CO_2驱替沥青质原油长岩芯实验及数值模拟

The Long Core Experiment and Numerical Simulation Research on Asphaltic Oil with CO_2 Flooding

针对CO2驱油过程中出现的沥青质固相沉积现象,综合考虑注气过程中沥青质在多孔介质中的沉积、吸附及堵塞效应,建立了CO2驱替含沥青质原油多相多组分渗流模型。以长岩芯实验为基础,拟合实验数据表明使用本文建立的模型计算的采收率与实验值更接近。同时对CO2气驱过程中沥青质沉积规律进行了探讨,模拟研究表明,注入CO2过程中,沥青质沉积首先发生在注入端;沥青质吸附也首先发生在注入端,但随着注入气量的增加,存在解吸附过程;沥青质沉积前缘与注气前缘一致,说明注入CO2是导致原油中的沥青质沉积的主要原因。

Gas injection especially carbon dioxide injection may cause asphaltene deposit. In this paper, in order to analyze me deposition trend and the influence of deposition on oil recovery, the multiphase multicomponent numerical model considering asphaltene deposition, adsorption and plugging is established. Then, based on long core flooding experiment, the fitting data indicate that the oil recovery calculated by this numerical model is closer to experiment results than that by regular model. Finally, the asphaltene deposition tendency during CO2 flooding is discussed, which indicate that higher accumulation of deposited asphaltene is shown primarily at the injection part of the core. Meanwhile, adsorbed asphaltene, also accumulated at the inlet side of the core, is desorbed gradually with the gas injection, asphaltene deposition front accord with injected gas front, which indicates that injected carbon dioxide is the main reason for asphaltene deposition.