Neopaleozoic tectonic evolution and hydrocarbon analysis in Bamai-Tazhong area,Tarim Basin
GUO Qian, PU Ren-hai
1 State Key Laboratory of Continental Dynamics,Northwest University,Xi'an,Shanxi,710069,China;
2 Department of Geology,Northwest University,Xi'an,Shanxi,710069,China
Abstract：From a paleostructure map of Bamai-Tazhong area in Tarim Basin based on drilling information and seismic data,and through the restoration of Neopaleozoic deposit thickness in Bamai-Tazhong,this paper elaborates that hydrocarbon,after entering reservoir,migrated from the ancient structure nose shaped salient to pitch up direction,and that the hydrocarbon migration,accumulation and dissipation were revealed after leaving source rocks or source rock area.The observations are obtained as follows: 1.The ancient uplift and depression pattern of Bamai-Tazhong in Neopaleozoic period was very different from nowadays,these two uplifts were preliminarily formed during Neopaleozoic,and had the NW extension direction during Carboniferous.The high point of Tazhong uplift was further west than the present time.Hetian River area between these two uplifts is now a low uplift,but it used to be an ancient depression and saddle.The SW Maikit slope was a WE depression which extended deeper from west to east.2.The top surface tectonic evolution of Donghe sandstone show that oil and gas generated in Manjiaer depression migrated to north before latest cretaceous,failed to accumulate in Tazhong uplift.Hydrocarbon migrated to south after neogene and was captured into reservoirs at the No.1 and No.10 high traps in Tazhong uplift,while low structure traps in the south slope of Tazhong uplift could not get hydrocarbon.This probably is the reason for a few dry holes.3.The north Maikit slope and Hetian River low uplift were migration and accumulation areas of multi-struture period.The high structure and the north side of Tazhong uplift were provision and accumulation areas to Manjiaer depression during himalayan period.The eastern area of Tazhong uplift was the final migration oriented area and also the updip pinch-out zone of Donghe sandstone,which consists of multiple sets of reservoirs,a favorable exploration area in Bamai-Tazhong.
