Large scale of prospecting and exploration have been carried out in Dong-ming depression and several oil and gas pools have been found since 1975.Now a big oilfield-Zhongyuan Oilfield is founded there and the place has become one of the important production bases in the eastern part of China.Dongming depression is a graben bounded faults formed since early Tertiary (Eocene-Oligocene).The lower Tertiary can be divided into two sedimentary cycles separated by the base of the second member of the Shaheje Formation.The early

middle and late phases of each cycle had different ways of compensation and different complex of sedimentary facies.Subaerial and subaqueous alluvial fans

mass-flow and lacustrine flood plain sediments are well developed in this downwarped environment.Source rocks are developed in the middle phase of each cycle

and the third member of the Shaheje Formation is the main source rock.Organic matters

mainly of humus-sapropel type

are of middle abundance.The depth of upperand lower limits favourable to oil generation are 2

400m (90℃) and 4

100m(145℃) respectively.Dongming depression is lying in between Liaolan fault and Changyuan fault

comprising two subbasins and one uplift.The differential in time and strenth of faults'movements has controlled various kinds of subordinate basins and led to a number of local structures to form.Most of the structures are basement uplifting anticlinal structures and faulted-blocks.They constitute li-thostructural traps in combination with sandstones.The oil and gas pools can be divided into four groups:1)Inherited anticlinal oil pools;2)Anticlinal oil pools evolved from earlier stepfaults;3)Faulted block pools occurred on later step-faulted zone;and 4)Faultsealed oil pools developed on shallow slope of a half-graben.