Study On Reservoir Characteristic Of Chang-2Member Of Late Triassic Yanchang Formation In The Northern Zhiluo Oilfield, Ordos Basin

ZhiLuo oil field is located in southeast Ordos basin, and Chang2are main oil bearing series in Late Triassic. According to its drilling, logging and experimental analysis data, and through these experimental methods such as the X-ray diffraction, physical property test, scanning electron microscope, intrusive mercury experiment etc. The paper analyzed sedimentary facies, lithology, pores structure, diagenesis, physical property of Chang8reservoirs, which provides geological basis for development adjustment of the area, the following results are received by this researching:Chang2reservoir of Yanchang formation is divided into three member:Chang21, Chang22, Chang23. Chang2’member are the major oil producing member in study area.The study area of Chang2is situated in Yan’an delta front. Micro-facies are mainly occurred in the submerge distributary channel and distributary interchannel, the channel is a distribution of NE-SW tending and a stable channel development, moreover, its sandbodies are fundamentally together.Chang2reservoirs is mainly fine arkose feldspar sandstone. Compositional Maturity is low and textural maturity is low too. Grain size sorting is better and the grain shape is mostly subangnlar. The conclusion can be drawn that the reservoir space of the Chang2oil-bearing is dominated by inter-granular pore, and secondary dissolution Pore, main microthroat caused by low permeability, which formed extra-low permeable reservoir. Pore throat type is mainly small pore-micro throat. Dominant diagenesis types are compaction, cementation, replacement and dissolution. Furthermore, the reservoir is during late diagenesis A stage at present.Macroscopically the reservoir physical properties are mainly influenced and controlled by the sedimentary environment, While microscopically impacted by the diagenesis. The reservoirs are divided into four categories according to lithology, porosity and permeability. It Ⅱ and Ⅲare mainly developed in study area.