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束缚水饱和度是油气层评价的重要参数之一，它是分析储层产液性质，计算油水相对渗透率和产水率的关键参数。莺歌海盆地D气田出现的纯气层，其束缚水饱和度在20％～70％范围内变化。通过对D气田束缚水饱和度影响因素的研究，发现由于岩性细、孔隙结构复杂形成高束缚水含量时，束缚水饱和度不仅与岩石本身物性有关，而且气柱高度对其有较大影响。相同物性的储层，随气柱高度的增大，束缚水饱和度减小；若气柱高度相同，束缚水饱和度随孔隙度的减小而增大。章给出了束缚水饱和度与孔隙度和自由水界面以上高度的关系。通过实际应用表明，利用这种关系能较好地评价莺歌海盆地天然气层，这对低电阻率油气层及复杂油气层的测井评价有重要参考价值。

Research on the Log Evaluation Method of Irreducible Water Saturation in Yinggehai Basin

??Irreducible water saturation is one of the important parameters of evaluating hydrocarbon reservoirs,being the key parameter of analyzing the nature of the fluid producted from the reservoir and calculating oil-water relative permeability and water production rate.The irreducible water saturations in the net gas formation in D field in Yinggehai Basin change from 20%??70%.Through investigating the factors influencing the irreducible water saturation in D field,it was found out that when irreducible water content is high because of fine sand grains and complicated pore structure,the irreducible water satruation is related to not only the petrophysical property of rock itself but also gas column height.In regard to the reservoirs with the same petrophysical property,the irreducible water saturation decreases with the increase in the gas column height;and if the reservoirs have identical gas column height,the irred ucible water saturation increases with the decrease in porosity.The relationship between the irreducible water saturation and the porosity and gas column height is put forward in the paper.Through applying on the spot,it was proved that the natural gas reservoirs in Yinggehai Basin may be satisfactorily evaluated by use of such a relationship,so it has important reference value to the log evaluation of both low resistivity reservoirs and complex reservoirs.