The Relationship Between Structural Characteristics And The Hydrocarbon Reservoir Of Midwest Area In Yingxiongling Tectonic Belt

Yingxiongling tectonic belt is located in the western Qaidam Basin.Because of the great breakthrough in oil and gas exploration since 2015,this area has become a hot spot of overland oil and gas exploration and development in our country.For complex structure,predecessors have done a lot of research,but failed to get a unified understanding,which restricts further oil and gas exploration development.This paper studies the low-high structure pattern of main hydrocarbon source rocks(T4 seismic reflection layer),local structure,fault type and tectonic evolutionary characteristics by comprehensively using 3D seismic,drilling,logging,cores,thin sections etc.foundational data,what's more,this paper also analyses the relationship between tectonics and hydrocarbon reservoirs.The main conclusions are as follows:(1)The major low-high structure pattern of main hydrocarbon source rocks(T4 seismic reflection layer)in midwest area in Yingxiongling is encircled depression-center uplift type.The tectonic point of Surrounding Youyuangou-Shizigou depression-uplift is located in the vicinity of Huatugou oilfield,besides,the tectonic point of Surrounding Youshashan-Gasikule depression-uplift is located in the periphery of Youyuangou oilfield.(2)Using 3D seismic data identifies the wedge type,lens type,anticline etc.three local structures and arc type(such as FA1,FA2,FA3,FA4,FA5 fault),"Z" type(such as Shibei fault),oblique type(such as Shibei shallow faults)in total of 11 faults,besides,this paper also maps the 11 main fault planes,such as Shizigou,FA1,FA2,FA3,FA4,FA5,FN1,Shibei,XI and Youshashan faults.(3)Using 3D seismic sections studies the different composition between the fault section and rocks on both sides.This paper totally identifies and divides ridge type,valley type,same inclination half ridge-half valley type,inversion inclination half ridge-half valley type and parallel type etc.in total of 15 types.(4)The structural evolution of this area can be divided into two stages.The first stage ranges from the early Lower Ganchaigou Formation(E31)to late Upper Ganchaigou(N12)Formation.In this stage,stratum accepts stable sediment and eventually becomes monoclinic depression;the second stage ranges from Lower Youshashan(N21)to Qigequan(Q)Formation,in this stage,the lens structure associated with the gypsum rock formed firstly,wedge type structure,arc fault and "Z" type fault subsequently appear in succession,and keep on developing.(5)Combining with drilling,logging,oil testing data,lens type structure,wedge type structure,and the arc fault,"Z" type fault have discovered industrial oil and gas reservoirs in Midwestern Yingxiongling area.