A thickener for preparing fracturing wastewater and its preparation method
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-26
- Publication Date
- 2026-08-14
AI Technical Summary
若直接采用油田污水、压裂返排液进行配制，现有稠化剂普遍存在诸多技术缺陷：污水中高浓度无机盐及钙镁离子会严重抑制聚合物分子水化舒展，导致溶胀慢、增黏能力大幅下降、基液黏度不足；高价金属离子易与聚合物分子链发生络合、卷曲、沉降，造成交联滞后、交联不均匀、冻胶稳定性差、耐温耐剪切性能衰减严重，无法满足长时携砂施工要求；污水中原油、悬浮物、细菌及杂质会破坏稠化剂分子结构，体系易分层、降解快、破胶可控性差，破胶后残渣含量高，对储层及支撑裂缝造成二次伤害；现有解决方案多采用污水预处理工艺，包括沉降、过滤、除硬、降矿化度、杀菌调质等工序，工艺流程复杂、设备投入大、现场占用空间多，大幅增加压裂施工综合成本，且预处理后仍无法完全适配常规稠化剂使用
[0017]通过水溶液自由基聚合工艺，结合精准控温、氮气保护、低速搅拌及后段干燥成型，确保产品在高矿化度、高钙镁、含油含悬浮物的油田污水中仍具备快速溶解、高效增黏、耐温耐剪切及低残渣特性。
Abstract
Description
Technical Field
[0001] This invention belongs to the field of oilfield fracturing technology, specifically relating to a thickener for fracturing wastewater preparation and its preparation method. Background Technology
[0002] With the large-scale development of tight oil, shale oil, and low-permeability reservoirs in domestic oil and gas fields, hydraulic fracturing has become a core technology for enhancing production. Fracturing operations require a huge amount of water per well, and conventional fracturing fluids are mostly prepared with fresh water, which not only consumes a large amount of precious fresh water resources but also results in high costs for water intake, transportation, and treatment. At the same time, oilfield production processes generate large amounts of produced water, downhole flowback fluid, and operational wastewater. This type of wastewater is characterized by high total mineralization, high calcium and magnesium ion content, oil content, suspended solids, bacteria, and impurities. Direct discharge can easily cause soil and water pollution, and environmental treatment costs are high; simple reinjection can lead to formation blockage and reservoir damage.
[0003] Currently, most conventional fracturing thickeners used in field operations are natural guar gum, hydroxypropyl guar gum, and ordinary polyacrylamide polymers, which are only suitable for use with clean water or water sources with low mineralization. If oilfield wastewater and fracturing flowback fluid are used directly for preparation, existing thickeners generally have many technical defects: high concentrations of inorganic salts and calcium and magnesium ions in wastewater will severely inhibit the hydration and expansion of polymer molecules, resulting in slow swelling, a significant decrease in thickening capacity, and insufficient viscosity of the base fluid; high-valence metal ions are prone to complexing, coiling, and settling with polymer molecular chains, causing delayed cross-linking, uneven cross-linking, poor gel stability, and severe attenuation of temperature and shear resistance, which cannot meet the requirements of long-term sand-carrying operations; crude oil, suspended solids, bacteria, and impurities in wastewater will destroy the molecular structure of the thickener, making the system prone to stratification, rapid degradation, poor controllability of gel breaking, and high residue content after gel breaking, causing secondary damage to the reservoir and supporting fractures; existing solutions mostly adopt wastewater pretreatment processes, including sedimentation, filtration, hardening removal, demineralization, sterilization, and conditioning, which are complex processes, require large equipment investment, and occupy a lot of on-site space, significantly increasing the overall cost of fracturing operations, and even after pretreatment, they are still not fully compatible with conventional thickeners.
[0004] Existing publicly available literature and commercial products lack a dedicated fracturing thickener formulation system that can be directly adapted to high-mineralization oily wastewater without deep pretreatment, thus failing to meet the multiple needs of on-site resource reuse of oilfield wastewater, cost reduction and water conservation, and environmental protection and emission reduction. Summary of the Invention
[0005] To address the aforementioned technical problems, this invention provides a fracturing fluid thickener specifically designed for use in wastewater fracturing fluid preparation. This thickener is resistant to salt, calcium and magnesium ions, and oil contamination; it is suitable for direct preparation with wastewater; it is temperature and shear resistant; and it produces low residue and low damage. The application of this thickener in wastewater-based fracturing fluid preparation is particularly suitable for oilfield wastewater fracturing fluid systems with high salinity, high calcium and magnesium ion content, and containing oil and suspended solids.
[0006] The technical solution adopted in this invention is as follows: a thickener for preparing fracturing wastewater, the components and weight parts of the thickener being: 24-30 parts of 2-acrylamido-2-methylpropanesulfonic acid, 24-28 parts of 2-hydroxyethyl acrylate, 24-28 parts of sodium vinyl sulfonate, 8-10 parts of sodium itaconic acid, 3-5 parts of Tween-60 (TW-60), 200-300 parts of deionized water, and 1-2 parts of azobisisobutyrazoline hydrochloride.
[0007] Furthermore, the components and weight parts of the thickener are as follows: 24 parts of 2-acrylamido-2-methylpropanesulfonic acid, 24 parts of 2-hydroxyethyl acrylate, 24 parts of sodium vinyl sulfonate, 8 parts of sodium itaconic acid, 3 parts of Tween-60, 200 parts of deionized water, and 1 part of azobisisobutyrazoline hydrochloride.
[0008] Furthermore, the components and weight parts of the thickener are as follows: 27 parts of 2-acrylamido-2-methylpropanesulfonic acid, 26 parts of 2-hydroxyethyl acrylate, 26 parts of sodium vinyl sulfonate, 9 parts of sodium itaconic acid, 4 parts of Tween-60, 250 parts of deionized water, and 1.5 parts of azobisisobutyrazoline hydrochloride.
[0009] Furthermore, the components and weight parts of the thickener are as follows: 30 parts of 2-acrylamido-2-methylpropanesulfonic acid, 28 parts of 2-hydroxyethyl acrylate, 28 parts of sodium vinyl sulfonate, 10 parts of sodium itaconic acid, 5 parts of Tween-60, 300 parts of deionized water, and 2 parts of azobisisobutyrazoline hydrochloride.
[0010] Furthermore, the preparation method of the thickener includes the following steps:
[0011] Step 1: 24-30 parts of 2-acrylamido-2-methylpropanesulfonic acid, 24-28 parts of 2-hydroxyethyl acrylate, 24-28 parts of sodium vinyl sulfonate, 8-10 parts of sodium itaconic acid, 3-5 parts of Tween-60, 200-300 parts of deionized water, and 1-2 parts of azobisisobutyrazoline hydrochloride are sequentially added to a mixing tank. The stirring device is turned on to fully mix and disperse the components. Stirring continues until all monomers, additives, and initiators are completely dissolved and the system is homogeneous, transparent, and free of agglomeration and precipitation, resulting in a uniformly stirred reaction material.
[0012] Step 2: Transfer the reactants obtained in Step 1 to the reactor, and adjust the motor speed of the reactor to 100-150 rpm.
[0013] Step 3: Introduce nitrogen gas into the reactor. After introducing nitrogen gas into the reactor for 30 minutes, heat the reactor to 45℃~55℃ and stir for 2h~3h.
[0014] Step 4: After stirring for 2 to 3 hours, stop stirring and maintain the temperature at 45°C to 55°C for 12 to 16 hours, then allow it to cool naturally to room temperature.
[0015] Step 5: After cooling to room temperature, transfer the material in the reactor to the cutting machine for cutting. After cutting, transfer it to the drying oven for drying at 105℃ for 12 hours.
[0016] Step 6: After drying for 12 hours, allow the material to cool naturally to room temperature. Remove the material and transfer it to a pulverizer to be pulverized into fine particles of 0.5-1mm. This will produce a thickener for fracturing wastewater preparation.
[0017] By employing an aqueous free radical polymerization process, combined with precise temperature control, nitrogen protection, low-speed stirring, and post-drying molding, the product is ensured to retain its rapid dissolution, efficient thickening, temperature and shear resistance, and low residue characteristics even in oilfield wastewater with high mineralization, high calcium and magnesium content, and oil and suspended solids.
[0018] The beneficial effects of this invention are as follows: This invention provides a fracturing fluid thickener specifically formulated for use in wastewater, which is resistant to salt, calcium and magnesium ions, and oil contamination; suitable for direct preparation in wastewater; temperature and shear resistance; and exhibits low residue and low damage. The preparation method is controllable, with mild conditions, no high temperature or high pressure, and no organic solvent residue. Through nitrogen protection, low-temperature initiation, isothermal maturation, and low-temperature drying, the polymer molecular chains are guaranteed not to degrade or break. The product exhibits excellent solubility, thickening properties, salt resistance, and stability, making it suitable for industrial-scale mass production and long-term storage in oilfields. The application of this thickener in wastewater-prepared fracturing fluids is particularly suitable for fracturing fluid systems directly prepared from oilfield wastewater with high salinity, high calcium and magnesium ion content, and oil and suspended solids. Detailed Implementation
[0019] Example 1
[0020] The preparation method of the thickener for fracturing wastewater No. 1 includes the following steps:
[0021] Step 1: Weigh out 24 parts of 2-acrylamido-2-methylpropanesulfonic acid, 24 parts of 2-hydroxyethyl acrylate, 24 parts of sodium vinyl sulfonate, 8 parts of sodium itaconic acid, 3 parts of Tween-60, 200 parts of deionized water, and 2 parts of azobisisobutyrazoline hydrochloride according to the preset ratio, and put them into a special mixing tank in sequence. Turn on the stirring device to mix and disperse them thoroughly. Continue stirring until all monomers, additives and initiators are completely dissolved and the system is homogeneous, transparent, without agglomeration or precipitation, to obtain a uniformly stirred reaction material.
[0022] Step 2: Transfer the well-stirred material to the reaction vessel, and adjust the motor speed of the reaction vessel to 100-150 rpm;
[0023] Step 3: Introduce nitrogen gas into the reactor. After 30 minutes of nitrogen introduction, heat the reactor to 45℃~55℃ and stir for 2h~3h.
[0024] Step 4: After stirring for 2 to 3 hours, stop stirring and maintain the temperature at 45℃ to 55℃ for 12 hours, then allow it to cool naturally to room temperature.
[0025] Step 5: After cooling to room temperature, transfer to the cutting machine for cutting, and then transfer to the drying oven for drying. The drying temperature is set to 105℃ and the drying time is 12 hours.
[0026] Step 6: After drying for 12 hours, allow the material to cool naturally to room temperature, remove the material, and transfer it to a pulverizer for crushing. The pulverizer will crush the material into a size of 0.5-1mm to obtain No. 1 thickener for fracturing wastewater preparation.
[0027] Example 2
[0028] The preparation method of the thickener for fracturing wastewater preparation No. 2 includes the following steps:
[0029] Step 1: Weigh out 27 parts of 2-acrylamido-2-methylpropanesulfonic acid, 26 parts of 2-hydroxyethyl acrylate, 26 parts of sodium vinyl sulfonate, 9 parts of sodium itaconic acid, 4 parts of Tween-60, 250 parts of deionized water, and 3 parts of azobisisobutyrazoline hydrochloride according to the preset ratio, and put them into a special mixing tank in sequence. Turn on the stirring device to mix and disperse them thoroughly. Continue stirring until all monomers, additives and initiators are completely dissolved and the system is homogeneous, transparent, without agglomeration or precipitation, to obtain a uniformly stirred reaction material.
[0030] Step 2: Transfer the well-stirred material to the reactor, and adjust the motor speed of the reactor to 100-150 rpm.
[0031] Step 3: Introduce nitrogen gas into the reactor. After 30 minutes of nitrogen introduction, heat the reactor to 45℃~55℃ and stir for 2h~3h.
[0032] Step 4: After stirring for 2 to 3 hours, stop stirring and maintain the temperature at 45℃ to 55℃ for 14 hours, then allow it to cool naturally to room temperature.
[0033] Step 5: After cooling to room temperature, transfer to the cutting machine for cutting. After cutting, transfer to the drying oven for drying. Set the drying temperature to 105℃ and dry for 12 hours.
[0034] Step 6: After drying for 12 hours, allow the material to cool naturally to room temperature, remove the material, and transfer it to a pulverizer for crushing. The pulverizer will crush the material into a size of 0.5-1mm to obtain No. 2 thickener for fracturing wastewater preparation.
[0035] Example 3
[0036] The preparation method of the thickener for fracturing wastewater preparation No. 3 includes the following steps:
[0037] Step 1: Weigh out 30 parts of 2-acrylamido-2-methylpropanesulfonic acid, 28 parts of 2-hydroxyethyl acrylate, 28 parts of sodium vinyl sulfonate, 10 parts of sodium itaconic acid, 5 parts of Tween-60, 300 parts of deionized water, and 4 parts of azobisisobutyrazoline hydrochloride according to the preset ratio, and put them into a special mixing tank in sequence. Turn on the stirring device to mix and disperse them thoroughly. Continue stirring until all monomers, additives and initiators are completely dissolved and the system is homogeneous, transparent, without agglomeration or precipitation, to obtain a uniformly stirred reaction material.
[0038] Step 2: Transfer the well-stirred material to the reactor, and adjust the motor speed of the reactor to 100-150 rpm.
[0039] Step 3: Introduce nitrogen gas into the reactor. After 30 minutes of nitrogen introduction, heat the reactor to 45℃~55℃ and stir for 2h~3h.
[0040] Step 4: After stirring for 2 to 3 hours, stop stirring and maintain the temperature at 45℃ to 55℃ for 16 hours, then allow it to cool naturally to room temperature.
[0041] Step 5: After cooling to room temperature, transfer to the cutting machine for cutting. After cutting, transfer to the drying oven for drying. Set the drying temperature to 105℃ and dry for 12 hours.
[0042] Step 6: After drying for 12 hours, allow the material to cool naturally to room temperature, remove the material, and transfer it to a pulverizer for crushing. The pulverizer will crush the material into a size of 0.5-1mm to obtain No. 3 thickener for fracturing wastewater preparation.
[0043] Example 4
[0044] Fracturing flowback fluid with a mineralization of 32000 mg / L and a Ca²⁺ concentration of 1200 mg / L was prepared by adding 0.4% of thickener from fracturing flowback fluid No. 1-3 to each fluid to form a base solution, which was then used as a comparative example.
[0045] The test is as follows:
[0046] 1. The fracturing fluid base fluid prepared with the thickeners of Examples 1-3 is subjected to fracturing at 90°C for 510 seconds. -1 The fracturing fluid viscosity was tested after 2 hours of rate shearing to evaluate its temperature and shear resistance.
[0047] 2. The viscosity of the fracturing fluid base fluid prepared with the thickeners of Examples 1-3 was measured at room temperature.
[0048] 3. Add 0.2% crosslinking agent to the fracturing fluid base fluid prepared with the thickeners of Examples 1-3, and measure its crosslinking time.
[0049] 4. Add 0.2% crosslinking agent and 0.1% breaker to the fracturing fluid base fluid prepared with the thickeners in Examples 1-3, break the gel for 4 hours, filter, dry, weigh, and measure the gel residue.
[0050] 5. Add 400 mL of the fracturing fluid base fluid prepared with the thickener in Examples 1-3 into a 500 mL graduated cylinder, add 20% fine 60-mesh quartz sand, stir well, and then measure the sand suspension time.
[0051] Data Comparison Table
[0052] Example 1 (0.4%) 51.63 67 32.37 22.16 26.3 Example 2 (0.4%) 55.71 61 35.43 23.73 28.8 Example 3 (0.4%) 53.07 67 33.81 22.81 26.9 Commercially available guar gum (0.4%) 8.79 173 2.13 46.31 0 Commercially available polymer thickener (0.4%) 11.36 367 4.38 157.13 0
[0053] The results showed that the thickener used for fracturing wastewater preparation was superior to existing guar gum thickener systems and polymer thickeners in terms of solubility viscosity, crosslinking time, temperature and shear resistance, debonding residue, and sand suspension in all embodiments. The viscosity was greater than 51 mpa•s, the crosslinking time was less than 70s, the shear resistance viscosity at 90℃ was greater than 32 mpa•s, the debonding residue was less than 24 mg / L, and the sand suspension time was greater than 26h.
Claims
1. A thickener for preparing fracturing wastewater, characterized in that: The components and weight parts of the thickener are as follows: 24-30 parts of 2-acrylamido-2-methylpropanesulfonic acid, 24-28 parts of 2-hydroxyethyl acrylate, 24-28 parts of sodium vinyl sulfonate, 8-10 parts of sodium itaconic acid, 3-5 parts of Tween-60, 200-300 parts of deionized water, and 1-2 parts of azobisisobutyrazoline hydrochloride.
2. The thickener for preparing fracturing wastewater according to claim 1, characterized in that: The components and weight parts of the thickener are: 24 parts of 2-acrylamido-2-methylpropanesulfonic acid, 24 parts of 2-hydroxyethyl acrylate, 24 parts of sodium vinyl sulfonate, 8 parts of sodium itaconic acid, 3 parts of Tween-60, 200 parts of deionized water, and 1 part of azobisisobutyrazoline hydrochloride.
3. The thickener for preparing fracturing wastewater according to claim 1, characterized in that: The components and weight parts of the thickener are as follows: 27 parts of 2-acrylamido-2-methylpropanesulfonic acid, 26 parts of 2-hydroxyethyl acrylate, 26 parts of sodium vinyl sulfonate, 9 parts of sodium itaconic acid, 4 parts of Tween-60, 250 parts of deionized water, and 1.5 parts of azobisisobutyrazoline hydrochloride.
4. The thickener for preparing fracturing wastewater according to claim 1, characterized in that: The components and weight parts of the thickener are: 30 parts of 2-acrylamido-2-methylpropanesulfonic acid, 28 parts of 2-hydroxyethyl acrylate, 28 parts of sodium vinyl sulfonate, 10 parts of sodium itaconic acid, 5 parts of Tween-60, 300 parts of deionized water, and 2 parts of azobisisobutyrazoline hydrochloride.
5. The thickener for preparing fracturing wastewater according to claim 1, characterized in that: The preparation method of the thickener includes the following steps: Step 1: 24-30 parts of 2-acrylamido-2-methylpropanesulfonic acid, 24-28 parts of 2-hydroxyethyl acrylate, 24-28 parts of sodium vinyl sulfonate, 8-10 parts of sodium itaconic acid, 3-5 parts of Tween-60, 200-300 parts of deionized water, and 1-2 parts of azobisisobutyrazoline hydrochloride are sequentially added to a mixing tank. The stirring device is turned on to fully mix and disperse the components. Stirring is continued until all components are completely dissolved and the system is homogeneous, transparent, and free of agglomeration and precipitation, resulting in a uniformly stirred reaction material. Step 2: Transfer the reactants obtained in Step 1 to the reactor, and adjust the motor speed of the reactor to 100-150 rpm; Step 3: Introduce nitrogen gas into the reactor. After introducing nitrogen gas into the reactor for 30 minutes, heat the reactor to 45℃~55℃ and stir for 2h~3h. Step 4: After stirring for 2 to 3 hours, stop stirring and maintain the temperature at 45℃ to 55℃ for 12 to 16 hours, then allow it to cool naturally to room temperature. Step 5: After cooling to room temperature, transfer the material in the reactor to the cutting machine for cutting. After cutting, transfer it to the drying oven for drying at 105℃ for 12 hours. Step 6: After drying for 12 hours, allow the material to cool naturally to room temperature. Remove the material and transfer it to a pulverizer to be pulverized into fine particles of 0.5-1mm. This will produce a thickener for fracturing wastewater preparation.