Numerical simulation of different displacement modes of composite cold drive and thermal recovery in ordinary heavy oil reservoirs

To address the challenges in ordinary heavy oil reservoirs during the mid-to-late stages of steam huff and puff operations， such as low reservoir pressure， low oil-steam ratio， and channeling risks associated with conventional water injection for energy replenishment， this study focused on the C reservoir in Shengli Oilfield. Reservoir numerical simulation was employed to investigate the feasibility of composite cold drive and thermal recovery. Firstly， the mechanism of three kinds of normal temperature displacement media， such as viscosity reducer， polymer， and nitrogen foam， was characterized by numerical simulation. Then， the optimal normal temperature displacement medium was obtained by comparing its recovery characteristics. Finally， the feasibility of composite cold drive and thermal recovery was clarified by combining the effect of composite huff and puff operations at the production end. The results show that compared with the development effects of three different normal temperature displacement media， the input-output ratio of polymer flooding is up to 2.06， and the cumulative oil increment of nitrogen foam flooding is up to 1 884 t， but the input-output ratio is only 1.23. The cumulative oil increment of viscosity reducer flooding is only 723 t. After careful consideration， polymer flooding is selected as the optimal normal temperature displacement medium. Compared with pure cold drive and pure thermal recovery， the cumulative oil production after composite cold drive and thermal recovery increases by 7 328 t and 3 034 t， respectively. Using composite cold drive and thermal recovery technology can reduce the oil-water mobility ratio， delay the pressure decline， and extend the huff and puff cycle. In addition， under the premise that the pressure is supplemented， the liquid production and the production pressure difference can be appropriately increased to improve the composite cold drive and thermal recovery effect.