Paleo-nowadays Geological Tectonic Of Western Qaidam Basin And Its Relationship With Hydrocorbon Accumulation

The western Qaidam Basin is one of the hot areas of oil and gas exploration in china.In recent years,great progress has been made in the study of basin structure,regional structure,fault structure and local structure in the western Qaidam basin,but it is not enough to study the tectonics which have close relationship with hydrocarbon accumulationThis thesis selects the Alar,Wunan,Yingzhong,Yingdong,Nanyishan,Dafengshan,Jiandingshan,Dongping as study areas.Choose paleogene and neogene's reservoir and cap rock series as the main research object,according to the regional geology,seismic and drilling data,carried out the research work.This dissertation obtained the following conclusions:(1)The source-reservoir-cap rocks' present tectonic framework of western Qaidam Basin can be divided into seven low and high units,those units are:Alar low and high unit,Yingdong-Youshashan low and high unit,Wunan low and high unit,Youquanzi-Kaitemilike low and high unit,Nanyishan-Dafengshan low and high unit,Jiandingshan low and high unit,Dongping low and high unit.The source-reservoir-cap rocks' tectonic framework in later youshashan(N21)can be divided into four low and high units,those units are:Alar low and high unit,Nanyishan low and high unit,Dafengshan low and high unit,Dongping low and high unit.The source-reservoir-cap rocks' tectonic framework in shizigou(N21)can be divided into four low and high units,those units are:Alar low and high unit,Youquanzi low and high unit,Nanyishan-Dafengshan low and high unit,Dongping low and high unit.(2)By researching the relationship between faults and tectonic framework,author found that the Alar fault,XI fault,Youshashan fault,Fengnan fault,Fengbei fault,Yinan fault,Yibei fault,Pingdong fault along the slope most of time.In very little time,they cut the slope.By researching the evolution history of major faults,author found that Alar fault,XI fault,Youshashan fault are activity in each period.Fengnan fault,Fengbei fault,Yinan fault,Yibei fault are activity in later period.Pingdong fault is activity in earlier period.In fault related structures,The formation tendency to favorable oil and gas into the fault section,the formation tendency to deviate from the section is favorable for oil and gas output fault.The ridges of fault plane and fault-related fold are also closely related to hydrocarbon accumulation.(3)The migration of oil and gas are decided by ancient tectonic in the western Qaidam Basin when the present tectonic frameworks are different from ancient tectonic frameworks.In the same area between ancient tectonic and present tectonic,ridge line is the enrichment area of oil and gas,such as:Yuexi oilfield,Yuejin No.2 oilfield,Yuedong oilfield,Nanyishan oilfield,dafengshan Oilfield.In the different area between ancient tectonic and present tectonic,ancient ridge line is the enrichment area of oil and gas,even if present tectonic framework is a syncline,such as:zhahaquan-lvcaotan Oilfield.(4)Puts forward some favorable targets to the western of Qaidam Basin next exploration work:In alar ancient tectonic,north of the ancient ridge line is a favorable exploration target.In Nanyishan present tectonic,the syncline which on the ancient ridge line is a favorable exploration target.