Oil And Gas Accumulation Characteristics Analysis In Xihu Depression,East China Sea Basin

Xihu depression is located in the middle of the east China sea basin,with the Ningbo 17 and 22-1-1,and other large and medium gas fields found,for the future of deep gas exploration and development become the Xihu depression of exploration,it is necessary to clarify the cause of the Xihu sag of crude oil and natural gas,source,distribution characteristics and hydrocarbon accumulation pattern..Xihu sag of the crude oil mainly comes from coal and mudstone,organic matter abundance distribution are high organic matter maturity and hydrocarbon source rocks are widely distributed;Natural gas is mainly from coal measures hydrocarbon source rocks,organic matter abundance is high,or deeper strata are mainly distributed to the lake group,at the stage of high mature hydrocarbon generation.Mainly sandstone reservoir.Channel system,the Xihu sag of the main oil and gas vertical migration along the fault,and lateral migration along the sand body or unconformable surface.Cover both is different,the crude oil mainly mudstone cap rock,natural gas and affected by Pinghu set of internal overpressure sealing gas accumulation,gathered to lake within the group.Similar trap type,mainly in fault block,anticline,semi anticline trap is given priority to,etc.Xihu sag of crude oil,high saturated hydrocarbon content,from the characteristics of saturated hydrocarbon and light hydrocarbon analysis of crude oil were mainly derived from terrigenous organic matter,but in different parts of the crude oil on these characteristics and obvious differences,reflect different parent material source of crude oil.Using crude oil,carbon isotope,light hydrocarbons and a series of data analysis found that Xihu sag in Pinghu oil mainly for coal measures hydrocarbon source rocks or source contribution,and crude oil are mainly mudstone contribution Huangyan area.Xihu depression gas methane content is high,give priority to with moisture.Using characteristics and light hydrocarbon component carbon isotope analysis of causes and sources of natural gas found that Xihu depression is mainly for the coal gas,natural gas is mainly for the kerogen thermal cracking causes directly,and mainly from Pinghu set of hydrocarbon source rocks,Pinghu area mixing source gas existed at the same time,and sources of Huangyan district is unified.Xihu sag of the oil and gas accumulation by hydrocarbon generation center,fault distribution and overpressure sealing the three factors,lead to oil and gas fields of the Xihu depression has been found that the oil and gas field split's greatest hydrocarbon-generating center in the Xihu depression within or near,at the same time,fault development for oil and gas migration and accumulation,and overpressure controls the Xihu sag of vertical distribution characteristics of oil and gas,the overpressure gas within the group gathered in Pinghu,and flower set term is given priority to with condensate,resulting in the western slope belt for the characteristics of gas under the oil reservoir distribution.