Clay Minerals (2000) 35, 5-12
The effects of indigenous and introduced microbes on deeply buried hydrocarbon reservoirs, North Sea
I. Spark, I. Patey, B.Duncan, Corex (UK) Ltd, A. Hamilton, C.Devine and C,McGovern-Traa, University of Aberdeen
Abstract
Anaerobic bacteria were identified in live drilling muds and cores from nine different North Sea and Irish Basin oilfields, varying in depth from 3500 to 15000ft, and at temperatures up to 150ºC. The anaerobic bacteria may be introduced into the reservoir during drilling operations or injection of water, but in many cases the bacteria are indigenous to the oilfield reservoirs. Confirmation of the indigenous anaerobic bacteria was made using molecular biology techniques (165 rDNA sequence analysis), comparing microbial populations present in the blank drilling mud as supplied to wellsite, in the live drilling mud taken during coring, and in the live core. The role of anaerobic bacteria in oilfield diagenesis is not fully understood, though pyrite precipitation, and exopolymer and H2S gas production were noted in this study, up to temperatures of 95ºC.