佳县—子洲地区太原组砂体成因及对储层的影响

按砂体的沉积特征和成因，可将鄂尔多斯盆地东部佳县－－子洲地区的太原组砂体分为潮汐沟道砂体，河道砂体和潮下砂坝砂体三类，不同成因的砂体，在结构组分，构造，测井曲线和展布形态等方面均有较大的差异，这些特征又明显地影响后期成岩作用类型和强度，从而控制着储层的孔隙类型，物性，分布等特征，研究表明，最有利于储层形成 与演化的砂体为潮汐沟道砂体，高的成分和结构成熟度导致胶结作用较强，压实和溶解作用表现不明显，使砂体内保留有相对多的粒间孔和高岭石晶间孔，物性也较好；这类砂体多呈条带状分布于太2时的中，南部地区，该区块的太2段亦是今后重点勘探的区块，河道砂体和潮下砂坝砂体的沉积特征决定了它们的储集性能不及潮汐沟道砂体，且分布局限，属于较差的储集砂体类型。

THE CAUSE OF FORMATION OF SAND BODIES AND THE CONTROL ON RESERVOIR OF TAIYUANFORMATION IN JIAXIAN-ZIZHOU AREA

According to depositional characteristics and cause of formation of the sand bodies, the sandstones in Jiaxian-Zizhou area, Ordos basin can be divided into three types, they are the tidal-channel sandstone, channel sandstone and subtidal bar. The sandstones with different causes of formation have differences in such aspects as the texture components, the depositional structure, the well log as well as the sand shapes, which have apparent effect on late diagenesis types and strength, and in turn, they control the pores types, porosity and permeability of the reservoir. The study shows the tidal-channel sandstone plays the most favorable role in the reservoir formation and evolution. Higher mature degree of the component and texture make stronger cementation. The dissolution and compaction are not obvious. All these make it possible that more grain pores and inter kaolinite crystal pores are kept and the sandstones have higher porosity and permeability. The second section of Taiyuan Formation in the middle and south area will be important target in following exploration. The deposition of channel sands and subtidal sands determine that their accumulation property is poorer than tidal channel sands, and their distribution is restricted, they are composed of poor reservoir.