Strike-slip characteristics, forming mechanisms and controlling reservoirs of Dazhuluogou fault in Junggar Basin

Key words:  Dazhuluogou fault  strike-slip structure  forming mechanism  controlling reservoirs  northwestern margin

Abstract:

Using the shear structural theory and physical simulation experiments, this study focuses on the strike-slip characteristics, forming mechanisms and controlling reservoirs of Dazhuluogou fault in the northwestern margin of Junggar Basin. Comprehensive analyses of the field outcrops are combined with high precision 3D seismic data in the framework of simple shear model. The results show that the Dazhuluogou fault which was formed in a twist-compression environment is a dextral strike-slip fault, which belongs to the derived structure of Daerbute fault. It is suggested from the stratigraphic distribution relationship and fluid inclusion information that the Dazhuluogou fault was initialized during the Indosinian movement and was active in the Yanshan movement. The development of the fault was along the R shearing plane in the simple shear model of Sylvester, where secondary structures were evolved before the strike-slip fault system was formed. Rocks in the Dazhuluogou fault zone were severely ruptured and broken, and some evolved into mylonites and schists. The closure in the main and secondary faults in strike-slip fault system is strong, resulting in the forming of a series of faulted block traps. The shear structures which developed in the northwestern margin of Junggar Basin are relevant to the oil and gas accumulation obviously.