O

2+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

O

2+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 O

2+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.