Study On Sequence Stratigraphy?Sedimentary Facies And Reservoir Characteristics Of Sangtamu Formation In Late Ordovician In Eastern Tarim Basin

The paper that I have wrote is used to study the Sangtamuzu Formation in Late Ordovician in Eastern Tarim Basin by the theories of Sequence Stratigraphy,Sedimentology and Petroleum Geology.And I studied the Sequence Stratigraphy of the area by using the many kinds of the geological and geophysical data,and built the framework of sequence stratigraphy in this area.And then through the analyzing of the features of the sedimentary facies,I determined the types of sedimentary facies in this area,analysed the characteristics of the main sandstone characteristics,and finally made sure the favorable zones for exploration.Firstly,with making use of the seismic,well logging,core and outcrop data,I identified and tracked of the sequence boundaries at all levels,and built the isochronous framework of sequence stratigraphy of the Sangtamuzu Formation in Late Ordovician in Eastern Tarim Basin.There are 6 ? level sequences in this area,and there are HST,TST and LST in each sequence.By analyzing well logging data and outcrop characteristics,I agreed the fact that the depositional system of deep-water submarine fan is main sedimentary face in the isochronous framework of sequence stratigraphy of the area.And there are 5 sedimentary subfacies in the depositional system,such as braided gravity flow channels deposition in the mid-fan,natural levee and overbank deposition in the mid-fan,turbidite channels deposition in the lower fan,sheet turbidite deposition in the lower fan and basin plain.Meanwhile,I studied main well of the area at vertical analysis of sedimentary facies,and by those analyzed the section evolution of sedimentary facies.Combined with the evolution of sedimentary facies in the vertical and section,the outcrop characteristics of the area,the palaeo-geomorphology recovery,and the distribution of sand rate,I analyzed the distribution of the sedimentary facies in the area.Secondly,I also discussed the major control factor for the region sedimentary facies feature:ancient landforms,source system,the sea level and so on.By using the way of stratigraphic extension,I' recovered the Sangtamu Formation deposition paleogeomorphology pattern in the area with the residual stratum thickness and erosion thickness.Form the paleogeomorphology pattern,we can see that the area is located in a deep sea basin.Through distribution of sand ratio and the measurement of bottom mold structure in outcrop,I argue that the provenance system in the region mainly from the eastern edge of the Kuluktage uplift and the southeastern margin of Altyn Orogenic belt.The sea-level change controls the size of the deep-water submarine fan of gravity flow.Finally,on the basis of the analysis of sequence stratigraphy and sedimentary facies in this area,I point the fact that the main reservoir sandstone are located braided gravity flow channels of the mid-fan and turbidite channels of the lower fan.But these sandstone have the poor performance as the reservoir,such as value of the porosity and penetration is much lower than else.The main reasons behind the result are the far distance from the source area to the baisn,post-compaction and so on.The major part of reservoir sandstone is class ? or class ? in this area.Combined the physical characteristics of reservoir sandstone with deep-water gravity flow depositional model,I maintained that the part where subsidence depth is not very large is the favorable reservoir zone,such as the zone of Yingnan 2 well.