Lecture items

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Lecture items

• Electric Properties of Rocks.
• Factors affecting resistivity of reservoirs
• Electrical Logs
• (Self Potential log, Conventional resistivity
  logs , Laterologs, Dual Laterologs,
  Microspherically focused logs, Induction logs).

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Factors affecting resistivity of reservoirs

• Salinity 8 1/R
• Temperature 8 1/R
• Saturation 8 1/R
• Presence of hydrocarbons 8 R
• Lithology plays an indirect role for
  controlling resistivity

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• Electrical Logs
• - Self Potential log,
• - Conventional resistivity logs ,
• - Focused resistivity Logs,
• - Microspherically focused logs,
• - Induction logs.

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Self (Spontaneous) Potential (SP) log

• Objectives
• To understand the physical principles behind the
  operation of spontaneous potential (SP) logging.
• To learn how to interpret SP logs in terms
• of lithology and petrophysical properties.
• To understand what corrections needed to be
  applied to SP log before using it for
  interpretation.

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• Definition.
• Units Presentation.
• Applications.
• Theory of measurement.
• -Shale-base line Sand line
• -SSP, PSP and SP log readings
• Factors affecting on log readings.

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SP log Definition

• The SP is a measure and record of direct current
  (DC) voltage differences between the naturally
  occurring potential of a moveable electrode in
  the well bore, and the potential of a fixed
  electrode located at the surface.
• The SP log is recorded on the left hand track of
  the log in track 1
• It is measured in millivolts (mv).

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SP log General Uses

• The SP log is used to identify impermeable zones
  such as shale, and permeable zones such as sand,
• Detect boundaries of permeable beds,
• Determination formation water resistivity(Rw),
• Calculation the volume of shale in permeable beds.

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Theory of Measurement