THE BURIAL DIAGENESIS AND THE ORIGIN OF THE PORES/FRACTURES IN THE LIMESTONES OF THE QIULITAGE GROUP, CAMBRIAN—ORDOVICIAN SYSTEMS IN THE NORTHEASTERN TARIM BASIN

The origins of pores and fractures in the limestones reservoirs of the Qiulitage Group,the Northeastern Tarim Basin are closely related to various burial diagenesis in which the dolomitization is the key process for the limestones. Our recent researches suggest that the aplitic lozenge dolomites limited obviously by stylolites could be produced by burial-volume increasing dolomization. Among the five stages of fracturations,only the third and fifth ones matched the time with the migration of oil/gas in the area. Therefore,the space of pores and fractures could be preserved from the filling up of calcites. In addition,the type Ⅲ stylolites reworked by fracturation can be turned into effective fractures for oil/gas accumulation.