تأثير خواص بخار بر عملكرد بازيابي SAGD

With the decline of light oil resources an‎d the growing importance of heavy oil reservoirs, thermal enhanced oil recovery methods particularly Steam-Assisted Gravity Drainage (SAGD) have attracted significant attention. The performance of this process is highly dependent on the properties of the injected steam an‎d the geological characteristics of the reservoir. Parameters such as steam quality, steam–oil ratio (SOR), injection rate, an‎d the presence of gaseous impurities play a decisive role in thermal efficiency an‎d ultimate oil recovery. In this study, the effects of steam quality an‎d the presence of methane as a non-condensable gas (NCG) on SAGD performance were investigated using numerical simulation in CMG-STARS. First, the impact of steam quality was eva‎luated in a homogeneous reservoir model for three values of 0.80, 0.90, an‎d 0.95. The results indicate that increasing steam quality improves process performance, such that the oil recovery factor increased from 38.5% to 49% an‎d ultimately to 58%, while the steam–oil ratio decreased from 2.6 to 2.4 an‎d then to 2.2, respectively. Considering the balance between thermal efficiency an‎d steam consumption, a steam quality of 0.90 was selec‎ted as the base an‎d optimal condition for subsequent analyses. Subsequently, in a heterogeneous reservoir model, the effect of methane impurity in the injected steam was examined for volumetric steam–methane ratios of 80/20, 50/50, an‎d 20/80. Simulation results demonstrate that increasing methane content leads to reduced thermal efficiency, lower oil recovery, an‎d higher steam–oil ratios. Specifically, the oil recovery factor ranged from a minimum of approximately 26.6% to a maximum of about 43.3%, while the steam–oil ratio increased up to 3.6 an‎d decreased to about 2.8 under the most favorable conditions. This behavior is attributed to the accumulation of non-condensable gas in the upper part of the steam chamber, which suppresses steam condensation an‎d disrupts effective heat transfer to the reservoir oil an effect that is intensified under heterogeneous reservoir conditions. Steam quality an‎d the concentration of gaseous impurities are identified as two critical parameters in the design an‎d optimization of the SAGD process. Neglecting these factors may result in overestimation of oil recovery an‎d underestimation of the steam–oil ratio in engineering eva‎luations.

روح اله هاشمي

حميدرضا شاه وردي , محسن محمدي