致密油是非常规油气资源的重要组成部分,资源潜力巨大,是今后较为现实的油气资源接替领域之一.中国致密油藏勘探开发起步较晚,总体研究程度较低,特别是对致密油藏有效储层物性下限的研究相对薄弱.通过分析致密油成藏动力学机制,以生油增压作为油气充注的主要动力,毛细管压力为主要阻力,确定油气充注的临界条件;即生油增压等于毛细管力,建立判别致密油藏有效储层物性下限的方法.应用所建立的有效储层物性下限的判别方法计算出玛湖凹陷西斜坡风城组组致密储层在埋深为2 500~3 000 m、3 000~3 500 m、3 500~4 000 m和4 000~4 500 m时有效储层的临界孔喉半径分别为0.287 μm、0.230 μm、0.187 μm和0.147 μm;所对应的临界孔隙度分别为5.70%、4.33%、3.53%和1.95%;所对应的临界渗透率分别为0.148 mD、0.083 mD、0.059 mD和0.030 mD,有效储层物性下限随埋藏深度的增加逐渐减小.%Tight oil is important ingredient of the unconventional petroleum resources.The resources potential is enormous.Tight oil will be one of the realistic replacements of hydrocarbon resources.Dense reservoir exploration and development started late in China, and the degree of overall studying is low, especially for the research of petrophysical lower limit values of effective reservoir of dense reservoir.Through the analysis of the dynamic mechanism of dense oil reservoir, the geological model of the hydrocarbon migration to dense reservoir and charge process is established.In this model, the oil expansion force is the main motivation of charge process and the capillary pressure is the main resistance.According to the underground percolation theory, not only the expression of oil generating and pressure increasing is established, but also the discriminative approach of petrophysical lower limit values of effective reservoir of dense reservoir.By applying this discriminative approach, it is can be calculated that in the west slope of Mahu sag in Jimusar sag, the critical pore and throat radius are 0.287 μm、0.230 μm、0.187 μm and 0.147 μm, in the depth of 2 500~3 000 m、3 000~3 500 m、3 500~4 000 m and 4 000~4 500 m, and the corresponding critical porosity and permeability are 5.70%, 4.33%, 3.53%, 1.95%, and 0.148 mD, 0.083 mD, 0.059 mD, 0.030 mD respectively.The lower limit of effective reservoir physical properties decreases with the increase of burial depth.
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