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. Self (Spontaneous) Potential (SP) log
* Definition. * Units& Presentation. * Applications. * Theory of measurement. -Shale-base line& Sand line -SSP, PSP and SP log readings * Factors affecting on log readings.
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). SP log “ Definition ”
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 ”