Polyamine drilling fluid for oil and gas field drilling and preparation method and application thereof

Abstract

The application discloses an oil-gas field drilling polyamine drilling fluid and a preparation method and application thereof, relates to the technical field of oil-gas field drilling, and the polyamine drilling fluid is prepared from the following raw materials in the total volume of 100 mL of water: 1.0-2.0 g of bentonite, 0.2-0.3 g of a tackifier, 0.2-0.4 g of an alkalinity regulator, 0.1-0.2 g of a coating agent, 3.0-4.0 g of a nano fluid loss additive, 3.0-4.0 g of a lubricant, 5.0-6.0 g of a polyamine inhibitor, 6.0-8.0 g of an inorganic salt, and a weighting material, wherein the density of the polyamine drilling fluid is 1.5-1.8 g / cm 3 . The polyamine drilling fluid has good rheological property, strong inhibitory property and lubricating property, can keep the well wall of a shale formation stable for a long time, reduce the drilling friction of the shale formation, has good biodegradability and meets the environmental protection requirements.

Description

Technical Field

[0001] This invention relates to the field of oil and gas field drilling technology, specifically to a polyamine drilling fluid for oil and gas field drilling, its preparation method, and its application. Background Technology

[0002] In recent years, oil and gas development has gradually shifted towards the development of complex wells such as deep wells, ultra-deep wells, and extended reach wells. However, the continuous reduction in drilling costs, coupled with environmental pressures related to waste cuttings disposal, has significantly limited the use of oil-based drilling fluids in drilling operations. Currently, water-based drilling fluids developed for large sections of mudstone in shale formations, such as silicate drilling fluids and organic or inorganic salt polysulfonate drilling fluids, while exhibiting some good mudstone inhibition and plugging performance and achieving certain application results, suffer from several drawbacks. First, their lubrication effect is far inferior to that of oil-based drilling fluids, failing to effectively reduce drilling friction and prevent stuck pipe. Second, the polyamine and silicate inhibitors used are ineffective and mostly composed of polymers that are difficult to decompose, failing to achieve the goal of preventing collapse. Third, the high concentrations of chloride salts used can severely impact soil and water bodies. In August 2024 alone, 60 wells in the Southwest Oil and Gas Field Company's work area experienced complex malfunctions, including 10 wells with collapses and stuck pipe causing drilling difficulties. The processing time for stuck pipe accounted for 17.45%, especially in shale gas blocks where the stuck pipe loss time reached as high as 130.83 days. Drilling in formations containing large sections of mudstone and shale urgently requires a water-based drilling fluid system with good rheological properties and strong anti-collapse and anti-sticking performance. Polyamine treatment agents can significantly improve the anti-collapse and anti-sticking performance of drilling fluids. Therefore, the development of a polyamine drilling fluid for oil and gas field drilling is urgently needed.

[0003] Patent CN201110334894.4 discloses a polyamine strong inhibitor for drilling fluid and its preparation method; patent CN108148564A discloses a polyamine inhibitor for water-based drilling fluid and its preparation method. The treatment agents in the above two patents cannot achieve the sealing and strong lubrication and anti-sticking performance required for drilling in large mudstone formations, and the treatment agents in their formulations are difficult to meet environmental protection requirements.

[0004] Patent CN102250595B discloses a drilling fluid for drilling active mudstone and shale formations, which has a certain anti-collapse effect on shale formations. However, its drilling fluid formula does not sufficiently enhance the inhibitory properties, making it difficult to cope with the problem of cuttings hydration and mud-making when drilling large sections of mudstone formations.

[0005] Research indicates that when drilling in easily collapsible formations containing large sections of mudstone, existing drilling fluids are insufficient to reduce downhole complications such as wellbore collapse and ensure drilling safety. In particular, existing water-based drilling fluids are unable to form an oil film effect on the wellbore and improve the contact between the drill string and the wellbore, thus failing to reduce drilling friction and prevent sticking or pressure buildup that is prone to occur during drilling operations in large mudstone sections. Summary of the Invention

[0006] Given that the current drilling fluids' anti-collapse and anti-sticking properties are insufficient to meet the drilling requirements of large sections of mudstone formations, the purpose of this invention is to provide a polyamine drilling fluid for oil and gas field drilling, its preparation method, and its application. This polyamine drilling fluid has good rheological properties, strong inhibition and lubrication properties, can maintain the stability of the wellbore in shale formations for a long time, reduce drilling friction in shale formations, and has good biodegradability, meeting environmental protection requirements.

[0007] This invention is achieved through the following technical solution:

[0008] In a first aspect, this application provides a polyamine drilling fluid for oil and gas field drilling. Based on a total water volume of 100 mL, the raw material components include 1.0–2.0 g of bentonite, 0.2–0.3 g of thickener, 0.2–0.4 g of alkalinity adjuster, 0.1–0.2 g of coating agent, 3.0–4.0 g of nano-filtration reducer, 3.0–4.0 g of lubricant, 5.0–6.0 g of polyamine inhibitor, 3.0–4.0 g of micro / nano plugging agent, and 6.0–8.0 g of inorganic salt. It also includes weighting materials. The density of the polyamine drilling fluid is 1.5–1.8 g / cm³. 3 .

[0009] In one specific embodiment, the bentonite includes sodium bentonite.

[0010] In one specific embodiment, the thickener comprises low-viscosity polyanionic cellulose.

[0011] In one specific embodiment, the alkalinity regulator includes any one or a combination of two of sodium carbonate and sodium hydroxide.

[0012] In one specific embodiment, the coating agent comprises a zwitterionic polymer strong coating agent.

[0013] In one specific embodiment, the coating agent is FA367.

[0014] In one specific embodiment, the preparation method of the nano-filtration loss reducing agent includes the following steps:

[0015] Isopropanol and ethyl cellulose were added to the reaction vessel and stirred until dissolved. Then, the mixture was ultrasonically dispersed. The pH was adjusted to alkaline using sodium hydroxide solution, nitrogen gas was introduced, and the mixture was heated to 30°C. After stirring for 20–24 hours, the temperature was raised to 70–80°C.

[0016] Chloroacetic acid was dissolved in isopropanol, and the resulting solution was slowly added dropwise to the above reaction solution to carry out the etherification reaction. The mixture after the reaction was cooled to room temperature and then centrifuged. The precipitate was washed with ethanol to obtain a solid product.

[0017] The solid product is dried and then pulverized to obtain a nano-filtration loss reducer.

[0018] In one specific embodiment, 5 to 10 parts by weight of ethyl cellulose are added to 100 parts by weight of isopropanol.

[0019] In one specific embodiment, a sodium hydroxide solution is used to adjust the pH value to 7.5–8.

[0020] In one specific embodiment, 1 to 2 parts by weight of isopropanol are added to 10 to 20 parts by weight of chloroacetic acid.

[0021] In one specific embodiment, the drying temperature of the solid product is 60–80°C.

[0022] In one specific embodiment, the lubricant is an environmentally friendly lubricant, and its preparation method includes the following steps:

[0023] Water, pine fatty acid, and triethylenediamine were added to the reaction vessel, and the amidation reaction was carried out at a temperature of 80–90°C.

[0024] The temperature is raised to 160-180℃, and triethanolamine oleate is added. After stirring and reacting, polytetrafluoroethylene micro powder and ethanol are added and mixed to obtain an environmentally friendly lubricant.

[0025] In one specific embodiment, 30-35 parts by weight of pine fatty acid, 10-20 parts by weight of triethylenediamine, 20-30 parts by weight of triethanolamine oleate, 15-25 parts by weight of polytetrafluoroethylene micro powder, and 15-25 parts by weight of ethanol are added to 100 parts by weight of water.

[0026] In one specific embodiment, the method for preparing the polyamine inhibitor includes the following steps:

[0027] After mixing maleic anhydride and diethanolamine, the mixture is transferred to a reaction vessel and reacted at 160℃~180℃. The temperature is then lowered to 90℃~100℃, and citric acid is added to react with the amine bonds in a directional manner. After the reaction, the mixture is cooled to room temperature to obtain the polyamine inhibitor.

[0028] In one specific embodiment, the raw material components for preparing the polyamine inhibitor, by weight fraction, include 20-30 parts by weight of maleic anhydride, 60-70 parts by weight of diethanolamine, and 15-20 parts by weight of citric acid.

[0029] In one specific embodiment, the inorganic salt includes any one or a combination of two of potassium chloride, sodium chloride, and potassium formate.

[0030] In one specific embodiment, the micro-nano sealing agent includes any one or more of white asphalt, nano limestone, and nano silica in combination.

[0031] In one specific embodiment, the weighting material comprises barite with a density of 4.2–4.4 g / cm³. 3 .

[0032] Secondly, this application provides a method for preparing polyamine drilling fluid for oil and gas field drilling, comprising the following steps:

[0033] Bentonite, alkalinity regulator, thickener, coating agent, nano-filtration reducer, lubricant, polyamine inhibitor, inorganic salt, and weighting material are added to the reaction vessel in the specified proportions under stirring conditions. After stirring and reacting, polyamine drilling fluid for oil and gas field drilling is obtained.

[0034] Thirdly, this application provides an application of the above-mentioned polyamine drilling fluid for oil and gas field drilling or the polyamine drilling fluid for oil and gas field drilling prepared by the above-mentioned preparation method, including its application in drilling long sections of mudstone.

[0035] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0036] (1) All materials used in this invention are environmentally friendly, biodegradable, have low biotoxicity, and are environmentally friendly. The prepared polyamine drilling fluid has good rheological properties, strong inhibition and lubrication properties, can maintain the stability of the shale formation well wall for a long time, reduce the drilling friction of the shale formation, and has good biodegradability, which meets the environmental protection requirements.

[0037] (2) The nano-filtration loss reducer of the present invention has a certain amount of hydroxyl and carboxyl groups in its molecular structure, which gives it strong surface charge and hydration ability and strong dispersion stability. Nanocellulose has excellent properties such as large specific surface area, strong rigidity and strong surface activity, and is more likely to form a stable adsorption layer on the clay surface through hydrogen bonding, forming a spatial network structure, improving the colloidal stability of drilling fluid, preventing bentonite from agglomerating, which is conducive to forming a dense filter cake, thereby significantly reducing the filtration loss of drilling fluid.

[0038] (3) The lubricant of the present invention combines physical lubrication and chemical lubrication, which can not only form an oil film effect on the well wall and improve the contact state between the drill bit and the well wall, but also add polytetrafluoroethylene micro powder to change rolling friction into sliding friction, which greatly improves the lubrication effect.

[0039] (4) The polyamine inhibitor of the present invention mainly utilizes its macromolecular long chain molecular structure and various hydration and adsorption groups to strongly adsorb onto the surface of clay and drill cuttings, coat the drill cuttings, block the micro-cracks on the drill cuttings, prevent free water from entering the interior of the drill cuttings, slow down the hydration expansion and spalling speed of the drill cuttings, thereby effectively controlling the growth of low concentration solids in the drilling fluid and inhibiting interlayer hydration to achieve the purpose of inhibiting shale hydration expansion; the micro-nano plugging agent can achieve a three-level plugging effect through different particle size distributions. It can not only fill the micro-cracks on the surface of shale, but also the nanoparticles can make the formed plug more compact and prevent the deep intrusion of the filtrate.

[0040] (5) The polyamine drilling fluid prepared in this invention can maintain good rheological properties, lubricity and low filtration loss, and has a strong ability to inhibit shale hydration. It has a wide applicable density range and can meet the drilling needs of large mudstone sections. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. The illustrative embodiments and descriptions of this invention are only used to explain this invention and are not intended to limit this invention.

[0042] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other embodiments, well-known materials or methods have not been specifically described in order to avoid obscuring the invention.

[0043] Throughout this specification, references to “an embodiment,” “an example,” or “an example” mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the invention. Therefore, the phrases “an embodiment,” “an example,” “an example,” or “an example” appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. The term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0044] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60–120 and 80–110 are listed for a specific parameter, it is understood that ranges of 60–110 and 80–120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0045] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0046] The sodium bentonite used in the following examples is the drilling fluid test soil specified in SY / T5490.

[0047] Sodium hydroxide was of analytical grade and purchased from Tianjin Beichen Fangzheng Reagent Factory.

[0048] Sodium chloride and potassium formate were industrial samples. Sodium chloride was purchased from Guangzhou Yimin Chemical Trading Co., Ltd., and potassium formate was purchased from Jinan Xuzhou Chemical Technology Co., Ltd.

[0049] FA367 was purchased from Chengdu Dedao Industrial Co., Ltd.

[0050] The nano-limestone was purchased from Shangxing Chemical Technology Co., Ltd. in Dianbai District, Maoming City.

[0051] The barite was purchased from the Lingshou County Mineral Products Processing Plant.

[0052] Isopropanol was of analytical grade and purchased from Chuandong Chemical Group.

[0053] Ethyl cellulose was purchased from Guangdong Yuemei Chemical Co., Ltd.

[0054] Chloroacetic acid was purchased from Shijiazhuang Bide Chloroacetic Acid Co., Ltd.

[0055] The pine oil fatty acids were purchased from Jining Baiyi Chemical Co., Ltd.

[0056] Triethylenediamine was purchased from Jinan Xinling Chemical Technology Co., Ltd.

[0057] Triethanolamine oleate was purchased from Jinan Yongtai Chemical Co., Ltd.

[0058] The polytetrafluoroethylene (PTFE) micro powder was purchased from Dongguan Shanyi Plastics Co., Ltd.

[0059] Ethanol was purchased from Fuchen (Tianjin) Chemical Reagent Co., Ltd.

[0060] Maleic anhydride was purchased from Zibo Haiyi Fine Chemical Co., Ltd.

[0061] Diethanolamine was purchased from Suzhou Boyuan Chemical Co., Ltd.

[0062] Citric acid was purchased from Suzhou Ouyang Chemical Technology Co., Ltd.

[0063] Example 1

[0064] This embodiment provides a method for preparing polyamine drilling fluid for oil and gas field drilling. The formula is as follows: based on a total water volume of 100 mL, the raw material components include 2.0 g of bentonite (sodium bentonite), 0.2 g of thickener (low-viscosity polyanionic cellulose), 0.2 g of alkalinity adjuster (sodium hydroxide), 0.1 g of coating agent (FA367), 3.0 g of nano-filtration reducer, 3.5 g of environmentally friendly lubricant, 6.0 g of polyamine inhibitor, 4.0 g of sodium chloride, 3.0 g of potassium formate, 3.5 g of nano-limestone, and also includes barite. The addition of barite makes the density of the polyamine drilling fluid 1.7 g / cm³. 3 .

[0065] The specific preparation method is as follows:

[0066] S1. Preparation of nano-filtration loss reducing agent

[0067] S1-1. Add 100 parts by weight of isopropanol and 10 parts by weight of ethyl cellulose to a round-bottom flask and stir until dissolved. Disperse the mixture by ultrasonication for 2 hours using an ultrasonic cell disruptor. Adjust the pH to 8 with a 30% NaOH aqueous solution. Purge with nitrogen gas and heat to 30°C. Continue stirring for 24 hours and then raise the temperature to 80°C.

[0068] S1-2. Dissolve 15 parts by weight of chloroacetic acid in 2 parts by weight of isopropanol, and slowly add the solution to the liquid in the round-bottom flask at a rate of one drop every 30 seconds, and carry out the etherification reaction for 3 hours.

[0069] S1-3. After cooling the mixture obtained from the etherification reaction to room temperature, centrifuge it. Wash the centrifuged precipitate three times with ethanol. Dry the obtained solid product at 80°C for 24 hours. The pulverized powder is the nano-filtration loss reducer.

[0070] S2. Preparation of environmentally friendly lubricants

[0071] S2-1. Add 100 parts by weight of water to the reactor, then add 35 parts by weight of pine fatty acid and 15 parts by weight of triethylenediamine, and react at 80°C for 3 hours to undergo an amidation reaction.

[0072] S2-2. Heat to 170℃, add 20 parts by weight of triethanolamine oleate, stir for 2 hours, add 25 parts by weight of polytetrafluoroethylene micro powder and 25 parts by weight of ethanol, mix for 1 hour, and you will get an environmentally friendly lubricant.

[0073] S3, Preparation of polyamine inhibitors

[0074] After mixing 28 parts by weight of maleic anhydride and 70 parts by weight of diethanolamine evenly, the mixture was transferred to a reaction vessel and reacted at 180°C under vacuum for 4 hours. The temperature was then lowered to 90°C, and 17 parts by weight of citric acid were added to react with the amine bonds in a directional manner for 2 hours. After cooling to room temperature, the resulting product was the polyamine inhibitor.

[0075] S4. Preparation of polyamine drilling fluid for oil and gas field drilling

[0076] S4-1. Measure 400mL of water into a 1000mL high-speed stirring cup, add 8.0g of sodium bentonite at a speed of 8000r / min, and stir at high speed for 20min.

[0077] S4-2. Add 0.8g of sodium hydroxide to the product prepared in step S4-1 and stir at high speed for 20min.

[0078] S4-3. Add 0.8g of low-viscosity polyanionic cellulose to the product of step S4-2 and stir at high speed of 10000r / min for 20min.

[0079] S4-4. Add 0.4g FA367 to the product of step S4-3 and stir at high speed for 20min.

[0080] S4-5. Add 12.0g of the nano-filtration loss reducer prepared in step S1 to the product of step S4-4, and stir at high speed for 20min.

[0081] S4-6. Add 14.0g of nano limestone to the product of step S4-5 and stir at high speed for 20min.

[0082] S4-7. Add 14.0g of the environmentally friendly lubricant prepared in step S2 to the product of step S4-6, and stir at high speed for 20min.

[0083] S4-8. Add 24.0g of the polyamine inhibitor prepared in step S3 to the product of step S4-7, and stir at high speed for 20min.

[0084] S4-9. Add 16.0g of sodium chloride and 12.0g of potassium formate to the product from step S4-8, and finally add barite to increase the density of the drilling fluid to 1.7g / cm³. 3 Stir at high speed for 30 minutes to obtain polyamine drilling fluid.

[0085] In this embodiment, the aging conditions during performance testing were 140°C for 16 hours and rheological properties were tested at 50°C.

[0086] Example 2

[0087] This embodiment provides a method for preparing polyamine drilling fluid for oil and gas field drilling. The formula is as follows: based on a total water volume of 100 mL, the raw material components include 1.0 g of bentonite (sodium bentonite), 0.3 g of thickener (low-viscosity polyanionic cellulose), 0.2 g of sodium carbonate, 0.15 g of sodium hydroxide, 0.2 g of coating agent (FA367), 4.0 g of nano-filtration reducer, 3.0 g of environmentally friendly lubricant, 5.5 g of polyamine inhibitor, 6.0 g of sodium chloride, 3.0 g of potassium formate, and 3.0 g of white bitumen. It also includes barite, and the addition of barite makes the density of the polyamine drilling fluid 1.5 g / cm³. 3 .

[0088] The specific preparation method is as follows:

[0089] S1. Preparation of nano-filtration loss reducing agent

[0090] S1-1. Add 100 parts by weight of isopropanol and 5 parts by weight of ethyl cellulose to a round-bottom flask and stir until dissolved. Disperse the mixture by ultrasonication for 1 hour using an ultrasonic cell disruptor. Adjust the pH to 8 with a 30% NaOH aqueous solution. Purge with nitrogen gas and heat to 30°C. Continue stirring for 22 hours and then raise the temperature to 70°C.

[0091] S1-2. Dissolve 12 parts by weight of chloroacetic acid in 2 parts by weight of isopropanol, and slowly add it to the liquid in the round-bottom flask at a rate of one drop every 30 seconds to carry out the etherification reaction for 2.5 hours.

[0092] S1-3. After cooling the mixture obtained from the etherification reaction to room temperature, centrifuge it. Wash the centrifuged precipitate twice with ethanol. Dry the obtained solid product at 70°C for 16 hours. The pulverized powder is the nano-filtration loss reducer.

[0093] S2. Preparation of environmentally friendly lubricants

[0094] S2-1. Add 100 parts by weight of water to the reactor, then add 32 parts by weight of pine fatty acid and 18 parts by weight of triethylenediamine, and react at 80°C for 3 hours to undergo an amidation reaction.

[0095] S2-2. Heat to 160℃, add 25 parts by weight of triethanolamine oleate, stir for 1 hour, add 15 parts by weight of polytetrafluoroethylene micro powder and 15 parts by weight of ethanol, mix for 1 hour, and you will get an environmentally friendly lubricant.

[0096] S3, Preparation of polyamine inhibitors

[0097] After mixing 20 parts by weight of maleic anhydride and 65 parts by weight of diethanolamine evenly, the mixture was transferred to a reaction vessel and reacted at 160°C under vacuum for 4 hours. The temperature was then lowered to 100°C, and 15 parts by weight of citric acid were added to react with the amine bonds in a directional manner for 2 hours. After cooling to room temperature, the resulting product was the polyamine inhibitor.

[0098] S4. Preparation of polyamine drilling fluid for oil and gas field drilling

[0099] S4-1. Measure 400mL of water into a 1000mL high-speed stirring cup, add 4.0g of sodium bentonite at a speed of 8000r / min, and stir at high speed for 20min.

[0100] S4-2. Add 0.8g sodium carbonate and 0.6g sodium hydroxide to the product prepared in step S4-1, and stir at high speed for 20min.

[0101] S4-3. Add 1.2g of low-viscosity polyanionic cellulose to the product of step S4-2 and stir at high speed of 10000r / min for 20min.

[0102] S4-4. Add 0.8g FA367 to the product of step S4-3 and stir at high speed for 20min.

[0103] S4-5. Add 16.0g of the nano-filtration loss reducer prepared in step S1 to the product of step S4-4, and stir at high speed for 20min.

[0104] S4-6. Add 12.0g of white asphalt to the product of step S4-5 and stir at high speed for 20min.

[0105] S4-7. Add 12.0g of the environmentally friendly lubricant prepared in step S2 to the product of step S4-6, and stir at high speed for 20min.

[0106] S4-8. Add 22.0g of the polyamine inhibitor prepared in step S3 to the product of step S4-7, and stir at high speed for 20min.

[0107] S4-9. Add 24.0 g of potassium chloride to the product from step S4-8, and finally add barite to increase the density of the drilling fluid to 1.5 g / cm³. 3 Stir at high speed for 30 minutes to obtain polyamine drilling fluid.

[0108] In this embodiment, the aging conditions during performance testing were 120°C for 16 hours and rheological properties were tested at 50°C.

[0109] Example 3

[0110] This embodiment provides a method for preparing polyamine drilling fluid for oil and gas field drilling. The formula is as follows: based on a total water volume of 100 mL, the raw material components include 1.5 g of bentonite (sodium bentonite), 0.25 g of thickener (low-viscosity polyanionic cellulose), 0.2 g of sodium carbonate, 0.2 g of sodium hydroxide, 0.15 g of coating agent (FA367), 3.5 g of nano-filtration reducer, 4.0 g of environmentally friendly lubricant, 5.0 g of polyamine inhibitor, 8.0 g of sodium chloride, and 4.0 g of nano-silica. It also includes barite, and the addition of barite makes the density of the polyamine drilling fluid 1.8 g / cm³. 3 .

[0111] The specific preparation method is as follows:

[0112] S1. Preparation of nano-filtration loss reducing agent

[0113] S1-1. Add 100 parts by weight of isopropanol and 7 parts by weight of ethyl cellulose to a round-bottom flask and stir until dissolved. Disperse the mixture by ultrasonication for 2 hours using an ultrasonic cell disruptor. Adjust the pH to 8 with a 30% NaOH aqueous solution. Purge with nitrogen gas and heat to 30°C. Continue stirring for 20 hours and then raise the temperature to 70°C.

[0114] S1-2. Dissolve 10 parts by weight of chloroacetic acid in 1 part by weight of isopropanol, and slowly add it to the liquid in the round-bottom flask at a rate of one drop every 30 seconds, and carry out the etherification reaction for 2 hours.

[0115] S1-3. After cooling the mixture obtained from the etherification reaction to room temperature, centrifuge it. Wash the centrifuged precipitate three times with ethanol. Dry the obtained solid product at 60°C for 20 hours. The pulverized powder is the nano-filtration loss reducer.

[0116] S2. Preparation of environmentally friendly lubricants

[0117] S2-1. Add 100 parts by weight of water to the reactor, then add 30 parts by weight of pine fatty acid and 20 parts by weight of triethylenediamine. React at 90°C for 4 hours to induce an amidation reaction.

[0118] S2-2. Heat to 180℃, add 30 parts by weight of triethanolamine oleate, stir for 2 hours, add 20 parts by weight of polytetrafluoroethylene micro powder and 20 parts by weight of ethanol, mix for 2 hours, and you will get an environmentally friendly lubricant.

[0119] S3, Preparation of polyamine inhibitors

[0120] After mixing 30 parts by weight of maleic anhydride and 60 parts by weight of diethanolamine evenly, the mixture was transferred to a reaction vessel and reacted under vacuum at 170°C for 5 hours. Then, the temperature was lowered to 90°C, and 20 parts by weight of citric acid were added to react with the amine bonds in a directional manner for 3 hours. After cooling to room temperature, the resulting product was the polyamine inhibitor.

[0121] S4. Preparation of polyamine drilling fluid for oil and gas field drilling

[0122] S4-1. Measure 400mL of water into a 1000mL high-speed stirring cup, add 6.0g of sodium bentonite at a speed of 8000r / min, and stir at high speed for 20min.

[0123] S4-2. Add 0.8g sodium carbonate and 0.8g sodium hydroxide to the product prepared in step S4-1, and stir at high speed for 20min.

[0124] S4-3. Add 1.0g of low-viscosity polyanionic cellulose to the product of step S4-2 and stir at high speed of 10000r / min for 20min.

[0125] S4-4. Add 0.6g FA367 to the product of step S4-3 and stir at high speed for 20min.

[0126] S4-5. Add 16.0g of the nano-filtration loss reducer prepared in step S1 to the product of step S4-4, and stir at high speed for 20min.

[0127] S4-6. Add 16.0g of nano-silica to the product of step S4-5 and stir at high speed for 20min;

[0128] S4-7. Add 16.0g of the environmentally friendly lubricant prepared in step S2 to the product of step S4-6, and stir at high speed for 20min.

[0129] S4-8. Add 20.0g of the polyamine inhibitor prepared in step S3 to the product of step S4-7, and stir at high speed for 20min.

[0130] S4-9. Add 24.0 g of sodium chloride to the product from step S4-8, and finally add barite to increase the density of the drilling fluid to 1.8 g / cm³. 3 Stir at high speed for 30 minutes to obtain polyamine drilling fluid.

[0131] In this embodiment, the aging conditions during performance testing were 160°C for 16 hours and rheological properties were tested at 50°C.

[0132] The performance of the environmentally friendly lubricant, polyamine inhibitor, nano-filtration reducer, and polyamine drilling fluid prepared using the methods of Examples 1-3 was tested.

[0133] The testing standards are as follows:

[0134] (1) The density of the drilling fluid was determined using the methods and instruments specified in GB / T16783.1-2014 "Field Testing of Drilling Fluids for Petroleum and Natural Gas Industry - Part 1: Water-based Drilling Fluids";

[0135] (2) The plastic viscosity of the drilling fluid was determined using the methods and instruments specified in GB / T16783.1-2014 "Field Testing of Drilling Fluids for Petroleum and Natural Gas Industry - Part 1: Water-based Drilling Fluids";

[0136] (3) The dynamic shear force of the drilling fluid shall be determined by the method and instruments specified in GB / T16783.1-2014 "Field Testing of Drilling Fluids for Petroleum and Natural Gas Industry - Part 1: Water-based Drilling Fluids";

[0137] (4) The API filtration loss and high-temperature and high-pressure filtration loss of drilling fluid shall be determined by the methods and instruments specified in GB / T16783.1-2014 "Field Testing of Drilling Fluids for Petroleum and Natural Gas Industry - Part 1: Water-based Drilling Fluids";

[0138] (5) The inhibition performance of shale inhibitors and drilling fluids was determined using the methods and instruments specified in “NB / T10121-2018 Evaluation Method for the Inhibitory Effect of Drilling Fluid on Shale”.

[0139] (6) The lubrication performance of high-temperature resistant environmentally friendly lubricants and drilling fluids was determined using the methods and instruments specified in "Q-SY 17088-2016 Technical Specification for Liquid Lubricants for Drilling Fluids";

[0140] (7) The filtration loss reduction performance of the high-temperature resistant environmentally friendly filtration loss reduction agent was determined using the methods and instruments specified in “SY / T7626-2021 Water-based Drilling Fluid Filtration Loss Reducing Polymers”.

[0141] (8) The biotoxicity of drilling fluid shall be determined by the methods and instruments specified in “SY / T6788 2020 Environmental Protection Technical Evaluation Requirements for Water-Soluble Oilfield Chemical Agents”.

[0142] Table 1 below shows the test results of the lubrication performance of the environmentally friendly lubricants prepared in Examples 1 to 3 in soil-moving slurry.

[0143] Table 1. Lubricating performance of environmentally friendly lubricants in soil-moving slurry in Examples 1-3.

[0144] Test sample Lubrication coefficient reduction rate / % Example 1 97.33 Example 2 96.97 Example 3 98.26

[0145] As can be seen from the data of Examples 1 to 3 in Table 1, the three high-temperature resistant and environmentally friendly lubricants of the present invention all have a purity of over 96%, exhibiting good lubrication performance.

[0146] Table 2 below shows the test results of the inhibitory performance of the polyamine inhibitors prepared in Examples 1 to 3.

[0147] Table 2 Inhibitory performance of polyamine inhibitors in Examples 1-3

[0148] Test sample Rolling recovery rate / % Linear expansion rate / % Pulping reduction rate / % Example 1 98.66 36.21 98.19 Example 2 98.23 36.33 97.54 Example 3 99.01 36.57 97.96

[0149] As can be seen from the data of Examples 1-3 in Table 2, the three polyamine inhibitors of the present invention all have a rolling recovery rate of over 98%, a linear expansion rate of over 36%, and a pulping reduction rate of over 97%, demonstrating good inhibition performance.

[0150] Table 3 below shows the performance evaluation results of the nano-filtration loss reducers prepared in Examples 1-3 in freshwater drilling fluid.

[0151] Table 3 Performance evaluation of micro / nano filtration loss reducers in freshwater drilling fluids in Examples 1-3

[0152] Test sample AV <![CDATA[FL HTHP ]]> Example 1 20 18.6 Example 2 20 19.4 Example 3 20 19.0

[0153] Note: Experimental conditions: aging at 120℃ for 16 hours.

[0154] AV: Apparent viscosity of drilling fluid, mPa·s;

[0155] FL HTHP Drilling fluid high temperature and high pressure water loss (3.5MPa, 120℃, 30min), mL.

[0156] As can be seen from the data of Examples 1 to 3 in Table 3, the three nano-filtration loss reducers of the present invention all have a high-temperature and high-pressure filtration loss of less than 20 mL in freshwater drilling fluid, showing good filtration loss reduction performance.

[0157] Table 4 below shows the basic performance test results of the shale green high-temperature and high-density water-based drilling fluids prepared in Examples 1 to 3.

[0158] Table 4. Basic properties of the anti-collapse and anti-locking polyamine drilling fluids in Examples 1-3.

[0159]

[0160]

[0161] Note: T: Aging temperature, °C;

[0162] ρ: Drilling fluid density, g / cm³ 3 ;

[0163] PV: Plastic viscosity of drilling fluid, mPa·s;

[0164] YP: Dynamic shear force of drilling fluid, Pa;

[0165] FL API Drilling fluid pressure loss (0.7 MPa, T, 30 min), mL;

[0166] FL HTHP Drilling fluid high-temperature and high-pressure water loss (3.5MPa, T, 30min), mL;

[0167] EC 50 Biotoxicity by luminescent bacteria method, mg / L.

[0168] As shown in Table 4, Examples 1, 2, and 3, the polyamine drilling fluid for oil and gas field drilling of the present invention operates at 120–160°C and 1.5–1.8 g / cm³. 3 Under these conditions, it maintains good rheological properties; the filtration loss at high temperature and high pressure is less than 8 ml, and the rolling recovery rate is over 95%, exhibiting strong inhibition performance and low filtration loss, which can effectively prevent collapse accidents during drilling operations in large sections of mudstone; the friction coefficient is less than 0.10, exhibiting good extreme pressure lubrication performance, which can effectively prevent stuck drill and pressure accidents during drilling operations in large sections of mudstone; it has a wide applicable density and temperature range, low toxicity, good biodegradability, and is environmentally friendly.

[0169] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A polyamine drilling fluid for oil and gas field drilling, characterized in that, Based on a total water volume of 100 mL, the raw material composition includes 1.0–2.0 g of bentonite, 0.2–0.3 g of thickener, 0.2–0.4 g of alkalinity adjuster, 0.1–0.2 g of coating agent, 3.0–4.0 g of nano-filtration reducer, 3.0–4.0 g of lubricant, 5.0–6.0 g of polyamine inhibitor, 3.0–4.0 g of micro / nano plugging agent, and 6.0–8.0 g of inorganic salt. It also includes a weighting material, wherein the density of the polyamine drilling fluid used as the weighting material is 1.5–1.8 g / cm³. 3 .

2. The polyamine drilling fluid for oil and gas field drilling according to claim 1, characterized in that, The bentonite includes sodium bentonite.

3. The polyamine drilling fluid for oil and gas field drilling according to claim 1, characterized in that, The thickener includes low-viscosity polyanionic cellulose.

4. The polyamine drilling fluid for oil and gas field drilling according to claim 1, characterized in that, The alkalinity regulator includes any one or a combination of two of sodium carbonate and sodium hydroxide.

5. The polyamine drilling fluid for oil and gas field drilling according to claim 1, characterized in that, The coating agent includes a zwitterionic polymer strong coating agent.

6. The polyamine drilling fluid for oil and gas field drilling according to claim 1, characterized in that, The coating agent is FA367.

7. The polyamine drilling fluid for oil and gas field drilling according to claim 1, characterized in that, The preparation method of the nano-filtration loss reducer includes the following steps: Isopropanol and ethyl cellulose were added to the reaction vessel and stirred until dissolved. Then, the mixture was ultrasonically dispersed. The pH was adjusted to alkaline using sodium hydroxide solution, nitrogen gas was introduced, and the mixture was heated to 30°C. After stirring for 20–24 hours, the temperature was raised to 70–80°C. Chloroacetic acid was dissolved in isopropanol, and the resulting solution was slowly added dropwise to the above reaction solution to carry out the etherification reaction. The mixture after the reaction was cooled to room temperature and then centrifuged. The precipitate was washed with ethanol to obtain a solid product. The solid product is dried and then pulverized to obtain a nano-filtration loss reducer.

8. The polyamine drilling fluid for oil and gas field drilling according to claim 7, characterized in that, Add 5 to 10 parts by weight of ethyl cellulose to 100 parts by weight of isopropanol.

9. The polyamine drilling fluid for oil and gas field drilling according to claim 7, characterized in that, Adjust the pH to 7.5–8 using a sodium hydroxide solution.

10. A polyamine drilling fluid for oil and gas field drilling according to claim 7, characterized in that, Add 1 to 2 parts by weight of isopropanol to 10 to 20 parts by weight of chloroacetic acid.

11. The polyamine drilling fluid for oil and gas field drilling according to claim 7, characterized in that, The drying temperature for solid products is 60–80℃.

12. The polyamine drilling fluid for oil and gas field drilling according to claim 1, characterized in that, The lubricant is an environmentally friendly lubricant, and its preparation method includes the following steps: Water, pine fatty acid, and triethylenediamine were added to the reaction vessel, and the amidation reaction was carried out at a temperature of 80–90°C. The temperature is raised to 160-180℃, and triethanolamine oleate is added. After stirring and reacting, polytetrafluoroethylene micro powder and ethanol are added and mixed to obtain an environmentally friendly lubricant.

13. The polyamine drilling fluid for oil and gas field drilling according to claim 12, characterized in that, Add 30-35 parts by weight of pine fatty acid, 10-20 parts by weight of triethylenediamine, 20-30 parts by weight of triethanolamine oleate, 15-25 parts by weight of polytetrafluoroethylene micro powder, and 15-25 parts by weight of ethanol to 100 parts by weight of water.

14. The polyamine drilling fluid for oil and gas field drilling according to claim 1, characterized in that, The preparation method of the polyamine inhibitor includes the following steps: After mixing maleic anhydride and diethanolamine, the mixture is transferred to a reaction vessel and reacted at 160℃~180℃. The temperature is then lowered to 90℃~100℃, and citric acid is added to react with the amine bonds in a directional manner. After the reaction, the mixture is cooled to room temperature to obtain the polyamine inhibitor.

15. A polyamine drilling fluid for oil and gas field drilling according to claim 14, characterized in that, The raw materials for preparing polyamine inhibitors, by weight fraction, include 20-30 parts by weight of maleic anhydride, 60-70 parts by weight of diethanolamine, and 15-20 parts by weight of citric acid.

16. The polyamine drilling fluid for oil and gas field drilling according to claim 1, characterized in that, The inorganic salt includes any one or a combination of two of potassium chloride, sodium chloride, and potassium formate.

17. The polyamine drilling fluid for oil and gas field drilling according to claim 1, characterized in that, The micro / nano sealing agent includes any one or more of white asphalt, nano limestone, and nano silica in combination.

18. The polyamine drilling fluid for oil and gas field drilling according to claim 1, characterized in that, The weighting material includes barite with a density of 4.2–4.4 g / cm³. 3 .

19. A method for preparing a polyamine drilling fluid for oil and gas field drilling, characterized in that, Includes the following steps: Bentonite, alkalinity regulator, thickener, coating agent, nano-filtration reducer, lubricant, polyamine inhibitor, inorganic salt, and weighting material are added to the reaction vessel in the specified proportions under stirring conditions. After stirring and reacting, polyamine drilling fluid for oil and gas field drilling is obtained.

20. The application of a polyamine drilling fluid for oil and gas field drilling according to any one of claims 1 to 8, or a polyamine drilling fluid for oil and gas field drilling prepared by the preparation method of claim 19, characterized in that, This includes applications in drilling long sections of mudstone.

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