Abstract: According to the systematic analysis of hydrocarbon accumulation conditions, hydrocarbon distribution and reservoir-controlling factors, the shallow-middle reservoirs in No.1 structure of the Nanpu sag are above-source reservoirs where hydrocarbons came from the third and first members of Shahejie Formation and the third member of the Dongying Formation. Laterally, hydrocarbons are mainly distributed in the major part of the structure, and abundant on both sides of the oil-migrating fault; hydrocarbons are dispersed farther from the major part of the structure. Vertically, there are many oil-bearing horizons with long oil producing intervals, and the oil-bearing intervals are concentrated; the farther from the source rocks, the less hydrocarbons are accumulated; hydrocarbons are mainly endowned in the first member of Dongying Formation and the fourth member of Guantao Formation under the thick regional volcanic cap-rocks. The characteristics of hydrocarbon distribution are closely related to several reservoir-controlling factors. First, the inherited positive structure is a favorable destination of hydrocarbon migration, and hydrocarbons may probably accumulate within the traps with conducting system. Second, oil-migrating fault is a key element for hydrocarbon accumulation, and it constitutes a complex conducting system with the sand framework, through which hydrocarbons migrate into shallow-middle favorable traps. Third, local low-relief structure, lateral volcanic sealing and overlying cap-rocks are favorable factors for the formation of structural-lithologic reservoirs. Fourth, good reservoir sand types and facies belts are favorable for hydrocarbon accumulation.

Key words: above-source reservoir, characteristics of hydrocarbon accumulation, oil-migrating fault, sedimentary sand body, No.1 structure of Nanpu sag