鄂尔多斯盆地北部上古生界储层物性影响因素

鄂尔多斯盆地北部上古生界储层主要为山西组和下石盒子组砂岩,其储集物性差,主要为致密储层,次为低渗透储层.平面上,由南向北,距物源愈近,砂岩粒度越粗,杂基含量越低,成岩压实作用和晚成岩期胶结作用越弱,物性条件逐渐变好.纵向上,随地层变新,其沉积相从三角洲前缘亚相至三角洲平原亚相再到河流相,物性呈变好趋势.因此,鄂尔多斯盆地北部上古生界储层物性北好南差的特征,主要是由于沉积相和成岩作用差异所致.

Factors affecting reservoir properties of Upper Paleozoic in Ordos basin

The Upper Paleozoic reservoirs in the north of Ordos basin are mainly composed of the sandstones of Shanxi and Xiashihezi Formations. Being densely compacted and of low permeability, they are generally considered low quality reservoirs. From south to north, the grain-size increases and the matrix content decreases while the sandstones get nearer to the source region. The reservoir properties improve gradually northward because of the weaker compaction and cementation. The reservoir properties display a trend of improvement upwards while the strata get newer and the sedimentary facies change from deltaic front to deltaic plain and to fluvial. So the characteristics that the property of the Upper Paleozoic reservoir in the north of Ordos basin degrades southward are mainly the result of the variation in the sedimentary facies and diagenesis.