The theory of prolific depression is essentially to let us have an idea of "depression fully filled with oil and gas" namely

the depression with rich source rocks

high resource abundances

enriched-oil and gas

and to search for not only reservoirs in positive structural zone

but also more important to search for reservoirs in negative structural zone as well

and to search for different subtle reservoirs in particular. There are various subtle reservoirs such as lithologic reservoir

stratigraphic reservoir

especially as well as volcanic rock reservoir and buried hill reservoir etc.

the reserves of which making up almost 40% of the total proved reserves in the study area.The prolific depression in Dongyang

Zhanhua

Western and Eastern Liaoning

Damintun

Raoyang

Qikou and Banqiao etc.have been discovered with high resource abundances

and large well- developed subtle reservoirs with great potential for the exploration of oil and gas. Deep buried hill

turbidite body in the sag zone

sand body in the steep gradient zone

the third member from Shahejie- Formation and the Mesozic volcanic rock

water encroachment overlapping delta sand body in the gentle slope zone as well as complex subtle blocks etc.are believed to be major projecting areas for the exploration of oil and gas in prolific subtle reservoirs.