Borehole gravity: uses, advantages, and disadvantages

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Revision as of 21:17, 13 May 2014 by FWhitehurst (talk | contribs) (FWhitehurst moved page Basics of borehole gravity to Borehole gravity: uses, advantages, and disadvantages: most important term first, plus was inaccurate)
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Borehole gravity uses

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

Exploration purposes

  • Locating nearby salt structures
  • Locating distance to nearby structures (e.g., reefs) for step-outs and sidetracks
  • Better synthetic seismograms

Production purposes

  • Measuring bulk density when radioactive tools are too risky
  • Logging cased holes for lithologic changes
  • Calculating overburden for hydrofracture jobs
  • Monitoring injection fluids
  • Monitoring reservoirs during fluid withdrawal
  • Exploring for bypassed, behind-casing gas zones
  • Evaluating reservoir porosity, especially in carbonate reservoirs where other tools are not as reliable

Borehole gravity advantages

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

  • Directly measures bulk density
  • Is a deep imaging tool
  • Is effective in both cased and uncased wells
  • Is unaffected by washouts, hole rugosity, or mud invasion effects
  • Can help determine seismic wavelet scale density
  • Is a passive measurement, e.g., does not have active radioactive sources

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