页岩油吸附与游离定量评价模型及微观赋存机制

页岩油的赋存状态影响其可动性及可采性。为了定量评价不同赋存状态页岩油含量(吸附量与游离量)及其比例,建立了一系列数学模型,初步形成了页岩油吸附与游离定量评价理论框架,可用于分析:①非饱和吸附状态(0

Quantitative evaluation models of adsorbed and free shale oil and its microscopic occurrence mechanism

The occurrence state of shale oil affects both its mobility and recoverability.In order to quantitatively evaluate the shale oil contents in different occurrence states (adsorbed and free) and their ratios,a series of mathematical models and a theoretical framework for quantitative evaluation of adsorbed and free shale oil were established.They can be used to evaluate:①the contents of adsorbed and free single-component hydrocarbons under unsaturated adsorption conditions (0<p/p₀<1);②the contents of adsorbed and free single-component hydrocarbons and mixed hydrocarbons (remaining oil) and their ratios under saturated adsorption conditions (p/p₀ ≥ 1).The models have comprehensively taken into account the microscopic occurrence characteristics of shale oil (density of adsorbed and free phases,thickness of adsorbed phase),microscopic structure of shale pores (morphology,size,pore volume,specific surface area) and physical properties of shale reservoir (porosity,oil saturation,apparent density).According to the models and the target area of lacustrine shale oil in eastern China (a case study of Dongying sag),the microscopic occurrence mechanisms of shale oil are preliminarily revealed and the following understandings are obtained:① the contents of adsorbed and free oil and their ratios are jointly controlled by multiple influential parameters;② the impact of pore size is significant when the pore size is less than 50 nm or so,while when the pore diameter is larger than 50 nm or so,the impact is relatively weak,and the content of free oil depends on the volume of oil-bearing pores.