A fluid loss additive, its preparation method and application

Abstract

The application relates to a filtrate reducer and a preparation method and application thereof, the preparation raw material of the filtrate reducer comprises a combination of polymerized monomers and a crosslinking agent; the polymerized monomers comprise a combination of alkenyl amide, alkenyl sulfonic acid, rigid monomers and alkenyl cation monomers; and the crosslinking agent has a structure of formula I. The preparation raw material of the filtrate reducer is designed, the obtained filtrate reducer has the properties of resisting high temperature and salt, and simultaneously has good rheological properties and filtrate reduction properties, and can meet the needs of the development of the anti-high-temperature and anti-salt drilling fluid technology.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of oil field chemical industry, and particularly relates to a filtrate reducer and a preparation method and application thereof. BACKGROUND

[0002] With the continuous increase of energy demand in China, the dependence on foreign oil is increasing, and the energy situation is severe. Deep and ultra-deep oil and gas has become the focus of development. As an important part of drilling engineering, the performance of drilling fluid directly affects the drilling cost and drilling cycle of deep and ultra-deep wells. At present, the bottom hole temperature of deep wells in China can reach more than 200℃, and there are many salt-containing formations in deep formations. The high temperature and high salt environment of deep wells easily leads to the deterioration of the performance of drilling fluid, and it is difficult to meet the needs of safe drilling. Therefore, temperature-resistant and salt-resistant drilling fluid is a key technology for deep formation drilling, and plays an irreplaceable important role in the exploration and development of deep and ultra-deep oil and gas resources.

[0003] In the drilling process, the invasion of drilling fluid filtrate into the formation will cause shale hydration and swelling, resulting in reservoir damage, and even leading to wellbore instability and other downhole complex accidents. The filtrate reducer is the core treatment agent to ensure the stability of the performance of the drilling fluid. The mechanism of the filtrate reducer generally has the following types: (1) the filtrate reducer is adsorbed on the surface of clay particles to prevent the flocculation of clay particles, so that the clay becomes fine particles, which is beneficial to form a more dense mud cake and reduce the water loss; (2) the hydration group of the filtrate reducer can thicken the hydration film of the clay particles, and reduce the permeability of the mud cake; (3) the fine particles of the filtrate reducer can enter the gap of the mud cake, and block the micro-pore cracks of the mud cake, so that the mud cake is thin and dense; (4) the filtrate reducer can appropriately increase the viscosity of the drilling fluid, so that the filtrate is difficult to penetrate out of the mud cake, and the permeability is reduced.

[0004] At present, the high-temperature-resistant filtrate reducer is mainly composed of synthetic polymers, and the related products have certain temperature-resistant and salt-resistant ability. However, with the development of deep well drilling, the actual bottom hole working temperature is continuously rising, and the probability of drilling complex formations is increasing, which leads to the unsatisfactory performance of the filtrate reducer in deep well drilling. The temperature-resistant and salt-resistant performance of the filtrate reducer still cannot meet the actual needs, so it is very urgent to develop a new type of polymer filtrate reducer with better performance. Traditional polymer filtrate reducers are generally based on 2-acrylamide-2-methyl 1-propane sulfonic acid (AMPS), N-vinyl pyrrolidone (NVP) and other monomers, and are prepared by aqueous solution polymerization. Such polymers are linear polymers, and have limited high-temperature resistance. In addition, they have the disadvantages of high viscosity, easy chain breaking at high temperature, weak anti-degradation ability, and are difficult to meet the needs of rheological property and filtration loss control of drilling fluid under the conditions of deep well high temperature and high salt. Therefore, the polymer filtrate reducer with non-linear branched and cross-linked structure has gradually become a research hotspot.

[0005] CN114773539A discloses a water-based drilling fluid with high-temperature-resistant and high-salt-resistant micro-crosslinking hydrophobic association viscosity-increasing and filtration-reducing agent and a preparation method thereof; the viscosity-increasing and filtration-reducing agent is prepared by copolymerization of comonomers, crosslinking agents, cosolvents and initiators in water; the comonomers include vinyl monomers, sodium styrene sulfonate, maleic anhydride and long hydrophobic chain ester monomers; the filtration-reducing agent effectively reduces the filtration loss of drilling fluid, improves the viscosity of drilling fluid and maintains the rheological stability of drilling fluid under high-temperature and high-salt conditions, and can be applied to deep high-salt formation oil and gas drilling.

[0006] CN111285964A discloses a temperature-resistant and salt-resistant micro-crosslinking filtration-reducing agent for drilling fluid and a preparation method thereof, which is prepared by using appropriate crosslinking agents and chain transfer agents to generate a micro-crosslinking filtration-reducing agent, and has the following advantages: containing crosslinked microsphere structures, which can effectively reduce the filtration loss of drilling fluid; containing various temperature-resistant and adsorption groups, which have excellent temperature-resistant and salt-resistant properties; and having a relatively low molecular weight, which has a small influence on the rheological properties of drilling fluid.

[0007] CN116063623A discloses a preparation method of an ultrabranched polymer for drilling fluid, which comprises copolymerization of organic acid monomers, organic amide monomers, a first branching agent, a second branching agent and a chain transfer agent under the action of a pH regulator and a chain transfer agent to obtain an ultrabranched polymer for drilling fluid; the reversible addition fragmentation chain transfer (RAFT) polymerization method provided by the application adopts a rapid polymerization process, uses diene monomers, branching agents and chain transfer agents to prepare water-soluble snowflake-like ultrabranched polymer filtration-reducing agents in an aqueous solution system at a high polymerization rate and high conversion, and the filtration-reducing agents have a double-layer branched structure, good solubility, high rheological properties, no crosslinking, a large number of branched end groups, a narrow molecular weight distribution and good temperature resistance, and have a low viscosity effect.

[0008] The prior art generally prepares a non-linear filtration-reducing agent by introducing functional monomers into the filtration-reducing agent molecules or using crosslinking agents, and in order to avoid excessive viscosity-increasing effect of the filtration-reducing agent, an additive or a chain transfer agent is generally used in the polymerization process, and the preparation process is complex and the cost is relatively high. Therefore, it is necessary to design the raw materials for preparing the filtration-reducing agent, so that the filtration-reducing agent with a micro-crosslinking structure can be obtained by simple preparation of raw materials without affecting the viscosity effect of the filtration-reducing agent, to meet the needs of the development of current temperature-resistant and salt-resistant drilling fluid technology. SUMMARY

[0009] In view of the deficiencies of the prior art, the purpose of the present application is to provide a filtration-reducing agent, a preparation method and application thereof. The present application designs the raw materials for preparing the filtration-reducing agent, so that the obtained filtration-reducing agent has temperature-resistant and salt-resistant properties, and has good rheological properties and filtration-reducing properties, which can meet the needs of the development of temperature-resistant and salt-resistant drilling fluid technology.

[0010] To achieve the above object, the present application adopts the following technical solutions.

[0011] In a first aspect, the present application provides a fluid loss additive, wherein the raw materials for preparing the fluid loss additive comprise a combination of polymerized monomers and a crosslinking agent; the polymerized monomers comprise a combination of alkenyl amide, alkenyl sulfonic acid, rigid monomer and alkenyl cationic monomer; and the crosslinking agent has a structure as shown in Formula I:

[0012]

[0013] wherein R1, R2 and R3 are each independently selected from any one of C2-C6 linear alkylene.

[0014] The fluid loss additive provided by the present application is an anti-ultra-high-temperature anti-salt low-gel polymer fluid loss additive, which has excellent high-temperature resistance and salt resistance, and simple raw materials, and is suitable for deep well and ultra-deep well drilling, and can effectively improve the rheological properties of the mud and reduce the fluid loss during use.

[0015] The fluid loss additive provided by the present application is a micro-crosslinked copolymer prepared by four organic monomers of alkenyl amide, alkenyl sulfonic acid, rigid monomer and alkenyl cationic monomer, and a water-soluble acrylamide crosslinking agent having a structure as shown in Formula I; the rigid monomer can not only improve the adsorption capacity with clay, but also improve the temperature resistance of the fluid loss additive; the sulfonic acid group of the alkenyl sulfonic acid can play a good hydration effect, so that the fluid loss additive has good salt resistance and can enhance the stability of clay dispersion; the alkenyl cationic monomer can produce strong adsorption with clay, not only adsorbing clay, but also improving the salt resistance of the fluid loss additive; the micro-crosslinked structure formed by the water-soluble acrylamide crosslinking agent significantly improves the rigidity of the fluid loss additive, improves the temperature resistance and salt resistance of the fluid loss additive, and also ensures the fluidity of the molecular chain of the fluid loss additive.

[0016] In the present application, the C2-C6 can be C3, C4 or C5.

[0017] The C2-C6 linear alkylene includes ethylene, propylene, butylene, n-pentylene or n-hexylene.

[0018] In the present application, the crosslinking agent can be purchased, and for example, the crosslinking agent N-[tris(3-acrylamidopropyl methyl ether) methyl] acrylamide can be purchased from FUJIFILM Wako.

[0019] The following is a preferred technical solution of the present application, but is not a limitation on the technical solution provided by the present application, and the purpose and beneficial effects of the present application can be better achieved and realized through the following preferred technical solution.

[0020] As a preferred technical solution, the alkenyl amide includes any one of acrylamide, N,N-dimethyl acrylamide or N,N-diethyl acrylamide or a combination of at least two thereof.

[0021] Preferably, the alkenyl sulfonic acid includes 2-acrylamido-2-methyl-1-propane sulfonic acid.

[0022] Preferably, the rigid monomer includes any one of N-vinyl pyrrolidone, N-vinyl caprolactam or N-acryloyl morpholine or a combination of at least two thereof; the heterocyclic group contained in the rigid monomer not only improves the adsorption capacity to clay, but also the steric hindrance is larger, which further improves the temperature resistance of the fluid loss additive.

[0023] Preferably, the alkenyl cationic monomer includes dimethyl diallyl ammonium chloride and / or dodecyl dimethyl allyl ammonium chloride; the quaternary ammonium salt cationic group contained in the alkenyl cationic monomer can produce strong adsorption to clay, which not only adsorbs clay, but also improves the salt resistance of the fluid loss additive.

[0024] Preferably, the molar ratio of the alkenyl amide to the alkenyl sulfonic acid is (2-4):1, for example, it can be 2.1:1, 2.2:1, 2.4:1, 2.6:1, 2.8:1, 3:1, 3.2:1, 3.4:1, 3.6:1, 3.8:1, 3.9:1, etc.

[0025] Preferably, the molar ratio of the alkenyl amide to the rigid monomer is (3-8):1, for example, it can be 3.1:1, 3.2:1, 3.4:1, 3.6:1, 3.8:1, 4:1, 4.2:1, 4.4:1, 4.6:1, 4.8:1, 5:1, 5.2:1, 5.4:1, 5.6:1, 5.8:1, 6:1, 6.2:1, 6.4:1, 6.6:1, 6.8:1, 7:1, 7.2:1, 7.4:1, 7.6:1, 7.8:1, etc.

[0026] Preferably, the molar ratio of the alkenyl amide to the alkenyl cationic monomer is (6-16):1, such as 6.2:1, 6.5:1, 6.8:1, 7:1, 7.2:1, 7.5:1, 7.8:1, 8:1, 8.2:1, 8.5:1, 8.8:1, 9:1, 9.2:1, 9.5:1, 9.8:1, 10:1, 10.2:1, 10.5:1, 10.8:1, 11:1, 11.2:1, 11.5:1, 11.8:1, 12:1, 12.2:1, 12.5:1, 12.8:1, 13:1, 13.2:1, 13.5:1, 13.8:1, 14:1, 14.2:1, 14.5:1, 14.8:1, 15:1, 15.2:1, 15.5:1, 15.8:1, 16:1, etc.

[0027] Preferably, the crosslinking agent comprises N-[tris(3-acrylamidopropyl methyl ether)methyl] acrylamide and / or N-[tris(4-acrylamidobutyl methyl ether)methyl] acrylamide.

[0028] Preferably, the mass ratio of the polymerization monomer to the crosslinking agent is (100-400):1, such as 120:1, 140:1, 160:1, 180:1, 200:1, 220:1, 240:1, 260:1, 280:1, 300:1, 320:1, 340:1, 360:1, 380:1, etc.

[0029] Preferably, the raw material for preparing the fluid loss additive further comprises an initiator.

[0030] Preferably, the initiator comprises any one or a combination of at least two of a persulfate initiator, a redox initiator, or an azo initiator.

[0031] Preferably, the persulfate initiator comprises potassium persulfate and / or ammonium persulfate.

[0032] Preferably, the redox initiator comprises ammonium persulfate-sodium bisulfite.

[0033] Preferably, the azo initiator comprises azobisisobutyronitrile and / or azobisisobutyrimidazole hydrochloride.

[0034] Preferably, the mass ratio of the polymerization monomer to the initiator is (100-300):1, such as 120:1, 140:1, 160:1, 180:1, 200:1, 220:1, 240:1, 260:1, 280:1, 300:1, etc.

[0035] Preferably, the raw material for preparing the fluid loss additive further comprises a neutralizing agent.

[0036] Preferably, the neutralizing agent comprises sodium hydroxide.

[0037] Preferably, the raw material for preparing the fluid loss additive further comprises water.

[0038] Preferably, the mass percentage of the polymerized monomer in the raw material for preparing the fluid loss additive is 15-30%, for example, it can be 15.5%, 16%, 16.5%, 17%, 17.5%, 18%, 18.5%, 19%, 19.5%, 20%, 20.5%, 21%, 21.5%, 22%, 22.5%, 23%, 23.5%, 24%, 24.5%, 25%, 25.5%, 26%, 26.5%, 27%, 27.5%, 28%, 28.5%, 29%, 29.5%, etc.

[0039] Preferably, the weight average molecular weight of the fluid loss additive is 260-400 thousand, for example, it can be 260 thousand, 270 thousand, 280 thousand, 290 thousand, 300 thousand, 310 thousand, 320 thousand, 330 thousand, 340 thousand, 350 thousand, 360 thousand, 370 thousand, 380 thousand, 390 thousand, 400 thousand, etc.

[0040] In the second aspect, the present application provides a method for preparing the fluid loss additive according to the first aspect, and the method comprises:

[0041] The alkenyl amide, the alkenyl sulfonic acid, the rigid monomer, the alkenyl cationic monomer and the crosslinking agent are reacted to obtain the fluid loss additive.

[0042] The fluid loss additive provided by the present application is prepared by free radical copolymerization reaction, and the preparation method is simple and low in cost.

[0043] Preferably, the alkenyl sulfonic acid is used in the form of an aqueous alkenyl sulfonic acid solution.

[0044] Preferably, the aqueous alkenyl sulfonic acid solution is neutralized to neutral by using a neutralizing agent before use.

[0045] Preferably, the neutralizing agent is used in the form of a neutralizing agent aqueous solution.

[0046] Preferably, the mass percentage of the neutralizing agent in the neutralizing agent aqueous solution is 40-60%, for example, it can be 42%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, etc.

[0047] Preferably, the alkenyl cationic monomer is used in the form of an alkenyl cationic monomer aqueous solution.

[0048] Preferably, the mass percentage content of the alkenyl cationic monomer in the alkenyl cationic monomer aqueous solution is 50-60%, for example, it can be 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, etc.

[0049] Preferably, the crosslinking agent is used in the form of a crosslinking agent aqueous solution.

[0050] Preferably, the mass percentage content of the crosslinking agent in the crosslinking agent aqueous solution is 1-2%, for example, it can be 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, etc.

[0051] Preferably, the reaction is carried out in the presence of an initiator.

[0052] Preferably, the temperature of the reaction is 40-60℃, for example, it can be 42℃, 44℃, 46℃, 48℃, 50℃, 52℃, 54℃, 56℃, 58℃, 60℃, etc.

[0053] Preferably, the time of the reaction is 2-4h, for example, it can be 2h, 2.2h, 2.4h, 2.6h, 2.8h, 3h, 3.2h, 3.4h, 3.6h, 3.8h, 4h, etc.

[0054] Preferably, the reaction is carried out under a nitrogen atmosphere.

[0055] Preferably, after the reaction is completed, the steps of washing, drying and crushing are sequentially carried out.

[0056] Preferably, the preparation method specifically comprises the following steps:

[0057] (1) neutralizing the alkenyl sulfonic acid aqueous solution to neutral with a neutralizing agent aqueous solution;

[0058] (2) mixing the solution obtained in step (1), the alkenyl amide, the rigid monomer, and the alkenyl cationic monomer aqueous solution to obtain a mixed solution;

[0059] (3) reacting the mixed solution, the crosslinking agent aqueous solution and the initiator to obtain the fluid loss additive.

[0060] In a third aspect, the present application provides a drilling fluid, wherein the components of the drilling fluid comprise the fluid loss additive according to the first aspect.

[0061] Compared with the prior art, the present application has the following beneficial effects:

[0062] (1) The rigid monomer used in the present application has good chemical stability, strong temperature resistance and salt resistance, and the olefin cation monomer can still maintain the adsorption effect on clay even at high temperature, avoiding the precipitation and coagulation of clay at high temperature;

[0063] (2) The crosslinking agent used in the present application belongs to a water-soluble acrylamide crosslinking agent, and the micro-crosslinked structure formed significantly improves the rigidity of the fluid loss additive, improves the temperature resistance and salt resistance, and the crosslinked structure can also realize the physical plugging of the fluid loss additive to reduce fluid loss;

[0064] (3) The crosslinking agent used in the present application has more vinyl groups on each molecule than the commonly used diene crosslinking agent (such as N,N-methylene bisacrylamide), and the crosslinking points in the unit space are more, and the crosslinked network structure formed by the reaction is more stable;

[0065] (4) The crosslinking agent used in the present application has a long molecular branch, which can form a crosslinked network structure while still ensuring the fluidity of the molecular chain of the fluid loss additive, avoiding excessive thickening of the drilling fluid;

[0066] (5) The fluid loss additive provided by the present application has good rheological properties, temperature resistance and salt resistance, and especially good fluid loss reduction performance; the fresh water experimental slurry using the fluid loss additive provided by the present application has a FL API of 6-15.2 mL, an apparent viscosity of 50-98 mPa·s, a plastic viscosity of 38-57 mPa·s, and a dynamic shear of 10-41 Pa; the salt water experimental slurry using the fluid loss additive provided by the present application has a FL API of 9.5-18.2 mL, an apparent viscosity of 33-58 mPa·s, a plastic viscosity of 23-45 mPa·s, and a dynamic shear of 5-19 Pa. DETAILED DESCRIPTION

[0067] In order to facilitate the understanding of the present application, the present application lists the following examples. Those skilled in the art should understand that the examples are only to help understand the present application, and should not be regarded as a specific limitation on the present application.

[0068] Some components in the examples and comparative examples are as follows:

[0069] (1) 2-acrylamido-2-methyl-1-propane sulfonic acid: purchased from Aldrich;

[0070] (2) N-[tris(3-acrylamidopropyl methyl ether)methyl] acrylamide: purchased from FUJIFILM Wako.

[0071] The weight average molecular weight of the fluid loss additive provided in the following examples and comparative examples was measured by gel permeation chromatography (Tosoh HLC-8420 GPC).

[0072] Example 1

[0073] A fluid loss additive, raw materials for preparing the fluid loss additive including acrylamide, 2-acrylamido-2-methyl-l-propanesulfonic acid, dimethyldiallylammonium chloride, N-vinylpyrrolidone, sodium hydroxide, ammonium persulfate-sodium bisulfite, N-[tris(3-acrylamidopropyl methyl ether)methyl] acrylamide, and water;

[0074] The method for preparing the fluid loss additive includes the following steps:

[0075] (1) 16.6 g of 2-acrylamido-2-methyl-l-propanesulfonic acid was added to 150 mL of deionized water, the pH was adjusted to neutral with a 40% by mass NaOH solution, and then transferred to a 250 mL three-necked flask;

[0076] (2) 17.2 g of acrylamide, 10.8 g of 60 wt% dimethyldiallylammonium chloride aqueous solution, and 4.4 g of N-vinylpyrrolidone were added to the solution obtained in step (1) to obtain a uniform mixed solution by stirring;

[0077] (3) The mixed solution obtained in step (2) was purged with nitrogen gas to remove oxygen, heated to 40°C while stirring, and 200 mg of ammonium persulfate-sodium bisulfite (mass ratio of ammonium persulfate to sodium bisulfite: 1:1) was added. 200 mg of N-[tris(3-acrylamidopropyl methyl ether)methyl] acrylamide was dissolved in 10 mL of distilled water, and added dropwise while stirring, and the reaction was continued for 3 h after the addition. After the reaction was completed, a yellowish gel-like crude product was obtained, which was washed with anhydrous ethanol, dried, and pulverized to obtain the fluid loss additive. The weight average molecular weight of the fluid loss additive was about 400,000.

[0078] Example 2

[0079] A fluid loss additive, raw materials for preparing the fluid loss additive including N,N-dimethylacrylamide, 2-acrylamido-2-methyl-l-propanesulfonic acid, dimethyldiallylammonium chloride, N-vinylpyrrolidone, sodium hydroxide, azobisisobutyronitrile, N-[tris(3-acrylamidopropyl methyl ether)methyl] acrylamide, and water;

[0080] The method for preparing the fluid loss additive includes the following steps:

[0081] (1) 13 g of 2-acrylamido-2-methyl-1-propanesulfonic acid was added to 150 mL of deionized water, and the pH was adjusted to neutral with a 40% by mass NaOH solution, and then transferred to a 250 mL three-necked flask;

[0082] (2) 22.1 g of N,N-dimethylacrylamide, 5.5 g of 60 wt% dimethyldiallylammonium chloride aqueous solution, and 6.4 g of N-vinylpyrrolidone were added to the solution obtained in step (1), and a uniform mixed solution was obtained by stirring;

[0083] (3) The mixed solution obtained in step (2) was purged with nitrogen gas to remove oxygen, and 200 mg of azobisisobutyronitrile was added while stirring and heating to 40°C. 200 mg of N-[tris(3-acrylamidopropyl methyl)] acrylamide was dissolved in 10 mL of distilled water, and the solution was added dropwise while stirring, and the reaction was continued for 3 hours. After the reaction was completed, a yellowish gel-like crude product was obtained, which was washed with anhydrous ethanol, dried, and pulverized to obtain the filtrate reducer. The weight average molecular weight of the filtrate reducer was about 300,000.

[0084] Example 3

[0085] A filtrate reducer, the raw materials for the preparation of the filtrate reducer including N,N-dimethylacrylamide, 2-acrylamido-2-methyl-1-propanesulfonic acid, dimethyldiallylammonium chloride, N-vinylcaprolactam, sodium hydroxide, azobisisobutyronitrile, N-[tris(3-acrylamidopropyl methyl)] acrylamide, and water;

[0086] The method for preparing the filtrate reducer includes the following steps:

[0087] (1) 13.6 g of 2-acrylamido-2-methyl-1-propanesulfonic acid was added to 150 mL of deionized water, and the pH was adjusted to neutral with a 40% by mass NaOH solution, and then transferred to a 250 mL three-necked flask;

[0088] (2) 17.7 g of N,N-dimethylacrylamide, 7.7 g of 60 wt% dimethyldiallylammonium chloride aqueous solution, and 3.5 g of N-vinylcaprolactam were added to the solution obtained in step (1), and a uniform mixed solution was obtained by stirring;

[0089] (3) to the mixed solution obtained in step (2), nitrogen gas was filled to remove oxygen, and the solution was heated to 40°C while stirring, 200 mg of azobisisobutyronitrile was added, 200 mg of N-[tris(3-acrylamidopropyl methylether)methyl] acrylamide was dissolved in 10 mL of distilled water, and the solution was added dropwise while stirring, and the reaction was continued for 3 h after the addition. After the reaction, a yellowish gel-like crude product was obtained, which was washed with anhydrous ethanol, dried, and pulverized to obtain the filtrate loss additive. The weight average molecular weight of the filtrate loss additive was about 260,000.

[0090] Example 4

[0091] A filtrate loss additive and a method for preparing the same, which are different from those of Example 1 only in that the amount of 2-acrylamido-2-methyl-1-propanesulfonic acid is 30 g, and the remaining raw materials, process parameters, and steps are the same as those of Example 1. The weight average molecular weight of the filtrate loss additive is about 240,000.

[0092] Example 5

[0093] A filtrate loss additive and a method for preparing the same, which are different from those of Example 1 only in that the amount of 2-acrylamido-2-methyl-1-propanesulfonic acid is 11 g, and the remaining raw materials, process parameters, and steps are the same as those of Example 1. The weight average molecular weight of the filtrate loss additive is about 350,000.

[0094] Example 6

[0095] A filtrate loss additive and a method for preparing the same, which are different from those of Example 1 only in that the amount of N-vinylpyrrolidone is 10.7 g, and the remaining raw materials, process parameters, and steps are the same as those of Example 1. The weight average molecular weight of the filtrate loss additive is about 220,000.

[0096] Example 7

[0097] A filtrate loss additive and a method for preparing the same, which are different from those of Example 1 only in that the amount of N-vinylpyrrolidone is 2.7 g, and the remaining raw materials, process parameters, and steps are the same as those of Example 1. The weight average molecular weight of the filtrate loss additive is about 360,000.

[0098] Example 8

[0099] A filtrate loss additive and a method for preparing the same, which are different from those of Example 1 only in that the amount of 60 wt% dimethyldiallylammonium chloride aqueous solution is 15 g, and the remaining raw materials, process parameters, and steps are the same as those of Example 1. The weight average molecular weight of the filtrate loss additive is about 210,000.

[0100] Example 9

[0101] A filtrate reducer and a preparation method thereof, which are different from example 1 only in that the amount of 60wt% dimethyldiallylammonium chloride aqueous solution is 2.2g, and the rest of the raw materials, process parameters and steps are the same as those of example 1, and the weight average molecular weight of the filtrate reducer is about 420,000.

[0102] Example 10

[0103] A filtrate reducer and a preparation method thereof, which are different from example 1 only in that the amount of N-[tris(3-acrylamidopropyl methyl)] acrylamide is 0.5g, and the rest of the raw materials, process parameters and steps are the same as those of example 1, and the weight average molecular weight of the filtrate reducer is about 650,000.

[0104] Comparative example 1

[0105] A filtrate reducer, the preparation raw materials of the filtrate reducer comprising acrylamide, 2-acrylamido-2-methyl-1-propane sulfonic acid, dimethyldiallylammonium chloride, N-vinyl pyrrolidone, sodium hydroxide, ammonium persulfate-sodium bisulfite and water;

[0106] The preparation method of the filtrate reducer comprises the following steps:

[0107] (1) 16.6g of 2-acrylamido-2-methyl-1-propane sulfonic acid is added to 150mL of deionized water, the pH is adjusted to neutral with a 40wt% NaOH solution, and then transferred to a 250mL three-necked flask;

[0108] (2) 17.2g of acrylamide, 10.8g of 60wt% dimethyldiallylammonium chloride aqueous solution and 4.4g of N-vinyl pyrrolidone are added to the solution obtained in step (1), and a uniform mixed solution is obtained by stirring;

[0109] (3) The mixed solution obtained in step (2) is filled with enough nitrogen to exclude oxygen, heated to 40℃ while stirring, and 200mg of ammonium persulfate-sodium bisulfite (mass ratio of ammonium persulfate to sodium bisulfite is 1:1) is added, and the reaction is continuously stirred for 4h. After the reaction is completed, a light yellow gel-like crude product is obtained, which is washed with anhydrous ethanol, dried, and crushed to obtain the filtrate reducer, and the weight average molecular weight of the filtrate reducer is about 160,000.

[0110] Comparative example 2

[0111] A filtrate reducer and a preparation method thereof, which are different from example 1 only in that N-[tris(3-acrylamidopropyl methyl)] acrylamide is replaced by N,N-methylene bisacrylamide, and the rest of the raw materials, process parameters and steps are the same as those of example 1, and the weight average molecular weight of the filtrate reducer is about 380,000.

[0112] Comparative Example 3

[0113] A fluid loss additive and a preparation method thereof, which are different from Example 1 only in that the preparation raw materials are 19.1 g of acrylamide, 18.5 g of 2-acrylamido-2-methyl-1-propanesulfonic acid, 12.1 g of 60 wt% dimethyldiallylammonium chloride aqueous solution, and 0 g of N-vinylpyrrolidone, and the rest of the raw materials, process parameters, and steps are the same as those of Example 1, and the weight average molecular weight of the fluid loss additive is about 400,000.

[0114] Comparative Example 4

[0115] A fluid loss additive and a preparation method thereof, which are different from Example 1 only in that the preparation raw materials are 20.1 g of acrylamide, 19.5 g of 2-acrylamido-2-methyl-1-propanesulfonic acid, 5.2 g of N-vinylpyrrolidone, and 0 g of 60 wt% dimethyldiallylammonium chloride aqueous solution, and the rest of the raw materials, process parameters, and steps are the same as those of Example 1, and the weight average molecular weight of the fluid loss additive is about 360,000.

[0116] Performance test

[0117] The fluid loss additives provided by Examples 1-10 and Comparative Examples 1-4, and the fluid loss additive Driscal D (purchased from Chevron Phillips Chemical, Driscal D Polymer) were sequentially prepared into fresh water experimental slurry and salt water experimental slurry, and their rheological properties and fluid loss properties in the fresh water experimental slurry and the salt water experimental slurry were tested.

[0118] 1. In the fresh water experimental slurry, the preparation method is as follows:

[0119] 400 mL of tap water was added to a high-speed stirring cup, 16 g of bentonite and 0.56 g of anhydrous sodium carbonate were quantitatively added under continuous stirring, and stirred for 20 min, during which time at least two times were stopped to scrape the clay adhering to the wall of the container, and the fresh water base slurry was obtained after curing in a sealed container for 24 h; 8 g of the fluid loss additive was mixed and dissolved with 400 mL of the fresh water base slurry, and high-speed stirring was performed for 20 min to obtain the fresh water experimental slurry.

[0120] After the fresh water experimental slurry was aged at 240°C for 16 h, the performance of the fresh water experimental slurry before and after aging was tested according to the following method, and the test results are shown in Table 1.

[0121] (1) Apparent viscosity (AV): determined according to GB / T16783.1-2014 Drilling Fluids Field Testing, using a six-speed viscometer (Qingdao Haitongda Special Instrument Co., Ltd., ZNN-D6);

[0122] (2) Plastic viscosity (PV): According to GB / T16783.1-2014, the six-speed viscometer (Qingdao Haitongda Special Instrument Co., Ltd., ZNN-D6) was used to determine;

[0123] (3) Yield point (YP): According to GB / T16783.1-2014, the six-speed viscometer (Qingdao Haitongda Special Instrument Co., Ltd., ZNN-D6) was used to determine;

[0124] (4) API filtration loss (FL API ): According to GB / T16783.1-2014, the API filtration loss instrument (Qingdao Haitongda Special Instrument Co., Ltd., ZNS-2A) was used to determine the medium-pressure filtration loss of the fresh water experimental slurry before and after aging;

[0125] Table 1

[0126]

[0127]

[0128]

[0129] From the test data in Table 1, it can be seen that the addition of the filtration reducer provided by the present application in the fresh water experimental slurry can maintain the apparent viscosity and plastic viscosity of the fresh water experimental slurry before aging at a good level, and still can maintain a certain viscosity after aging at 240℃ for 16h, which shows that the viscosity increasing effect of the filtration reducer provided by the present application is moderate, and has good temperature resistance; and the FL API of the fresh water experimental slurry after high-temperature aging can reach at least 6mL, which has good filtration reduction effect.

[0130] From the comparison of the fresh water experimental slurry 1 and the fresh water experimental slurries 4-9, it can be seen that the filtration loss of the fresh water experimental slurry 1 before and after aging is lower, and has better temperature resistance, and the fresh water experimental slurry 1 has higher yield point after aging, which shows that the control of the molar ratio of each monomer in a suitable range can make the filtration reducer have good rheological property, filtration reduction property and temperature resistance.

[0131] From the comparison of the fresh water experimental slurry 1 and the fresh water experimental slurry 10, it can be seen that the filtration loss of the fresh water experimental slurry 1 before and after aging is lower than that of the fresh water experimental slurry 10, and has better temperature resistance, but the apparent viscosity and yield point of the fresh water experimental slurry 10 before and after aging are too high, which is not conducive to flow, and the amount of crosslinking agent is too much, which can deteriorate the rheological property and filtration reduction property of the filtration reducer.

[0132] From the comparison of fresh water experimental slurry 1 and fresh water experimental slurry 11, it can be seen that the filtration loss of fresh water experimental slurry 1 before and after aging is lower, and the temperature resistance is obviously better than that of fresh water experimental slurry 11, and the introduction of the crosslinking agent is conducive to improving the temperature resistance of the fluid loss additive.

[0133] From the comparison of fresh water experimental slurry 1 and fresh water experimental slurry 12, it can be seen that the filtration loss of fresh water experimental slurry 1 before and after aging is lower, and the temperature resistance is obviously better than that of fresh water experimental slurry 12, and compared with N,N-methylene bisacrylamide, the introduction of the crosslinking agent N-[tris(3-acrylamidopropyl methyl ether) methyl] acrylamide is conducive to improving the temperature resistance of the fluid loss additive.

[0134] From the comparison of fresh water experimental slurry 1 and fresh water experimental slurry 13, it can be seen that the filtration loss of fresh water experimental slurry 1 before and after aging is lower, and the temperature resistance is obviously better than that of fresh water experimental slurry 13, and the introduction of the rigid monomer is conducive to improving the temperature resistance of the fluid loss additive.

[0135] From the comparison of fresh water experimental slurry 1 and fresh water experimental slurry 14, it can be seen that the filtration loss of fresh water experimental slurry 1 before and after aging is lower, and the temperature resistance is obviously better than that of fresh water experimental slurry 14, and the introduction of the alkenyl cationic monomer is conducive to improving the temperature resistance of the fluid loss additive.

[0136] From the comparison of fresh water experimental slurry 1 and fresh water experimental slurry 15, it can be seen that the filtration loss of fresh water experimental slurry 1 before and after aging is lower, and the temperature resistance is obviously better than that of fresh water experimental slurry 15, and compared with the fluid loss additive Driscal D, the fluid loss additive provided by the application has better temperature resistance.

[0137] 2, test in salt water experimental slurry, the preparation method of the salt water experimental slurry is as follows:

[0138] In a high stirring cup, 400 mL of tap water is added, 16 g of bentonite, 0.56 g of anhydrous sodium carbonate and 60 g of sodium chloride are quantitatively added under continuous stirring, and stirred for 20 min, at least twice during the stirring, to scrape off the clay adhered to the wall of the container, and cured in a sealed container for 24 h to obtain a salt water base slurry; 12 g of fluid loss additive is mixed and dissolved with the salt water base slurry 400 mL, high-speed stirring for 20 min, and placed for 24 h to obtain the salt water experimental slurry;

[0139] After the salt water experimental slurry is hot-rolled and aged at 240℃ for 16h, the apparent viscosity, plastic viscosity, dynamic shear force and API filtration loss of the salt water experimental slurry before and after aging are tested according to the above method, and the test results are shown in Table 2:

[0140] Table 2

[0141]

[0142]

[0143] It can be known from the test data in Table 2 that the filtration loss values of the salt water experimental slurry prepared by using the filtrate reducer provided in the application before and after 240℃ hot rolling aging for 16h are small, the filtrate reducer has good filtration reduction performance, excellent temperature resistance and salt resistance, and the rheological performance is maintained at a good level before and after aging, and the high-temperature stability is better.

[0144] It can be known from the comparison of the salt water experimental slurry 1 and the salt water experimental slurries 4-9 that the filtration loss values of the salt water experimental slurry 1 before and after aging are lower, the salt water experimental slurry 1 has better temperature resistance and salt resistance, and the salt water experimental slurry 1 has higher dynamic shear force after aging, which indicates that the molar ratio of each monomer is controlled in a suitable range, so that the filtrate reducer has good rheological performance, filtration reduction performance and temperature resistance and salt resistance.

[0145] It can be known from the comparison of the salt water experimental slurry 1 and the salt water experimental slurry 10 that the filtration loss values of the salt water experimental slurry 1 before and after aging are lower than those of the salt water experimental slurry 10, and the salt water experimental slurry 1 has better temperature resistance and salt resistance, but the apparent viscosity and dynamic shear force of the salt water experimental slurry 10 before and after aging are too high, which is not conducive to flow, and the amount of crosslinking agent is too much, which can deteriorate the rheological performance and filtration reduction performance of the filtrate reducer.

[0146] It can be known from the comparison of the salt water experimental slurry 1 and the salt water experimental slurry 11 that the filtration loss values of the salt water experimental slurry 1 before and after aging are lower, and the temperature resistance and salt resistance of the salt water experimental slurry 1 are obviously better than those of the salt water experimental slurry 11, and the introduction of the crosslinking agent is beneficial to improving the temperature resistance and salt resistance of the filtrate reducer.

[0147] It can be known from the comparison of the salt water experimental slurry 1 and the salt water experimental slurry 12 that the filtration loss values of the salt water experimental slurry 1 before and after aging are lower, and the temperature resistance and salt resistance of the salt water experimental slurry 1 are obviously better than those of the salt water experimental slurry 12, and compared with N,N-methylene bisacrylamide, the introduction of the crosslinking agent N-[tris(3-acrylamidopropyl methyl ether) methyl] acrylamide is beneficial to improving the temperature resistance and salt resistance of the filtrate reducer.

[0148] It can be known from the comparison of the salt water experimental slurry 1 and the salt water experimental slurry 13 that the filtration loss values of the salt water experimental slurry 1 before and after aging are lower, and the temperature resistance and salt resistance of the salt water experimental slurry 1 are obviously better than those of the salt water experimental slurry 13, and the introduction of the rigid monomer is beneficial to improving the temperature resistance and salt resistance of the filtrate reducer.

[0149] It can be known from the comparison of the salt water experimental slurry 1 and the salt water experimental slurry 14 that the filtration loss values of the salt water experimental slurry 1 before and after aging are lower, and the temperature resistance and salt resistance of the salt water experimental slurry 1 are obviously better than those of the salt water experimental slurry 14, and the introduction of the alkenyl cationic monomer is beneficial to improving the temperature resistance and salt resistance of the filtrate reducer.

[0150] It can be known from the comparison of the salt water experimental slurry 1 and the salt water experimental slurry 15 that the filtration loss values of the salt water experimental slurry 1 before and after aging are lower, and the temperature resistance and salt resistance of the salt water experimental slurry 1 are obviously better than those of the salt water experimental slurry 15, and compared with the filtrate reducer Driscal D, the filtrate reducer provided in the application has better temperature resistance and salt resistance.

[0151] The above test results show that the filtrate reducer provided by the application improves the adsorption capacity with bentonite by introducing rigid monomers, and improves the temperature resistance of the filtrate reducer; the sulfonic acid group can play a good hydration effect, has good salt resistance and enhances the dispersion stability of bentonite; by introducing the alkenyl cation monomer, not only can the bentonite be adsorbed, but also the salt resistance of the filtrate reducer can be improved; the micro-crosslinked structure formed by the introduction of the water-soluble acrylamide crosslinking agent significantly improves the rigidity of the filtrate reducer, improves the temperature resistance and salt resistance of the filtrate reducer, and also ensures the fluidity of the molecular chain of the filtrate reducer. Therefore, the fresh water experimental slurry and the salt water experimental slurry using the filtrate reducer provided by the application have good rheological properties and filtrate reduction effect, and the performance remains stable after 16 hours of hot rolling aging at 240 DEG C, which is obviously better than the similar filtrate reducer Driscal D.

[0152] The applicant declares that the filtrate reducer, the preparation method and the application of the present application are illustrated by the above examples, but the present application is not limited to the above examples, that is, it does not mean that the present application must rely on the above examples to be implemented. It should be understood by those skilled in the art that any improvement of the present application, equivalent replacement of each raw material of the product of the present application, addition of auxiliary ingredients, selection of specific modes, etc. fall within the protection scope and disclosure scope of the present application.

Claims

1. A fluid loss additive, characterized in that: The raw materials for preparing the fluid loss reducer include a combination of a polymerizable monomer and a cross-linking agent; The polymerizable monomers include a combination of alkenyl amides, alkenyl sulfonic acids, rigid monomers, and alkenyl cationic monomers; The cross-linking agent has a structure as shown in Formula I: Wherein, R1, R2, and R3 are each independently selected from any one of C2-C6 straight-chain alkylene groups; The molar ratio of the alkenyl amide to the alkenyl sulfonic acid is (2-4):1; The molar ratio of the alkenyl amide to the rigid monomer is (3-8):1; The molar ratio of the alkenyl amide to the alkenyl cationic monomer is (6-16):1; The cross-linking agent includes N-[tris(3-acrylamidopropylmethylether)methyl]acrylamide and / or N-[tris(4-acrylamidobutylmethylether)methyl]acrylamide; The mass ratio of the polymerizable monomer to the cross-linking agent is (100-400):

1.

2. The fluid loss reducer according to claim 1, characterized in that The alkenyl amide includes any one of acrylamide, N,N-dimethylacrylamide or N,N-diethylacrylamide, or a combination of at least two thereof.

3. The fluid loss reducer according to claim 1, characterized in that The alkenyl sulfonic acid includes 2-acrylamido-2-methyl-1-propanesulfonic acid.

4. The fluid loss reducer according to claim 1, characterized in that The rigid monomer includes any one of N-vinyl pyrrolidone, N-vinyl caprolactam or N-acryloylmorpholine, or a combination of at least two thereof.

5. The fluid loss reducer according to claim 1, characterized in that The alkenyl cationic monomer includes dimethyldiallylammonium chloride and / or dodecyldimethylallylammonium chloride.

6. The fluid loss reducer according to claim 1, characterized in that The raw materials for preparing the fluid loss additive also include an initiator.

7. The fluid loss reducer according to claim 6, characterized in that The initiator includes any one of a persulfate initiator, a redox initiator or an azo initiator, or a combination of at least two of them.

8. The fluid loss reducer according to claim 7, characterized in that The persulfate initiator includes potassium persulfate and / or ammonium persulfate.

9. The fluid loss reducer according to claim 7, characterized in that The redox initiator includes ammonium persulfate-sodium bisulfite.

10. The fluid loss reducer according to claim 7, characterized in that: The azo initiator includes azobisisobutyronitrile and / or azobisisobutylimidazoline hydrochloride.

11. The fluid loss additive according to claim 1, characterized in that: The mass ratio of the polymerization monomer to the initiator is (100-300):

1.

12. The fluid loss additive according to claim 1, characterized in that The raw materials for preparing the fluid loss additive also include a neutralizer.

13. The fluid loss additive according to claim 12, characterized in that: The neutralizing agent includes sodium hydroxide.

14. The fluid loss additive according to claim 1, characterized in that The raw materials for preparing the fluid loss additive also include water.

15. The fluid loss additive according to claim 1, characterized in that The mass percentage of the polymerized monomer in the raw materials for preparing the fluid loss reducer is 15-30%.

16. The fluid loss additive according to claim 1, characterized in that The weight average molecular weight of the fluid loss reducer is 260,000-400,000.

17. A method for preparing the fluid loss additive according to any one of claims 1 to 16, characterized in that: The preparation method comprises: The filtrate reducer is obtained by reacting alkenyl amide, alkenyl sulfonic acid, rigid monomer, alkenyl cationic monomer and cross-linking agent.

18. The preparation method according to claim 17, characterized in that The alkenylsulfonic acid is used in the form of an aqueous alkenylsulfonic acid solution.

19. The preparation method according to claim 18, characterized in that Before use, the aqueous olefin sulfonic acid solution is neutralized to neutrality using a neutralizer.

20. The preparation method according to claim 19, characterized in that The neutralizing agent is used in the form of a neutralizing agent aqueous solution.

21. The preparation method according to claim 20, characterized in that The mass percentage of the neutralizer in the neutralizer aqueous solution is 40-60%.

22. The preparation method according to claim 17, characterized in that The alkenyl cationic monomer is used in the form of an alkenyl cationic monomer aqueous solution.

23. The preparation method according to claim 22, characterized in that The mass percentage of the alkenyl cationic monomer in the aqueous alkenyl cationic monomer solution is 50-60%.

24. The preparation method according to claim 17, characterized in that The crosslinking agent is used in the form of an aqueous crosslinking agent solution.

25. The preparation method according to claim 24, characterized in that The mass percentage of the crosslinking agent in the crosslinking agent aqueous solution is 1-2%.

26. The preparation method according to claim 17, characterized in that The reaction is carried out in the presence of an initiator.

27. The preparation method according to claim 17, characterized in that The reaction temperature is 40-60°C.

28. The preparation method according to claim 17, characterized in that The reaction time is 2-4 hours.

29. The preparation method according to claim 17, characterized in that The reaction was carried out under nitrogen atmosphere.

30. The preparation method according to claim 17, characterized in that After the reaction is completed, the steps of washing, drying and crushing are further carried out in sequence.

31. A drilling fluid, characterized in that: The components of the drilling fluid include the fluid loss reducer according to any one of claims 1 to 16.

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