Abstract: Based on the study on tectonic evolution history of Fuxin basin, along with qualitative and quantitative analysis of the confining history of fault, uplifting and denudation of structure, magmatic activity, mobility of ground water, sealing capability of caprock and oil-bounded fault after oil/gas entrapment, the preservation conditions of oil/gas reservoir in Fuxin basin are investigated with fuzzy evaluation method, and the basic content and method for studying preservation conditions of oil/gas reservoir in the fault-depression discussed.

Key words: Fuxin, Fault-depression basin, Reservoir preservation condition, Fault, Magma