Research Of Sequence Stratigraphy In Shizigou Formation Of Pliocene In Sanhu Region

After more than 40 years of natural gas exploration, the Quaternary stratigrapy in Sanhu region of eastern Qaidam Basin is the main purpose of layer. In recent years in order to make a larger breakthrough, Qinghai Oilfield strengthen research and exploration efforts on Pliocene in Sanhu region. Previous studies suggest that the Shizigou formation of Pliocene and the Quaternary formation is a continuous deposition process, which many respects are similar such as sedimentary environment, biological type, lithology and sedimentary evolution and so on. Thus Shizigou formation of Pliocene should also have the generation and reservoir capacity of biogas.On the basis of the theory the high resolution Sequence stratigraphy, Shizigou formation stratum framework is bulit in Sanhu region,and some lithology trap develop area is identified by seismic inversion in sequence stratum framework.The main research results are as follows.1. Based on the study of the data of core,log and seimsic, the framework of the high resolution sequence stratigraphy in Shizigou formation of Pliocene is established.6 sequence boundaries are identified ,5 sequence cycles and 10 systems tracts are identified and carried on contrast on the district.2. The project in the topographic relief backdrop of the ancient landform.The overall evolution of the depositional environment from alluvial fan to lake. Through the study of well logs and lithology characteristics,Shizigou formationof Pliocene identified sedimentary facies, including river flood plain, delta front,onshore sand dam, semi deep lake and so on.3.Lithologic trap develop areas are predicted through fine sequence division,seismic sequence comparison and seimic inversion in the ischronous stratigraphic framework.The regular pattern of the lithology pich-out and lenticular body are predicted.