt% to 21.1wt%; Preferably, in step III), the mass ratio of the first component to the second component is (0.99 to 1.84):1; Preferably, the second initiator is at least one of ammonium persulfate, benzoyl peroxide and potassium persulfate.

10. The drilling fluid according to claim 7, It is characterized in that The lubricating defoaming agent is polyether polyol and / or silicone; the shielding temporary plugging agent is at least one of 165 mesh, 325 mesh, 600 mesh, and 1250 mesh calcium carbonate; the weighting agent is sodium formate and optionally potassium chloride; Preferably, based on 100 parts by mass of the water, the amount of potassium chloride in the weighting agent is 0 to 15 parts by mass, and the amount of sodium formate is 30 to 60 parts by mass.

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