南堡凹陷物源体系发育特征与优质储层形成

Characteristics of Distribution of Provenance System and Formation of the High Quality Reservoir in Nanpu Sag

通过岩石成分、矿物组分、重矿物组合特征将南堡凹陷物源体系在平面上划分为5个:西南部物源体系、正南部物源体系、西北部物源体系、东北部物源体系、东部物源体系。不同物源体系孔隙度与渗透率分布规律的对比表明,储层物性最好的是来自西南部物源体系的储层,以中高孔中高渗为主,平均孔隙度为19.26%,平均渗透率为205.75×10-3μm2,其次是来自正南部物源体系的储层,以中低孔中高渗为主,平均孔隙度为13.59%,平均渗透率为123.44×10-3μm2。根据薄片观察、流体包裹体均一温度分布特征,分析出研究区储层成岩作用演化序列,并将南堡凹陷成岩体系分为6类,其中正南部物源体系下的沙一段与西南部物源体系下的东三段到沙三段成岩体系物性最好;成岩体系的形成与物源有关,分选好、杂基含量少的物源体系抗压能力强,压实作用相对较弱,有利于孔隙保存,并使溶蚀作用增强,物性得以改善,成岩后期也能形成优质储层。

Based on the research of rock composition,mineral components and heavy mineral assemblages,we divide the provenance system into five areas on the plane of Nanpu Sag.The provenance might come from southwest,south,northwest,northeast and east.According to the comparison of the distribution of porosity and permeability,we find that the physical properties of reservoirs in the area of the southwest provenance system are the best,in which the pore structure mainly consists of medium-high porosity,medium-high permeability,with an average prosity of 19.26% and average permeability of 205.75×10-3μm2.The second area in the physical characteristics is the south provenance system,having medium-low porosity and medium-high permeability,with an average prosity of 13.59% and average permeability of123.44×10-3μm2.The evolutionary sequence of diagenesis in the sag is discussed by the homogeneity temperature of fluid inclusion and thin section observation in the reservoir.In addition,the diagenetic system is divided into six categories,with the best property ones being the Es1 in south provenance system and Ed3-Es3 in southwest provenance system.These analyses lead to the conclusion that some relation should exist between the formation of diagenetic system and the provenance system.The study suggests that the provenance system with good sorting and few matrix content is difficult to be compacted,and has good conservation of reservoir space and reforming the reservoir physical property.So this is a favorable reservoir area to form high quality reservoirs in the later diagenesis.