DIFFERENCES IN RESERVOIRING CONDITIONS OF OIL AND NATURAL GAS AND RESERVOIRING MODELS OF GAS FIELDS IN CHINA
WANG Ting\|bin (Exploration and Production Research Institute, SINOPEC, Beijing 100083, China)
The differences in reservoiring conditions of natural gas and oil, as well as the multicycle developments and evolution histories of major gas bearing basins in China, and the geological environments characterized by relatively active tectonic movements in later period have resulted in the forming conditions of gas fields in China to be more complicated than those in many basins all over the world. Summarizing the reservoiring courses of large and medium gas fields in China, they can be divided into 4 types, being bounded by Neogene, Paleogene and Mesozoic, i.e. ①super\|late (Neogene to Quaternary) hydrocarbon generating and reservoiring type;②late(Paleogene to Neogene)hydrocarbon generating and reservoiring type;③early(Mainly in Mesozoic)hydrocarbon generating and accumulating and late(Paleogene to Quaternary)finalizing and reservoiring type; and④early(mainly in Mesozoic) hydrocarbon generating and reservoiring type. In China, those mainly of late and super\|late reservoiring and finalizing gas fields have the most extensive distribution and the best prospects; while those of early hydrocarbon generating and reservoiring type have also relatively good prospects in basins with good preservation conditions. The three major gas exploration areas in China are: the foreland basins in west\|central China, the three large cratonic composite basins (Sichuan, Ordos and Tarim), and the offshore rift and pericontinental basins. These indicate that the natural gas has mainly been finalized and reservoired in late and super\|late stages, which constitute the major enriched areas and domains of natural gas in China.