关键词: 中—低成熟度, 页岩油, 原位转化, 热-反应流耦合, 组分模型

Abstract: China’s onshore shale oil reserves are abundant with low maturity on the whole. The reservoirs include the remained hydrocarbons and unconverted solid organic matter, which have poor producing ability and insufficient formation energy, thus making it difficult to obtain economic yield only by conventional fracturing transformation technology. Therefore, in-situ underground heating and conversion technology has to be applied for effective exploitation. Along with the formation heating, multi-stage parallel chemical reactions occur between kerogen and retained hydrocarbons, and the fluid composition and reservoir space both change significantly, as a result of which the thermal-reactive flow coupling mechanism in the in-situ conversion process becomes more complex. For this problem, considering the effects of in-situ conversion decomposition of kerogen and hydrocarbons cracking on fluid composition and rock pore-permeability parameters, the authors establish a mathematical model of thermal-reactive flow coupling during the in-situ conversion of shale reservoirs and a numerical solution method. The validity of the mathematical model was verified by numerical calculations, the effects of heating temperature, heating pattern, initial kerogen concentration and other parameters on the development effect were analyzed, and the feasibility of exploitation by in-situ conversion of shale reservoirs was evaluated from the perspective of economic benefits. The in-situ conversion process of shale reservoirs was analyzed in terms of the thermal-reactive flow, and the proposed model and calculation method can be used to evaluate the development effect of in-situ conversion process of shale reservoirs and provide theoretical support for the efficient development of medium to low maturity shale reservoirs.

Key words: medium to low maturity, shale oil, in-situ conversion, thermal-reactive flow coupling, component model