Influence of Ordovician carbonate reservoir beds in Tarim Basin by faulting

The quality of the Ordovician carbonate reservoir beds in the Tarim Basin is closely related to the development of secondary pores, fractures and cavities. Karstification is important in improving the properties of reservoir beds, and karstification related to unconformity has caught wide attention. Compared with the recent research on the unconformity karst reservoir bed improvement, this paper shows a new way of carbonate reservoir bed transformation. Based on field survey, core and slices observation, transformation of Ordovician carbonate reservoir beds by faulting can be classified into three types: (1) Secondary faults and fracturs generated by faulting improved carbonate reservoir bed properties, which were named the Lunnan or Tazhong82 model; (2) upflow of deep geothermal fluids caused by faulting, with some components metasomatizing with carbonate and forming some secondary deposit, such as fluorite. It can improve carbonate reservoir bed properties obviously and is named the Tazhong 82 model; and (3) the faulting extending up to the surface increased the depth of supergene karstification and the thickness of reservoir bed. It is named the Hetianhe model. Transformation effect of carbonate reservoir beds by faulting was very significant, mainly distributed on the slopes or on the edge or plunging end of the uplift.