The Influence of the Carbon Dioxide-steam Alternate Ratio and the Permeability Difference Affect Oil Recovery of Steam Composite Flooding

摘要

By means of 4 groups 10 m single-filled sand pipe models with the same permeability and 5 groups of double-filling sand pipe models with 10 m average 5 permeability difference of 1.00, 1.85, 2.80, 3.65 and 4.29, The optimal alternation ratio of carbon dioxide-steam flooding after steam flooding and the effectiveness of composite flooding to enhance oil recovery in a range of permeability difference are studied. The experimental temperature is 200°C, 4 groups of single-tube model oil displacement experiments are carried out. The steam is driven to water cut of more than 98%, 0.5 ml(0.0078 PV) high-temperature foaming agent is injected. Then carbon dioxide-steam is injected alternately by 1:1, 1:2, 1:3, 1:4. The result shows that the optimal ratio of carbon dioxide-steam is 1:1. Base on carbon dioxide-steam optimal proportion of 1:1 alternately 5 permeability difference for 1～4.29 double tube model oil displacement experiments are finished. The result shows that the composite flooding increase recovery is 13.29% ～ 23.82% under the condition of heterogeneity, the effect is remarkable.