鄂尔多斯盆地陇东地区三叠系延长组长8储层特征

鄂尔多斯盆地陇东地区延长组长8油层段是重要的储集层之一,包括长81和长82两个砂岩组。通过储层岩石学、储层物性、孔隙结构及储层控制因素等方面对储层特征进行分析,总结并评价储层储集性能。研究结果表明,储层岩石类型主要为中细粒长石砂岩和岩屑长石砂岩,成分成熟度低,结构成熟度中—高;岩石物性总体较差,属低孔、低渗储层,发育粒间孔隙、溶蚀孔隙、晶间孔等孔隙类型,喉道以中细喉—细喉为主。储集性变化受沉积作用和成岩作用控制,沉积作用控制了储层砂体展布,进而影响其岩石学特征的表现,压实作用、胶结作用和溶蚀作用控制了储层孔隙结构特征及储层物性,根据岩性和物性分析特征可将储集岩分为4类,优质储层的勘探应以沉积作用控制的多套砂体相互叠置的水下分流河道沉积为重点。

RESERVOIR CHARACTERISTICS OF CHANG 8 OF YANCHANG FORMATION (TRIASSIC) IN LONGDONG AREA, ORDOS BASIN

The Chang 8 Member which is composed of Chang 8~1 and Chang 8~2 sandstone in Lengdong area in Ordos basin is an important oil reservoir.In this paper,the characteristics of reservoir strata is summarized and evaluated on the basis of petrological and physical features.the texture of porosity and the controlling features of reservoir strata.It was shown that the lithotypes are the medium-fine granular arkose and lithic arkose which have the characteristics of low compositional maturity.middle-high texture maturity,low porosity and permeability.The reservoir develops interparticle pore,solution pore and intercrystal pore.The main throat types is the medium-fine throat and fine throat.The sedimentation and diagenesis have played important roles in evolution of resevoir.Sedimentation controlled distribution of reservoir.Such diagenesis as compaction,solution and mentation controlled the physical and texture of porosity.Based on the lithology and physical property the formation can be divided into 4 types.The favourable reservoir is the submerged distributary chanel sandbodies