Oil & Gas Geology ›› 2004, Vol. 25 ›› Issue (4): 437-443.doi: 10.11743/ogg20040413

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Oil classification and biodegradation in Daerqi oilfield, Baiyinchagan depression

Tan Yuming1,2, Feng Jianghui1,2, Zhang Yunxian2, Jin Guangxing2,3, Pan Changchun1, Sheng Guoying1, Fu Jiamo1   

  1. 1. Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, Guangdong;
    2. Zhongyuan Oilfield Company, SINOPEC, Puyang, Henan;
    3. China University of Geosciences, Beijing
  • Received:2004-07-20 Online:2004-08-25 Published:2012-01-16

Abstract:

Based on oil physical features, group compositions, biomarker compounds and biodegradation, the crude oil in the Daerqi oilfield is classified into five types.Type I oil is a low viscosity and density, light oil. Its group composition is predominately the saturated hydrocarbon, with a low contents of nonhydrocarbon and asphaltic components. This type of oil is unbiodegraded, with a high sterane isomerization index and maturity. Type Ⅱ oil is immature and extremely viscous, with a relatively high density. Its group composition is dominated by nonhydrocarbon and asphaltic components, with a low content of saturated hydrocarbon. This type of oil is unbiodegraded, with a low sterane isomerization index. Type Ⅲ oil is a mixed product of type I oil and type Ⅱ oil. Type Ⅳ oil is a common viscous oil, with a relatively high viscosity and density, which is formed by biodegradation of type I oil. Type V oil could be caused by biodegradation of type Ⅲ oil. Its density and viscosity are similar to that of type Ⅳ oil, but sterane isomerization index is relatively low. Excluding the type Ⅱ oil (immature and extremely viscous oil) from the shallow immature source rock of the Duhongmu Formation, all the oil of other four types are mainly derived from the higher mature, deep-seated source rocks of the Tenggeer Formation and/or A'ershan Formation.

Key words: Daerqi oilfield, viscous oils, biomarkere, biodegradation

CLC Number: