CARBONATE ROCK RESERVOIR FEATURES AND OIL-GAS ACCUMULATING CONDITIONS IN THE ORDOVICIAN OF TAHE OILFIELD IN NORTHERN TARIM BASIN

The integral study of petroleum geology,geophysics and oil_gas exploration indicates that Tahe Oilfield formed on the basis of long_developed paleo_uplift is a large scale one which consists of karst_fracture reservoirs of Lower Ordovician carbonate rock.The carbonate rock reservoir developed on the environment of open_limited sea platform presents the features of karst_fracture reservoir of lower matrix porority,and permeability and stronge heterogeneity controlled by tectonisim and karstification because the reservoir underwent multi_stages superimposed reformation of tectonisim,karstification and diagenesis at late time.The karst_fracture reservoir of Tahe Oilfield is mainly distributed in the center platform of paleo_buried hill and the southern slope,and in the scope of 200 metres under uncomformity interface of weathering crust.A complex and multi_episodes oil_gas accumulating dynamic system in Tahe petroleum area is composed of paleo_buried hill,karst_fractures,faults,surface of uncomformity and conduit.