Preparation method of high-temperature-resistant, salt-resistant and calcium-resistant filtrate reducer for water-based drilling fluid
Through the polymerization reaction of PAC, AMPS, DMDAAC, NVP and Nano-SiO2, a non-sulfonated anti-high temperature, salt, and calcium filtration loss reduction agent was prepared, which solved the problem of poor performance in a high-temperature, high-salt, and high-calcium environment in the prior art, achieving an efficient and environmentally friendly filtration loss reduction effect.
Patent Information
- Application Number
- CN202510483453.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-17
- Publication Date
- 2025-08-08
AI Technical Summary
The existing filter reduction agents have poor performance in high temperature, high salt and high calcium environments, especially cellulose and starch materials have poor temperature resistance, poor environmental protection of sulfonated materials, complex acrylic synthesis and foreign monopoly, making it difficult to meet the needs of deep wells and ultra-deep wells.
The polymerization reaction was carried out in an oxygen-free environment with PAC, AMPS, DMDAAC, NVP and Nano-SiO2, and the pH was adjusted to 10-11. A non-sulfonated anti-high temperature, salt, and calcium filtration loss agent was prepared. The polymerization temperature was 70-75℃, and the reaction time was 8-10h. After washing and drying, the filter loss agent was obtained.
The prepared filter loss reducer is stable at high temperatures above 230°C, and is still effective at a salt concentration of more than 16% and a calcium ion concentration of more than 10,000 ppm. The filter loss reducer is excellent, environmentally friendly, and has low cost.
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Figure CN120441765A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of preparation of drilling fluid fluid loss reducers, and in particular to a preparation method of a high-temperature, salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid. Background Art
[0002] Fluid loss reducer is one of the key treatment agents for water-based drilling fluid. It forms a dense mud cake on the well wall to minimize the loss of drilling fluid filtrate to the formation, thereby reducing the occurrence of complex situations downhole during the drilling process.
[0003] Currently, there are several main types of fluid loss additives: cellulose, starch, humic acid, resin, and acrylic polymers. These types of fluid loss additives have varying performance and production costs. The choice of fluid loss additive during drilling fluid design depends on the formation type and well conditions.
[0004] High temperature and high density are typical well conditions in deep and ultra-deep well operations. When drilling fluid circulates underground, prolonged high temperatures can gradually render most treatment agents, including fluid loss agents, ineffective, thereby damaging the performance of the drilling fluid.
[0005] Cellulose and starch-based materials are widely used fluid loss control agents, but their temperature resistance is poor, and they gradually lose effectiveness at temperatures exceeding 120°C. While modified starch-based fluid loss control agents are also available, their temperature resistance is relatively limited, and they are essentially ineffective in drilling operations above 150°C. Cellulose and starch-based materials cannot be used in deep and ultra-deep wells due to their poor temperature resistance. Sulfomethyl lignite, a humic acid-based material, has become one of the high-temperature-resistant trisulfonic treatment agents, effectively controlling drilling fluid loss in well conditions above 200°C. Resin-based materials also perform well as high-temperature fluid loss control agents. Sulfonated phenolic resin and sulfonated lignite resin have been commonly used as water-based, high-temperature-resistant fluid loss control agents since the last century, and are widely used in high-temperature deep wells and salt-gypsum formations.
[0006] Sulfonated materials are currently the primary treatment for high-temperature, high-pressure wells. Humic acid and resin-based treatment agents have been widely used in deep and ultra-deep drilling operations. These treatment agents generally exhibit high temperature and salt tolerance, generally exceeding 200°C. They also exhibit excellent fluid loss reduction properties at high temperatures, making them particularly suitable for use in high-density deep-well drilling fluids. However, each has its limitations. Sulfonated lignite materials exhibit poor salt tolerance, gradually losing their fluid loss reduction effectiveness when salt concentrations exceed 3%. Sulfonated phenolic resins exhibit a salt tolerance that is related to the number of sulfonic acid groups incorporated into the material.
[0007] Humic acid and resin-based fluid loss additives share a common characteristic: the monomers used to synthesize these sulfonated materials are inherently toxic, contain high levels of heavy metal ions, and the treatment agents themselves are poorly biodegradable. This significantly conflicts with increasingly stringent environmental protection policies. Drilling operations in ecologically sensitive areas are increasingly requiring the use of desulfonated materials.
[0008] In the production process of acrylic acid-based treating agents, the performance of the synthesized products varies depending on the control conditions, the introduced functional groups, the degree of hydrolysis, etc. Among them, hydrolyzed polyacrylonitrile calcium salt and hydrolyzed polyacrylonitrile ammonium salt have excellent performance in high temperature, salt and calcium resistance, and inhibition of clay hydration.
[0009] Polymer fluid loss additives based on acrylamide have been extensively researched and have achieved considerable success. However, due to the complex production process and the high precision required to control the synthesis conditions, related treatment agents have not been widely used in China due to their performance stability, resulting in a monopoly in similar materials from some foreign companies in this field. Summary of the Invention
[0010] The present invention provides a method for preparing a high-temperature, salt-resistant, and calcium-resistant fluid loss reducer for water-based drilling fluid, aiming to provide a solution to the above technical problems.
[0011] To achieve the above object, the technical solution of one aspect of the present invention is:
[0012] A preparation method of a high-temperature, salt-resistant, and calcium-resistant fluid loss reducer for water-based drilling fluid, wherein the synthesis route is as follows:
[0013]
[0014] In some preferred embodiments, based on mass, PAC is 4.92-5.94 parts, AMPS is 19.74-22.74 parts, DMDAAC is 19.22-20.98 parts, NVP is 3.97-4.88 parts, Nano-SiO2 is 4.02-5.17 parts, initiator is 0.05-0.08 parts, and pH is 10-11.
[0015] In some preferred embodiments, the initiator is ammonium persulfate or potassium persulfate.
[0016] In some preferred embodiments, the reaction steps include adding AMPS to the PAC solution and adjusting the pH to 10-11 with a sodium hydroxide solution, then sequentially adding DMDAAC, NVP and Nano-SiO2, and after deoxygenation, adding an initiator in an oxygen-free environment to carry out a polymerization reaction.
[0017] In some preferred embodiments, the reaction temperature of the polymerization reaction is 70-75° C., and the reaction time is 8-10 h.
[0018] In some preferred embodiments, the reaction step includes adding AMPS to the PAC solution and adjusting the pH with sodium hydroxide solution, and further includes washing, drying and crushing steps.
[0019] In some preferred embodiments, the above washing step is washing with methanol multiple times.
[0020] The technical solution of one aspect of the present invention is: a high-temperature, salt-resistant, and calcium-resistant fluid loss reducer for water-based drilling fluid prepared by the above preparation method, wherein the molecular formula of the fluid loss reducer is as follows:
[0021]
[0022] The beneficial effects achieved by the present invention are:
[0023] The preparation method of the present invention is simple, low-cost and highly efficient. The prepared high-temperature-resistant, salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid is a non-sulfonated material and is environmentally friendly. The use of the non-sulfonated material reduces the negative impact on the environment. In terms of temperature resistance, the material can withstand high temperatures exceeding 230°C. The material has excellent salt resistance and can be stably used in environments with a salt concentration exceeding 16%. The material also has strong calcium resistance and can maintain a good effect under conditions where the calcium ion concentration exceeds 10,000 ppm. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 is the infrared spectrum of the fluid loss additive of Example 1;
[0025] Figure 2 This is the TGA curve of the fluid loss additive of Example 1. DETAILED DESCRIPTION
[0026] A preparation method of a high-temperature, salt-resistant, and calcium-resistant fluid loss reducer for water-based drilling fluid, wherein the synthesis route is as follows:
[0027]
[0028] Calculated by mass, PAC 4.92-5.94 parts, AMPS 19.74-22.74 parts, DMDAAC 19.22-20.98 parts, NVP 3.97-4.88 parts, Nano-SiO 2 4.02-5.17 parts, initiator 0.05-0.08 parts, pH 10-11.
[0029] The initiator is ammonium persulfate or potassium persulfate.
[0030] The reaction steps include adding AMPS to the PAC solution, adjusting the pH to 10-11 with a sodium hydroxide solution, adding DMDAAC, NVP and Nano-SiO2 in sequence, deoxygenating, and then adding an initiator to carry out a polymerization reaction in an oxygen-free environment.
[0031] The reaction temperature of the polymerization reaction is 70-75° C., and the reaction time is 8-10 h.
[0032] The reaction steps include adding AMPS to the PAC solution and adjusting the pH with a sodium hydroxide solution, and then washing, drying and crushing. The washing step is washing with methanol for multiple times.
[0033] The high temperature, salt and calcium resistant fluid loss reducer for water-based drilling fluid prepared by the above preparation method has the following molecular formula:
[0034]
[0035] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.
[0036] All raw materials of the present invention are not particularly limited in their sources and can be purchased from the market or prepared according to conventional methods well known to those skilled in the art.
[0037] All raw materials of the present invention are not particularly limited in purity. The present invention preferably uses analytically pure or prepared
[0038] All raw materials and process steps of the present invention, and their brands or abbreviations are conventional brands or abbreviations in the art. Each brand or abbreviation is clear and unambiguous within the field of its relevant use. Those skilled in the art can purchase them commercially or prepare them by conventional methods, or implement them using corresponding equipment, based on the brand, abbreviation and corresponding use.
[0039] (1) Main raw materials:
[0040] Low-viscosity polyanionic cellulose (PAC-LV), modified nano-silica (Nano-SiO2), NaOH (analytical grade), 2-acrylamido-2-methylpropanesulfonic acid (analytical grade) (AMPS), dimethyldiallylammonium chloride (technical grade) (DMDAAC), 1-vinyl-2-pyrrolidone (analytical grade) (NVP), ammonium persulfate (analytical grade), potassium persulfate (analytical grade).
[0041] High temperature resistant viscosity enhancer: Cited from Yan Lili, Sun Jinsheng, Wang Jianhua, Wang Chengbiao, Xu Bo, and Yang Zexing's "Preparation and Properties of a New High Temperature and Salt Resistant Drilling Fluid Viscosifier PADA"
[0042] The viscosity-enhancing ternary copolymer AMPS-DMAM-AN (PADA) was prepared by orthogonal experiment and inverse microemulsion polymerization with 2-acrylamido-2-methylpropanesulfonic acid (AMPS), N,N-dimethylacrylamide (DMAM) and acrylonitrile (AN) as comonomers, sorbitan monooleate (Span80) and polyoxyethylene sorbitan monooleate (Tween80) as composite emulsifiers, white oil as oil phase, NaHSO3 and (NH4)2S2O8 as redox initiators.
[0043] Sodium bentonite: in compliance with SY / T 5490-2016 requirements
[0044] 2) Experimental instruments:
[0045] Electric stirrer, heating mantle, analytical balance, nitrogen bottle, and several glass instruments.
[0046] 3) Artificial seawater formula:
[0047] Inorganic salts Concentration (g / L) NaCl 21.86±0.01 <![CDATA[Na2SO4]]> 3.23±0.01 <![CDATA[MgCl2]]> 4.53±0.01 <![CDATA[CaCl2]]> 0.93±0.01 KCl 0.64±0.01 <![CDATA[NaHCO3]]> 0.17±0.01 <![CDATA[Na2CO3]]> 0.02±0.01
[0048] Example 1:
[0049] 1) Accurately weigh 5.11 g of PAC and slowly add it to 180 mL of water while stirring until completely dissolved. Stir at 12,000 rpm for 20 minutes to obtain a PAC solution.
[0050] 2) Add 21.04 g of AMPS and stir with a magnetic stirrer until completely dissolved. Then add 20 mL of 20% sodium hydroxide solution and adjust the pH to 10.
[0051] 3) Add 20.12 g DMDAAC, 4.49 g NVP, and 4.72 g Nano-SiO2 in sequence, and transfer them to a pre-deoxygenated three-necked flask after they are completely dissolved;
[0052] 4) Continue to pass nitrogen and deoxygenate for at least 20 minutes;
[0053] 5) Add 10 mL of 0.67% ammonium persulfate solution, react at 75° C. for 10 h, wash with methanol several times to remove unreacted monomers, and dry and crush to obtain a fluid loss reducer sample.
[0054] Example 2
[0055] 1) Accurately weigh 4.92 g of PAC and slowly add it to 180 mL of water while stirring until completely dissolved. Stir at 12,000 rpm for 20 min to obtain a PAC solution.
[0056] 2) Add 19.74 g of AMPS and stir with a magnetic stirrer until completely dissolved. Then add 20 mL of 20% sodium hydroxide solution and adjust the pH to 11.
[0057] 3) Add 19.22 g DMDAAC, 3.97 g NVP, and 4.02 g Nano-SiO2 in sequence, and transfer them to a pre-deoxygenated three-necked flask after they are completely dissolved;
[0058] 4) Continue to pass nitrogen and deoxygenate for at least 20 minutes;
[0059] 5) Add 9.8 mL of 0.67% potassium persulfate solution, react at 75° C. for 10 h, wash with methanol several times to remove unreacted monomers, and dry and crush to obtain a fluid loss additive sample.
[0060] Example 3
[0061] 1) Accurately weigh 5.94 g of PAC and slowly add it to 180 mL of water while stirring until completely dissolved. Stir at 12,000 rpm for 20 minutes to obtain a PAC solution.
[0062] 2) Add 22.74 g of AMPS and stir with a magnetic stirrer until completely dissolved. Then add 20 mL of 20% sodium hydroxide solution and adjust the pH to 10.
[0063] 3) Add 20.98 g DMDAAC, 4.88 g NVP, and 5.17 g Nano-SiO2 in sequence, and transfer them to a pre-deoxygenated three-necked flask after they are completely dissolved;
[0064] 4) Continue to pass nitrogen and deoxygenate for at least 20 minutes;
[0065] 5) Add 11.5 mL of 0.67% ammonium persulfate solution, react at 75° C. for 10 h, wash with methanol several times to remove unreacted monomers, and dry and crush to obtain a fluid loss additive sample.
[0066] External spectroscopy
[0067] Take a certain amount of the fluid loss additive of Example 1 and measure the concentration of the fluid loss additive at 4000-400 cm-1 by using a smearing method and a Fourier transform infrared spectrometer. -1 Infrared spectrum across the wavelength range.
[0068] Perform infrared characterization analysis on the synthesized samples. Figure 2 Infrared spectrum of fluid loss reducer
[0069] Depend on Figure 2 It can be seen that 3417.42cm -1 It is the stretching vibration peak of -OH, 2927.76cm -1 It is the -CH2- stretching vibration absorption peak, 1630.11cm -1 is the C=O stretching vibration absorption peak in -CONH-, 1543.64 is the CN stretching vibration and NH bending vibration absorption peak in -CONH-, 1404.06cm -1 It is the absorption peak of CN in the five-membered heterocyclic ring, 1036.02 cm -1 Attributable to the -SO3H stretching vibration absorption peak, 464.35 cm -1 It is the Si-O-Si bending vibration absorption peak.
[0070] Thermogravimetric analysis
[0071] A 10 mg sample of the fluid loss additive prepared in Example 1 was placed in a silica crucible of known mass, and weighed on the sample stage of a thermogravimetric analyzer. The mass change of the fluid loss additive was recorded in the temperature range of 25°C to 800°C using nitrogen protection. The temperature gradient and nitrogen flow rate were 10°C / min and 20 mL / min, respectively.
[0072] Thermogravimetric analysis of the synthesized samples was performed, see Figure 2 TGA curve of fluid loss reducer
[0073] The relationship between mass loss and temperature of the fluid loss additive samples was determined using a thermogravimetric analyzer within the temperature range of 25°C to 800°C. Within the 25°C to 272°C temperature range, the mass of the fluid loss additive gradually decreased with increasing temperature, with a mass loss rate of 8.61%. This was primarily due to the dissociation of water molecules adsorbed on hydrophilic groups such as sulfonic acid groups. When the temperature exceeded 272°C, the polymer sample's mass rapidly decreased, reaching a maximum decomposition rate at 307°C and remaining nearly complete by 582°C, with a mass loss rate of 70.55%. During this period, groups such as amides absorbed significant amounts of heat, causing the polymer backbone and side chains to break to varying degrees, releasing gases such as NH3, SO2, and CO2.
[0074] The performance evaluation of the configured drilling fluid was conducted, and the fluid loss reducer samples were all selected from the fluid loss reducer product of Example 1.
[0075] Performance evaluation experiment 1:
[0076] The formula is as shown in Table 1: Prepare 1# and 2# water-based drilling fluids.
[0077] Table 1 Sodium bentonite based slurry formula 1
[0078]
[0079]
[0080] After aging at 230℃*16h, the test performance is shown in Table 2:
[0081] Table 2 Properties of sodium bentonite-based slurry
[0082] 1# 2# ф600 / ф300 6 / 4 8 / 5 ф200 / ф100 3 / 1 3 / 2 ф6 / ф3 0 / 0 0 / 0 GEL(Pa) 0 / 0 0 / 0 AV(mPa.s) 3 4 PV (mPa.s) 2 3 YP(Pa) 1 1 API, mL 44.6 22.8
[0083] The data in the table above show that after aging at 230°C, the API fluid loss of the slurry No. 2, which contains the fluid loss additive, is 50% lower than that of the base slurry No. 1. This indicates that the synthetic sample has excellent high-temperature fluid loss reduction performance.
[0084] Performance evaluation experiment 2:
[0085] The formula is as shown in Table 3: Preparation of base slurry, 1#, 2# and 3# high temperature and high pressure experimental formula.
[0086] Table 3 High temperature and high pressure experimental formula
[0087]
[0088]
[0089] Mud flow test temperature: 50℃
[0090] Table 4 Performance of high temperature and high pressure formula before aging
[0091] base slurry 1# 2# 3# ф600 / ф300 133 / 80 148 / 89 93 / 54 147 / 90 ф200 / ф100 59 / 35 66 / 39 39 / 21 66 / 39 ф6 / ф3 4 / 3 4 / 2 2 / 1 4 / 2 GEL(Pa) 1.5 / 2.5 1 / 3.5 0.5 / 1 1 / 3.5 AV(mPa.s) 66.5 74 46.5 73.5 PV (mPa.s) 53 59 39 57 YP(Pa) 13.5 15 7.5 16.5
[0092] Aging conditions: 200℃*16h, mud flow test temperature: 50℃
[0093] Table 5 Performance of high temperature and high pressure formula after aging
[0094]
[0095] From the experimental results of drilling fluid rheological test in Table 4 and Table 5, it can be seen that 1.8g / cm 3 After aging at 200°C, the high-temperature and high-pressure fluid loss of slurry 1# was 39.8 ml at 180°C. After adding the fluid loss reducer sample (slurry 2#), the high-temperature and high-pressure fluid loss dropped to 13 ml, a decrease of more than 60%.
[0096] After adding 16% sodium chloride to 2# slurry, the filtration loss at 180℃ high temperature and high pressure is only 15ml.
[0097] After adding 1% calcium chloride to the 2# slurry, the filtration loss at 180℃ and high temperature and high pressure was 21ml, indicating that the filtrate reducer sample has good resistance to high temperature, salt and calcium.
[0098] The above detailed description of the present invention is intended to enable persons familiar with the art to understand the contents of the present invention and implement them. It does not limit the scope of protection of the present invention. The present invention is not limited to the above embodiments. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of the present invention.
Claims
1. A method for preparing a high-temperature, salt-resistant, and calcium-resistant fluid loss reducer for water-based drilling fluid, characterized in that: Its synthetic route is:
2. The method for preparing a high-temperature, salt-resistant, and calcium-resistant fluid loss reducer for water-based drilling fluid according to claim 1, characterized in that: By mass, PAC 4.92-5.94 parts, AMPS 19.74-22.74 parts, DMDAAC 19.22-20.98 parts, NVP 3.97-4.88 parts, Nano-SiO 2 4.02-5.17 parts, initiator 0.05-0.08 parts, pH 10-11.
3. The method for preparing a high-temperature, salt-resistant, and calcium-resistant fluid loss reducer for water-based drilling fluid according to claim 1, characterized in that: The initiator is ammonium persulfate or potassium persulfate.
4. The method for preparing a high-temperature, salt-resistant, and calcium-resistant fluid loss reducer for water-based drilling fluid according to claim 1, wherein: The reaction steps include adding AMPS to the PAC solution, adjusting the pH to 10-11 with a sodium hydroxide solution, adding DMDAAC, NVP and Nano-SiO2 in sequence, deoxygenating, and then adding an initiator to carry out a polymerization reaction in an oxygen-free environment.
5. The method for preparing a high-temperature, salt-resistant, and calcium-resistant fluid loss reducer for water-based drilling fluid according to claim 1, characterized in that: The reaction temperature of the polymerization reaction is 70-75° C., and the reaction time is 8-10 h.
6. The method for preparing a high-temperature, salt-resistant, and calcium-resistant fluid loss reducer for water-based drilling fluid according to claim 1, characterized in that: After the reaction, the process also includes washing, drying and crushing steps.
7. The method for preparing a high-temperature, salt-resistant, and calcium-resistant fluid loss reducer for water-based drilling fluid according to claim 6, characterized in that: The washing steps were multiple washes with methanol.
8. The high temperature, salt and calcium resistant fluid loss reducer for water-based drilling fluid prepared according to any one of claims 1 to 7, characterized in that: The molecular formula of the fluid loss additive is as follows: