莺歌海盆地束缚水饱和度测井评价方法研究

RESEARCH ON THE LOG EVALUATION METHOD OF IRREDUCIBLE WATER SATURATION IN YINGGEHAI BASIN

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 2 0 %～ 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。文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 。

Irreducible water saturation is one of the imp or tant parameters of evaluating hydrocarbon reservoirs,being the key parameter of analyzing the nature of the fluid producted from the reservoir and calculating o il water relative permeability and water production rate.The irreducible water saturations in the net gas formation in D field in Yinggehai Basin change from 2 0%～70%.Through investigating the factors influencing the irreducible water sa turation 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 wate r satruation is related to not only the petrophysical property of rock itself bu t also gas column height.In regard to the reservoirs with the same petrophysical property,the irreducible water saturation decreases with the increase in the ga s 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 pu t forward in the paper.Through applying on the spot,it was proved that the natur al gas reservoirs in Yinggehai Basin may be satisfactorily evaluated by use of s uch a relationship,so it has important reference value to the log evaluation of both low resistivity reservoirs and complex reservoirs.