Biodegraded Oil and Its High Molecular Weight (C_(35+)) n-alkanes in the Qianmiqiao Region in the Bohai Bay Basin, Northern China  

作　　者：WANGTieguan ZHUDan LUHong ZHANGZhihuan YANGChiyin 

机构地区：[1]TheKeyLaboratoryofPetroleumAccumulationMechanismoftheEducationMinistryUniversityofPetroleum,Beijing102249 [2]TheKeyLaboratoryofPetroleumAccumulationMechanismoftheEducationMinistryUniversityofPetroleum,Beijing102249 [3]TheKeyLaboratoryofPetroleumAccumulationMechanismoftheEducationMinistryUniversityofPetroleum,Beijing102249／／GuangzhouInstituteofGeochemistry,ChineseAcademyofSciences,Guangzhou,Guangdong510640 [4]GeologicalResearchInstitute,DagangOilfield（Group）Co.Ltd.,Tianjin300280

出　　处：《Acta Geologica Sinica(English Edition)》2004年第4期993-1001,共9页地质学报（英文版）

基　　金：Th is study was supported by the National Natural Science Foundation of China(NSFC,no.40172056);the Research Fund for the Doctoral Program of Higher Education,China(RFDP,no.2000042506).

摘　　要：With a production of 208.2 m3/d, heavy oil was produced by drill stem test (DST) from three shallow reservoirs in Sand Group Nos. Ⅰ and Ⅲ of the Neogene Guantao Formation (NgⅠ and NgⅢ) and the Eogene Dongying Formation (Ed) in an exploratory well Ban-14-1 within the Qianmiqiao region, Bohai Bay Basin, northern China. Based on the GC and GC-MS data of the NgⅠ and NgⅢ heavy oil samples, all n-alkanes and most isoprenoid hydrocarbons are lost and the GC baseline appears as an evident 'hump', implying a large quantity of unresolved complex mixture (UCM), which typically revealed a result of heavy biodegradation. However, there still is a complete series of C14-C73 n-alkanes in the high-temperature gas chromatograms (HTGC) of the heavy oil, among which, the abundance of C30- n-alkanes are drastically reduced. The C35-C55 high molecular weight (HMW) n-alkanes are at high abundance and show a normal distribution pattern with major peak at C43 and an obvious odd-carbon-number predominance with CPI37-55 and OEP45-49 values of 1.17 and 1.16-1.20, respectively. According to GC-MS analysis, the heavy oil is characterized by dual source inputs of aquatic microbes and terrestrial higher plants. Various steranes and tricyclic terpanes indicate an algal origin, and hopane-type triterpanes, C24 tetracyclic terpane and drimane series show the bacterial contribution. With the odd-carbon-number preference, HMW n-alkanes provide significant information not only on higher plant source input and immaturity, but also on the strong resistibility to biodegradation.With a production of 208.2 m3/d, heavy oil was produced by drill stem test (DST) from three shallow reservoirs in Sand Group Nos. Ⅰ and Ⅲ of the Neogene Guantao Formation (NgⅠ and NgⅢ) and the Eogene Dongying Formation (Ed) in an exploratory well Ban-14-1 within the Qianmiqiao region, Bohai Bay Basin, northern China. Based on the GC and GC-MS data of the NgⅠ and NgⅢ heavy oil samples, all n-alkanes and most isoprenoid hydrocarbons are lost and the GC baseline appears as an evident 'hump', implying a large quantity of unresolved complex mixture (UCM), which typically revealed a result of heavy biodegradation. However, there still is a complete series of C14-C73 n-alkanes in the high-temperature gas chromatograms (HTGC) of the heavy oil, among which, the abundance of C30- n-alkanes are drastically reduced. The C35-C55 high molecular weight (HMW) n-alkanes are at high abundance and show a normal distribution pattern with major peak at C43 and an obvious odd-carbon-number predominance with CPI37-55 and OEP45-49 values of 1.17 and 1.16-1.20, respectively. According to GC-MS analysis, the heavy oil is characterized by dual source inputs of aquatic microbes and terrestrial higher plants. Various steranes and tricyclic terpanes indicate an algal origin, and hopane-type triterpanes, C24 tetracyclic terpane and drimane series show the bacterial contribution. With the odd-carbon-number preference, HMW n-alkanes provide significant information not only on higher plant source input and immaturity, but also on the strong resistibility to biodegradation.

关 键 词：high-temperature gas chromatography (HTGC) high molecular weight (HMW) n-alkane BIODEGRADATION heavy oil Bohai Bay Basin China 

分 类 号：P618.130.27[天文地球—矿床学] TE121.1[天文地球—地质学]