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延长油区侏罗系和上三叠统河流-湖泊三角洲相砂岩储层的物性受沉积相及埋藏-成岩作用的控制.河流相砂岩的物性好于三角洲相砂岩（平均孔隙度和平均渗透率分别为14.8％和12.7×10-3μm2,9.8％和5.8×10-3μm2）.埋藏压实作用是导致砂岩孔隙丧失的主要原因.碳酸盐是造成砂岩物性降低的主要胶结物.晚期成岩阶段富含有机酸和无机酸的酸性孔隙流体及表生成岩阶段的大气降水是形成次生孔隙及导致砂岩物性改善的主要介质.
The physical properties of the sandstone reservoirs in the Jurassic and Upper Triassic fluvial-lacustrine delta are controlled by sedimentary facies and burial-diagenesis in the Yanchang oilfield.The physical properties of the fluvial sandstone are better than those of the delta facies sandstone (average porosity and average permeability 14.8% and 12.7 × 10-3μm2, 9.8% and 5.8 × 10-3μm2 respectively.) Burial compaction is the main reason for the loss of sandstone porosity. Carbonate is the major cement that causes the decrease of sandstone physical properties. Late diagenetic stage Acidic pore fluids that are rich in organic acids and inorganic acids and atmospheric precipitation in the epigenesis stage are the major mediators that form secondary pores and lead to improved physical properties of the sandstone.