柴达木盆地北缘典型构造断层封闭性与天然气成藏

THE FAULT SEALABILITY OF TYPICAL STRUCTURES AND GAS POOL FORMED IN NORTH EDGE OF QAIDAM BASIN

柴达木盆地北缘冷湖五号二高点构造深部 4 2号、浅部Ⅰ号断层和南八仙构造深部仙南、浅部仙北断层对成藏起主要控制作用 ,通过地质分析和数理评价发现 ,这两个构造断层的封闭性具有明显的差异 :冷湖五号构造深部断层比浅部断层侧向封闭性好 ,南八仙构造浅部断层比深部断层侧向封闭好 ;不同构造深浅部对应的断层中 ,冷湖五号构造比南八仙构造的断层具更强的垂向封闭。南八仙构造仙南断层垂向封闭性较小 ,开启期发生于油气成熟到生烃高峰期 ,起通道作用 ,仙北断层具下开上闭性 ,有利成藏。

The plutonic fault_42,shallow fault_Ⅰin culmination_2 in Lenghu_5 structure,plutonic Xiannan fault and shallow Xianbei fault in Nanbaxian structure play a principal role in gas pool forming in north edge of Qaidam Basin.According to geological analysis and mathematical estimation,the fault sealability in those two structures shows obvious diversity:the lateral sealability of plutonic fault is better than that of the shallow one in Lenghu_5 structure;the lateral sealability of shallow fault is better than that of the plutonic one in Nanbaxian structure.The vertical sealability in Lenghu_5 structure is stronger sealability than that in Nanbaxian structure in corresponding depth in different structure synthem.The vertical sealability of Xiannan fault in Nanbaxian structure is relative inferior,which stretch as channel_way of oil_gas from maturation period of oil_gas to peak_period of hydrocarbon generation.Xianbei fault is patulous lower and obturation upper which is adventageous to gas pool formation.