The Depositional Feature And Favorable Area Prospecting Of Shahejie Formation In Gaoyang Area Of Lixian Slope

Oil and gas exploration in slope regions shows that there're favorable hydrocarbon accumulation conditions in the Lixian slope.And Gaoyang area,which is located in the high position of Lixian slope with relatively single tectonic style that has an active oil and gas discovery.However,it faces many problems,such as various sedimentary facies,multi-stage changes and so on.So the researchs of depositional feature in Gaoyang area of Lixian slope and reasonable forecasts for the favorable zones have important implications for the next step of the oil and gas exploration in Gaoyang area.Based on seismic,core,well drilling data,guided by the theory and technology of sequence stratigraphy,petroleum geology,the study of factor analysis,such as structure,sequence,sandstone thickness,oil-gas possibility of the second member of the Shahejie formation(Es2)to the lower of the first member of the Shahejie formation(Es1x),have been carried out in this paper.And then draws the characteristics of the sedimentary system in the distribution and indicate the distributary law of favorable zones.Through the studies above,the main conclusions of the paper are as follows:(1)A division scheme of Es2?Es1x is adjusted.A set of thin layer of oil shale which developments relatively stable in the entire district is redefined as the top boundary of Es1 x,and the whole Es1 x corresponds to the “special lithology” of the north part of Lixian slope.(2)The difference of sediment supply made the difference of sedimentary sequence in the Shahejie formation,the mainly sedimentary facies of the north are braided river delta and in the south are beach-bars of the shore-shallow lake.(3)A fine study of the sedimentary microfacies in the Es2?Es1x is carried out.On the base of core description,combined with well logging curve,templates for lithofacies and electrofacies have been established.Supported by studies of characteristics of sandstone thickness and sedimentary microfacies of connected wells profile,it is concluded that in Es2 the study area mainly developed braided river delta front,beach-bars of the shore-shallow lake,the microfacies include subaqueous distributary channel,distributary mouth bar,sheet sand and underwater interdistributary bay ect;in Es1 x mainly developed beach-bars of the shore-shallow lake,the microfacies include beach-bar,oolitic beach ect.(4)By analyzing characteristics of oil-gas features,this paper concludes its relationship between sedimentary facies and that productive layers in Es2 s lower sand group are mainly distributed in the oolitic beach,beach-bar and delta front;in Es2 s higher sand group are mainly distributed in delta front;in Es1 x are mainly distributed in beach-bar and oolitic beach.(5)This paper makes a reasonable forecast for the favorable zones in Es2s?Es1x,concluding that favorable zones for Es2 s was relatively large continuous distribution,favorable zones for Es1 x in scattered state.Through comprehensive study,this paper has defined sedimentary characteristics in Es2s?Es1x of Gaoyang area and made a reasonable forecast for the favorable zones.It's important to continual increase reserves in Huabei Oilfield in the future.