Analysis On Exploration Potential Of Mesozoic Buried Hill In Chengdao Oilfield

ChengDao Oilfield is located in the shallow waters of the Bohai Gulf,tectonically located in the southeast end of ChengBei low swell.This region is a large buried hill draping structural developed on pre-Tertiary basement.The Mesozoic buried hill experienced strong tectonic movement,with complex stratigraphic structure,various reservoir lithofacies and complex reservoir control factors,which has brought some difficulties for oil and gas exploration and development.In order to understand Geological structure characteristics,formation mechanism of reservoir and distribution of oil and gas,the main work carried out as follows :(1)study on the division and distribution of Mesozoic strata correlation;(2)study on control factors and evaluation of complex lithologic reservoir;(3)study on main controlling factors of hydrocarbon accumulation.After the study,buried hill in the region had experienced several stages of tectonic period,finally formed the characteristic structure pattern with west line hill,middle line hill and east line hill.The development of buried hill reservoirs is controlled by lithofacies,unconformity and fracture.There are two types of reservoir spaces,such as fractures and various pores,and two types of reservoir rocks,clastic rock and igneous rock.The reservoir property of Xiwa formation and Mengyin formation is the best,followed by Santai and Fangzi formation.The pebbly sandstone is the best in clastic reservoir,the next is sandstone.The reservoir is well developed within 100 m below the unconformity,and multistage weathering is more favorable.The reservoir near the main fault is the most favorable,and the igneous rock is generally fractured to produce high yield.It also points out the controlling factors and distribution law of Mesozoic buried hill oil and gas in Chengdao area.It is considered that the development of reservoir characteristics,lateral sealing of faults and the conditions of caprock and the conditions of oil and gas transportation will jointly control the oil and gas accumulation in buried hill.Oil and gas are mainly distributed in the well formed structural traps controlled by long term active faults.On the basis of research and understanding,submit 5 favorable exploration targets.