The Fine Description Of Reservoir In The Upper Part Of The Second Member Of Guantao Formation Of Neogene In L25-1 Block,Dalujia Area,Linpan Oil Field

Lin25-1 Block,one of the main fault block reservoir in Dalujia area of Linpan oil field,now has come into high water-cut stages,but it still has great development potential.There are many problems existing in the process of understanding reservoir in the upper part of the second member of Guantao formation in this block,including inaccurate information in stratigraphic correlation scheme,lack of detailed study of sedimentary microfacies,errors in the interpretation of oil wells,runaway estimates of reserves.In view of these problems and in order to further find out the distribution of remaining oil and improve the development effect,we need to make a fine description of upper part of the second member of Guantao formation reservoir in this block.In this paper,main research contents of the fined description of reservoir is guided by the theory of sedimentology and subsurface geology of oil and gas field.and it is based on core data and well logging data.Combining with the regional sedimentary background of the top layer of the second member of Guantao formation of Lin 25-1 block in Lin-pan oilfield,we firstly worked on the reservoir hierarchy division and correlation and finalized the programmme of the thin layer division and contrast.Based on that,we studied on the characteristics of sedimentary microfacies,secondary logging interpretation and reservoir heterogeneity.At last,we built the geological model of the upper part of the second member of Guantao formation in our research block with 3D geoscience modeling technique and re-estimated the reserves of the oil block.Based on the analysis of the reservoir hierarchy division and correlation,the reservoir of the upper part of the second member of Guantao formation of Lin 25-1 block are divided to two thin layers,the one on the top layer was named the I thin layer,and the layer at the bottom was named the II thin layer.Combined with the regional sedimentary background of the research,the sedimentary facies of this block are divided into three sedimentary subfacies,including river channel-filling,channel embankment,flood basin.And they are further invided into four sedimentary microfacies,including point bar microfacies,natural levee microfacies,crevasse-splay microfacies and flood plain microfacies.In the research,we use the reservoir parameter interpretation model to carry out the secondary logging interpretation to all wells in the block.And the result of the interpretation is that,if the porosity is less than 20%,the reservoir is dry layer,if the porosity is more than 20% and the water saturation is less than 40%,the reservoir is oil reservoir,and if the porosity is more than 20% and the water saturation is more than 40%,the reservoir is water reservoir.Based on this result,we analysed the characteristics of reservoir heterogeneity and judged that the type of the reservoir in the upper part of the second member of Guantao formation of this block is high porosity and permeability reservoir.We also get that the interlayer heterogeneity and the cengnei heterogeneity of each layers are moderate and the plane heterogeneity is weak.Finally,based on the related research achievement,we built geological models of the upper part of the second member of Guantao formation in Lin25-1 block with 3D geoscience modeling technique.The geological models include geology structure model,sedimentary facies model,Reservoir parameter models.And at last the reserve of the oil block is recalculated and it increased 29×104t,and point bar sand bodies of II thin layer should be the development emphasis.It provides the geological basis for forecasting the remaining oil distribution,adjustment of development plan and adjusting development plan,and improving development response.