A biodegradation experiment of crude oils in laboratory

To identify the chemical changes of crude oils in biodegradation,two oil samples from the BZ36-2-1 and PL14-3-1 wells in Bozhong Sag,Bohai Bay Basin,were biodegraded in laboratory under the 30℃ constant temperature with aerobic condition.The results show that the biodegradation process of crude oils is obviously affected by their initial chemical compositions.For the crude oil with high concentrations of alkanes,its biodegradation rate is much slower than the crude oil with low concentrations of alkanes.And lower molecular normal alkanes(nC_(10-20)) are biodegraded earlier than higher molecular normal alkanes(nC_(21-35)) in crude oils.The ability to resist biodegradation for phytane series is higher than that for normal alkane series.In the early stage of biodegradation,Pr/Ph ratio is hardly affected,but Pr/nC_(17) and Ph/nC_(18) ratios are easily affected.Therefore,much more attention should be paid when using those parameters for biodegraded oils.