NW margin of Junggar basin with relatively complicated structures is composed of western uplift and west part of Mahu depression. The development characteristics of present hydro dynamics fields have been studied by means of analyzing parameters of fluid physics and fluid chemistry

measuring pressure data in reservoirs

compaction and overpressure in mudstones and distribution of fluid potential. Fluid physicochemical features from various layers show different hydro dynamics distribution distinctions of its own

so as to recognize easily where gravity flow is strong and where frequent replacement of water between deep layer and shallow layer

namely; districts from Hongshanzui to Wuerhe in the Carboniferous System

Kelamay and adjacent Xia No. 40 well in the Permian

Ke No.114 wells and Feng No.1

Wuerhe in the Triassic

Baijiantan Baikouquan in the Jurassic. It is believed by measuring pressure in situ in sandstones that hydrostatic pressure is basically preserved in the Jurassic and Carboniferous

and overpressure to a certain extent would appear at some depth in the Triassic and Permian

where development of overpressure in plane occurs in Mabei and Xiazijie areas.It is indicated by calculating abnormal pressure in mudstones from compaction curves that the beginning depth of overpressure is between 1800～2300 m while the beginning corresponding layer is quite different

moreover thick layers of under compaction mudstone contribute markedly to abnormal pressure. It is believed by studying distribution of hydraulic head in the Permian and Triassic that hydrodynamic fields are present mainly as compaction flow

whereas in some high positions of structures or fractures around northwest margin of Junggar basin the fields are developed and present as gravity flow or meteoric ground water flow.