Langfang-Gu'an Depression

situated in Beijing-Tianjin region with an area of 2800 km

2

is a single faulted half-basin of the Eogene which developed on the Paleozoic-Proterozoic basement. It is suggested that: 1. According to oil source contrast and the analysis of the sedimentation and tectonics

the depression contains three categories and four kinds of source rock-reseryoir-cap assemblages. 2.The oil and gas pools can be divided into three categories and ten kinds based on their trapping origin. 3.Oil- and gas-bearing formations include the Minghuazhen Formation ofthe Neogene

the first

second

third and fourth members of the Eogene Sha-hejie Formation and the Ordovician as well. Vertically speaking

oil and gasmay probably distribute in a great depth

and the upper limit of wet-gas zoneis inferred to be in the depth of about 5000-5500m. The discovered pools mainly distribute in the Hexiwu and Liuquan structural belts which are located near oil-generating sags formed during the Late Shahejie stage

bot the exploration of stratigraphic and lithologic pools in Niubei slope zone and around Tongbeizhen sag should also be taken into account.