基于响应面方法的CO2重力稳定驱油藏优选

Optimum selection of CO2 gravity-stable flooding reservoir based on response surface methodology

周元龙 赵淑霞 何应付 王锐

中国石化石油勘探开发研究院，北京 100083

Research Institute of Exploration and Development, SINOPEC, Beijing 100083, China

江苏油田是典型的复杂断块油田，水驱后如何提高油藏采收率是目前存在的主要问题。CO2重力稳定驱是CO2非混相驱中能够最大程度提高断块油藏采收率的驱替方式，其实施的关键是选择合适的目标油藏。通过数值模拟研究，引入响应面试验设计和分析方法，考虑了油藏的渗透率、倾角、渗透率级差、原油黏度、油层厚度等5个主要影响因素，以换油率为评价指标，得到了CO2重力稳定驱响应面模型，并研究了各参数对CO2驱油效果的影响规律。结果表明：渗透率级差较大、原油黏度较高的油藏，实施CO2重力稳定驱的效果较差；倾角较大、渗透率较高、厚度较大的油藏，实施CO2重力稳定驱的效果较好。根据油藏地质参数计算换油率，基于换油率的高低对目标油藏进行排序，为优选实施CO2重力稳定驱油藏提供了依据。

Jiangsu Oilfield is a typical complex fault-block oilfield. How to improve reservoir recovery after water flooding is the main problem at present. Gravity-stable CO2 flooding is the most effective way to improve oil recovery in all non-miscible CO2 flooding. The key to its implementation is how to select suitable target reservoirs. Through numerical simulation, the response surface model of gravity-stable flooding was obtained by introducing the experimental design and analysis method of response surface. Considering five factors of permeability, dip angle, permeability gradient, crude oil viscosity and reservoir thickness, and taking oil exchange rate as evaluation index, the influence rule of each parameter on CO2 flooding effect was studied. The results show that the effect of CO2 gravity-stable flooding is poor when the permeability gradient is large and the viscosity of crude oil is high. The effect of CO2 gravity-stable flooding is better in reservoirs with larger dip angle, higher permeability and thicker thickness. The oil exchange rate is calculated according to the reservoir geological parameters; the target reservoir is ranked based on the oil exchange rate and is optimized, which provides a basis for the optimization of CO2 gravity-stable flooding reservoir in the oilfield.

10.6056/dkyqt201906017