鄂尔多斯盆地大牛地气田上古生界低孔渗砂岩储层评价

大牛地气田目前已发现的气藏有盒三、盒二、盒一、山二、山一和太一气藏。其中以块状砾岩相、含砾粗砂岩相、大型交错层理砂岩相是最好的岩石相类型；各层段岩石学特征的差异主要体现在岩石类型、骨架成分和填隙物类型成分上，储层岩石粒度、泥质含量、碎屑成分是影响储层物性的主要因素；研究区储层总体上属低孔、低渗储层，盒三 二段、山一段储集物性较好，盒一段、山二段、太原组储集物性较差；研究区储层总体上属于小孔、微细喉储层，盒三 二段、太原组的孔隙结构最好，山西组次之，盒一段最差；将储集岩按照组或段分为三类：盒三 二段，盒一段和山西组，太原组，分别进行了分类评价。大牛地气田上古生界主要目的层段具有整体含气的特点，储层品质的优劣决定了其含气性的好坏，因此寻找高产富集带可归结于寻找优质储层发育带。岩性圈闭的分布与各期河道、分流河道的主体发育位置趋势一致，有利储集相带、高产富集区的预测应以有利沉积相带为基础展开。

RESERVIOR EVALUATION FOR THE LOW POROSITY AND PERMEABILITY SANDSTONE OF UPPER PALEOZOIC IN THE DANIUDI GAS FIELD, ORDOS BASIN

The major target layers of H3,H2,H1,Shan2,Shan1 and Tai1 members of upper Paleozoic age in the Daniudi gas field of Ordos basin were characterized by low porosity and low permeability.These layers shared both similarity and discrepancy.The former determined the chracter of gas bearing and the latter determined the stand and fall of gas bearing.On the basis of studies on the reservoir character,the discrepancy of characteristics of rocks,pore types and pore textures,the method and criterion of evalution for the reservoir,gas layer,production capacity were established.Accordingly,an empiric formula was proposed for the prediction of production capacity for different layers and members.