Metal friction reducer for coiled tubing and preparation method and application thereof

Abstract

The application belongs to the technical field of downhole operation, and particularly relates to a metal friction-reducing agent for coiled tubing, a preparation method and application thereof. The solvent, polyethylene glycol, lubricity improver, water-soluble emulsifier and stabilizer are mixed and subjected to high-speed shearing reaction to obtain the metal friction-reducing agent for coiled tubing. By controlling the molecular weight and conductivity of the polyethylene glycol and selecting the high-density drilling fluid extreme-pressure lubricant as the lubricity improver, the metal friction-reducing agent has excellent compatibility, good extreme-pressure lubricity and salt resistance in the coiled tubing operation, and shows good compatibility and adaptability in different work areas and field flowback water.

Description

Technical Field

[0001] This invention belongs to the field of downhole operation technology, specifically relating to a metal friction reducer for coiled tubing, its preparation method, and its application. Background Technology

[0002] Coiled tubing technology is a process for downhole operations using continuous, seamless, and repeatedly bendable high-strength steel tubing. Unlike traditional segmented tubing, it can be wound onto large drums, reaching lengths of several kilometers, enabling continuous tripping and tripping without frequent disassembly and reconnection. It plays an increasingly important role in oil and gas field exploration and development. Its core features include: (1) a coupling-free design, avoiding the strength weaknesses and sealing problems at traditional tubing joints; (2) high toughness and flexibility, allowing bending through complex wellbore trajectories, suitable for horizontal and highly deviated wells; (3) pressurized operation capability, enabling operations under pressurized conditions at the wellhead, avoiding formation contamination; and (4) a continuous circulation system, achieving uninterrupted fluid circulation and improving operational efficiency.

[0003] Coiled tubing technology has achieved large-scale and routine application. However, due to its small diameter, low rigidity, and inability to rotate, coiled tubing experiences increased friction during wellbore running, leading to tubing buckling and even "self-locking," which reduces running depth and limits extension capacity. Conventional drilling fluids using water-based lubricants cannot fully dissolve in field backflow, resulting in poor lubrication. Metal drag reducers used in fracturing, primarily designed to reduce fluid flow resistance, cannot meet the requirements of reducing sliding friction between the coiled tubing and casing walls and increasing effective tubing thrust during coiled tubing operations. To improve coiled tubing extension capacity, adding lubricating materials (i.e., metal friction reducers) to the wellbore working fluid to reduce frictional resistance at the "metal-to-metal" interface between the tubing and casing walls is a common industry practice. However, existing metal friction reducers applied to coiled tubing suffer from poor compatibility with field backflow and fracturing fluid standard brine, and the reduction rate of lubrication coefficient needs further optimization.

[0004] Therefore, there is an urgent need for a metal friction reducer that, through component design and proportioning, improves compatibility with field backflow water, fracturing fluid standard brine, etc., while effectively increasing the lubrication coefficient reduction rate, thus enabling its better application in coiled tubing related technical fields. Summary of the Invention

[0005] The purpose of this invention is to provide a metal friction reducer for coiled tubing, its preparation method, and its application. This invention involves mixing a solvent, polyethylene glycol, a lubricity enhancer, a water-soluble emulsifier, and a stabilizer, followed by a high-speed shear reaction to obtain the metal friction reducer for coiled tubing. By controlling the molecular weight and conductivity of the polyethylene glycol, and selecting a high-density drilling fluid extreme pressure lubricant as the lubricity enhancer, along with the combined effects of other components, it exhibits excellent compatibility, good extreme pressure lubricity, and salt resistance in coiled tubing operations. It demonstrates good compatibility and adaptability in backflow tests in different work areas.

[0006] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing a metal friction reducer for coiled tubing, comprising the following steps: Solvent, polyethylene glycol, lubricity enhancer, water-soluble emulsifier and stabilizer are mixed and subjected to high-speed shear reaction to obtain a metal friction reducer for coiled tubing; The lubricity enhancer is a high-density extreme pressure lubricant for drilling fluids, with a density of 0.90~1.00 g / cm³. 3 The lubrication coefficient reduction rate in room temperature fresh water is ≥85%, and the lubrication coefficient reduction rate in room temperature standard brine is ≥70%.

[0007] As a preferred embodiment, the mass ratio of the solvent, polyethylene glycol, lubrication enhancer, water-soluble emulsifier, and stabilizer is 0.5~1:1~1.5:1~2:0.1~0.5:0.01~0.05.

[0008] As a preferred embodiment, the solvent is one or both of tap water and desalinated water.

[0009] As a preferred embodiment, the solvent is preferably tap water and desalinated water; the mass ratio of desalinated water to tap water in the solvent is (1~4):1.

[0010] The demineralized water of this invention provides a high-purity aqueous phase, ensuring complete dissolution and uniform dispersion of the friction reducer. This avoids precipitation, flocculation, or system turbidity caused by excessive calcium and magnesium ions in tap water alone, fundamentally improving compatibility. Trace elements in tap water can form coordination bonds with polar groups such as hydroxyl, carboxyl, and amine groups in the friction reducer, enhancing its adsorption strength on the metal surface and forming a denser, shear-resistant lubricating film while reducing interfacial friction resistance. The synergistic effect of both can effectively improve the lubrication coefficient reduction rate while ensuring system stability and good compatibility.

[0011] As a preferred embodiment, the polyethylene glycol is one or more of PEG200, PEG300, and PEG400; The PEG200 has a hydroxyl value of 534~590 mgKOH / g, a molecular weight of 190~210, and an electrical conductivity of ≤0.5 μS / cm; The PEG300 has a hydroxyl value of 340~416 mgKOH / g, a molecular weight of 285~315, and an electrical conductivity of ≤0.5 μS / cm; The PEG400 has a hydroxyl value of 267~295 mgKOH / g, a molecular weight of 380~420, and an electrical conductivity of ≤0.5 μS / cm.

[0012] The low molecular weight of the polyethylene glycol in this invention ensures that it is a viscous liquid at room temperature. Its short molecular chains and low internal friction allow it to flow rapidly and penetrate into the gaps between friction pairs at the micron or even nanometer scale. Furthermore, during relative movement of the friction pairs, the low molecular weight polyethylene glycol is more easily carried into the contact area, forming a hydrodynamic film with load-bearing capacity, thereby improving the lubrication coefficient reduction rate. Simultaneously, the low electrical conductivity of polyethylene glycol avoids the risk of precipitation with other components in the formulation, ensuring the long-term stability of the system and effectively increasing compatibility.

[0013] As a preferred embodiment, the lubricity enhancer is HEP-1, a high-density extreme pressure lubricant for drilling fluids from Deshunyuan Petroleum, with a density of 0.90 g / cm³. 3 The lubrication coefficient decreased by 88% in fresh water at room temperature and by 76% in standard brine at room temperature.

[0014] HEP-1, an extreme pressure lubricant for high-density drilling fluids, is made from mineral oil and vegetable oil as base oils. It is modified through a high-temperature and high-pressure reaction and supplemented with extreme pressure additives containing S, B, N, etc., and surfactants. It is used to improve the extreme pressure lubrication performance of high-density drilling fluids under high temperature and high salt conditions. It does not increase viscosity and has low foaming, making it an excellent extreme pressure lubricant. Its molecules contain strong adsorption groups and have a high content of extreme pressure elements, which can form a chemical adsorption film with high film strength and toughness on the well wall and drill string. It also contains strong hydration groups and has excellent salt resistance. When applied to metal friction reducers, it can improve compatibility and reduce the lubrication coefficient.

[0015] As a preferred embodiment, the water-soluble emulsifier has an HLB value of 11 to 13.

[0016] As a preferred embodiment, the water-soluble emulsifier is one or both of alkyl glycoside APG-1214 and alkylphenol polyoxyethylene ether OP-7.

[0017] As a preferred embodiment, the water-soluble emulsifier is alkyl glycoside APG-1214 and alkylphenol polyoxyethylene ether OP-7; the mass ratio of alkyl glycoside APG-1214 to alkylphenol polyoxyethylene ether OP-7 is (1~4):1.

[0018] The salt-out-driven ordered arrangement of the alkyl glycoside APG-1214 of this invention, combined with the steric hindrance effect of polyethylene glycol, forms a dual anti-salt mechanism. Simultaneously, the hydrogen bond network between the hydroxyl groups of the APG sugar ring and the oxygen atoms of the polyethylene glycol ether enhances the density and shear resistance of the interfacial film. Alkylphenol polyoxyethylene ether OP-7 can rapidly reduce the surface tension of the liquid, allowing the processing fluid to spread quickly and penetrate into the tiny contact area between the tool and the workpiece. The combination of these two components facilitates the formation of a fine and stable emulsion and improves the overall performance of the metal friction reducer.

[0019] As a preferred embodiment, the stabilizer is one or more of guar gum, sodium carboxymethyl cellulose, hydroxyethyl cellulose, and xanthan gum.

[0020] As a preferred embodiment, the high-speed shear reaction steps are as follows: controlling the reaction temperature at 25~40℃, first mixing the solvent and polyethylene glycol and stirring at a rate of 10000~12000 r / min for 10~20 min, then slowly adding the stabilizer in small amounts and stirring at a rate of 10000~12000 r / min for 20~30 min, then adding the lubricating enhancer and stirring at a rate of 10000~12000 r / min for 20~30 min, and finally adding the water-soluble emulsifier and stirring at a rate of 10000~12000 r / min for 30~40 min.

[0021] In a second aspect, the present invention provides a metal friction reducer for coiled tubing prepared by the preparation method described in the first aspect.

[0022] Thirdly, the present invention provides an application of a metal friction reducer prepared by the preparation method described in the first aspect in coiled tubing downhole operations.

[0023] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: (1) The metal friction reducer of the present invention introduces low molecular weight polyethylene glycol with strong hydrophilic hydroxyl groups (-OH) and ether bonds (-O-) at both ends of the molecular chain, and has good water solubility and lubricity. On the one hand, it can improve lubricity, and on the other hand, it can reduce the surface tension of the aqueous phase, increase the compatibility between the oil phase and the aqueous phase, and facilitate the formation of a stable oil-in-water emulsion. In addition, the salting-out driven ordered arrangement of APG and the steric hindrance effect of PEG form a dual salt resistance mechanism. The hydrogen bond network between the hydroxyl groups of APG sugar ring and the oxygen atoms of PEG ether enhances the compactness and shear resistance of the interfacial film. This salt-resistant metal friction reducer forms a stable oil-in-water emulsion through the interaction of its components. This emulsion dissolves instantly in water and forms a robust boundary lubrication layer on polar surfaces such as metals, providing protection even under high pressure or low speed conditions. This reduces direct metal contact, lowers friction and wear, and exhibits excellent compatibility with coiled tubing working fluids, as well as good extreme pressure lubrication and salt resistance. It has demonstrated good performance in field backflow tests in various work areas, effectively reducing friction between metal tubing strings in complex wellbores by 30% and improving tubing string running-in capability by 8%. Furthermore, this product has a simple manufacturing process, is free of organochlorine compounds, is safe and environmentally friendly, and is suitable for widespread application.

[0024] (2) The metal friction reducer of the present invention uses polyethylene glycol with low molecular weight and low electrical conductivity, uses extreme pressure lubricant for high density drilling fluid as lubrication enhancer, and uses desalinated water and tap water as compound solvents and controls the mass ratio of the two. It uses alkyl glycoside APG-1214 with HLB value of 11~13 and alkylphenol polyoxyethylene ether OP-7 as compound water-soluble emulsifier. Through the synergistic effect of each component, the friction reducer has good compatibility and effectively improves the lubrication coefficient reduction rate, so that it can be well applied in coiled tubing downhole operations. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0026] Figure 1 This represents the dissolved state of the metal friction reducer in the coiled tubing working fluid in Example 1 of the present invention.

[0027] Figure 2 The change in the depth of continuous tubing before and after adding the metal friction reducer of Example 1 of the present invention. Detailed Implementation

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] The sources of some components in the examples and comparative examples are as follows: PEG200, with a hydroxyl value of 534~590 mgKOH / g, a molecular weight of 190~210, and an electrical conductivity of 0.2 μS / cm, was purchased from Haian Petrochemical Plant in Jiangsu Province. PEG300, with a hydroxyl value of 340~416 mgKOH / g, a molecular weight of 285~315, and an electrical conductivity of 0.3 μS / cm, was purchased from Haian Petrochemical Plant in Jiangsu Province. PEG400, with a hydroxyl value of 267~295 mgKOH / g, a molecular weight of 380~420, and an electrical conductivity of 0.4 μS / cm, was purchased from Haian Petrochemical Plant in Jiangsu Province. PEG-1000, with a hydroxyl value of 107~118 mgKOH / g, a molecular weight of 950~1050, and an electrical conductivity of 1.8 μS / cm, was purchased from Haian Petrochemical Plant in Jiangsu Province. HEP-1, an extreme pressure lubricant for high-density drilling fluids, was purchased from Shandong Deshunyuan Petroleum Technology Co., Ltd. Lubricant HY-204 was purchased from Shandong Deshunyuan Petroleum Technology Co., Ltd. Alkyl glycoside APG-1214, HLB value 12~13, purchased from Jinan Shenghe Chemical Co., Ltd. Alkylphenol polyoxyethylene ether OP-7, HLB value 11.5~12.5, purchased from Haian Petrochemical Plant, Jiangsu Province; Guar gum, CAS No. 9000-30-0, purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Sodium carboxymethyl cellulose, CAS No. 9004-32-4, was purchased from Sinopharm Chemical Reagent Co., Ltd. Hydroxyethyl cellulose, CAS No. 9004-62-0, was purchased from Sinopharm Chemical Reagent Co., Ltd. Xanthan gum, CAS No. 11138-66-2, was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0030] Example 1 This embodiment provides a method for preparing a metal friction reducer for coiled tubing, comprising the following steps: By weight, with the reaction temperature controlled at 30℃, 1 part of tap water and 1 part of polyethylene glycol PEG400 were mixed and stirred at 10000 r / min for 20 min. Then, 0.04 parts of sodium carboxymethyl cellulose stabilizer were slowly added and stirred at 10000 r / min for 30 min. Next, 2 parts of HEP-1 high-density drilling fluid extreme pressure lubricant were added and stirred at 10000 r / min for 30 min. Finally, 0.5 parts of water-soluble emulsifier (0.25 parts of alkyl glycoside APG-1214 and 0.25 parts of alkylphenol polyoxyethylene ether OP-7) were added and stirred at 12000 r / min for 30 min to obtain a metal friction reducer for coiled tubing.

[0031] Example 2 This embodiment provides a method for preparing a metal friction reducer for coiled tubing, comprising the following steps: By weight, with the reaction temperature controlled at 25℃, 0.5 parts of solvent tap water and 1.5 parts of polyethylene glycol PEG200 were mixed and stirred at 10000 r / min for 20 min. Then, 0.03 parts of stabilizer xanthan gum were slowly added and stirred at 10000 r / min for 30 min. Next, 1.5 parts of lubrication enhancer high-density drilling fluid extreme pressure lubricant HEP-1 were added and stirred at 10000 r / min for 30 min. Finally, 0.5 parts of water-soluble emulsifier (0.25 parts of alkyl glycoside APG-1214 and 0.25 parts of alkylphenol polyoxyethylene ether OP-7) were added and stirred at 12000 r / min for 30 min to obtain a metal friction reducer for coiled tubing.

[0032] Example 3 This embodiment provides a method for preparing a metal friction reducer for coiled tubing, comprising the following steps: By weight, with the reaction temperature controlled at 40℃, 0.8 parts of solvent demineralized water and 1.2 parts of polyethylene glycol PEG300 were mixed and stirred at 12000 r / min for 10 min. Then, 0.01 parts of stabilizer guar gum were slowly added and stirred at 12000 r / min for 20 min. Next, 1 part of lubrication enhancer high-density drilling fluid extreme pressure lubricant HEP-1 was added and stirred at 10000 r / min for 30 min. Finally, 0.1 parts of water-soluble emulsifier (0.08 parts of alkyl glycoside APG-1214 and 0.02 parts of alkylphenol polyoxyethylene ether OP-7) were added and stirred at 10000 r / min for 40 min to obtain a metal friction reducer for coiled tubing.

[0033] Example 4 This embodiment provides a method for preparing a metal friction reducer for coiled tubing, comprising the following steps: By weight, with the reaction temperature controlled at 35℃, 1 part solvent (0.5 parts desalinated water and 0.5 parts tap water) and 1.4 parts polyethylene glycol PEG400 were mixed and stirred at 11000 r / min for 15 min. Then, 0.05 parts stabilizer hydroxyethyl cellulose were slowly added and stirred at 11000 r / min for 25 min. Next, 1.8 parts lubricant HEP-1 for high-density drilling fluid extreme pressure lubricant were added and stirred at 11000 r / min for 25 min. Finally, 0.4 parts water-soluble emulsifier (0.3 parts alkyl glycoside APG-1214 and 0.1 parts alkylphenol polyoxyethylene ether OP-7) were added and stirred at 10000~12000 r / min for 30~40 min to obtain a metal friction reducer for coiled tubing.

[0034] Comparative Example 1 The difference between this comparative example and Example 1 is that 1 part polyethylene glycol is replaced with 1 part tap water as the solvent, and the water-soluble emulsifier is changed to alkylphenol polyoxyethylene ether OP-7.

[0035] Comparative Example 2 The difference between this comparative example and Example 1 is that 1 part of polyethylene glycol is replaced with 1 part of tap water as the solvent.

[0036] Comparative Example 3 The difference between this comparative example and Example 1 is that PEG1000 was used instead of PEG400. Comparative Example 4 The difference between this comparative example and Example 1 is that the lubricant HY-204 was used instead of the extreme pressure lubricant HEP-1 for high-density drilling fluid.

[0037] Comparative Example 5 This comparative example uses a common water-based lubricant for performance comparison.

[0038] Performance testing Performance testing was conducted in accordance with Sinopec's enterprise standard "QSH CG0160-2021".

[0039] Table 1 Performance Test Results

[0040] Note: The standard brine formula shall be formulated in accordance with the technical requirements for fracturing drag reducers in Sinopec enterprise standard QSH CG0160-2021.

[0041] Compared to Example 1, replacing 1 part of the solvent with 1 part of polyethylene glycol, and replacing all water-soluble emulsifiers with alkylphenol polyoxyethylene ether OP-7, resulted in a decrease in the compatibility of the metal friction reducer and a reduction in the lubrication coefficient (Comparative Example 1) due to the lack of polyethylene glycol's effect and the absence of compounding with the water-soluble emulsifier. Compared to Example 1, replacing 1 part of the solvent with 1 part of polyethylene glycol resulted in a decrease in the compatibility of the metal friction reducer and a reduction in the lubrication coefficient (Comparative Example 2). Compared to Example 1, Replacing PEG400 with PEG1000 resulted in poor additive effect due to the excessively large molecular weight and high conductivity of PEG-1000, leading to decreased compatibility of the metal friction reducer and reduced lubrication coefficient reduction rate (Comparative Example 3). Compared with Example 1, replacing the high-density drilling fluid extreme pressure lubricant HEP-1 with lubricant HY-204 resulted in decreased compatibility of the metal friction reducer and reduced lubrication coefficient reduction rate (Comparative Example 4).

Claims

1. A method for preparing a metal friction reducer for coiled tubing, characterized in that, Includes the following steps: Solvent, polyethylene glycol, lubricity enhancer, water-soluble emulsifier and stabilizer are mixed and subjected to high-speed shear reaction to obtain a metal friction reducer for coiled tubing; The lubricity enhancer is a high-density extreme pressure lubricant for drilling fluids, with a density of 0.90~1.00 g / cm³. 3 The lubrication coefficient reduction rate in room temperature fresh water is ≥85%, and the lubrication coefficient reduction rate in room temperature standard brine is ≥70%.

2. The method for preparing a metal friction reducer for coiled tubing according to claim 1, characterized in that, The mass ratio of the solvent, polyethylene glycol, lubrication enhancer, water-soluble emulsifier, and stabilizer is 0.5~1:1~1.5:1~2:0.1~0.5:0.01~0.

05.

3. The method for preparing a metal friction reducer for coiled tubing according to claim 1, characterized in that, The solvent is one or both of tap water and desalinated water.

4. The method for preparing a metal friction reducer for coiled tubing according to claim 1, characterized in that, The polyethylene glycol is one or more of PEG200, PEG300, and PEG400; The PEG200 has a hydroxyl value of 534~590 mgKOH / g, a molecular weight of 190~210, and an electrical conductivity of ≤0.5 μS / cm; The PEG300 has a hydroxyl value of 340~416 mgKOH / g, a molecular weight of 285~315, and an electrical conductivity of ≤0.5 μS / cm; The PEG400 has a hydroxyl value of 267~295mgKOH / g, a molecular weight of 380~420, and an electrical conductivity of ≤0.5μS / cm.

5. The method for preparing a metal friction reducer for coiled tubing according to claim 1, characterized in that, The lubrication enhancer is HEP-1, a high-density drilling fluid extreme pressure lubricant from Deshunyuan Petroleum.

6. The method for preparing a metal friction reducer for coiled tubing according to claim 1, characterized in that, The HLB value of the water-soluble emulsifier is 11~13; The water-soluble emulsifier is one or both of alkyl glycoside APG-1214 and alkylphenol polyoxyethylene ether OP-7.

7. The method for preparing a metal friction reducer for coiled tubing according to claim 1, characterized in that, The stabilizer is one or more of guar gum, sodium carboxymethyl cellulose, hydroxyethyl cellulose, and xanthan gum.

8. The method for preparing a metal friction reducer for coiled tubing according to claim 1, characterized in that, The steps of the high-speed shear reaction are as follows: control the reaction temperature at 25~40℃, first mix the solvent and polyethylene glycol and stir at a rate of 10000~12000r / min for 10~20min, then slowly add the stabilizer in small amounts and stir at a rate of 10000~12000r / min for 20~30min, then add the lubricating enhancer and stir at a rate of 10000~12000r / min for 20~30min, and finally add the water-soluble emulsifier and stir at a rate of 10000~12000r / min for 30~40min.

9. A metal friction reducer for continuous tubing, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the friction reducer obtained by the preparation method according to any one of claims 1 to 8 in coiled tubing downhole operations.

Images