Oil & Gas Geology ›› 2011, Vol. 32 ›› Issue (5): 760-767.doi: 10.11743/ogg20110515

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Reconstruction of the Late Ordovician palaeogeomorphology and reservoir prediction in Yanchang exploration area,the Ordos Basin

Han Minqiang1, Pu Renhai2, Liu Haijuan2, Guo Xiangdong3, Liu Baoping3   

  1. 1. Remote Sensing Application Institute,Aerophotogrammetry and Remote Sensing Bureau,CNACG,Xi'an,Shaanxi 710054,China;
    2. Department of Geology,Northwest University,Xi'an,Shaanxi 710069,China;
    3. Department of Gas Exploration and Development,Oil and Gas Exploration Company of Yanchang Petroleum Group,Yan'an,Shaanxi 716000,China
  • Received:2010-05-20 Revised:2011-07-01 Online:2011-10-28 Published:2011-12-16

Abstract:

Major breakthroughs have been achieved in gas exploration in the Ordovician Majiagou Formation in Yanchang exploration area.These discoveries show that the development and distribution of gas-bearing layers have a close relationship with the furrow erosion palaeogeomorphology on top of the Ordovician.By using such techniques such as fine subdivision and correlation of the Majiagou Formation,thickness mapping of the Benxi Formation on the unconformity,forward modeling-based identification of eroded furrows on seismic section,and seismic inversion,we mapped the paleogeology of the pre-Upper Paleozoic and recognized two NW-SE trending eroded furrows on top of the Ordovician.The comprehensive analysis of the paleogeomorphogloic map and wave impedance map shows that the distribution of favorable reservoirs with low wave impedance in the Ordovician is consistent with the locations of erosion furrows and the eroded slopes on both sides.Moreover,it is also consistent with the locations of wells that produce gas from the Ordovician and that have favorable oil/gas shows.The research indicates that favorable reservoirs occur near Y112 well in Ganquan area,Y113-Y101 wells in the northwest of the study area and Y118-Y119-Y108 wells in central of the study area.These areas should be the major target areas for further exploration of the Ordovieian.

Key words: palaeogeomorphology, eroded furrow, forward modeling, impedance inversion, Majiagou Formation, Ordos Basin

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