Sp log
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The Self Potential (SP) log measures the natural voltage difference between an electrode in the borehole and a reference electrode at the surface without applying any artificial current. It is recorded in millivolts on the left track of the log. The SP log principle involves conductive fluid in the borehole creating a potential difference from formation fluids due to salinity variations. SP logs are used to identify permeable zones like sand and impermeable zones like shale, detect boundaries between permeable beds, and determine formation water resistivity and shale volume.
Sp log
- 3. * Definition. * Units& Presentation. * Applications. * Theory and Principle of measurement.
- 4. ObjectivesObjectives 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. Self (Spontaneous) Potential (SP) log
- 5. 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. SP logSP log ““DefinitionDefinition””
- 6. OROR It is the measurement of natural potential difference or self potential , between electrode in a bore hole and reference electrode at surface. No artificial current are applied.
- 8. Units and PresentationUnits and Presentation The SP log is recorded on the left hand track of the log in track #1 It is measured in millivolts (mv).
- 9. Principle of MeasurementPrinciple of Measurement 1(Conductive fluid in the bore hole 2(Porous and permeable bed surrounded by impermeable bed. 3(Difference in salinity between bore hole fluid and formation fluid.
- 10. 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. SP log “General Uses”