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对青海柴达木盆地油砂山油田下油砂山组砂、泥岩样品的分析测试表明，下油砂山组湖相三角洲砂岩的成分成熟度和结构成熟度均较低，成岩作用已达到中成岩阶段的成熟Ａ期或Ｂ期；早成岩阶段的主要成岩作用是碳酸盐胶结作用以及压实作用引起的颗粒重排；中成岩阶段未成熟期则以机械压实作用为主，半成熟期以方解石和方沸石胶结作用为主，成熟Ａ期或Ｂ期的主要成岩事件是烃类大量成熟引起的晚期溶蚀。该三角洲体系中河道砂体、河口坝砂体和较厚的前缘席状砂体的孔、渗性较好，浅湖席状砂体因早期碳酸盐胶结强烈而储集性差。沉积环境及成分、结构的差别是造成砂体成岩演化史和储集性能差异的主要原因。砂岩储层以粒间原生孔隙为主、次生孔除为辅，喉道较发育。
The analysis of sand and mudstone samples from the lower reaches of the Yushashan Formation in the Yushaoshan Oilfield, Qaidam Basin, Qinghai Province indicates that the compositional maturity and structural maturity of the Lower Yushanian sandstone in the delta are low and the diagenesis has reached the stage of diagenesis Mature stage A or B; the main diagenesis in the early diagenetic stage is the grain rearrangement caused by carbonate cementation and compaction; the immature stage in the diagenetic stage is dominated by mechanical compaction and the semi-mature stage is calcite And the main zeolite cementation. The main diagenetic events in mature stage A or B are advanced dissolution caused by the massive maturation of hydrocarbons. The permeability of channel sand body, estuary bar sand body and thick front sand body in the delta system is better, and shallow lacustrine sand body has poor reservoir property due to early cementation of carbonate. Sedimentary environment, composition and structure difference are the main reasons that cause the evolution of diagenesis and reservoir performance of sand body. Sandstone reservoirs are dominated by intergranular primary pores, secondary pores are secondary, and throats are well developed.