摘要
水驱过程中油水岩反应不断改变导致产出原油的组分不断变化,深入探究其规律及机理有助于实现油藏的精准高效开发。本文将实验与分子动力学模拟相结合研究水驱过程中原油组分的变化规律及背后的油—水—岩作用机理。首先,长岩心驱替实验与族组分分析、傅里叶变换红外线光谱实验相结合系统地研究水驱过程中原油组分的变化规律。而后,分子动力学模拟从分子尺度探究油—水—岩作用机理。实验发现:无水采收期,产出原油组分含量变化较小。见水之后,饱和烃含量下降与—CH3和—CH2—吸收峰明显降低相验证,芳香烃含量上升与—CH—离平面振动和苯环对称伸缩振动增强相统一,胶质和沥青质含量小幅度上升对应于含氧/氮官能团吸收峰微弱增加。模拟发现:原油组分在方解石表面形成饱和烃—芳香烃—胶质—沥青质的吸附序列;水驱过程中水分子先后与饱和烃、芳香烃以及游离态胶质、沥青质接触并将其先后驱离方解石表面。最终,吸附态胶质、沥青质稳定存在,一端锚定在方解石表面,一端牵引着少量未被驱离的芳香烃和饱和烃。原油组分极性越强与方解石表面相互作用越强,静电力贡献越大、范德华力影响越小。原油组分极性越相近,分子间相互作用越强,含芳香族化合物之间发育π键相互作用,饱和烃通过范德华力与其他组分相互作用。原油组分之间相互作用使得原油组分在方解石表面表现为整体性的运动特征,同时造成非极性原油组分的滞留。本研究将实验与分子动力学研究相结合从分子尺度解释水驱过程中原油组分变化规律及背后的油—水—岩作用机理,为靶向提高采收率技术的应用提供理论支撑。
During water flooding, the crude oil-water-rock interaction constantly changes as the composition of produced oil keeps changing, and the changing rules and mechanisms are of great importance for the efficient development of oil reservoirs. Experiments and molecular dynamic simulations are combined in this study to investigate the composition changes of produced crude oil during water-flooding and reveal their in-depth mechanisms. Firstly, long core displacement experiments together with compound-grouped fraction experiments, and Fourier transform infrared spectroscopy experiments shed light on the change rules of crude oil composition during water-flooding. Secondly, molecular dynamic simulation is used to study the change mechanisms of crude oil compositions at a molecular scale. Experiments results showed that the change of the produced oil composition in the water-free stage is small, while this change is much larger at the water breakthrough stage. Saturated hydrocarbons keep decreasing as verified by the continuous decrease of-CH3 and-CH2-bands. Aromatic hydrocarbon increases significantly with the enhancement of-CH-off-plane vibration and benzene symmetrical stretching vibrations. Meanwhile, small increases of resin and asphaltene are also observed with a slight increase of the oxygen/nitrogen functional groups. Molecular dynamic simulation results indicated that the saturated hydrocarbon-aromatic hydrocarbon-resin-asphaltene adsorption sequence is adsorbed on calcite surfaces. In the water flooding process, water molecules successively contact with saturated hydrocarbon, aromatic hydrocarbon, and free resin and asphaltene, consequently displacing them away from the calcite surfaces. Finally, the adsorbed resin and asphaltenes remain stable, one end is anchored on calcite surfaces, and the other side is dragging a small amount of aromatic and saturate hydrocarbons that still have not been driven away. The stronger the polarity of the crude oil components, the stronger the interaction between crude oil comp
作者
柴汝宽
刘月田
何宇廷
CHAI Rukuan;LIU Yuetian;HE Yuting(State key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum-Beijing,Beijing 102249,China)
出处
《石油科学通报》
2021年第1期114-126,共13页
Petroleum Science Bulletin
基金
国家科技重大专项(2017ZX05032004-002)
国家重点基础研究发展计划(973计划)(2015CB250905)
中国石油重大科技专项(2017E-0405
2020D-5007-0203)联合资助。
关键词
碳酸盐岩油藏
原油组分
族组分分析
傅里叶变换红外光谱
分子动力学模拟
油—水—岩作用
carbonate reservoir
crude oil components
compound-grouped fractions analysis
Fourier Transform Infrared Spectroscopy
molecular dynamic simulation
crude oil-water-calcite interaction
