Difference between revisions of "Borehole gravity: uses, advantages, and disadvantages"

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  | part    = Predicting the occurrence of oil and gas traps
 
  | part    = Predicting the occurrence of oil and gas traps
 
  | chapter = Applying gravity in petroleum exploration
 
  | chapter = Applying gravity in petroleum exploration
  | frompg  = 15-1
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  | frompg  = 15-16
  | topg    = 15-28
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  | topg    = 15-16
 
  | author  = David A. Chapin, Mark E. Ander
 
  | author  = David A. Chapin, Mark E. Ander
 
  | link    = http://archives.datapages.com/data/specpubs/beaumont/ch15/ch15.htm
 
  | link    = http://archives.datapages.com/data/specpubs/beaumont/ch15/ch15.htm
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==Borehole gravity uses==
 
==Borehole gravity uses==
  
Borehole gravity is especially effective for the following exploration and production purposes:
+
Borehole [[gravity]] is especially effective for the following exploration and production purposes:
  
 
'''Exploration purposes'''
 
'''Exploration purposes'''
  
* Locating nearby salt structures
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* Locating nearby [[salt structure]]s
* Locating distance to nearby structures (e.g., reefs) for step-outs and sidetracks
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* Locating distance to nearby structures (e.g., [[reef]]s) for [[step-out]]s and [[sidetrack]]s
 
* Better [[synthetic seismogram]]s
 
* Better [[synthetic seismogram]]s
  
 
'''Production purposes'''
 
'''Production purposes'''
  
* Measuring bulk density when radioactive tools are too risky
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* Measuring [[Basic_open_hole_tools#Density|bulk density]] when radioactive tools are too risky
* Logging cased holes for lithologic changes
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* [[Basic cased hole tools|Logging cased holes]] for lithologic changes
* Calculating overburden for hydrofracture jobs
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* Calculating [[overburden]] for [[hydrofracture]] jobs
* Monitoring injection fluids
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* Monitoring [[injection fluid]]s
 
* Monitoring reservoirs during fluid withdrawal
 
* Monitoring reservoirs during fluid withdrawal
 
* Exploring for bypassed, behind-casing gas zones
 
* Exploring for bypassed, behind-casing gas zones
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The following characteristics give [[borehole gravity]] surveys advantages in certain situations:
 
The following characteristics give [[borehole gravity]] surveys advantages in certain situations:
  
* Directly measures bulk density
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* Directly measures [[Basic_open_hole_tools#Density|bulk density]]
 
* Is a deep imaging tool
 
* Is a deep imaging tool
 
* Is effective in both cased and uncased wells
 
* Is effective in both cased and uncased wells
* Is unaffected by washouts, hole rugosity, or mud invasion effects
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* Is unaffected by [[washout]]s, [[hole rugosity]], or [[mud invasion]] effects
* Can help determine seismic wavelet scale density
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* Can help determine [[seismic wavelet scale density]]
 
* Is a passive measurement, e.g., does not have active radioactive sources
 
* Is a passive measurement, e.g., does not have active radioactive sources
  
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* Direction away from the well to distant source cannot be determined without other information
 
* Direction away from the well to distant source cannot be determined without other information
* Engineering limitations of the tool restricts use to certain candidate wells (hole size, low deviation, slow reading)
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* Engineering limitations of the tool restricts use to certain candidate wells ([[hole size]], [[low deviation]], slow reading)
 
* Only a few tools presently available for use
 
* Only a few tools presently available for use
 
* Expensive to operate
 
* Expensive to operate
 
==Theory==
 
Density effects caused by downhole geology can be detected by very sensitive instrumentation and by knowing precisely where the sensor is located in the borehole. For petroleum exploration, gravity typically is measured in microgals (μGal). Typical exploration anomalies are on the order of
 
  
 
==See also==
 
==See also==
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[[Category:Predicting the occurrence of oil and gas traps]]  
 
[[Category:Predicting the occurrence of oil and gas traps]]  
 
[[Category:Applying gravity in petroleum exploration]]
 
[[Category:Applying gravity in petroleum exploration]]
 +
[[Category:Treatise Handbook 3]]

Latest revision as of 15:11, 31 January 2022

Exploring for Oil and Gas Traps
Series Treatise in Petroleum Geology
Part Predicting the occurrence of oil and gas traps
Chapter Applying gravity in petroleum exploration
Author David A. Chapin, Mark E. Ander
Link Web page
Store AAPG Store

Borehole gravity uses

Borehole gravity is especially effective for the following exploration and production purposes:

Exploration purposes

Production purposes

Borehole gravity advantages

The following characteristics give borehole gravity surveys advantages in certain situations:

Borehole gravity disadvantages

The following characteristics give borehole gravity surveys disadvantages in certain situations:

  • Direction away from the well to distant source cannot be determined without other information
  • Engineering limitations of the tool restricts use to certain candidate wells (hole size, low deviation, slow reading)
  • Only a few tools presently available for use
  • Expensive to operate

See also

External links

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Borehole gravity: uses, advantages, and disadvantages
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