东海盆地西湖凹陷中央隆起带古近系花港组储层特征及成岩孔隙演化

Reservoir Characteristics and Evolution of Diagenetic Porosity of Huagang Formation of Paleogene in the Central Anticlinal Belt of Xihu Sag,Donghai Basin

通过岩石薄片、铸体薄片、扫描电镜、X-射线衍射等多种分析测试方法,对西湖凹陷中央隆起带古近系花港组储层特征及成岩孔隙演化特征进行了详细研究。研究表明:研究区古近系花港组砂岩类型主要为长石岩屑质石英砂岩,其成分成熟度和结构成熟度均为中等;成岩作用是控制该区储层物性的关键因素,其中压实作用和胶结作用主要为破坏性成岩作用,溶蚀作用则为建设性成岩作用,其形成的次生孔隙极大地改善了储层物性;古地温、有机质镜质体反射率等资料显示,北部宁波—嘉兴地区成岩演化进程稍快,花港组埋深大于3 600m开始进入中成岩B期,而南部天外天—黄岩地区总体上仍为中成岩A期,因而南部较北部具有更良好的储集条件。

Based on the analysis of general thin-section, casting lamella, scanning electron microscope, X-ray diffraction and other analytical methods, the characteristics and evolution of diagenetic porosity of Huagang Formation of Paleogene in the central anticlinal belt of Xihu Sag were studied in detail. The result shows that feldspathic-lithic quartz sandstone is the main sandstone type, with medium maturity of texture and component. Diagenesis is the main controlling factor o{ reservoir physical properties. During the process of diagenesis,compaction and cementation are the main destructive digenesis, while dissolution is the con- structive digenesis. Vitrinite reflectance and other data indicate that Huagang Formation in the northern part buried deeper than 3 600m is at B-period of middle diagenetic stage,while that of the southern part is at A period,which shows that the reservoir condition of southern part is better than that of the northern part.