鄂尔多斯盆地白于山地区三叠系延长组长4+5储层特征

Reservoir characteristics of the fourth and the fifth units of Triassic Yanchang Formation in Baiyushan area, Eerduosi Basin

白于山地区长4+5储集岩形成于三角洲前缘水下分流河道,为细粒长石砂岩和岩屑长石砂岩.储层孔隙类型以粒间孔、粒内溶蚀孔、铸模孔或残余铸模孔和胶结物溶蚀孔为主.成岩作用主要有压实作用、胶结作用和溶蚀作用.受沉积相及成岩作用的影响,储层物性具低孔、低渗的特点,孔隙度在0.35%～16.22%之间,平均为11.40%,渗透率在(0.004～182.000)×10-3μm2之间,平均为1.260×10-3μm2.长4+5储集岩分为4类,大部分属于Ⅱ,Ⅲ类.

The sandstones of the fourth and the fifth units of Trias sic Yanchang Formation deposit in subaqueous distributary channels and are composed of fine a rkoses. The types of pores in the reservoir are mainly intergranular pores, intr agranular dissolved pores, moldic pores/ relic moldic pores and cement dissolved pores. The diageneses occurred in the sandstones are mainly compaction, cementa tion and dissolution. The sandstones are of low porosity and low permeability be cause of their sedimentation and diageneses. The porosity ranges from 0.35% to 1 6.22% with a mean of 11.40%. The permeability ranges from 0.004×10^(-3) μm ~2 to 182×10^(-3)μm^2 with a mean of 1.26×10^(-3)μm^2. The sandston es are c lassified into four types and the most of them are typeⅡ and type Ⅲ.