Changes

==Anomalies relate to traps==

==Anomalies relate to traps==

A further assumption is that the anomaly at the surface can be related reliably to a petroleum accumulation at depth. The success with which this can be done is greatest in areas of relatively simple geology and becomes increasingly difficult as the geology becomes more complex. The geochemical or microbial anomaly at the surface represents the end of a petroleum migration pathway, a pathway that can range from short-distance vertical migration at one end of the spectrum to long-distance lateral migration at the other extreme.<ref name=ch18r46>Thrasher, J., A., Fleet, A., J., Hay, S., J., Hovland, M., Duppenbecker, S., 1996b, [http://archives.datapages.com/data/specpubs/memoir66/17/0223.htm Understanding geology as the key to using seepage in exploration: the spectrum of seepage styles], in Schumacher, D., Abrams, M., A., eds., Hydrocarbon Migration and Its Near-Surface Expression: [http://store.aapg.org/detail.aspx?id=75 AAPG Memoir 66], p. 223–241</ref> Relationships between surface geochemical anomalies and subsurface accumulations can be complex; proper interpretation requires integrating seepage data with geological, geophysical, and hydrologic data. Understanding geology—and, hence, petroleum dynamics—is the key to using seepage data in exploration.

A further assumption is that the anomaly at the surface can be related reliably to a petroleum accumulation at depth. The success with which this can be done is greatest in areas of relatively simple geology and becomes increasingly difficult as the geology becomes more complex. The geochemical or microbial anomaly at the surface represents the end of a petroleum migration pathway, a pathway that can range from short-distance vertical migration at one end of the spectrum to long-distance lateral migration at the other extreme.<ref name=ch18r46>Thrasher, J., A., Fleet, A., J., Hay, S., J., Hovland, M., Duppenbecker, S., 1996b, [http://archives.datapages.com/data/specpubs/memoir66/17/0223.htm Understanding geology as the key to using seepage in exploration: the spectrum of seepage styles], in Schumacher, D., Abrams, M., A., eds., Hydrocarbon Migration and Its Near-Surface Expression: [http://store.aapg.org/detail.aspx?id=75 AAPG Memoir 66], p. 223–241.</ref> Relationships between surface geochemical anomalies and subsurface accumulations can be complex; proper interpretation requires integrating seepage data with geological, geophysical, and hydrologic data. Understanding geology—and, hence, petroleum dynamics—is the key to using seepage data in exploration.

==Seepage styles==

==Seepage styles==