西南石油大学学报(自然科学版) ›› 2011, Vol. 33 ›› Issue (3): 53-60.

• 地质勘探 • Previous Articles     Next Articles

he Discovery and Characteristics of Covered-pressurization Karst During Early Hercynian in South Tahe Oilfield

YAN Wei 1 WANG Xing-zhi 1 DING Yong 2 L¨U Hai-tao 2 LIU Chun-ge 2
  

  1. 1. School of Resources and Environment，Southwest Petroleum University, Chengdu, Sichuan 610500, China;
    2. Development Department of NWBC，SINOPEC, Urumqi, Xinjiang 830011, China
  • Received:1900-01-01 Revised:1900-01-01 Online:2011-06-20 Published:2011-06-20

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Abstract: The Ordovician formations of Tahe Oilfield mainly undergo two karsts of mid-Caledonian and early Hercynian. The predecessors considered that because of the thick aquifuge in Sangtamu Group（O3），the effecting range of early-Hercynian karst was controlled by the edge line of the Sangtamu Group: The Northern part which lack

the Sangtamu Group was the affecting area of early-Hercynian karst，while，the Southern part which was covered by the Sangtamu Group was the the affecting area of only mid-Caledonian karst. Recent research shows that for the reason of its favourable factors, such as high-uplift amplitude of structure，long time exposure，highly development of fractures，fluent hydrodynamic etc, it is extremely beneficial to karst effections. On top of that，the early Hercynian karstis able to break through the restriction of the Sangtamu aquifuge. The coverage of the Sangtamu group only
changes the model of early-Hercynian karst：from crust karst to Covered-Pressurization karst. The discovery of this karst has a great guiding significance to the exploration for cavity- reservoirs in the southern and southwestern areas. It points out that，only the fault zones which are connected with the main region can be the favourable reservoir zones，otherwise, Reservoir would be less developed.

Key words:

Tahe Oilfield, Ordovician, the edge line of the Sangtamu Group, early-Hercynian, mid-Caledonian, Covered-Pressurization karst

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