Experimental investigation of in situ combustion (ISC) in heavy oil thermal recovery

With the intensification of global climate change, there is an urgent need to change the energy structure of oil and gas to reduce the impact on the environment. As a thermally enhanced oil recovery technique, in situ combustion (ISC) is very important for reducing carbon emissions in the petroleum industry through the comprehensive utilization of oil displacement and storage in reservoirs. In this paper, the similarity parameters of a three-dimensional (3D) physical simulation of ISC were determined, the temperature field changes in the combustion process were monitored in real time, and a 3D field map was obtained. The oxidation characteristics of heavy oil were examined via thermogravimetry (TG), and the results showed that the oxidation process of heavy oil had three stages. The experimental results indicated that ISC could greatly increase the reservoir temperature, improve the quality of crude oil through high-temperature cracking, reduce the viscosity of crude oil and enhance the oil fluidity. The recovery factor from the ISC reached 53.27%. The formation of the coking zone was caused by various chemical and physical changes that occurred at high temperatures. Moreover, the formation process led to a concentration of the remaining oil in the small-aperture channels in the coking zone; this reduced the fluidity and increased the production difficulty. This study could provide guidance for the development of heavy oil reservoirs.