In this paper experimental studies, to confirm and understand oil production accelerated when propane is used as additive during steam injection, are presented. Distillation experiments were performed using seven-component synthetic oil consisting of equal weights of alkanes. For comparison purposes three different distillations were investigated: dry-, steam- and steam-propane distillation, and the latter at a propane-steam mass ratio of 0.05.
Based on the experimental results, it can say that the components appear to boil off at lower temperatures with steam-propane injection than with pure steam injection (with reference to dry distillation). Lowering of hydrocarbon boiling points by steam-propane injection appears to be the fundamental phenomenon that can explain:
higher yields during distillation of the synthetic oil, and
production acceleration, reduction in produced oil density and viscosity, and improved steam injectivity during steam-propane displacement of crude oils.
The experimental results clearly indicate the importance of distillation on oil recovery during steam- or steam-propane injection.
The experimental procedure and method of analysis developed in this study will be beneficial to future researches in understanding the effect of propane as steam additive on actual crude oils.
Recent experimental and simulation studies confirm oil production is accelerated when propane is used as an additive during steam injection. Ferguson et al.(1) find that:
propane:steam mass ratio of 5:100 accelerates the start and peak of oil production by 20% and 13% pore volume steam injected compared to steam injection alone;
oil recoveries appear to be similar in all cases, 63% - 70% of Original Oil in Place (OOIP);
the start of production is practically the same for 0:100 and 1:100 propane:steam ratio and for 5:100 nitrogen:steam ratio requirement.
The authors show only lab results without any explanation about the propane effect in the oil displacement.
On the other hand Tinns (3) and Rivero (4) show with their experimental results the following: First, with steam-propane injection, start of oil production was accelerated by 17% compared to that with pure steam injection. In the field, this could translate into significant gains in discounted revenues and reduction in steam injection costs. Second, steam injectivity with propane as an additive was up to three times higher than that for pure steam injection. Third, oil production acceleration and injectivity increase were practically the same for runs with propane as a steam additive (irrespective of the propane:steam mass ratios). Propane appears to be a viable steam additive at propane:steam mass ratios as low as 2.5:100.
Plazas(5) additionally shows with distillation experiments of two crude oil types performed up to 300 ° C the following main results:
for the case of 25.1 ° API crude oil, the yield with steam-propane distillation, 63 wt% of original oil, is significantly higher than that with pure steam distillation, 42 wt% of original oil;
for the case of 34.2 ° API crude oil, yields for steam-propane and for pure steam distillations are very similar, about 54wt% of original oil.
In this work distillation experiments were performed using seven-component synthetic oil consisting of equal weights of the following alkanes: n-pentane (n-C5), n-hexane (n-C6), n-heptane (n-C7), n-octane (n-C8), n-nonane (n-C9), n-decane (n-C10), and n-pentadecane (n-C15).
