摘要： 鄂尔多斯盆地陇东地区长8₂储集层平均孔隙度为8.8%,平均渗透率为0.64×10^-3μm²,属于低孔低渗储集层。强烈的压实作用是储集层物性变差主要原因,碳酸盐胶结作用促使储集层物性进一步变差。尽管储集层物性整体较差,但在普遍低孔低渗背景下仍发育相对高孔渗的优质储集层。对优质储集层进行了分析,总结了优质储集层的典型特征,统计表明:优质储集层的塑性组分含量较低,孔隙类型以绿泥石胶结残余粒间孔和溶孔为主,孔隙结构以中小孔—中细喉为主。在此基础上,分析了优质储集层成因机理。研究认为:分流河道、河口坝等微相高能厚层砂体有利于优质储集层发育,相对低的塑性组分含量和绿泥石环边胶结有利于粒间孔隙的保存,溶蚀作用是次生孔隙形成的最主要成岩作用。

关键词: 低孔低渗, 优质储集层, 塑性组分, 绿泥石环边, 溶蚀作用, 陇东地区, 鄂尔多斯盆地

Abstract: The reservoirs of the Chang 8₂ interval of Yanchang Formation in Longdong area of Ordos Basin have low porosity(average 8.8%)and low permeability(average 0.64×10^-3 μm²). The strong compaction is the main reason for the poor reservoir properties,and the carbonate cementation further reduces the reservoir physical properties. Although the reservoir physical property is generally poor,the high quality reservoirs have relatively high porosity and permeability are developed on the background of tight reservoirs. The high-quality reservoirs are analyzed and their typical characteristics are summarized. The statistical results show that the high-quality reservoirs have lower plastic component content,pore types are dominated by dissolution pores and residual intergranular pores cemented with chlorite, and pore structures are mainly small-medium pores with fine-medium throats. Based on the above understanding,the formation mechanism of the high quality reservoirs is analyzed. The study suggests that:High energy and thick sandbodies of distributary channel,mouth bar,etc., are conducive to form high-quality reservoirs;relatively low plastic component content and chlorite rim are in favor of preservation of intergranular pores; and dissolution is the most important diagenesis for the formation of secondary pores.

Key words: low porosity and low permeability, high-quality reservoirs, plastic component, chlorite rim, dissolution, Longdong area, Ordos Basin

中图分类号: 

• P618.3