低浓度两亲聚合物驱油体系增效方法与机理研究

The associated structures of amphiphilic polymers formed in aqueous solution play an important role in the process of chemical flooding, which can increase the swept volume and improve the displacement efficiency. However, the viscosity and its emulsifying ability of the amphiphilic polymer system decrease greatly when the polymer concentration is lower than its critical association concentration (CAC), and its oil displacement efficiency is reduced due to absence of unique network structure. In this study, aiming at the shortcoming of amphiphilic polymers, a series of enhanced methods of low concentration amphiphilic polymers will be studied systematically and the evaluation criteria for determining associative strength by cyclodextrin method will be established. In particular, a host-guest system consisting of specifically designed β-cyclodextrin polymers and amphiphilic polymers via an “inclusion mechanism” is proposed in order to increase the oil displacement capability of the polymers at low concentrations. The formation conditions and host-guest matching mechanism of inclusion systems will be studied, and the synergistic mechanism of host and guest polymer at low concentration will be further discussed. The dynamic behavior of emulsified crude oil with low concentration inclusion system and the stabilization mechanism at the oil-water interface will be studied, and the corresponding emulsification kinetic model will be established. The relationship between the microstructure of the inclusion system and its capability of expanding swept volume or improving washing efficiency in the reservoir environment will be explored. Thus, it is expected that the properties of the inclusion system can be controlled by the molecular structures of the polymers involved, and its performance in oil displacement will be improved significantly than that of the system formed with the amphiphilic polymers alone.

两亲聚合物水溶液的缔合结构对化学驱体系扩大波及体积和提高洗油效率具有重要作用，但当两亲聚合物浓度低于临界缔合浓度（CAC）时，其溶液不能形成独特的缔合网络结构导致体系增粘及乳化能力减弱而影响驱油效率。针对两亲聚合物这一缺陷，系统性研究一系列低浓度两亲聚合物增效方法并建立环糊精法测定缔合强度的评价准则。提出设计合成特定系列β-环糊精聚合物与两亲聚合物，通过包合作用构筑主客体驱油体系的新思路来强化其低浓度下驱油效果。研究主客体聚合物驱油体系的匹配关系与形成条件，阐明两亲聚合物疏水缔合作用与主客体包合作用的协同增效机理。研究低浓度包合体系乳化原油的动态行为与油水界面稳定机制，建立相应的乳化动力学模型。探索油藏环境下包合体系的微观结构与扩大波及体积、提高洗油效率的关系，达到微观上包合体系分子结构可调控、宏观上驱油能力增强的目的，为低浓度高效包合驱油体系基础理论研究提供科学依据。

两亲聚合物是一种由于亲水性分子链上带有疏水基团从而具有两亲性能的水溶性聚合物。由于疏水基团的存在，两亲聚合物能够与环糊精主体聚合物产生包合作用，进而在低于临界缔合浓度（CAC）的前提下实现低浓高黏的目的。本文从分子设计的角度出发，设计合成了系列客体两亲聚合物与主体环糊精聚合物，并通过动态光散射、原子力显微镜、扫描电镜、流变等方法系统研究了低浓度两亲聚合物包合体系的分子结构、包合作用、环境因素以及各调控方法对体系的影响规律。并研究了低浓度两亲聚合物包合体系稳定乳状液的影响规律，通过室内的岩心驱替实验与微观驱油实验探究了包合体系提高采收率效果与机理。通过上述研究，阐明了两亲聚合物的调控规律以及低浓度两亲聚合物包合体系的作用机理，确定了高粘度—低浓度的两亲聚合物/环糊精聚合物二元体系，建立了低浓高效两亲聚合物的调控与乳化关系，揭示了其增强乳化作用的机理及乳状液的稳定机理，探明了驱替过程中低浓度两亲聚合物包合体系的动态影响规律。为两亲聚合物、两亲聚合物/环糊精聚合物二元复合驱驱油配方设计提供理论指导，为两亲聚合物驱提高采收率及采出液处理提供了理论基础，为高效驱油剂研制及驱油机理研究提供了科学依据。