Shangzhi-Shimen Region

with a total area of about 10000km

2

is situ-ated at the northwest margin of the Jiangnan Old Land.The basic struc-tural type is two depressions in the north and south and a uplift in be-tween.Start from north to south

it is composed of Taiqing shan-Hongjiaguan syncline zone

Siwangshan-Huangchang anticline zone and Dayong-Shimen syncline zone.The source beds are the Lower Silurian

Or dovician

Lower Cambrian

the Dengying and Doushantuo Formations of the Upper Sinian

the mainre servoir is the Dengying Formation.The fractures in this region are characterized by well developed combinedstriks of different directions and multi-stage activities.They are usually filled by low-temperature hydrothermal deposits

some of them have ther-mal springs accociated with nitrogen.All this may be harmfull to hydro-carbon preservation.The preservation condition of Siwangshan-Huangchang anticline zone is better

Yanzhiyan anticline

a part of the anticline zone

formed earlier than others and has favourable trap condition.