疏水缔合水溶性聚合物在多孔介质中缔合机理研究

【作者】 纪朝凤；

【导师】 李允；

【作者基本信息】 西南石油学院 ， 油气田开发工程， 2004， 博士

【摘要】 疏水缔合聚合物是目前理想的抗盐抗温和抗剪切的新型聚合物。由于其独特的耐盐抗温及其抗剪切性，使缔合聚合物成为目前世界石油业，特别是三次采油领域聚合物未来发展的趋势和方向。 目前，大多数研究发现，在宏观条件下，疏水缔合聚合物溶液浓度在低于临界缔合浓度(CAC)时，其溶液主要发生分子内缔合；在高于CAC时，聚合物溶液中主要发生分子间缔合，使得疏水缔合聚合物溶液中产生“结构”，形成“动态物理胶联网络结构”，增加其流体力学体积，大大提高了聚合物溶液的粘度。 由于这种缔合作用的存在，在剪切作用下，这种超分子结构的动态物理交联网络容易被破坏，因而溶液呈现典型的假塑性行为；但随着剪切作用的降低或消除，大分子链间的物理交联重新形成，其粘度又将恢复。从而表现出独特的抗剪切的特性；小分子电解质的加入使溶液的极性增加，疏水缔合作用增强，具有明显的抗盐性；同时由于疏水缔合是熵驱动的吸热效应，其溶液具有一定的耐温、增粘性。从而表现出了疏水缔合聚合物溶液独特的抗温、抗盐、抗剪切的特性。 本文从油田应用的角度出发，应用不同的方法，从各个方面研究了疏水缔合聚合物在多孔介质中的缔合，探讨影响疏水缔合聚合物在多孔介质中缔合的因素，分析了疏水缔合聚合物在油田中的应用，必须进一步降低其在油藏条件下的临界缔合浓度。 因此，本文的重点主要放在疏水缔合聚合物溶液在多孔介质中的缔合存在性及其缔合行为的描述和影响疏水缔合聚合物在多孔介质中缔合的因素研究。 首先通过文献调研，疏水缔合聚合物在宏观条件下的缔合机理及其影响因素；然后通过室内实验，研究所选用的疏水缔合聚合物在温度为60℃，矿化度为5309.74mg／L的条件下的临界缔合浓度CAC为1000mg／L。在浓度高于CAC以上，其溶液具有很好的抗剪切性和剪切恢复特性。 在模拟油藏条件下疏水缔合聚合物溶液流变性研究中，发现在油藏条件下，其溶液形成分子间缔合的浓度范围发生明显变化。 通过应用粒间流速和阻力系数，研究疏水缔合聚合物在多孔介质中的渗流特征，发现在一定的浓度条件下，溶液的阻力系数表现出了在宏观条件下当聚合物溶液高于临界缔合浓度时，才具有的抗剪切性和剪切恢复性。而吸附滞留实验研究表明，在多孔介质中，疏水缔合聚合物的这种现象并不是由于疏水缔合聚合物溶液的大量吸附滞留造成的累积效应所应起的，说明疏水缔合聚合物在多孔介质中确实存在明显的缔合作用。 进一步研究表明，当聚合物溶液浓度高于1000mg／l～1100mg／l范围内，即高于宏观条件下的临界缔合浓度时，疏水缔合聚合物溶液在多孔介质中才会发生缔合行为。 因此，研究认为在多孔介质中疏水缔合聚合物也存在一个临界缔合浓度点，这与其在的多孔介质的环境有很大的关系。其中聚合物溶液的浓度、所处的压力、温度和多孔介质本身的特性有很大的关系，而矿化度和流速对临界缔合浓度影响不大。 本文通过验证了疏水缔合聚合物在多孔介质中存在缔合，并考察了影响其缔合的影响因素，为进一步降低油藏条件下聚合物溶液的临界缔合浓度，将这种新型耐温抗盐抗剪切的疏水缔合聚物广泛应用到油田中提供理论指导。 关键词:疏水缔合聚合物，流变性、模拟油藏环境，多孔介质，渗流特征，缔合行为，临界缔合浓度，影响因素更多还原

【Abstract】 Hydrophobically associating polymer (HAP) is a new and ideal polymer at present, which has the characteristics of salt -resistance, thermal endurance and shear-resistance. Its unique properties have made it the trend and direction of the future development of polymer in the world oil industry, especially in the field of tertiary oil recovery.Nowadays, most research results have shown that, microscopically, blow the CAC, intra-molecular association will occur the HAP solution; while above CAC, intermolecular association occurs instead, forming dynamically physical cross-linked network structure in the HAP solution .As a result, the fluid mechanical volume is increased, as well as the viscosity of the solution.Due to this association reaction, the dynamically physical cross-linked network of the super-molecular structure can be easily destroyed on the condition of shear, therefore the solution exhibits typical pseudo-plastic behavior; however, as the shear effect decreases or disappears, the cross-links of macromolecular chains will be formed again, and polymer solution viscosity restores again. Therefore. The polymer shows the unique property of shear-resisting. The addition of small-molecule electrolyte increases the polarity of the solution can enhances the hydrophobically association action, thus making it obviously salt-resistance. At the same time, the solution has a feature of thermal endurance and viscosity increase, which result from the entropy-driving endothermal effect of association. All of the characteristics mentioned above can account for that HAP solution uniquely salt-resistance, thermal -endurance and shear-resistance.Starting at the application of HAP in oil field, the association behavior was investigated in different ways and different angels, and the factors influencing this association behavior in porous media was also studied. And the conclusion was drawn that the condition of the application of HAP in the oilfield is that the CAC of polymer should be lowered further.Therefore, the focus of this paper is on the existence of the association of HAP in the porous media, the description of association behavior and the study on the factors affecting the association behaviors.Through investigation of Hydrophobically associating polymer documents, the association mechanism and influencing factors of which had been obtained under macroscopic condition, after experiment in lab, the critical associating concentration (CAC) was 1000mg/l at 60Cand at 5309.74mg/l salinity for Hydrophobically associating polymer selected and investigated. When polymer solution concentration is above CAC, the characteristics of shearing thinning and shearing resistance exhibited.During the course of study on hydrophobically associating polymer rheological properties .we drew a conclusion that under the condition of simulate oil reservoir, the concentration scope of intermolecular association varies obviously.Employing inter-granule velocity and factor of resistance to study on the characteristics of Hydrophobically associating polymer flowing through in porous media. And the characteristics of shearing thinning and shearing resistance exhibited under macroscopic condition when the concentration is above CAC. And the absorb-resort experiment results indicated that the phenomena mentioned above is not the result from accumulation effect in the porous media, which results from large absorb-resort of Hydrophobically associating polymer molecules. So we can draw a conclusion that hydrophobically associating polymer has shown obvious association behavior in porous media.The further step research results indicated that association behavior of Hydrophobically associating polymer would occur only if the concentration is higher than 1000mg/1 and 1 100mg/1, namely called CAC under the condition of microscope.Research results showed that there exists critical association concentration in porous media for hydrophobically associating polymer, which has close relationship with the surroundings of porous media such as concentration, temperat更多还原