Geological Architecture And Tectonic Evolution In The Eastern Segment Of The Tabei Uplift

Uplift is an important window to understand the formation and evolution of basins.Besides,uplift is the main part of hydrocarbon accumulation,and is an important area of oil and gas exploration.In Tabei uplift,several hundred million tons of large-sized oil and gas fields are found,such as Tahe,Lunan and Yingmaili,but all of them are distributed in the middle and west of the Tabei Uplift,however,the oil and gas exploration in the eastern of Tabei uplift is very small.The study of geological architecture and tectonic evolution in the eastern part of the Tabei uplift plays an important role in explaining the difference in hydrocarbon accumulation.The main methods of research include: making the well section;making seismic synthesis records,summarizing the characteristics of seismic formation;using the theory of fault related folds,to interpretate the fault and combinate the faults;studying the three dimensional geometry of the fault;reconstructing the structure of the structural section section,determining the key change period;analyzing its genetic mechanism.The influence of tectonic evolution on hydrocarbon migration and accumulation is to optimize the exploration area;analysising of the control effect of tectonic evolution on oil and gas.There are the conclusion:1.There are 3 regional unconformities in the eastern segment of the Tabei Uplift,including Z/An Z(Td),D/S(Tg5)and T/AnT(Tg),by which,divided stratum into four tectonic stratigraphic sequences from bottom to top: the basement metamorphic rock series,Sinian to Silurian structural layer,Devonian to Carboniferous structural layer and Triassic to Cenozoic structural layer.2.The main faults in the east of the Tabei uplift include the Yeyungou fault(as the northern boundary of the Tabei uplift),the Luntai fault and the Yanan fault(as the main components of the high part of the Tabei uplift),the Kunan fault,the Baliying fault and the Dgeleke fault zone(as the adjustment faults between the internal structural units of the Tabei uplift).3.The structural restoration of the geological section of the regional reflects that the eastern part of the Tabei Uplift mainly formed a large fault fold in the basement slipping layer in the middle and late Caledonian period,the uplift initially formed in Hercynian period;the Luntai fault,the Kunan fault,the Baliying fault formed;and in the Indosinian period to Himalaya,uplift reformed,the tectonic deformation is weaker in Caohu sag to Kuerle and is stronger in Kongquehe slope.4.The main dynamic sources of structural deformation in the eastern segmengt of the Tabei uplift are the closure of western Kunlun ocean basin in the early Ordovician and the closure of south Tianshan oceanic basin in the Carboniferous Permian,the activity of the fracture are the response in the basin.The main fault zones,such as the formation of Yeyungou fault,the Yanan fault in the late Ordovician,the formation of Lutai fault,the Kunan fault in the Carboniferous to Permian.5.There is a good petroleum geological conditions in study area,in which the Cambrian to middle Ordovician hydrocarbon source rocks began to generate hydrocarbons in the late Ordovician period.Oil and gas migrated and accumulated in the high tectonic traps.The primary oil and gas reservoirs have been greatly damaged in the Carboniferous to Permian.Therefore,the exploration of oil and gas in the study area should look for residual oil and gas reservoirs and lithologic reservoirs below the unconformity.