东海陆架盆地N气田花港组储层特征及分类评价

东海陆架盆地西湖凹陷古近系花港组储层为典型的低孔、低渗储层。基于大量岩心物性、粒度、薄片、压汞等资料,对N气田目的层储层岩性、物性和孔隙结构特征进行精细评价。结果表明:N气田花港组储层岩性以细砂岩为主,矿物成分构成稳定,以石英为主,黏土含量低,岩性较纯;随着埋藏变深,孔隙变差,粒间孔减少,溶蚀孔增加,孔喉半径减小,连通性变差;局部发育砂砾岩,且渗透率大于细砂岩一个数量级以上,可作为甜点储层开发。基于实验和试油资料统计结果,建立了一套适用于花港组储层的综合分类评价标准,包含孔隙度、渗透率、饱和度和地质特征4类储层重要参数,分类结果特征鲜明,分类依据科学可靠,为该区域低孔、低渗储层勘探开发提供依据。

Characteristics and classification of the Paleogene reservoirs in Huagang Formation of Gas Field N,East China Sea Basin

The Paleogene Huagang Formation in the N gas field of Xihu Sag in the East China Sea Basin is a typical tight reservoir of lowporosity and low-permeability.Based on a large number of testing data for core property,particle size,thin section and mercury testing,the lithology,physical properties and pore structures of the reservoirs in the gas field N are carefully studied in this paper.The Huagang Formation is dominated by fine quartz sandstone with little clay.With the increase in burial depth,the intergranular pores decrease,the dissolution pores increase,and the porosity becomes worse in general,as the pore throat diameter is reduced and the connectivity deteriorated.Glutenite sometimes occurs locally,the permeability of which is more than one order higher than that of the fine sandstone,and thus becomes sweet areas for oil production.Based on the statistical results of testing data,a comprehensive evaluation standard specially applicable to the Huagang reservoir is established,which contains four important reservoir parameters,namely porosity,permeability,saturation and geological features.The classification results are distinctive and reliable.Facts prove that it is an effective tool for exploration and development of tight low-porosity and low-permeability reservoirs in the region.