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32 Cards in this Set
- Front
- Back
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FDC
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Formation Density Compensated Log
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PE
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Photo Electric Log
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CDL
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Compensated Density Log
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LDT
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Litho-Density Tool
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HSDL
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Spectral Density Tool
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ZDL
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Compensated Z-Density Tool
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FDC & PE measure __ & __.
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1. bulk density
2. porosity |
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Matrix/Grain Densities for:
Sandstone Limestone Dolomite |
- 2.65 g/cc
- 2.71 g/cc - 2.87 g/cc |
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General Porosity Formula
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=Matrix - Bulk/Matrix - Fluid
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Source Material for FDC Tool
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Ce137
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Dense formations absorb __ gamma rays.
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many
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Low density formations absorb __ gamma rays.
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fewer
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High count rates at detector indicate __-__ formations.
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low density
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Difference in detectors count rates reflects (4):
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1. spacing
2. formation density 3. mudcake density 4. mudcake thickness |
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Gamma rays interact with matter via three mechanisms:
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1. compton scattering
2. photoelectric effect 3. pair production |
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Compton Scattering
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gamma rays collide with electrons and then electrons are ejected out losing energy
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Photoelectric Effect
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gamma rays collide with electrons and lose all energy. photon is ejected
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Pair Production
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gamma rays interact with atoms to produce electrons and positrons
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Intensity (in) =
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Intensity (out) e ^ -ux
u = mass absorption coefficient x = thickness |
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Gamma ray diminishes over a distance at a factor of:
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1/2
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Compton scattering measures the __ density
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electron
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Density (bulk) pb =
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1.074Pe - 0.1883
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Electron density and Bulk Density have a __ relationship.
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linear
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Porosity requires __ & __ to become absolute
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1. fluid density
2. lithology |
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If correction is greater then 0.06 g/cc, density values should be used __.
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qualitatively
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Tool Investigates:
2 inches 5 inches |
- 50%
- 90% |
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Litho Density Tool measures: (2)
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- bulk density
- photoelectric absorption index (Pe) |
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Pe =
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(0.1z)^3.6
z = atomic # |
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Pe is independent of: (2)
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- porosity
- fluid content |
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Pe uses: (3)
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1. lithological interpretation
2. analyze two-mineral matrices 3. porosity |
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Combine __ & __ with Pe to analyze complex lithologies
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- density
- neutron porosity |
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The mineral Barite makes Pe __.
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useless
Pe = 266.8 |
