The spontaneous potential log (SP) measures the natural or spontaneous potential difference (sometimes called self-potential) that exists between the borehole and the surface in the absence of any artificially applied current. It is a very simple log that requires only an electrode in the borehole and a reference electrode at the surface.

Spontaneous potential log, commonly called the self potential log or SP log, is a passive measurement taken by oil industry well loggers to characterise rock formation properties. The log works by measuring small electric potentials (measured in millivolts) between depths with in the borehole and a grounded electrode at the surface.

Jul 28, 2016 · Well logs present a concise, detailed plot of formation parameters versus depth. From these plots, interpreters can identify lithologies, differentiate between porous and nonporous rock and quickly recognize pay zones in subsurface formations.

Jan 29, 2025 · Well logs provide insight into the formations and conditions in the subsurface, aimed primarily at detection and evaluation of possibly productive horizons.

Nov 30, 2000 · Spontaneous-potential logs record potentials or voltages developed between the borehole fluid and the surrounding rock and fluids. Spontaneous-potential logs can be used in the determination of lithology and water quality.

Jul 4, 2017 · Petrophysicists look at the well log patterns, recognize the trends, and then turn those patterns into reservoir knowledge. Well logs can tell us many stories about our reservoir. Each colorful line, each curve deflection and each curve type create the story of our reservoir.

Apr 5, 2022 · Water resistivity or R w, is a critical component of log analysis in calculating water saturation using the Archie equation. R w can be measured from a sample of formation water taken from the zone of interest at the well site or a nearby well, or it can be calculated using spontaneous potential (SP) log data.

Fig. 9.1 shows a typical SP log, which is represented in Track 1 as a solid curve and shows departures to the left from a base line (or shale line) reading on the right to a sand line on the left in the cleanest nonshale zones. The scale of the log is in millivolts, abbreviated mV.

The spontaneous potential log, commonly called the self potential log or SP log, is a passive measurement taken by oil industry well loggers to characterize rock formation properties.

SP Log Operation An electrode (usually lead) is sent down to the well and an electrical potential is registered at different points in the hole with respect to surface electrode. Therefore SP is a recording of the difference in potential (Voltage difference or direct