Experimental and analytical modeling studies of steam injection with hydrocarbon additives to enhance recovery of San Ardo heavy oil

摘要

Experimental and analytical studies have been carried out to better understandproduction mechanisms of heavy oil under steam injection with propane and petroleumdistillate as steam additives. The studies have been conducted for heavy oil from SanArdo field (12oAPI, 2800 cp at 53.3oC), under current reservoir conditions.The experiments consist of injecting pure steam, steam-propane, and steampetroleumdistillate into a vertical cell containing a mixture of sand, water and San Ardooil. The injection cell (68.58 cm long with an ID of 7.376 cm) is placed inside a vacuumjacket, set at the reservoir temperature of 53.3oC. Superheated steam at 230oC is injectedat 5.5 ml/min (cold-water equivalent) simultaneously with propane or a petroleumdistillate slug. The cell outlet pressure is maintained at 260 psig. Six runs wereperformed, two runs using pure steam, two steam-propane runs using 5:100propane:steam mass ratio, and two steam-petroleum distillate runs using 5:100petroleum distillate:steam mass ratio.We develop a simplified analytical model that describes steam frontadvancement and oil production for the 1D displacement experiments. The modelincorporates heat and material balance, fillup time and Darcy??????s law pertaining to theinjection cell. The analytical model results are compared against the experimental data toverify the validity of the model.The main results of the study are as follows. First, experimental results indicatethat compared to pure steam injection, oil production was accelerated by 30% for 5:100propane:steam injection and 38% for 5:100 petroleum distillate:steam injection respectively. Second, steam injectivity with steam-propane and steam-petroleumdistillate increases to 1.4 and 1.9 times respectively, compared with pure steam injection.Third, steam front advancement and oil production data are in good agreementwith results based on the new analytical model. The analytical model indicates that theoil production acceleration observed is due to oil viscosity reduction resulting from theaddition of propane and petroleum distillate to the steam. Oil viscosity at the initialtemperature with pure steam injection is 2281 cp, which is reduced to 261 cp withsteam-propane injection and 227 cp with steam-petroleum distillate injection.