Difference between revisions of "Surficial geochemistry: limitations and uncertainties"

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  | part    = Predicting the occurrence of oil and gas traps
 
  | part    = Predicting the occurrence of oil and gas traps
 
  | chapter = Surface geochemical exploration for petroleum
 
  | chapter = Surface geochemical exploration for petroleum
  | frompg  = 18-1
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  | frompg  = 18-7
  | topg    = 18-27
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  | topg    = 18-7
 
  | author  = Dietmar Schumacher
 
  | author  = Dietmar Schumacher
 
  | link    = http://archives.datapages.com/data/specpubs/beaumont/ch18/ch18.htm
 
  | link    = http://archives.datapages.com/data/specpubs/beaumont/ch18/ch18.htm
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  | isbn    = 0-89181-602-X
 
  | isbn    = 0-89181-602-X
 
}}
 
}}
While the potential benefits of a successful surface geochemical exploration program are very real and can significantly affect the economics of an exploration or development program, the user must be aware of limitations associated with geochemical exploration methods. Some limitations of surface geochemical exploration are related to geology; others are related to the method itself.
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While the potential benefits of a successful surface geochemical exploration program are very real and can significantly affect the [[economics]] of an exploration or development program, the user must be aware of limitations associated with geochemical exploration methods. Some limitations of surface geochemical exploration are related to geology; others are related to the method itself.
  
 
==Limitations related to geology==
 
==Limitations related to geology==
 
The following are limitations of surface geochemical prospecting related to geology:
 
The following are limitations of surface geochemical prospecting related to geology:
  
* The geochemical expression of seepage is complex and varied.
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* The geochemical expression of [[Seepage activity and surficial geochemistry|seepage]] is complex and varied.
* There is generally no simple one-to-one correlation between a surface anomaly and a subsurface accumulation. Some anomalies approximate the productive limits of an accumulation, but many do not.
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* There is generally no simple one-to-one correlation between a surface anomaly and a subsurface [[accumulation]]. Some anomalies approximate the productive limits of an accumulation, but many do not.
 
* Successful integration of surface geochemical data with subsurface geology becomes increasingly difficult as the geology becomes more complex.
 
* Successful integration of surface geochemical data with subsurface geology becomes increasingly difficult as the geology becomes more complex.
* False seep anomalies can be caused by reworked hydrocarbons and/or reworked source rocks.
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* False seep anomalies can be caused by reworked [[hydrocarbon]]s and/or reworked [[source rock]]s.
* Reservoirs that are significantly underpressured or contain heavy oil may not be detected by some surface geochemical methods.
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* [[Reservoir]]s that are significantly [[Underpressure causes|underpressured]] or contain [[heavy oil]] may not be detected by some surface geochemical methods.
  
 
==Limitations related to the method==
 
==Limitations related to the method==
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* No single method works everywhere; there are many methods to choose from.
 
* No single method works everywhere; there are many methods to choose from.
* A surface anomaly generally cannot be related to a specific source reservoir or depth; however, compositional fingerprinting techniques can sometimes discriminate seepage from different reservoir zones.
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* A surface anomaly generally cannot be related to a specific [[Source rock|source]], [[reservoir]], or depth; however, [[Gas chromatography: data obtained|compositional fingerprinting techniques]] can sometimes discriminate seepage from different reservoir zones.
 
* Undersampling and/or use of improper sampling techniques causes ambiguity that leads to interpretation failures.
 
* Undersampling and/or use of improper sampling techniques causes ambiguity that leads to interpretation failures.
 
* Discovery of a surface geochemical anomaly does not guarantee discovery of commercially significant volumes of hydrocarbon.
 
* Discovery of a surface geochemical anomaly does not guarantee discovery of commercially significant volumes of hydrocarbon.
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[[Category:Predicting the occurrence of oil and gas traps]]  
 
[[Category:Predicting the occurrence of oil and gas traps]]  
 
[[Category:Surface geochemical exploration for petroleum]]
 
[[Category:Surface geochemical exploration for petroleum]]
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[[Category:Treatise Handbook 3]]

Latest revision as of 21:19, 24 January 2022

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

While the potential benefits of a successful surface geochemical exploration program are very real and can significantly affect the economics of an exploration or development program, the user must be aware of limitations associated with geochemical exploration methods. Some limitations of surface geochemical exploration are related to geology; others are related to the method itself.

Limitations related to geology

The following are limitations of surface geochemical prospecting related to geology:

  • The geochemical expression of seepage is complex and varied.
  • There is generally no simple one-to-one correlation between a surface anomaly and a subsurface accumulation. Some anomalies approximate the productive limits of an accumulation, but many do not.
  • Successful integration of surface geochemical data with subsurface geology becomes increasingly difficult as the geology becomes more complex.
  • False seep anomalies can be caused by reworked hydrocarbons and/or reworked source rocks.
  • Reservoirs that are significantly underpressured or contain heavy oil may not be detected by some surface geochemical methods.

Limitations related to the method

The following are limitations of surface geochemical prospecting related to the method:

  • No single method works everywhere; there are many methods to choose from.
  • A surface anomaly generally cannot be related to a specific source, reservoir, or depth; however, compositional fingerprinting techniques can sometimes discriminate seepage from different reservoir zones.
  • Undersampling and/or use of improper sampling techniques causes ambiguity that leads to interpretation failures.
  • Discovery of a surface geochemical anomaly does not guarantee discovery of commercially significant volumes of hydrocarbon.
  • Geochemical exploration methods cannot replace existing exploration technology; however, they can add value to existing geological and geophysical exploration data.

See also

External links

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Surficial geochemistry: limitations and uncertainties
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