Physical property characteristics of Yanchang Formation reservoir in the southwest of Ordos Basin and their controlling fac-tors： taking Chang 3 and Chang 4 ＋ 5 reservoirs in Longdong area as an example

分析鄂尔多斯盆地西南部陇东地区延长组储层物性特征及其控制因素，发现沉积和成岩控制储层物性。沉积微相带不同，储层物性就不同；成岩作用中压实-压溶作用、胶结作用对储层物性具有破坏作用，溶蚀作用是储层物性改善的关键因素。沉积微相带是控制油气藏储层展布的内在因素，成岩作用是储层形成过程中控制物性演化的外部因素。

Yangchang Formation reservoir in Longdong area, the southwest of Ordos Basin is low porosity and low permeability res- ervoir. Sedimentary microfacies and diageneses determine the physical property of the reservoir. Different sedimentary microfacies zone has different physical property. Compaction-pressolution and cementation have destructive effect on the physical property of the reser- voir, and dissolution is the key to improving the physical property of the reservoir. Sedimentary microfacies is the intrinsic factor to con- trol the oil and gas reservoir distribution, and diageneses are the exterrlal factor of controlling the physical property evolution of the oil and gas reservoir.