Sedimentary Characteristics And Prediction Of Favorable Traps Of Kepingtage Formation Of Silurian In The North Slope Of Tazhong Area

The sequence stratigraphy and sedimentary system of Kepingtage formation in tarim basin have been analysed systematically with the applying of sequence stratigraphy and the theory of modern sedimentology and the analysis of outcrop section,core,logging and seismic data.The following results have been achieved:With the analysis of Tazhong Western Dawangou and Sishichang outcrop?core?logging and seismic data,three typical sequence interface can be recognised in the research area:regional unconformities,sedimentary environment turnaround surface and sequence superposition style turnaround surface.The Kepingtage formation in tarim basin can be divided into two third-order sequences(Sql-Sq2)and five forth-order sequences(C1-C5)on these bases.With the Using of the 2-D data in Tazhong,3-D data in Shun 1 area,the development characteristics of depositional system in third-order sequence Sql and Sq2,tidal flat,onshore,braided river delta and neritic shelf can develop in this area,shoreline sedimentary system developed in the period of Sql and tidal flat,onshore,braided river delta sedimentary system developed in the period of Sq2.According to the comparison of residual thickness maps and the rate of sand tostratigraphy under the sequence framework,we summarized the distribution condition and characteristics of evolution of depositional system,clarified the distribution range of coastal sand dam and tidal channel which have exploration prospect and established the development mode of shelf-coastal-tidal flat-delta in north slope area in Tazhong.On the basis of earthquake and well data,we can identify four kinds of non-structural traps which include stratigraphic overlap trap,lithological updip trap,lens trap and channel filling trap in this research area and summarize their distributions and forming conditions.In the period of Sql,research area main develop stratigraphic overlap trap(overlaping the bottom boundary T70 of Kepingtage formation).In the period of Sq2,we can identify stratigraphic overlap trap(overlaping the internal stratigraphy of Kepingtage formation),lithological updip trap,lens trap and channel filling trap.With the comprehensive study of sequence stratigraphy,sedimentary system distribution and hydrocarbon accumulation conditions,we think the north slope of Tazhong area develop ? favorable traps--stratigraphic overlap trap(overlaping the internal stratigraphy of Kepingtage formation),in north,central and south of Tazhong area develop ? favorable traps-channel filling trap,stratigraphic overlap trap(overlaping the bottom boundary T70 of Kepingtage formation),and in the northwestern Tazhong area develop ?favorable traps-lens trap,lithological updip trap.