Karstification of Carbonate Reservoir in Hetian River Gas Field of Tarim Basin

Hetian river gas field,a large-scale carbonate gas pool recently found or proved in Tarim basin,is well-developed in karstification for its major reservoirs such as Ordovician buried hill limestone and Carboniferous bioclastic limestone.Based on the time,location and mechanism of each type of karsts,the primarily developed karstifica tions in- clude interlayer karst and weathering crust karst formed by atmospheric fresh water process as well as buried karst,of which Ordovician buried hill karst was formed by organic acid action,while Carboniferous bioclastic limestone buried karst by sulfidation dissolution.The karstification is mainly controlled by lithology,structure,palaeogeomorphology and palaeoclimate,and it could improve porosity and permeability in the carbonate reservoir.