E. Delamaide (E. Delamaide) | F. Kalaydjian (F. Kalaydjian)
The use of foam to improve sweep efficiency during gas or steam injection has been studied since the end of the 50s. Foam reduces the mobility of gas or steam and this effect is amplified when the permeability increases, thereby correcting the effect of heterogeneity. However, although the consequences of the process are now generally recognized, it is still impossible to quantify them in terms of increase in oil production or reduction of quantities of gas/steam injected. The analysis of the field tests that have been performed in the past 20 years can help in the quantification and forecast of foam performance.
This paper presents conclusions resulting from a comprehensive analysis of steam-foam field tests. They show that, at the present time, steam-foam injection is most efficient in layered reservoirs. Injection of slugs of surfactant with steam in this type of reservoirs can yield an average 3.9bbl of incremental oil per kilogram of surfactant injected. The process is economically attractive even in these times of low oil prices, with a cost of $2 to $3 per barrel of incremental oil.
Continuous injection of surfactant with steam, more adapted to in-depth mobility control in non-stratified, heterogeneous reservoirs. It is a much less efficient method, with an average efficiency of 0.3 bbl of incremental oil per kilogram of surfactant injected, and is not economical.
Finally, guidelines for the design of steam-foam injection tests are provided, and injection pressure during steam-foam is related to steam quality and concentration of the surfactant.