超稠油的碳纳米-微波协同作用降黏机理研究

70% global oil reserves are heavy oil. The high viscosity and poor liquidity of heavy oil lead to many difficulties in its development, storage and transportation. In recent years, as a new technology, viscosity reduction with nanotechnology has become a hot spot in heavy oil study. However, because of nanoparticles’ poor dispersion and its high cracking reaction temperature, nanotechnology cannot be widely applied. This project proposes a super heavy oil viscosity reduction method under synergism of carbon nano-catalyst and microwave. In this project, the viscosity reduction mechanism of using microwave alone function on super heavy oil is studied. New type of low temperature carbon nano-catalyst is developed and its structure characterization is carried out. Furthermore, the viscosity reduction mechanism of the developed carbon nano-catalyst acting on super heavy oil is studied. And then a physical model in nanoscale for the interaction among microwave, carbon nano-catalyst and super heavy oil is established. The influence rule for the component of super heavy oil, types and components of carbon nano-catalyst, microwave characteristics on the modification conditions and viscosity of the heavy oil is clarified. Main control factors are identified and the quantitative prediction model is developed for the viscosity reduction under the co-influence of carbon nano-catalyst and microwave. Also, the viscosity reduction mechanism is revealed under synergism of carbon nano-catalyst and microwave for super heavy oil. The expected results will lay a foundation on super heavy oil transportation with high viscosity reduction and drag reduction.

全球范围内70%的石油储量都属于稠油。稠油因粘度高、流动性差，导致其在开发、储运等方面存在诸多困难。近年来，纳米技术作为提高稠油降黏的一项新技术成为研究热点，但因纳米颗粒分散性差、裂解反应温度高等问题使其无法推广应用。本项目提出一种利用低温新型碳纳米催化剂协同微波作用进行超稠油改质降黏的方法。主要研究包括：通过实验研究探明微波作用于超稠油的降粘机理；制备低温新型碳纳米催化剂并进行结构表征，通过实验研究探明碳纳米催化剂作用于超稠油的降黏机理；构建纳米尺度下微波及碳纳米催化剂与超稠油间的相互作用模型，查明超稠油组分、碳纳米催化剂种类及组分、微波特性等对超稠油改质发生条件、稠油黏度等特征的影响规律；深入研究碳纳米-微波协同作用下影响超稠油改质降黏效果的主控因子并构建稠油粘度定量预测模型，揭示超稠油在碳纳米-微波协同作用下的降黏机理，为最终实现超稠油管输过程中高效降黏减阻目标奠定基础。

本项目围绕所提出的碳纳米-微波协同效应，开展了超稠油在碳纳米-微波协同作用下的降黏机理研究。通过研究发现： .①超稠油的致黏机理：(a)辽河超稠油不含蜡，其胶质含量达42.29wt%、沥青质含量达15.81wt%；(b)胶质沥青质中氮化物、硫化物的大分子在苯环π-π共轭作用下形成缔合体微粒，电负性强的杂原子（硫、氮、氧）以氢键形式使沥青质的层状堆积变得紧密，进而形成胶质沥青质超分子结构，不易与活性组分充分接触，抑制了改质降黏效果。.②碳纳米复合降黏剂作用下的超稠油降黏机理：(a)油溶性降黏剂分子极性基团能够吸附胶质沥青质形成氢键吸附作用，增大分子间距，增加降黏体系分子势能和非键势能，长链烷基促进降黏剂分散性和溶解性，抑制聚集体缔合，达到超稠油降黏目的；(b)碳纳米管凭借优良导电和导热性能提升稠油分子势能，增大分子间距；(c)碳纳米复合降黏剂分子的长直链烷基及极性芳基、酯基等提高了降黏剂与胶质沥青质的吸附能力，防止结构再聚集，使稠油黏度降低。.③碳纳米-微波协同作用下的超稠油降黏机理：(a)微波辐射的“非热效应”可降低反应活化能，减少胶质及沥青质重组分；微波辐射的选择特性对胶质沥青质等极性大分子效果显著；(b)碳纳米复合降黏剂可更好地吸收微波，提高微波降粘效果；微波可使碳纳米复合降黏剂在较低的反应温度下产生活化作用，促使稠油化学裂化反应程度加大，实现稠油不可逆降粘。.④含水稠油在碳纳米-微波协同作用下的降黏机理：(a)单独微波作用对含水稠油四组分含量的影响较大，但油样的缩合度增大，芳香烃减少，会有吸附水残留，影响降黏效果；(b)碳纳米复合降黏剂可使芳香烃加氢或开环；(c) 碳纳米-微波协同作用能够促使胶质沥青质大分子裂解成藿烷甾烷类和多环芳香烃，促进加氢反应，同时水分的存在也增强了含氮物质的裂解，起协同降黏效果。