Abstract:

Recently, dolomiticrock exploration of Junggar Basin has made a sustained breakthrough and opened a completely new exploration field. Definition of dolomiticrock is concluded, and the effective reservoir type, characteristics of occurrence and formation mechanism of dolomite are determined based on previous research conclusions, core observation, thin section, and so on. The dolomiticrock with special lithology and limited distribution mainly develops in Permian Fengcheng Formation of Wuxia district of the northwest margin. The dolomite has seven types of occurrence，including lameltate, uniform distribution, snow shape, irregular layered shape, crumb shape, fracture filling shape and exotic dolomite clastics. Corresponding, dolomite has five types of formation mechanism, including parasyngenetic dolomitization, mixed dolomitization, buried dolomitization, diagenetic dolomitization and weatheringtransportation of external dolostone. The effective dolomiticrock reservoirs whose space is microfissure, include dolomiticsiltstone, dolomiticmudstone, muddy dolomite, and so on. Development degree and dispositional relationship of fissure and karst cave have an important impact on the level of capacity. Overall, the microand macrodistribution characteristics of different types of dolomite are different, and their superimposed effect controls the whole features of the present dolomite.

Key words: Junggar Basin, Fengcheng Formation, dolomite, reservoir characteristic, formation mechanism