Abstract: Hydrocarbon accumulation system is known as a unified complex capable of hydrocarbon accumulation under favorable geologic environment, which consists of hydrocarbon generation, reservoiring, capping, transportation, trapping, preservation and other key elements. It takes the accumulation unit as a closed, complex, relatively independent and open system, with features of integrity, hierarchy, relevance, openness, dynamics and comparability. The study of accumulation system should be guided by systematic scientific ideas, highlight integrity, probe into the accumulation factors qualitatively and quantitatively, find out main controlling factor, analyze the effect of environmental factor on the system, and finally determine the accumulation function integrates by considering all the factors mentioned above.

Key words: system theory, hydrocarbon accumulation system, accumulation factor, accumulation function, accumulation unit