CaCl_2对HPAM溶液流变性能的影响机制研究
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摘要
无机盐离子特别是二价无机盐离子能显著降低HPAM溶液的粘度,对HPAM溶液流变性能产生重要的影响。考察了CaCl_2对HPAM溶液粘度、HPAM流体力学半径、HPAM微观形貌的影响,并通过核磁共振技术分析了CaCl_2对HPAM溶液流变性能影响的作用机理。结果表明,高浓度CaCl_2会加剧HPAM溶液粘度的降低,而低浓度CaCl_2(0. 5 mmol/L)具有抑制HPAM溶液粘度降低的作用,流体力学半径增大是低浓度CaCl_2抑制HPAM溶液粘度降低的主要原因; CaCl_2具有提高HPAM流体力学半径的作用,该作用与CaCl_2、HPAM羧酸根离子的浓度密切相关,随着体系中羧酸根离子浓度的升高,Ca~(2+)的最低交联浓度降低,对C(COO-)-C(CaCl_2) min的关系曲线进行拟合,得到关系式y=8. 82×10~(-8)x~(-0. 73),线性相关系数R~2> 0. 99。该研究阐明了CaCl_2对HPAM溶液流变性能的影响机制——Ca~(2+)/COO~-螯合作用,对我国西部高盐高钙油藏利用廉价HPAM研制耐抗性冻胶堵剂具有重大的参考意义。
Inorganic salts,especially two valent inorganic salts,can significantly reduce the viscosity of HPAM solution and have an important influence on the rheological properties of HPAM solution. The effect of CaCl_2 on the microstructure,hydrodynamic radius and viscosity of HPAM were investigated. Besides,the mechanism of CaCl_2 on the rheological properties of HPAM was studied by NMR. The results indicate that: CaCl_2 solution with high concentration decreases the viscosity of HPAM,while the one with low concentration( 0. 5 mmol/L) increases the viscosity of HPAM; The increase of the hydrodynamic radius is the main reason for the decrease of the viscosity of HPAM solution with low concentration of CaCl_2; CaCl_2 has the effect of increasing the HPAM hydrodynamic radius,which is closely related to the concentration of the carboxylic acid root ions of CaCl_2 and HPAM molecules. With the increase of the concentration of carboxyacid ion in the system,the minimum crosslinking concentration of Ca2 +decreases.The relationship curve of C( COO-)-C( CaCl_2) min is fitted,and the relational y = 8. 82 × 10-8x-0. 73( R2> 0. 99) is obtained,which is the basic reason why the CaCl_2 solution with low concentration can improve the HPAM hydrodynamic radius and decrease the viscosity loss rate. The mechanism of CaCl_2 on the rheological properties of HPAM solution is clarified,which is Ca2 +crosslinking with the carboxyl in HPAM canprovide theoretical reference and support for the future development of the salt-resistant polymer and gel.It is of great significance for developing resistant gel plugging agents by using cheap HPAM for high salt and high calcium reservoirs in Western China.
Inorganic salts,especially two valent inorganic salts,can significantly reduce the viscosity of HPAM solution and have an important influence on the rheological properties of HPAM solution. The effect of CaCl_2 on the microstructure,hydrodynamic radius and viscosity of HPAM were investigated. Besides,the mechanism of CaCl_2 on the rheological properties of HPAM was studied by NMR. The results indicate that: CaCl_2 solution with high concentration decreases the viscosity of HPAM,while the one with low concentration( 0. 5 mmol/L) increases the viscosity of HPAM; The increase of the hydrodynamic radius is the main reason for the decrease of the viscosity of HPAM solution with low concentration of CaCl_2; CaCl_2 has the effect of increasing the HPAM hydrodynamic radius,which is closely related to the concentration of the carboxylic acid root ions of CaCl_2 and HPAM molecules. With the increase of the concentration of carboxyacid ion in the system,the minimum crosslinking concentration of Ca2 +decreases.The relationship curve of C( COO-)-C( CaCl_2) min is fitted,and the relational y = 8. 82 × 10-8x-0. 73( R2> 0. 99) is obtained,which is the basic reason why the CaCl_2 solution with low concentration can improve the HPAM hydrodynamic radius and decrease the viscosity loss rate. The mechanism of CaCl_2 on the rheological properties of HPAM solution is clarified,which is Ca2 +crosslinking with the carboxyl in HPAM canprovide theoretical reference and support for the future development of the salt-resistant polymer and gel.It is of great significance for developing resistant gel plugging agents by using cheap HPAM for high salt and high calcium reservoirs in Western China.
引文
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