Analysis on the Main Influential Factors of Post-steam In-situ Combustion Performance in Heavy Oil Reservoir

We systematically studied the influential factors of post-steam in-situ combustion (ISC) project conducted in complex heavy oil reservoir in China using laboratory one-dimensional combustion experiments, reservoir simulation outputs, and data collected from the field application. The ISC project showed vastly different production performances in different regions of the field and two types of representative factors which acts on the whole ISC production stages were identified. As for a post-steam ISC process, oil viscosity and the pre-ISC recovery factor are the main reservoir parameters affecting the performance of ISC process and numerical model reflecting these two factors were established to analysis the production characteristics of producers. Type I group has a low oil viscosity ( ＜ 8000 mPa s) and a high steam-flooded recovery factor ( ＞ 30 %); after ISC treatment, these producers show a high initial water cut, while some experience channeling issues and hence produce a large quantity of flue gas. Type II group has a high oil viscosity ( ＞ 20,000 mPa s) and a low cyclic steam stimulation (CSS) recovery factor (15-20 %); these producers have a high air injection pressure exceeding the fracture pressure. Results show that corresponding remedial methods applied to these two well groups can effectively enhanced oil recovery.