Original Articles: 2014 Vol: 6 Issue: 3
Biomarker characters and biodegradation of petroleum in Gangxi oil field, China
Biomarker characters and biodegradation of petroleum were investigated in Gangxi oil field, China, using GC-MS analysis. TIC profiles suggested that the petroleum in oil reservoir was biodegraded seriously by indigenous microbiota, due to the secondary alteration processes (water flooding since 1972). The n-alkanes were missing in most of oil samples. The iso-alkanes were present in all of the samples but in low concentration. The polycyclic aromatic hydrocarbons were degraded at different degrees. The PAHs of 2 rings were almost missing, while that of 3 or 4 rings were present at low degraded rate. These suggested that the indigenous microorganism of oil well might have ability to degrade petroleum and it could be used for remedying oil spill. Through analysis of 28 kinds of biomarker, these oils showed similar characteristics: mid content of gammacerane, abundant hopane, and low content of oleanane. These meant that the source of oil might be prokaryotic organisms and algal, and the reservoirs was a not highly reducing and anoxic environment. The maturity parameters of 20S / (20S + 20R) and ββ / (ββ + αα) showed these oil was mature oil, and the maturity degree of oil samples increased as order: 2#, 5#, 3# or 1#, 4#, 6#.