Study On The Sedimentary Characteristics And Its Control On Reservoir Of Carboniferous To Permian In Linxing Area

In this paper,the sand formation group of Carboniferous—Permian coal bearing strata in Linxing area of ordos basin is divided.The distribution of sand body and its physical properties were analyzed in detail.The sedimentary characteristics of each layer in the region are studied systematically.It reveals the controlling effect of sedimentation on the formation and distribution of sand body.The study shows that the main developing barrier beach sedimentary facies of Benxi formation in Linxing region,further identify the subfacies of barrier island and three kinds of microfacies:mud flat,sand flat and peat plateau.The main developmental barrier of Taiyuan formation is barrier coastal sedimentary facies,only in the vicinity of Kangning town development of meandering river delta deposit,identify the barrier island subfacies and six sedimentary microfacies are mud flat,sand flat,mixed plateau,carbonate tidal flat,distributary channel and shunt depression.The Shanxi formation development of meandering river delta sedimentary facies.Among them,the second member of Shanxi formation developed delta plain deposit.The first member of Shanxi formation is mainly composed of delta front deposits and locally developed delta plain deposits.Including the five types of sedimentary microfacies are peat bog,underwater distributary channel,distributary channel,distributary bay and shunt depressions.The eight member of Shihezi formation main development braided river delta deposit,it can be recognized two subfacies are braided river delta front and braided river delta plain,and four sedimentary microfacies can be identified,it is underwater distributary channel,distributary channel,shunt bay and flood plain.By studying the identification of sandstone reservoirs,electron microscopy,physical measurement data and so on.It is believed that the dense sandstone in the study area is dominated by lithic sandstone,the cement is mainly siliceous,carbonate and clay minerals,the pore types are mainly intergranular pores,granular pores and microfractures.The average permeability is shown as:the second member of Taiyuan formation>the eighth member of Shihezi formation>the second member of Shanxi formation>the first member of Shanxi formation.The average porosity is shown as:the eighth member of Shihezi formation>the second member of Taiyuan formation>the second member of Shanxi formation>the first member of Shanxi formation.Combining the sedimentary characteristics of the region with the sand body characteristics,it is found that sedimentation plays an important role in controlling the thickness,spread and property of the sand body.It can be seen that underwater distributary channel,distributary channel,barrier island and sand flat,these four microfacies sedimentary sand bodies have the characteristics of large thickness and good physical properties,they are the main microfacies of high quality reservoir sand body development in this district.Comprehensive research results,the favorable regionalization of the reservoir sand body in the relevant stratum of the region is divided into two levels.I level favorable area for sandstone reservoir in all kinds of factors are relatively best matching and porosity of>9.3%,II level favorable area for sandstone reservoir in all kinds of factors are relatively well matching and porosity of>8.5%.Finally,the development zone of high quality sandstone reservoir in Linxing area is divided.It is considered that the advantages area of the sandstone reservoir are:Zhao jia ping township—LX-10 well,Area near Mengjia ping township,Lei jia qi township—Tu ban township—LX-1 well,LX-22 well—He jia hui township.