The Presence of Sulphate Reducing Bacteria in Oil Field Waters

Abstract

The reduction of sulphates in natural waters through the agency of sulphate-reducing bacteria with the generation of H2S has been thoroughly established by the work of many observers. The situations in which they have been found include river muds, brackish canal muds, sewerage soils, lake and dune sands, and muds of the ocean bottom and of the Black Sea. Many of the waters associated with petroleum in oil pools are so low in sulphates as to indicate that a natural reduction of sulphates has been in progress. This fact has been recognized by several observers but the reduction was attributed to the petroleum, that is, to dead organic matter. Available experimental data fail to afford any evidence that dead organic matter is capable of reducing sulphates at ordinary temperatures although such reduction can proceed at high temperatures. With the usual precautions observed in bacteriological work, water samples were collected from 30 producing oil wells of Illinois, ranging in depth from 400 to 1866 feet and producing from Ordo-vician, Mississippian, and Pennsylvanian horizons. These waters were low in sulphate and all but 2 carried sulphate-reducing bacteria. The active bacterium was isolated from 5 cultures.