Jiyang Depression

a typical terrestrial rifted basin experienced complicated tectonism and sedimentation

contains many well-developed subtle reservoirs.Research on the forming mechanism of the subtle reservoirs reveals three important theoretical understandings.First

steep and slow slope fault-steps and innerand outer-basin slope-breaks shaped during fault-dominated tectonism control the formation and distribution of reservoir rocks(also known as 'faulting-slope-controlled sandstone')

making the place an ideal area for exploration of subtle reservoirs.Secondly

different hydrocarbon conducting paths with the shape of meshwork-carpet

capi-tal letter 'T'

ladder

and fractures

develop and operate inside the particular time-space tract in the basin

constituting a complex hydrocarbon transportation system(also known as 'compound transportation')and providing information for the evaluation of exploration direction of subtle reservoirs.Finally

the coupling relation between facies(receiving condition)and liquid potential(driving condition)determines reservoiring conditions and charateristics(also know as 'facies-potential-controlled reservoirs').These understandings constitute the kernel idea of subtle reservoir exploration and promote effectively the petroleum exploration in Jiyang depression during the Tenth Five-Year Plan.