GAS COMPOSITION IN ULTRA-HIGH PRESSURE METAMORPHIC FLUID AND GAS POOL-FORMING CONDITIONS IN OROGENIC BELT
Tao Shizhen\ Wei Yanzhao (Research Institute of Petroleum Exploration and Development of China,Beijing\ 100083) Liu Deliang\ Yang Xiaoyong(China University of Science and Technology,Hefei\ 230026) Yang Hongqing(China University of Geosciences,Beijing\ 1
Traditional oil\|gas geological study and exploration\|development almost concentrated in basin. The collisional and sutural belt of plates (or landmasses), orogenic belts being advantageous places where abiogenic gas produce and discharge, this is a new field in natural gas geological study. The components of fluid inclusions in ultra\|high pressure metamorphic rocks in the Dabie orogenic belt were analyzed with laser Raman probe technology. The study results show that there are not only CO\-2 (50%), H\-2, N\-2, H\-2S etc., but also high content gas of mantle\|derived hydrocarbon (CH\-4 etc., amount to 23 6%). Meanwhile, there are enormous CO\-2 originating from carbonate rocks and other carbon\|bearing rocks in shallow synthem through dynamic metamorphism in the Dabie ultra\|high pressure metamorphic belt. The formation conditions of abiogenic gas can exist in ultra\|high pressure metamorphic belt where nappe structure, ductile fault and mylonite can turn into the trap, cover and conservative conditions of abiogenic gas. Study results provide new thought train, direction and field for oil gas geological study and exploration\|development.