The Qaidam Basin is located in the northeastern part of the Qinghai-Tibet Plateau (or Tibetan Plateau). It is the world's highest altitude petroliferous basin (the altitude is usually more than 3000m above sea level). But this basin is more famous for its ‘double complex’ in terms of surface and subsurface structures.

Our study areas, YingXi and YingZhong are located at the southwest of YingXiongling structural belt within the Qaidam basin. From the , we can see the "double complex" structures very clearly. The surface is full of wind erosion mountains . The serious elevation variation proposes huge challenge for seismic data acquisition, statics correction and near surface modeling. Meanwhile the subsurface is thrusted severely . The shallow part is thrusted with detachment faults and mainly comprised of severely deformed fold and Shizgou fault, which is the main fault of the survey. The horizon offset across it is usually quite large up to 2km. The study zone is more than 4000m deep where it is thrusted into imbricate fans with very strong overlying structural disturbing. The structure is cut by several groups of low angle faults. This kind of geological condition may produce quite good traps for oil and gas. Besides the overlying salt layers of the study zone extend to certain range which can be very good seal to prevent the oil and gas from migrating upward along Shizgou fault.

These extremely complex geological situations cause a series of world-class E&P difficulties, such as how to obtain better seismic image, where to drill exploration wells, how to design and drill horizontal development wells with higher success rate, and how to submit OOIP or Reserve to the country for so complex region, etc. But to solve these difficulties, one thing is the key, i.e. the accurate structural delineation. This also the final goal of our work. In this paper we will discuss and show how we reach it by integrated Geophysical & Geological modeling.

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