Wilhelms A, Larter S R, Head I, Farrimond P, di-Primio R, Zwach C
Norsk Hydro Research Centre, PO 7190, 5020 Bergen, Norway.
Nature. 2001 Jun 28;411(6841):1034-7. doi: 10.1038/35082535.
Biodegradation of crude oil by bacterial activity--which has occurred in the majority of the Earth's oil reserves--is known to reduce greatly the quality of petroleum in reservoirs. For economically successful prospecting for oil, it is therefore important to understand the processes and conditions in geological formations that lead to oil biodegradation. Although recent studies speculate that bacterial activity can potentially occur up to temperatures as high as 150 degrees C (refs 3, 4), it is generally accepted that effective petroleum biodegradation over geological timescales generally occurs in reservoirs with temperatures below 80 degrees C (ref. 2). This appears, however, to be at odds with the observation that non-degraded oils can still be found in reservoirs below this temperature. Here we compile data regarding the extent of oil biodegradation in several oil reservoirs, and find that the extensive occurrence of non-biodegraded oil in shallow, cool basins is restricted to those that have been uplifted from deeper, hotter regions of the Earth. We suggest that these petroleum reservoirs were sterilized by heating to a temperature around 80-90 degrees C during deep burial, inactivating hydrocarbon-degrading organisms that occur in the deep biosphere. Even when such reservoirs are subsequently uplifted to much cooler regions and filled with oil, degradation does not occur, implying that the sterilized sediments are not recolonized by hydrocarbon-degrading bacteria.
细菌活动对原油的生物降解作用——地球上大多数石油储备中都已发生这种作用——已知会大幅降低油藏中石油的质量。因此，为了实现经济上成功的石油勘探，了解导致石油生物降解的地质层中的过程和条件很重要。尽管最近的研究推测细菌活动在高达150摄氏度的温度下都可能发生（参考文献3、4），但人们普遍认为，在地质时间尺度上有效的石油生物降解通常发生在温度低于80摄氏度的油藏中（参考文献2）。然而，这似乎与在该温度以下的油藏中仍能发现未降解石油的观察结果相矛盾。在此，我们汇总了几个油藏中石油生物降解程度的数据，发现浅的、低温盆地中大量未生物降解石油的存在仅限于那些从地球较深、较热区域隆起的盆地。我们认为，这些油藏在深埋过程中被加热到80 - 90摄氏度左右，使深部生物圈中存在的烃降解生物失活，从而实现了杀菌。即使这些油藏随后被抬升至凉爽得多的区域并充满石油，降解也不会发生，这意味着经过杀菌的沉积物不会被烃降解细菌重新定殖。
