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根据沉积微相、储层宏观和微观特征等多种参数,针对鄂尔多斯盆地大牛地气田山西组山二段致密砂岩储层特征进行研究。结果表明:大牛地气田下二叠统山西组山二段辫状河三角洲平原砂岩储层以岩屑砂岩和岩屑石英砂岩为主,成分成熟度中等,结构成熟度偏高。砂岩孔隙度主要分布区间为2%~14.11%,平均孔隙度为4.65%,渗透率主要分布区间为0.02×10~(-3)μm~2~3×10_(-3)μm~2,平均值0.92×10~(-3)μm~2,研究区砂岩储层成岩作用以机械压实、胶结和溶蚀为主,机械压实以及石英加大和方解石胶结是降低孔隙度的主要成岩作用,砂岩孔隙类型以粒间溶蚀孔隙为主。通过开展储层综合评价,确定各段储层分类标准,将山二段砂岩储层划分为3类,其中Ⅰ类为相对高孔高渗天然气储层,Ⅱ类为相对中等储层,Ⅲ类为较差储层,建立了山二段砂岩储层评价标准体系并刻画了不同级别储层展布特征。
According to sedimentary microfacies, macroscopic and microscopic characteristics of reservoirs and other parameters, the characteristics of tight sandstone reservoirs in the second member of Shanxi Formation in Daniudi gas field of Ordos Basin are studied. The results show that the Braided River delta plain sandstone reservoirs in the Lower Permian of the Second Member of the Daniudi Gas Field are mainly composed of lithic sandstone and lithic quartz sandstone, with medium maturity and high structural maturity. The porosity of sandstone is mainly distributed in the range of 2% -14.11% with an average porosity of 4.65% and the permeability is mainly distributed in the range of 0.02 × 10 ~ (-3) μm ~ 2 ~ 3 × 10 ~ (-3) μm ~ The value of which is 0.92 × 10 ~ (-3) μm ~ 2. The diagenesis of sandstone reservoirs in the study area is dominated by mechanical compaction, cementation and dissolution. Mechanical compaction and quartz addition and calcite cementation are the major diagenesis to reduce porosity. Sandstone The type of pores is dominated by intergranular dissolution pores. By carrying out comprehensive reservoir evaluation, the classification criteria of each reservoir are determined, and the sand reservoirs of Shan 2 Member are divided into three types, of which type Ⅰ is relatively high-porosity and high-permeability natural gas reservoirs, type Ⅱ is relatively medium reservoir, For the worse reservoirs, a sandstone reservoir evaluation standard system was established and the features of different levels of reservoir distribution were established.