Evaluation of SAGD Performance in the Presence of Non-Condensable Gases

Abstract

In the steam assisted gravity drainage (SAGD) process, the addition of small amounts of non-condensable gases to steam may improve oil recovery. The gas accumulates at the top of the reservoir where it provides an insulation effect and forces the steam chamber to spread laterally. The result is a more efficient use of steam and the potential for greater recovery of oil.Six experiments were conducted in two different geometries to study the effect of non-condensable gas on the performance of SAGD. These experiments consisted of steam-only, steamcarbon dioxide and steam-n-butane injection. Three SAGD experiments were carried out in a scaled 3-D model packed with crushed limestone premixed with a 12.4° API heavy crude. In these experiments, the steam-only case had the highest recovery, as expected. However, using carbon dioxide or nbutane with steam reduced the steam consumption. In both those cases, recovery was lower than the steam-only case.The other SAGD experiments were carried out using limestone core plugs saturated with the same heavy oil. Similar trends were observed for core plug experiments; however, the recovery was better when n-butane was added to steam. The presence of n-butane had a positive effect on the oil recovery and required less steam consumption than the other two cases.Differences between the experiments were identified by means of analytical modeling. All the experiments were modeled with respect to Butler's SAGD theory and Reis' linear model. The results of the 3-D experiments were matched by all models, whereas the results of the core scaled experiments were better represented with Reis' linear model because of the heterogeneity present in the core plugs.The addition of non-condensable gas to steam in a SAGD operation was evaluated using physical models of different geometries. The experimental results indicated that for both geometries, steam consumption was reduced by using either carbon dioxide or n-butane. More experimental studies are needed to asses the effect of non-condensable gas addition on increasing oil recovery.

Performance of a SAGD Process with Addition of CO2, C3H8, and C4H10 in a Heavy Oil Reservoir

“…Oil recovery is the highest for steam-only SAGD compared to all the solvent(s)-aided SAGD process. This finding is also found in the laboratory SAGD experiments (Canbolat et al, 2004). Overall, the best result for the solvent(s)-aided SAGD process (including one solvent addition, double and triple solvent mixture addition) is achieved with 5% volume addition of C 4 H 10 in the C 4 H 10 -SAGD process.…”

Machine-Learning Approach for Forecasting Steam-Assisted Gravity-Drainage Performance in the Presence of Noncondensable Gases

“…Reduced steam-chamber growth and oil rates were observed in the presence of NCG in other experiments. 4 However, comparable oil recoveries were observed with and without NCG in core plug experiments. Other sets of experiments to evaluate the wind-down process by injecting NCG after SAGD resulted in a recovery of 12.5%.…”

“…The need for high volumes of steam, particularly in thin, low-quality reservoirs, is a significant restriction of SAGD due to the requirement of continuous steam production on the surface. This could be avoided by adding noncondensable gases (NCG) such as carbon dioxide (CO 2 ) or methane (CH 4 ) (i.e., the steam and gas push (SAGP) mechanism) or additionally by injecting liquefied petroleum gases such as propane (C 3 H 8 ) or n -butane ( n -C 4 H 10 ) (i.e., the vapor extraction (VAPEX) process). , In steam and gas push (Figure ), NCG such as carbon dioxide (CO 2 ), methane (CH 4 ), and nitrogen (N 2 ) are coinjected with steam. Because NCG have a lower density than condensate steam, they begin to rise within the reservoir and accumulate at the top of the depletion chamber …”

3D experimental investigation on enhanced oil recovery by flue gas assisted steam assisted gravity drainage

“…Flue gas, usually composed of carbon dioxide and nitrogen, has the properties of noncondensate gas that experiences no obvious condensation (Dong et al, 2017), can steadily exist in the stream chamber (Bagci and Gumrah, 2004;Li et al, 2019;Yuan et al, 2010) to migrate to the top of the steam zone to provide a barrier to reduce heat loss (Heron et al, 2008), and diminish the pressure of steam chamber (Yee and Stroich, 2004). In addition, some heat can be transferred to cold oil to promote the development of the steam chamber again to enhance the recovery factors (Aherne and Birrell, 2002;Canbolat et al, 2004;Wang et al, 2017). Non-Condensable Gasses not only can enhance the thermal efficiency of SAGD (Liu et al, 2012), but also can enhanced gas from shale layers recovery, Davarpanah and Mirshekari (2019) proposed a modified unipore diffusion model to study adsorption of methane and carbon dioxide at different pressure ranges, the result shows that the production of gas from shale layers is increased because of methane and carbon dioxide.…”

“…The results showed that the heat spread ranges of steam zone and hot water zone are expanded because of injecting flue gas, and the heat utilization rate was improved. The flue gas can accumulate at the top of the reservoir where it provides an insulation effect and forces the steam chamber to spread laterally (Canbolat et al, 2004). Ahmadi (2015) utilized numerical simulation method to compare with effect for EOR different gas injection methods (N 2 , CO 2 , produced reservoir gas, and flue gas), and found that the ultimate oil recovery was greatest for flue gas injection.…”