变形分解对柴达木盆地北缘油气运聚的影响

柴北缘反“S”型构造是柴达木中、新生代叠合盆地在长期演化中形成的大型复合构造,其雏形最早源于早侏罗世的不对称倒“V”字型盆-岭构造,最后定型于新生代晚期(N2)柴北缘压剪断裂作用.将柴北缘压剪断裂系统的总应变分解为剪切应变分量与压缩应变分量,其剪切应变分量较小的区段也是压缩应变分量较大的区段.压缩应变分量较大的区段对应的冷湖构造带与鄂博梁构造带中的区段是油气流失的区段,而剪切应变分量较大的区段对应的冷湖构造带与鄂博梁构造带中的区段则是油气聚集的区段.因此,反“S”型构造中的冷湖六号、七号区段是油气流失区,冷湖三号、四号、五号区段及南八仙-马海一带是油气聚集区.

Effects of deformation partitioning on hydrocarbon migration-accumulation in the northern margin of Q aidam Basin

The reverse "S" structure in the northern margin of Qaidam Basin is a large compound structure evolved from the MesoNeozoic Qaidam Superimposed Basin. The compound structure initiated from an asymmetric inverted Vtype basinmountain structure in the Early Jurassic and finalized by the compressionshear fracturing in the Late Cenozoic. The total strain of compressionshear fracture system in the northern margin of Qaidam Basin was decomposed into a shearstrain component and a compressionstrain component. In the area of smaller shearstrain component, the compressionstrain component is larger. The areas with the larger shearstrain component in Lenghu and Eboliang structural belts have good hydrocarbon accumulation, such as No.3, No.4 and No.5 districts in the Lenghu structural belt and NanbaxianMahai area, while the areas with larger compressionstrain components in Lenghu and Eboliang structural belts have the spaces for hydrocarbon loss, such as No.6 and No.7 districts in Lenghu structural belt.