High-temperature resistant solid-free drilling fluid and preparation method thereof

Abstract

The application provides an anti-high-temperature solid-phase-free drilling fluid and a preparation method thereof, and belongs to the technical field of drilling fluids in petroleum engineering. The anti-high-temperature solid-phase-free drilling fluid comprises the following components: an anti-high-temperature tackifier, an anti-high-temperature fluid loss reducer, a high-temperature stabilizer, a nano plugging agent, a pH regulator, a weighting agent and water; wherein the anti-high-temperature tackifier is a copolymer with allyl glyceryl ether, 2-acrylamide-2-methylpropanesulfonic acid and N-vinylpyrrolidone as raw materials; and the anti-high-temperature fluid loss reducer is a 2-acrylamide-2-methylpropanesulfonic acid self-polymer or a copolymer with other acrylamide monomers. The system has good rheological property, temperature resistance and fluid loss reduction performance, and is low in cost.

Description

Technical Field

[0001] This invention belongs to the field of drilling fluid technology in petroleum engineering, specifically relating to a high-temperature resistant solids-free drilling fluid and its preparation method. Background Technology

[0002] Traditional water-based and oil-based drilling fluids often use materials such as barite, iron ore, and calcium carbonate to increase the weight of the system, resulting in a high solids content. This can be very damaging to reservoirs, especially sensitive ones. Increased solids content also leads to poor lubrication and difficulty in controlling the rheological properties of the drilling fluid, reducing drilling rates. Therefore, reducing the use of solids is crucial for reservoir protection.

[0003] Solids-free drilling fluids generally refer to drilling fluid systems that do not contain a clay phase. The density of such systems can be adjusted by adding salts, such as sodium chloride, sodium formate, potassium chloride, and potassium formate. A certain amount of viscosifiers, filtration loss reducers, high-temperature protectants, and plugging agents also need to be added. Because they do not contain a solid phase, such drilling fluid systems can effectively solve the above-mentioned problems.

[0004] In the prior art, patent CN116265561A discloses a solids-free drilling fluid system using Chevron Phillips HE300 viscosifier, a high-temperature and calcium-resistant filtration loss reducer from Sinopec Engineering Technology Research Institute, and flow pattern regulators as treatment agents. This system is resistant to temperatures up to 180℃ and salt concentrations up to 15000 mg / L. However, imported HE300 has the disadvantage of high price. Patent CN105131915A discloses a solids-free drilling fluid system using polyanionic cellulose as a filtration loss reducer and Dristemp as a viscosifier, achieving a maximum density of 2.3 g / cm³. 3 This system boasts a temperature resistance of up to 200℃ and exhibits strong stability, inhibition, and lubrication at high temperatures. However, similar to patent CN116265561A, it utilizes imported viscosity modifiers, making system cost a significant obstacle to its large-scale adoption. To address the inherent limitations of existing solid-free systems in balancing temperature resistance and cost, research into developing domestically produced solid-free drilling fluid systems is urgently needed. Summary of the Invention

[0005] To address the problem of insufficient temperature resistance in existing solid-free drilling fluids, this invention provides a novel high-temperature resistant solid-free drilling fluid and its preparation method. The solid-free drilling fluid system of this invention has a temperature resistance of up to 200℃, exhibiting good temperature resistance and promising application prospects.

[0006] One of the objectives of this invention is to provide a high-temperature resistant, solid-free drilling fluid.

[0007] The second objective of this invention is to provide a method for preparing the high-temperature resistant solids-free drilling fluid.

[0008] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0009] In a first aspect, the present invention provides a high-temperature resistant solids-free drilling fluid, the high-temperature resistant solids-free drilling fluid comprising the following components: a high-temperature resistant viscosifier, a high-temperature resistant filtration loss reducer, a high-temperature stabilizer, a nano-plugging agent, a pH adjuster, a weighting agent, and water;

[0010] The high-temperature resistant thickener is a copolymer made from allyl glycerol ether, 2-acrylamide-2-methylpropanesulfonic acid and N-vinylpyrrolidone;

[0011] The high-temperature filtration reduction agent is a self-polymer of 2-acrylamide-2-methylpropanesulfonic acid, or a copolymer of it with other acrylamide monomers.

[0012] In some embodiments, based on 100 mL of water, the amount of high-temperature resistant viscosifier added is 0.5–2 g, the amount of high-temperature resistant filtration reducer added is 1.5–3 g, the amount of high-temperature stabilizer added is 0.3–1.5 g, the amount of nano-plugging agent added is 1–3 g, and the amount of pH adjuster added is 0.1–0.5 g; the density of the high-temperature resistant solids-free drilling fluid is 1.05–1.50 g / cm³. 3 The amount of weighting agent to be added is determined based on the density requirements.

[0013] High-temperature resistant tackifier:

[0014] In this invention, the high-temperature resistant tackifier is a copolymer made from allyl glycerol ether, 2-acrylamide-2-methylpropanesulfonic acid and N-vinylpyrrolidone; the molecular weight of the high-temperature resistant tackifier is preferably 5 million to 15 million.

[0015] The copolymer was developed by the inventor. The preparation method of the high-temperature resistant thickener is as follows:

[0016] (1) Dissolve 1-3 parts by weight of N-vinylpyrrolidone, 5-7 parts by weight of 2-acrylamide-2-methylpropanesulfonic acid, and 1-4 parts by weight of allyl glycerol ether in deionized water to prepare a 20%-50% aqueous solution, and adjust the pH to 6-8 with sodium hydroxide.

[0017] (2) Based on the mass of the three monomers in step (1) as 100%, add 0.01%-0.5% of oxidant, 0.01%-0.5% of reducing agent, 0.01%-0.3% of azobisisobutyramidine hydrochloride, and 0.005%-0.05% of crosslinking agent, and stir to dissolve; wherein the oxidant is selected from one or more of ammonium persulfate, potassium persulfate, hydrogen peroxide, and sodium persulfate; the reducing agent is selected from one or more of sodium bisulfite, ferrous ammonium sulfate, and urea; and the crosslinking agent is selected from one or more of N'N-methylenebisacrylamide and divinylbenzene.

[0018] (3) Purge with high-purity nitrogen for 30 minutes, set the initial reaction temperature to 5-15℃, and after reacting for 30 minutes, adjust the temperature to 30-50℃.

[0019] (4) After reacting for 2-10 hours, a high-temperature resistant thickener with a solid content of 20%-45% is obtained. The product is dried and pulverized to obtain a high-temperature resistant thickener powder.

[0020] The amount of high-temperature resistant thickener added is, for example, 0.5g, 1g, 1.5g, 2g, etc., but is not limited to these.

[0021] This high-temperature viscosity improver can increase the viscosity and dynamic shear force of solid-free drilling fluid systems.

[0022] High-temperature filtration loss reducer:

[0023] In this invention, the high-temperature filtration loss reducer is a self-polymer of 2-acrylamide-2-methylpropanesulfonic acid, or a copolymer of it with other acrylamide monomers, including one or more of methacrylamide, N-isopropylacrylamide, N'N-methylenebisacrylamide, and N'N-dimethylacrylamide.

[0024] The amount of high-temperature filtration loss reducer added is, for example, 1.5g, 2g, 2.5g, 3g, etc., but is not limited to this.

[0025] High-temperature fluid loss reducers can reduce drilling fluid fluid loss.

[0026] High temperature stabilizer:

[0027] In some embodiments, the high-temperature stabilizer is sodium sulfite.

[0028] The amount of high-temperature stabilizer added is, for example, 0.3g, 0.5g, 0.6g, 0.8g, 1g, 1.2g, 1.5g, etc., but is not limited to these.

[0029] Nanoparticle plugging agent:

[0030] In some embodiments, the nano-blocking agent is a polymer nanosphere. Preferably, the polymer nanosphere is a methyl methacrylate polymer microsphere with a particle size of 20-800 nm.

[0031] The amount of nano-blocking agent added is, for example, 1g, 1.5g, 2g, 2.5g, 3g, etc., but is not limited to these.

[0032] Nanoparticle sealants can seal micro- and nano-pores and cracks, reduce filtration loss, and improve cake quality.

[0033] pH adjuster:

[0034] In some embodiments, the pH adjuster is selected from at least one of sodium hydroxide and sodium carbonate.

[0035] The amount of pH adjuster added is, for example, 0.1g, 0.2g, 0.3g, 0.4g, 0.5g, etc., but is not limited to these.

[0036] Weighting agent:

[0037] In some embodiments, the weighting agent is selected from organic salts and / or inorganic salts. Preferably, the inorganic salt is selected from potassium chloride and / or sodium chloride. Preferably, the organic salt is selected from at least one of sodium formate and potassium formate.

[0038] In this invention, the cost of the solids-free drilling fluid system is significantly reduced by employing a self-developed high-temperature resistant viscosity enhancer. Simultaneously, the rheological properties of the drilling fluid system are comparable to those of systems using expensive materials. Compared to existing foreign products, the self-developed high-temperature resistant viscosity enhancer increases viscosity by 40% at the same dosage, while maintaining comparable temperature resistance. The high-temperature filtration reducer and viscosity enhancer complement each other, effectively reducing filtration loss and increasing the temperature stability of this solids-free drilling fluid system.

[0039] Secondly, the present invention provides a method for preparing the above-mentioned high-temperature resistant solids-free drilling fluid, comprising the following steps:

[0040] Add the high-temperature resistant thickener, high-temperature filtration reducer, high-temperature stabilizer, nano-blocking agent, pH adjuster, and weighting agent to the water and mix thoroughly.

[0041] In some embodiments, the preparation method includes: mixing a high-temperature resistant thickener with water, and then sequentially mixing it with a high-temperature resistant filtration reducer, a pH adjuster, a high-temperature stabilizer, a nano-blocking agent, and a weighting agent.

[0042] In one specific embodiment, the preparation method includes:

[0043] (1) Prepare a high-temperature resistant thickener solution: Set the stirring speed to 4000-12000 r / min, slowly add 0.5-2g of high-temperature resistant thickener to 100mL of water, and continue stirring for 5-20 minutes after adding to ensure it is fully dissolved;

[0044] (2) Set the stirring speed to 4000-12000 r / min, slowly add 1.5-3g of high temperature resistance and filtration loss reduction agent, and continue stirring for 5-20 minutes after adding to ensure it is fully dissolved;

[0045] (3) Set the stirring speed to 4000-12000 r / min, add 0.1-0.5 g of pH adjuster, and continue stirring for 2-5 minutes after adding to ensure it is fully dissolved;

[0046] (4) Set the stirring speed to 4000-12000 r / min, add 0.3-1.5 g of high temperature stabilizer, and continue stirring for 2-5 minutes after adding to ensure it is fully dissolved;

[0047] (5) Set the stirring speed to 4000-12000 r / min, add 1-3g of nano-blocking agent, and continue stirring for 3-7 minutes after adding to ensure it is fully dissolved;

[0048] (6) Set the stirring speed to 4000-12000 r / min, add a certain amount of weighting agent according to the design density of the drilling fluid, and continue stirring for 10-20 minutes to fully dissolve it;

[0049] (7) After the above components in the drilling fluid are dissolved or evenly dispersed, a high-temperature resistant solid-free drilling fluid is obtained.

[0050] Beneficial effects:

[0051] (1) The solid-free drilling fluid system described in this invention has no harmful solid phase during the preparation process, which causes little damage to the oil and gas reservoir and is conducive to increasing the production of oil and gas wells.

[0052] (2) The solid-free drilling fluid system described in this invention has good rheological properties and temperature resistance, which can meet the needs of on-site construction in oil and gas fields.

[0053] (3) The solid-free drilling fluid system of the present invention has low filtration loss and thin mud cake, which can effectively protect the reservoir and improve well wall stability.

[0054] The present invention has been described in detail above; however, the above embodiments are merely illustrative in nature and are not intended to limit the invention. Furthermore, this document is not limited to the foregoing prior art or the invention itself, or to any theory described in the following embodiments. Detailed Implementation

[0055] The present invention will be further described below with reference to the embodiments. It should be noted that the following embodiments are provided for illustrative purposes only and do not constitute a limitation on the scope of protection of the present invention.

[0056] Unless otherwise specified, the raw materials, reagents, and methods used in the embodiments are all conventional raw materials, reagents, and methods in the art.

[0057] N-vinylpyrrolidone is from Shandong Xinghai Chemical Co., Ltd.;

[0058] 2-Acrylamide-2-methylpropanesulfonic acid is from Jiangsu Shenglun Chemical Technology Co., Ltd.

[0059] Allyl glycerol ether is from Shanghai Demao Chemical Co., Ltd.;

[0060] N'N methylenebisacrylamide is from Qingdao Huawiruisi New Materials Co., Ltd.

[0061] Preparation Example 1: Preparation of High-Temperature Tackifier

[0062] (1) Dissolve 5g N-vinylpyrrolidone, 35g 2-acrylamide-2-methylpropanesulfonic acid, and 10g allyl glycerol ether in deionized water cooled to 4°C to prepare a 35% aqueous solution, and adjust the pH to neutral by adding sodium hydroxide.

[0063] (2) Add 0.05g ammonium persulfate, 0.05g sodium bisulfite, and 0.15g azobisisobutyramidine hydrochloride, stir to dissolve, then add 0.003g N'N methylenebisacrylamide, and stir to dissolve.

[0064] (3) Purge with high-purity nitrogen for 30 minutes, set the temperature to 8°C, and after reacting for 30 minutes, raise the temperature to 30°C.

[0065] (4) After reacting for 10 hours, a high-temperature resistant tackifier block is obtained. The block is dried and crushed to obtain a high-temperature resistant tackifier powder.

[0066] Preparation Example 2: Preparation of High-Temperature Tackifier

[0067] (1) Dissolve 3g N-vinylpyrrolidone, 15g 2-acrylamide-2-methylpropanesulfonic acid, and 12g allyl glycerol ether in deionized water cooled to 4°C to prepare a 20% aqueous solution, and adjust the pH to neutral by adding sodium hydroxide.

[0068] (2) Add 0.15g ammonium persulfate, 0.15g sodium bisulfite, and 0.003g azobisisobutyramidine hydrochloride, stir to dissolve, then add 0.0015g N'N methylenebisacrylamide, and stir to dissolve.

[0069] (3) Purge with high-purity nitrogen for 30 minutes, set the temperature to 10°C, and after reacting for 30 minutes, raise the temperature to 50°C.

[0070] (4) After reacting for 6 hours, a high-temperature resistant thickening and filtration loss reducing agent block is obtained. The block is dried and crushed to obtain a high-temperature resistant thickening and filtration loss reducing agent powder.

[0071] Preparation Example 3: Preparation of High-Temperature Tackifier

[0072] (1) Dissolve 2g N-vinylpyrrolidone, 12g 2-acrylamide-2-methylpropanesulfonic acid and 8g allyl glycerol ether in deionized water cooled to 4°C to prepare a 50% aqueous solution, and adjust the pH to neutral by adding sodium hydroxide.

[0073] (2) Add 0.0022g ammonium persulfate, 0.0022g sodium bisulfite, and 0.0066g azobisisobutyramidine hydrochloride, stir to dissolve, then add 0.011g N'N methylenebisacrylamide, and stir to dissolve.

[0074] (3) Purge with high-purity nitrogen for 30 minutes, set the temperature to 5°C, and after reacting for 30 minutes, raise the temperature to 40°C.

[0075] (4) After reacting for 2 hours, a high-temperature resistant thickening and filtration loss reducing agent block is obtained. The block is dried and crushed to obtain a high-temperature resistant thickening and filtration loss reducing agent powder.

[0076] Example 1

[0077] (1) Add 400mL of water to a high-speed stirring cup and stir at 10000r / min. While stirring, add 4g of anti-high temperature thickener and continue stirring for 15 minutes.

[0078] (2) While stirring, add 8g of high-temperature filtration loss reducer HFL (2-acrylamide-2-methylpropanesulfonic acid filtration loss reducer, purchased from Hubei Hanko New Technology Co., Ltd.), and continue stirring for 15 minutes.

[0079] (3) While stirring, add 1g of pH adjuster sodium hydroxide and continue stirring for 5 minutes.

[0080] (4) While stirring, add 2g of high temperature stabilizer sodium sulfite and continue stirring for 5 minutes.

[0081] (5) While stirring, add 6g of methyl methacrylate polymer microspheres with a particle size of D50 600nm (purchased from Great Wall Drilling Engineering Co., Ltd. Chemical Company) and continue stirring for 5 minutes.

[0082] (6) Add 135g of sodium formate while stirring, and continue stirring for 20 minutes.

[0083] (7) After the above components in the drilling fluid are dissolved or evenly dispersed, a solid-free drilling fluid system 1 is obtained.

[0084] Example 2

[0085] Solid-free drilling fluid was prepared according to the method of Example 1, except that the amount of high-temperature viscosifier was adjusted to 6g to obtain solid-free drilling fluid system 2.

[0086] Example 3

[0087] Solid-free drilling fluid was prepared according to the method in Example 1, except that the amount of high-temperature filtration loss reducer added was adjusted to 6g, resulting in solid-free drilling fluid system 3.

[0088] Example 4

[0089] Solid-free drilling fluid was prepared according to the method in Example 1, except that the amount of nano-plugging agent added was adjusted to 8g, resulting in solid-free drilling fluid system 4.

[0090] Example 5

[0091] Solid-free drilling fluid was prepared according to the method in Example 1, except that the amount of sodium formate added was adjusted to change the density of the solid-free drilling fluid sample from 1.1 g / cm³. 3 Adjust to a density of 1.5 g / cm³ 3 , thus obtaining a solids-free drilling fluid system 5.

[0092] Comparative Example 1

[0093] Solid-free drilling fluid was prepared according to the method of Example 1, except that the high-temperature thickener in Example 1 was replaced with high-temperature thickener HE300 (Chevron Phillips Chemical Company, brand name vinyl polymer HE300).

[0094] Comparative Example 2

[0095] Solid-free drilling fluid was prepared according to the method of Example 1, except that the high-temperature filtration reducer HFL of Example 1 was replaced with the same amount of PAC-LV (polyanionic cellulose, Renqiu Deli Petroleum Additives Co., Ltd.).

[0096] The solid-free drilling fluid systems prepared in Examples 1-5 and Comparative Examples 1-2 were respectively placed into aging tanks and hot-rolled in a high-temperature roller furnace at 200°C for 16 hours. After removal, they were stirred at 10000 r / min for 10 minutes. According to GB / T 16783.1-2014 "Field Testing of Drilling Fluids for Petroleum and Natural Gas Industry - Part 1: Water-based Drilling Fluids", the apparent viscosity, plastic viscosity, dynamic shear force, and medium-pressure filtration loss at room temperature (FL) of each sample were determined. API ) and high temperature and high pressure filtration loss (FL) HTHPThe test results are shown in the table below.

[0097] Table 1 Performance test results of solids-free drilling fluid system

[0098]

[0099]

[0100] Table 1 shows the performance of different samples of the solids-free drilling fluid system. The performance results of the examples and comparative examples show that the system exhibits good rheological properties, temperature resistance, and filtration loss reduction performance. Compared with Example 1, Comparative Example 1 shows a certain reduction in viscosity and dynamic shear force, and a certain increase in filtration loss at room temperature under medium pressure and at high temperature and high pressure. More importantly, the high-temperature viscosifier described in this invention costs less than 50% of the cost of the high-temperature viscosifier HE300 used in Comparative Example 1, significantly reducing the cost of the solids-free drilling fluid system. The filtration loss at room temperature under medium pressure and at high temperature and high pressure in Comparative Example 2 are significantly greater than those in Example 1, indicating that the solids-free drilling fluid system of this invention has a good filtration loss reduction effect.

[0101] The above embodiments are merely illustrative of the technical solutions of the present invention and are not intended to limit it. 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 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, without departing from the spirit and substance defined by the claims of the present invention; and such modifications or substitutions are still within the scope defined by the claims of the present invention.

Claims

1. A high-temperature resistant, solids-free drilling fluid, characterized in that, The high-temperature resistant solids-free drilling fluid comprises the following components: high-temperature resistant viscosifier, high-temperature filtration reducer, high-temperature stabilizer, nano-plugging agent, pH adjuster, weighting agent, and water; Based on 100 mL of water, the addition amounts of the high-temperature resistant viscosifier are 0.5–2 g, the high-temperature resistant filtration reducer is 1.5–3 g, the high-temperature stabilizer is 0.3–1.5 g, the nano-plugging agent is 1–3 g, and the pH adjuster is 0.1–0.5 g; the density of the high-temperature resistant solids-free drilling fluid is 1.05–1.50 g / cm³. 3 ; The high-temperature resistant thickener is a copolymer made from allyl glycerol ether, 2-acrylamide-2-methylpropanesulfonic acid and N-vinylpyrrolidone; the molecular weight is 5 million to 15 million. The preparation method of the high-temperature resistant thickener is as follows: (1) Dissolve 1-3 parts by weight of N-vinylpyrrolidone, 5-7 parts by weight of 2-acrylamide-2-methylpropanesulfonic acid, and 1-4 parts by weight of allyl glycerol ether in deionized water to prepare a 20%-50% aqueous solution, and adjust the pH to 6-8 with sodium hydroxide. (2) Based on the mass of the three monomers in step (1) as 100%, add 0.01%-0.5% of oxidant, 0.01%-0.5% of reducing agent, 0.01%-0.3% of azobisisobutyramidine hydrochloride, and 0.005%-0.05% of crosslinking agent, and stir to dissolve; wherein the oxidant is selected from one or more of ammonium persulfate, potassium persulfate, hydrogen peroxide, and sodium persulfate; the reducing agent is selected from one or more of sodium bisulfite, ferrous ammonium sulfate, and urea; and the crosslinking agent is selected from one or more of N'N-methylenebisacrylamide and divinylbenzene; (3) Purge with high-purity nitrogen for 30 minutes, set the initial reaction temperature to 5-15℃, and after 30 minutes of reaction, adjust the temperature to 30-50℃; (4) After reacting for 2-10 hours, a high-temperature resistant thickener with a solid content of 20%-45% is obtained. The product is dried and pulverized to obtain a high-temperature resistant thickener powder. The high-temperature filtration reduction agent is a self-polymer of 2-acrylamide-2-methylpropanesulfonic acid, or a copolymer of it with other acrylamide monomers.

2. The high-temperature resistant solids-free drilling fluid according to claim 1, characterized in that, The high-temperature stabilizer is sodium sulfite.

3. The high-temperature resistant solids-free drilling fluid according to claim 1, characterized in that, The nano-blocking agent is a polymer nanosphere; The polymer nanospheres are methyl methacrylate polymer microspheres with a particle size of 20-800 nm.

4. The high-temperature resistant solids-free drilling fluid according to claim 1, characterized in that, The pH adjuster is selected from at least one of sodium hydroxide and sodium carbonate.

5. The high-temperature resistant solids-free drilling fluid according to claim 1, characterized in that, The weighting agent is selected from organic salts and / or inorganic salts; The inorganic salt is selected from potassium chloride and / or sodium chloride; The organic salt is selected from at least one of sodium formate and potassium formate.

6. A method for preparing a high-temperature resistant solids-free drilling fluid according to any one of claims 1-5, characterized in that, Includes the following steps: (1) Preparation of high temperature resistant thickener solution: Set the stirring speed to 4000-12000r / min, slowly add 0.5-2g of high temperature resistant thickener to 100mL of water, and continue stirring for 5-20 minutes after adding to make it fully dissolved; (2) Set the stirring speed to 4000-12000 r / min, slowly add 1.5-3g of high temperature resistance and filtration loss reduction agent, and continue stirring for 5-20 minutes after adding to ensure it is fully dissolved; (3) Set the stirring speed to 4000-12000 r / min, add 0.1-0.5 g of pH adjuster, and continue stirring for 2-5 minutes after adding to ensure it is fully dissolved; (4) Set the stirring speed to 4000-12000 r / min, add 0.3-1.5 g of high temperature stabilizer, and continue stirring for 2-5 minutes after adding to ensure it is fully dissolved; (5) Set the stirring speed to 4000-12000 r / min, add 1-3g of nano-blocking agent, and continue stirring for 3-7 minutes after adding to ensure it is fully dissolved; (6) Set the stirring speed to 4000-12000 r / min, add a certain amount of weighting agent according to the design density of the drilling fluid, and continue stirring for 10-20 minutes to fully dissolve it; (7) After the above components in the drilling fluid are dissolved or dispersed evenly, a high-temperature resistant solid-free drilling fluid is obtained.

Images