Experimental study on mechanism of inter-well steam channeling and steam channeling control capability of multicomponent thermal composite system in difficult- to-produce heavy oil reservoirs

Taking typical difficult-to-produce heavy oil reservoirs as the research object, a multi-scale physical simulation experimental device for heavy oil thermal recovery and corresponding similarity criteria were established. The evolution characteristics of the temperature field and saturation field, as well as the variation patterns of development indices during cyclic steam stimulation, were clarified, and the steam channeling control capability of multicomponent thermal composite system was evaluated. It is found that, during cyclic steam stimulation, steam channeling primarily occurs along the main flow line in the direction of the maximum pressure differential horizontally, while steam channeling appears in the upper part of the reservoir as a result of steam override vertically. High-temperature steam causes the separation of light and heavy components in the heavy oil, with the light components being preferentially produced. The interaction between high-temperature steam and the reservoir induces particle migration and mineral dissolution, accelerating the steam channeling and thus degrading the development performance in later cycles. As the steam temperature increases, the heavy oil in large pores is continuously produced, and the oil displacement efficiency increases significantly. The multicomponent thermal composite flooding systems including the nitrogen foam system, the high-temperature profile control and displacement system, and the thermosetting profile control system all effectively mitigate steam channeling and significantly enhance oil recovery. They rank as the thermosetting profile control system, the high-temperature profile control and displacement system, and the nitrogen foam system, in a descending order of the increase in pressure differential and the enhancement of oil recovery.