Changes

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.

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.;;<ref name=ch18r5>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.</ref> general), Beghtel et al.;<ref name=ch18r7>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.</ref> microbial), Cunningham et al.;<ref name=ch18r10>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.</ref> helium), Curry;<ref name=ch18r11>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.</ref> radiometrics), Duchscherer;<ref name=ch18r12>Duchscherer, W., Jr., 1984, Geochemical hydrocarbon prospecting, with case histories: Tulsa, PennWell Publishing Co., 196 p.</ref> soil carbonate), Foote;<ref name=ch18r13>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.</ref> [[magnetics]]), Klusman;<ref name=ch18r18 /> general), Machel;<ref name=ch18r24>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.</ref> magnetics), Price;<ref name=ch18r31>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.</ref> microbial), Rock;<ref name=ch18r35>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.</ref> geobotany), Saunders et al.;<ref name=ch18r37>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.</ref> general); Schumacher;<ref name=ch18r39 /> general), Schumacher and Abrams;<ref name=ch18r39 /> general), Sternberg (1991; electrical), Tedesco<ref name=ch18r44>Tedesco, S., A., 1995, Surface Geochemistry in Petroleum Exploration: New York, Chapman and Hall, Inc., 206 p.</ref> iodine), and Weart and Heimberg;<ref name=ch18r48>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.</ref> radiometrics).

Additional information about these various indirect geochemical methods can be found in Al Shaieb et al. (general),<ref name=ch18r5>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.</ref> Beghtel et al. (microbial),<ref name=ch18r7>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.</ref> Cunningham et al. (helium),<ref name=ch18r10>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.</ref> Curry (radiometrics),<ref name=ch18r11>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.</ref> Duchscherer (soil carbonate),<ref name=ch18r12>Duchscherer, W., Jr., 1984, Geochemical hydrocarbon prospecting, with case histories: Tulsa, PennWell Publishing Co., 196 p.</ref> Foote ([[magnetics]]),<ref name=ch18r13>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.</ref> Klusman (general),<ref name=ch18r18 /> Machel (magnetics),<ref name=ch18r24>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.</ref> Price (microbial),<ref name=ch18r31>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.</ref> Rock (geobotany),<ref name=ch18r35>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.</ref> Saunders et al. (general),<ref name=ch18r37>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.</ref> Schumacher (general),<ref name=ch18r39 /> Schumacher and Abrams (general),<ref name=ch18r39 /> Sternberg 1991{{Citation needed}} (electrical), Tedesco (iodine),<ref name=ch18r44>Tedesco, S., A., 1995, Surface Geochemistry in Petroleum Exploration: New York, Chapman and Hall, Inc., 206 p.</ref> and Weart and Heimberg (radiometrics).<ref name=ch18r48>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.</ref>

==See also==

==See also==