Oil & Gas Geology ›› 2009, Vol. 30 ›› Issue (3): 337-342,349.doi: 10.11743/ogg20090313

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Features of organic matter and formation environment of marine carbonate rocks

Zhou Xinke, Xu Huazhen   

  1. SINOPEC Petroleum Exploration and Production Research Institute, Beijing 100083, China
  • Received:2009-01-05 Online:2009-06-25 Published:2012-01-16

Abstract:

Marine carbonate rocks are usually formed on neritic continental shelf where sea water evaporates fu-riously,living organism flourishes,and Eh and pH values change easily.Turbulent sea water with its high oxygen content destroys the soft parts of dead organism and forms carbonate rocks with low-abundance and low grade organic matters.Worldwide,carbonate rocks with TOC less than 0.2% and kerogen type of Ⅲ or Ⅱ2 are common.It is therefore concluded that pure carbonates can not serve as effective source rocks.The TOC of carbonate rocks increases as the shale content becomes bigger,and only a small amount of marls with TOC larger than 0.5% may be effective source rocks.

Key words: neritic continental shelf, abundance of organic matter, kerogen type, effective source rock, depositional setting, marine carbonate rock

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