Fault zone structures and its relationship with hydrocarbon migration and accumulation in petroliferous basin

Key words:  fault zone structure types  hydrocarbon vertical migration  fracture  fault transporting and sealing properties  reservoir controlling model

Abstract:

Combined core data, well logging and geochemistry, the relationship between fault zone structure and hydrocarbon migration and accumulation were discussed on the basis of the classification of fault zone types. The results show that fault zones can be divided into structural incomplete type, structural complete type and structural complex type according to the combination of fault core and damage zone. Fluid flow through fault zones shows the characteristics of "seismic pumping" high-efficient migration in the faulting period, and continuous migration in the connected induced fractures and pores during the period of fault static to filling of induced fractures and low-efficient migration in connected pores after the filling of induced fractures. The effects of each fault zone structural types on hydrocarbon are different during the period of fault static to filling of induced fractures. Structural incomplete type Ⅰ and Ⅲ are conductive fault zones, and the transporting capacity is controlled by fracture density and connectivity. Structural incomplete type Ⅱ are sealing fault zones, and the sealing capacity is controlled by the content of low permeable fault gouge and cataclasite. Structural complete and structural complex type fault zones are combined conduit-barrier, and the transporting capacity is related to the relative content of fault core and damage zone. Fault zones have the characteristics of time-space coupling reservoir controlling model, the migration and accumulation of hydrocarbon are controlled by different structural units in the open fault zone which matched well with hydrocarbon generation and expulsion.