科研之友
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摘要
Existing scales widely used to describe the extent of biodegradation of petroleum have insufficient resolution to usefully characterize many heavy oil and bitumen occurrences, including the volumetrically dominant heavily and severely biodegraded oil accumulations in the foreland basins of western Canada and Venezuela. In these and other deposits, existing classifications or descriptions of the biodegradation level may vary only slightly, yet oil may vary in viscosity by orders of magnitude. The %26quot;Manco%26quot; biodegradation scale proposed here is based on integrating the extent of degradation of various members of compound classes not included in previous biodegradation scales. They include alkyl aromatic and alkyl thiophenic compounds that show variable extent of alteration in samples degraded to uniform levels on standard scales, but which may show variation in local degradation systematics related to biodegradation mechanisms and extent of oil mixing. The Manco scale uses a combination of a consideration of the extent of alteration within a compound class together with a consideration of biodegradation across a range of compound classes. It can be reliably used as a basis for interpreting geochemical changes in heavily biodegraded oil suites and can also be used to differentiate biodegraded oil samples likely to be amenable to cold production from those requiring production strategies such as steam or chemical flooding. As with other biodegradation scales, the scale may also provide evidence for the influx of later, higher quality oil into a reservoir fluid that had been previously biodegraded.
- 出版日期2012-4
