Abstract: On the basis of comprehensive geological study of hydrocarbon migration and accumulation of Neogene in eastern beach area of China, the simulation test for effects of changes in sandstone thickness and quality on hydrocarbon accumulation in two sides of conducting fault is conducted by means of 2-D model. The result shows that in one hand, in two sides of fault, the thick sand layers is the most favorable to become a reservoir; the intermediate sand layers are regarded as oil layers where quality is good and as water layers where quality is poor, appearing the oil layer, the oil-water layer and the water layer in turn in terms of distances from the conducting fault; the thin sand layers could not become oil layer until the quality is the best, otherwise, become water layer. Hence, the sand layer thickness plays a decisive role, while the quality has an important effect on becoming a reservoir, both of which there have been some complementary relations. In the other hand, the sand layers indirectly connected with the conducting sand beds and the conducting faults, the reservoirs are not only related to their thickness and quality, but also depend on the conducting sand beds' thickness and quality. Only connecting such sand beds with big thickness and fine quality, could the petroleum accumulation or oil layer be favorably formed; otherwise, oil-water layer or just water layer be formed instead of become oil layer. The changes of conducting sand beds' thickness and quality are the key for affecting petroleum accumulation within sand layers.

Key words: sandstone, thickness, petrophysical property, Neogene, simulation test, reservoir quality