Abstract:

In order to speed up the hydrocarbon exploration proceeding in Shuguang-Leijia area of west depression of Liaohe basin, according to classification method of subtle reservoirs, subtle reservoirs of the area have been classified into two kinds, which are the Pre Cenozoic buried hill reservoirs and the Paleogene special lithologic reservoirs, based on the hydrocarbon exploration results. The Pre Cenozoic buried hill reservoirs include Archean buried hill reservoirs,Middle-Upper Proterozoic buried hill reservoirs and Mesozoic buried hill reservoirs.The Paleogene special lithologic reservoirs include carbonate reservoirs, volcanic breccia rock reservoirs and basalt reservoirs. Based on comprehensive study of the geological background, reservoir-forming condition  and accumulation process of subtle reservoirs within the whole area, it is regarded that the geological conditions to form subtle reservoirs are favorable, such as multiple tectonic movement, complex tectonic background, favorable source conditions, cap rock with good feeling capacity, unblocked and multiple migrationaccumulation systems. The characteristics of reservoir-forming dynamic is discussed according to the theory of the dynamic system for reservoir-forming. It can be clearly seen that the Paleogene special lithologic reservoirs belong to self-sourced and sealed dynamic system, and the Pre Cenozoic buried hill reservoirs belong to outward-sourced and half-sealed dynamic system. The result shows that two kinds of subtle reservoirs have the petroleum geological and dynamic characteristics of the good matching conditions of source, reservoir, cap, trap, migration and accumulation.

Key words: accumulation condition, subtle reservoirs, reservoir-forming dynamic, Shuguang-Leijia area, petroleum gas