Experimental Study On Carbon Dioxide Assisted Steam Flooding In The Later Stage Of Steam Drive

The recovery efficiency of steam flooding in Qi 40 block has been greatly improved, however, the high temperature steam channeling in the late stage of steam drive is badly needed. The Qi 40 block output of natural oil sands produced four groups of permeability are basically consistent with the long single sand filling tube model and four groups of different permeability of long double sandpack model, permeability ratio were 1.85, 2.80, 3.65,4.29. The sand filled pipe model is divided into two types: a long 10 m diameter is 0.475 cm, the other is a long 10 m diameter is 0.443 cm. In the production process of the oil displacement model, the gas permeability of the model is linear with the L number ratio of the oil sand ratio in the case of the basic consistency of sand filling density. First of four groups of single model displacement experiment, experimental scheme is steam flooding and water rate reached more than 98% of the injected 0.5ml high temperature foaming agent, in the carbon dioxide and the steam at 1:1, 1:2, 1:3,1:4 proportion of alternating injection, carbon dioxide plug size 0.15 PV. Recovery rate increased by 4.09%, 4.47%, 1.93%, 2.56%,, but the 1:1 of the steam drive recovery rate is higher than the 1:2, so 1:1 is the optimal ratio of carbon dioxide and steam. To CO2 and steam optimal alternating ratio as the basis of four groups of different permeability of the twin model displacement experiments, the steam drive recovery was 61.48%, 56.22% and 40.60% and 35.88%. The enhanced oil recovery by carbon dioxide composite flooding was 13.29%, 15.51%, 20.95%, 23.82%, respectively. With the gradually increasing of permeability of steam flooding recovery decreased that of permeability is more strong reservoir heterogeneity. With the gradual increase of permeability ratio and steam flooding to improve oil recovery rate increases shows that carbon dioxide and high temperature foaming agent, foam into the high permeability layer of high permeable layers of plugging and to improve the low permeability layer producing degree of recovery rate can be greatly improved.