Environmental Factors Affecting Laterologs
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Questions and Answers

What is the 'Delaware Effect' seen in laterologs?

  • A sudden decrease in apparent resistivity due to a thick conductive bed like sandstone
  • A decrease in true resistivity when the invasion is deep
  • An increase in current flow due to the absence of adjacent beds
  • A gradual increase in apparent resistivity due to a thick non-conductive bed like salt or anhydrite (correct)

    • What type of mud is ideal for laterologs to give their truest resistivity?

  • Mud with no invasion
  • Highly resistive mud
  • Mud with low resistivity (correct)
  • Mud with medium resistivity

    • Why do highly resistive muds adversely affect laterologs?

  • Decrease the apparent resistivity (correct)
  • Enhance the tool's accuracy
  • Increase the true resistivity
  • Make the readings inconsistent

    • How does the Groningen Effect differ from the Delaware Effect in laterologs?

    <p>Groningen Effect causes a larger negative potential in the N electrode even with electrodes at the surface</p> Signup and view all the answers

    What thickness of mud is required for LL7 to be unaffected by adjacent beds?

    <p>At least 5 feet</p> Signup and view all the answers

    How does the invasion depth affect the accuracy of laterolog readings?

    <p>Shallow invasion gives truest resistivity readings</p> Signup and view all the answers

    What is the purpose of accurate estimates of lithology and porosity in reservoir evaluation?

    <p>To determine the saturation and volume of hydrocarbons in a reservoir</p> Signup and view all the answers

    Why is Rw often not a simple parameter to understand or characterize?

    <p>It varies both horizontally and vertically in formation water</p> Signup and view all the answers

    In the Archie equation, how does an increase in Rw affect calculated Sw?

    <p>Increases Sw</p> Signup and view all the answers

    What effect does a rise in Rw have on calculated Sw according to the Archie equation?

    <p>Increases Sw linearly</p> Signup and view all the answers

    Why might reservoirs in SE Asia have widely different salinity in the hydrocarbon leg compared to underlying water?

    <p>Due to the presence of meteoric water invasion</p> Signup and view all the answers

    What role does Rw play in the Archie equation and its variants?

    <p>It directly multiplies a parameter in the numerator</p> Signup and view all the answers

    What is the significance of measuring Rw accurately as the formation water freshens?

    <p>Rw is more sensitive at fresher water conditions</p> Signup and view all the answers

    Why is measuring Rw from recovered formation water samples not always ideal?

    <p>Iron contamination is often present in recovered samples</p> Signup and view all the answers

    How does a small change in salinity at low concentrations affect Rw compared to a similar change at high concentrations?

    <p>Small changes in salinity at low concentrations have more influence on Rw</p> Signup and view all the answers

    What is the key drawback of establishing Rw from previously measured values in a basin?

    <p>Dependence on this parameter affects analysis precision</p> Signup and view all the answers

    How can Rw be derived from a static spontaneous potential (SSP)?

    <p>Derive Rwe using chart SP-1</p> Signup and view all the answers

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