Palynofacies and kerogen analysis
|Exploring for Oil and Gas Traps|
|Series||Treatise in Petroleum Geology|
|Part||Predicting the occurrence of oil and gas traps|
|Author||Robert L. Fleisher, H. Richard Lane|
Definition of palynofacies
Combaz introduced the term palynofacies to describe the total organic content of a palynological assemblage (e.g., tracheids, woody tissue, microplankton, microforaminiferal linings). The relationship of these organic types to hydrocarbon generation is broached by Staplin and expressed geochemically by Tissot and Welte. Amorphous and structured algal-derived detritus is considered oil prone, whereas structured terrestrially sourced organic material is associated primarily with gas generation.
Palynofacies is a powerful analytical tool when used in conjunction with geological and geophysical information. Determination of kerogen types, abundance, and ratios of continental- vs. marine-derived components provide clues concerning depositional environment and hydrocarbon-generating potential (e.g., type and amount). Palynofacies data can be combined with ancillary biostratigraphic information in a sequence-stratigraphic framework to help recognize reservoir–source rock geometry.
Two major works integrate the geological and biological aspects of palynofacies research. Traverse includes several papers ranging from general overviews to detailed sequence-stratigraphic studies. This is complemented by Tyson's summation of the geochemical aspects of organic facies analysis. These two volumes should be the points of reference for designing any palynofacies study.
The classification of dispersed kerogen constituents is based primarily on their appearance, in an unoxidized state, using transmitted light with ancillary observation employing reflected fluorescent and ultraviolet methods. Many classification strategies have been proposed based on degradational state and biological derivation (i.e., plant vs. animal origin). However, sample processing schemes are not standardized between studies. This makes comparison between studies difficult unless applied to strata of the same age from the same basin. Classification and processing procedures are under scrutiny for standardization, and quantitative measurements are being assessed using optical scanners.
- Applications of biostratigraphy
- Biostratigraphic correlation and age determination
- Paleoenvironmental analysis
- Quantitative paleoenvironmental analysis
- Thermal maturation
- Biostratigraphy in sequence stratigraphy
- Combaz, A., 1964, Les palynofaciès: Revue de Micropaléontologie, vol. 7, p. 205–218.
- Staplin, F., L., 1969, Sedimentary organic matter, organic metamorphism, and oil and gas occurrence: Bulletin of Canadian Petroleum Geology, vol. 17, no. 1, p. 47–66.
- Tissot, B., P., Welte, O., N., 1984, Petroleum Formation and Occurrence: Berlin, Springer-Verlag, 233 p.
- Traverse, A., 1994, Sedimentation of organic particles: Cambridge, Cambridge University Press, 547 p.
- Tyson, R. A., 1995, Sedimentary organic matter—organic facies and palynofacies: London, Chapman & Hall, 651 p.
- Burgess, J., D., 1974, Microscopic examination of kerogen (dispersed organic matter) in petroleum exploration: GSA Special Paper 153, p. 19–30.
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- Lorente, M., A., 1990a, Digital image analysis: an approach for quantitative characterization of organic facies and palynofacies, in Fermont, W., J., J., Weegink, J., W., eds., International Symposium in Organic Petrology: Mededlingen Rijks Geologie Dienst, vol. 45, p. 103–109.
- Lorente, M., A., 1990b, Textural characteristics of organic matter in several subenvironments of the Orinoco Upper Delta: Geologie en Mijnbouw, vol. 69, p. 263–278.
- Highton, P., J., C., Pearson, C., A., Scott, A., C., 1991, Palynofacies and palynodebris and their use in Coal Measure palaeoecology and palaeoenvironmental analysis: Neues Jahrbuch für Geologie und Paläontologie, Abhandlung, vol. 183, no. 1–3, p. 135–169.