Surficial geochemistry and hydrocarbon detection methods

From AAPG Wiki
Jump to navigation Jump to search
Exploring for Oil and Gas Traps
Series Treatise in Petroleum Geology
Part Predicting the occurrence of oil and gas traps
Chapter Surface geochemical exploration for petroleum
Author Dietmar Schumacher
Link Web page
Store AAPG Store

Direct methods

Direct detection methods are geochemical exploration methods designed to detect the presence of hydrocarbons in soils, near-surface sediments, seafloor sediments, and waters.

Detection of light hydrocarbons

The analysis of light hydrocarbons (chiefly methane through pentane) in soils and soil gases represents one of the earliest surface geochemical methods used and is one of the most researched and tested geochemical survey approaches. Light hydrocarbons can reside in soils and shallow sediments in a number of ways:

  • Free gas in the effective porosity
  • Interstitial gas occluded in pore spaces between grains
  • Gas adsorbed onto sedimentary particles or trapped within carbonate cements
  • Gas dissolved in water or present in the atmosphere

Detection of heavier hydrocarbons

Volatile and semivolatile heavier hydrocarbons such as aromatic compounds, gasoline-range hydrocarbons, and even normal or biodegraded oils can also be found, particularly where migration occurs along fault and fracture pathways. These different manifestations have led to the development of different techniques for sampling and analyzing hydrocarbons. It is beyond the scope of this chapter to discuss the advantages and limitations of specific methods or sampling procedures; however, such information is available in publications by Abrams[1] Barwise and Hay[2] Brooks et al.[3] Horvitz[4] Jones and Drozd[5] Klusman[6] Price[7] Richers and Maxwell[8] Schiemer et al.[9] and Schumacher and Abrams.[10]

Indirect methods

Indirect methods for detecting hydrocarbon seepage and microseepage are based on what are assumed to be seepage-induced soil and sediment alteration. Indirect detection methods include the following:

  • Microbial
  • Helium
  • Radiometrics
  • Iodine
  • Soil alteration
  • Trace elements
  • Electrical
  • Magnetics
  • Biogeochemical
  • Geobotanical

Indirect detection of hydrocarbons

Some indirect detection methods are better understood and more consistently reliable than others. Microbial methods, for example, detect the presence of hydrocarbon-oxidizing microbes in soils and sediments. These microbes would not be expected to be present in significant concentrations if there were no hydrocarbon source present, such as from a hydrocarbon seep or microseep. Helium, by contrast, is not uniquely associated with petroleum. However, it is a common constituent of petroleum accumulations and due to its mobility, chemical inertness, and abiogenic nature forms a very good indirect geochemical marker.

The formation of radiation anomalies and other secondary alteration anomalies (soil carbonate, iodine, trace metal, Eh, pH, electrical, magnetic, geobotanical, etc.) is less well understood. The cause of these altered soils and sediments may well be seepage related, but migrating hydrocarbons are an indirect cause at best and not always the most probable cause. Even if due to hydrocarbons, the cause could be shallow biogenic gas and thus unrelated to leakage from deeper oil and gas accumulations.

Additional information about these various indirect geochemical methods can be found in Al Shaieb et al. (general),[11] Beghtel et al. (microbial),[12] Cunningham et al. (helium),[13] Curry (radiometrics),[14] Duchscherer (soil carbonate),[15] Foote (magnetics),[16] Klusman (general),[6] Machel (magnetics),[17] Price (microbial),[18] Rock (geobotany),[19] Saunders et al. (general),[20] Schumacher (general),[10] Schumacher and Abrams (general),[10] Sternberg 1991[citation needed] (electrical), Tedesco (iodine),[21] and Weart and Heimberg (radiometrics).[22]

See also

References

  1. ↑ Abrams, M., A., 1996, Distribution of subsurface hydrocarbon seepage in near-surface marine sediments, in Schumacher, D., Abrams, M., A., eds., Hydrocarbon Migration and Its Near-Surface Expression: AAPG Memoir 66, p. 1–14.
  2. ↑ Barwise, T., Hay, S., 1996, Predicting oil properties from core fluorescence, in Schumacher, D., Abrams, M., A., eds., Hydrocarbon Migration and Its Near-Surface Expression: AAPG Memoir 66, p. 363–371.
  3. ↑ Brooks, J., M., Kennicutt, M., C., Carey, B., D., 1986, Offshore surface geochemical exploration: Oil & Gas Journal, October 20, p. 66–72.
  4. ↑ Horvitz, L., 1985, Geochemical exploration for petroleum: Science, vol. 229, p. 821–827., 10., 1126/science., 229., 4716., 821
  5. ↑ Jones, V., T., Drozd, R., J., 1983, Predictions of oil or gas potential by near-surface geochemistry: AAPG Bulletin, vol. 67, p. 932–952.
  6. ↑ 6.0 6.1 Klusman, R., W., 1993, Soil gas and related methods for natural resource exploration: New York, John Wiley & Sons, 483 pp.
  7. ↑ Price, L. C., 1986, A critical overview and proposed working model of surface geochemical exploration, in Davidson, M. J., ed., Unconventional Methods in Exploration for Petroleum and Natural Gas IV: Dallas, Texas, Southern Methodist Univ. Press, p. 81–129.
  8. ↑ Richers, D., M., Maxwell, L., E., 1991, Application and theory of soil gas geochemistry in petroleum exploration, in Merrill, R., K., ed., Source and Migration Processes and Techniques: AAPG Treatise of Petroleum Geology No. 1, Handbook of Petroleum Geology, p. 141–158.
  9. ↑ Schiemer, E., J., Stober, G., Faber, E., 1985, Surface geochemical exploration for hydrocarbons in offshore areas—principles, methods and results, in Petroleum Geochemistry in Exploration of the Norwegian Shelf: London, Graham and Trotman, p. 223–238.
  10. ↑ 10.0 10.1 10.2 Schumacher, D., 1996, Hydrocarbon-induced alteration of soils and sediments, in Schumacher, D., Abrams, M., A., eds., Hydrocarbon Migration and Its Near-Surface Expression: AAPG Memoir 66, p. 71–89.
  11. ↑ Al Shaieb, Z., Cairns, J., Puckette, J., 1994, Hydrocarbon-induced diagenetic aureoles: indicators of deeper, leaky reservoirs: Assoc. of Petroleum Geochemical Explorationists Bulletin, vol. 10, p. 24–48.
  12. ↑ Beghtel, F., W., Hitzman, D., O., Sundberg, K., R., 1987, Microbial oil survey technique (MOST) evaluation of new field wildcat wells in Kansas: Assoc. of Petroleum Geochemical Explorationists Bulletin, vol. 3, p. 1–14.
  13. ↑ Cunningham, K., I., Roberts, A., A., Donovan, T., J., 1987, Horizontal-gradient magnetic and helium surveys, in Bird, K., J., Magoon, L., B., eds., Petroleum Geology of the Northern Part of the Arctic National Wildlife Refuge, Alaska: USGS Bulletin 1178, p. 209–218.
  14. ↑ Curry, W., H., III, 1984, Evaluation of surface gamma radiation surveys for petroleum exploration in the deep Powder River basin, Wyoming, in Davidson, M., J., ed., Unconventional Methods in Exploration for Petroleum and Natural Gas III: Dallas, Southern Methodist Univ. Press, p. 25–39.
  15. ↑ Duchscherer, W., Jr., 1984, Geochemical hydrocarbon prospecting, with case histories: Tulsa, PennWell Publishing Co., 196 p.
  16. ↑ Foote, R. S., 1996, Relationship of near-surface magnetic anomalies to oil- and gas-producing areas, in Schumacher, D., Abrams, M. A., eds., Hydrocarbon Migration and Its Near-Surface Expression: AAPG Memoir 66, p. 111–126.
  17. ↑ Machel, H., G., 1996, Magnetic contrasts as a result of hydrocarbon seepage and migration, in Schumacher, D., Abrams, M., A., eds., Hydrocarbon Migration and Its Near-Surface Expression: AAPG Memoir 66, p. 99–109.
  18. ↑ Price, L. C., 1993, Microbial soil surveying: preliminary results and implications for surface geochemical oil exploration: Assoc. Petroleum Geochemical Explorationists Bulletin, vol. 9, p. 81–129.
  19. ↑ Rock, B., N., 1984, Remote detection of geobotanical anomalies associated with hydrocarbon microseepage using Thematic Mapper Simulation (TMS) and Airborne Imaging Spectrometer (AIS) data: International Union of Geological Sciences and UNESCO, BRGM document no. 82, p. 299–309.
  20. ↑ Saunders, D., F., Burson, K., R., Brown, J., J., Thompson, C., K., 1999, Model for hydrocarbon microseepage and related near-surface alterations: AAPG Bulletin, vol. 83, p. 170–185.
  21. ↑ Tedesco, S., A., 1995, Surface Geochemistry in Petroleum Exploration: New York, Chapman and Hall, Inc., 206 p.
  22. ↑ Weart, R., C., Heimberg, G., 1981, Exploration radiometrics: post-survey drilling results, in Davidson, M., J., Gottlieb, B., M., eds., Unconventional Methods in Exploration for Petroleum and Natural Gas II: Dallas, Southern Methodist Univ. Press, p. 116–123.

External links

find literature about
Surficial geochemistry and hydrocarbon detection methods 		Datapages button.png GeoScienceWorld button.png OnePetro button.png Google button.png
Retrieved from "https://wiki.aapg.org/index.php?title=Surficial_geochemistry_and_hydrocarbon_detection_methods&oldid=27224"