Numerical Research On Coke Zone Evolution And Combustion Front Propagation During THAI Process

Toe-to-Heel Air Injection(THAI)process is expected to have great potential in heavy oil recovery,and the evaluation of its stable state and displacement effect has been the main research direction in this field.In the process of displacement,coke zone and combustion front are the products of underground oil burning in situ,and also provide a large amount of heat for heavy oil viscosity reduction,which have an important impact on the development of fire flooding.Therefore,this paper mainly studies the evolution process of coke zone and combustion front in the results of simulation experiments.Based on the physical experiment,the numerical model of THAI is established and a good fitting effect is obtained.The coke zone after three-dimensional reconstruction based on the physical experiment is demonstrated.Moreover,the structural characteristics and evolution process of coke zone are studied combined with simulation experiments.The mathematical model is proposed to describe the propagation process of the combustion front.New parameters are proposed to study the override affection of the combustion front in propagation process.The effects of well space and gas injection rate of both coke zone and combustion front are mainly studied.The results show that the distribution range of coke from the coke zone and the surface temperature of combustion front are greatly affected from well space.Gas injection rate strongly determines the burning rate of coke and the override effect of combustion front.The laws and conclusions obtained in this paper are helpful to further deepen the understanding of the dynamic evolution during the process.What’s more,new idea and method for the following experimental research of THAI process are provided.