Abstract:

O₂₊₃ limestone reservoir rift in Tazhong 1# fracture zone can be divided into two types of structural rift and non-structural rift.It is believed that,on the basis of intersected relations of the rift and testing results of homogeneous temperature of calcite packet and rock Kaiser,O₂₊₃ limestone had gone through three times of tectonic movements,forming corresponding 3 phases of structural rifts.During the period of Late Caledonian and Early Hercynian,after the formation of diagenetic rift of paralle-bedding plane along O₂₊₃ limestone plane in the process of static pressure and in the process of NE-SW structure,a series of conjugate shear rifts of vertical bedding plane,high-angle stylolites as well as longitudinal and transverse tensional rifts due to accumulation of stress.The rifts of this period are filled with calcites.During Late Hercynian,early rifts were enlarged by the tectonic movements and new shear rifts were produced.In the late period of Late Hercynian,the tectonic movements were relatively static,rifts were filled with semitransparent calcites.Unfilled vertical structural shear rifts with good orientation of non-big scale were formed by the influence of the tectonic movements again during Himalayan period which played very important role in hydrocarbon accumulation.

Key words: fracture zone, Tazhong, rift, type, period, pattern