摘要
二叠系山西组煤系地层山2段是鄂尔多斯盆地榆林地区天然气勘探的主要目的层。该区榆林气田以山2段致密石英砂岩为主要储集层,而石英砂岩则是在普遍低渗致密储集层背景上相对高渗的砂岩储集类型。由于山西组煤系地层的孔隙水在较长的成岩时期呈酸性,致使石英砂岩的胶结物具有碳酸盐胶结物含量较低、硅质胶结物含量较高和高岭石十分发育的显著特征。石英砂岩的孔隙类型为残余粒间孔+次生溶蚀孔的孔隙组合,具有孔隙结构变化大、孔喉半径小、应力敏感性低和裂缝比较发育等特点。研究表明,在成岩期所遭受的压实作用和硅质胶结作用是造成山2段煤系地层石英砂岩致密化的主要原因。
The coal-bearing strata of the second member of Shanxi Formation are the main target strata for natural gas exploration in Yulin area of Ordos Basin,and the tight quartz sandstone with relatively high permeability of the second member of Shanxi Formation is the main reservoir in Yulin Gasfield. During the long diagenesis stages, the pore water in coal-bearing strata is acidity, which makes the cement in the quartz sandstone has the obvious characteristics of low content of carbonate cement, high content of siliceous cement and well developed kaolinite. The pore type of the quartz sandstone is the combination of remained intergranular pore and the secondary dissolved pore, and it is characterized by great change of pore structure, low radius of the pore throat, low stress sensitivity and well developed fracture. The research result shows that the compaction of the quartz sandstone is caused by the squeezing action and siliceous cementation during the diagenesis stage.
出处
《岩性油气藏》
CSCD
2010年第4期57-63,共7页
Lithologic Reservoirs
关键词
煤系地层
致密石英砂岩
储集特征
酸性水介质
成岩作用
山2段
榆林地区
coal-bearing strata
tight quartz sandstone
reservoir characteristics
acidulous water medium
diagenesis
the second member of Shanxi Formation
Yulin area