考虑分子扩散作用的裂缝性油藏CO_2混相驱数值模拟

Numerical simulation study of CO_2 miscible flooding on fractured reservoir considering molecular diffusion

与常规油藏不同,在裂缝性油藏注气开采中,分子扩散作用是提高基岩原油采出程度的主要机理之一,然而这一机理常被忽略或者认识不足。为了研究分子扩散作用对裂缝性油藏CO2混相驱的影响,文中建立并推导了考虑分子扩散作用的多相、多组分双重介质数学模型,并应用有限差分方法和Matlab软件编程进行模型的求解,同时与基于国外某裂缝性碳酸盐岩油藏建立的常规Eclipse双重介质组分数值模型进行了验证对比。计算结果表明,所建模型比Eclipse常规数值模型模拟结果可比性强、实用性好,能够准确描述分子扩散对注气开发的影响,为提高裂缝性油藏注气动态预测技术的准确性提供一定帮助。

Diffusion in fractured reservoirs,unlike in unfractured reservoirs,is one of the main mechanisms to improve recovery efficiency of matrix.However the mechanism used to be ignored or inadequately understood.In order to study the effect of molecular diffusion on CO2 miscible flooding of fractured reservoir,A multi-phase and multi-component double-medium mathematical model considering molecular diffusion effects is established,derived and solved by finite difference method and Matlab software.The example analysis of a abroad firactured carbonate reservoir is carried out by applying the model established above,the results shows that the established model can accurately simulate the effect of molecular diffusion on CO2 miscible flooding of the fractured reservoir.Compared with the results of Eclipse conventional numerical simulation,it has better applicability and certain comparability.In addition,the effects of molecular diffusion on reserve recovery,interfacial tension and miscible area are comprehensively evaluated.The results show that molecular diffusion can effectively reduce interfacial tension,increase miscible area and enhance oil recovery.The model can provide some help to improve the accuracy of the fractured reservoir dynamic forecasting technology of gas injection.