The propagating characteristics of combustion fronts and coke zones in the combustion assisted gravity drainage process were studied using 3D physical simulation experiments. The main mechanisms and factors affecting stable propagation of the combustion fronts were discussed. The experimental results show that the propagation of combustion front can be divided into startup stage, radial expands stage and moving forward stage. The top oil layer is ignited first at the startup stage. Ignition temperature, ignition time and air injection rate are the key parameters for successful ignition. At the radial expanding stage the combustion front grows in size and expands radically and downwards like a funnel, and the air injection rate should match the area of combustion front. After the combustion front propagates beyond the "toe" position, the burning zone would advance along the horizontal well at a certain angle. The controlled gas override and gas seal of the coke in the horizontal well contributes significantly to the overall stability of the process. In field pilot testing, well pattern, ignition parameters and regime of injection and production should be optimized to ensure the stable propagation of the combustion front.%通过三维物理模拟实验研究水平井火驱辅助重力泄油过程中不同阶段燃烧前缘和结焦带的展布规律,并分析各阶段燃烧前缘稳定推进机理及影响因素.燃烧前缘的扩展可分为点火启动、径向扩展和向前推进3个阶段.点火启动阶段,油层上部最先实现点火,点火温度、点火时间和注气速率是该阶段的关键操作参数.径向扩展阶段,燃烧前缘呈“漏斗状”继续向四周和下部扩展,此时调控的关键在于注气速率与燃烧前缘的面积相匹配.燃烧前缘推进到水平井趾端射孔段后,以一定的倾角朝水平井跟部方向推进,超覆式燃烧和结焦带对水平井筒的封堵是该阶段实现稳定泄油的重要原因.在矿场试验中,应从井网模式、点火参数和注采制度等方面采取优化措施来维持燃烧前缘的稳定推进.
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