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.

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.

Jul 28, 2016 · The spontaneous potential (SP) log was developed next and was presented along with resistivity logs. It is a measurement of the voltage difference between a movable electrode in the wellbore and a fixed electrode at the surface.

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.

Jan 18, 2022 · The procedure to determine Rw from the SP is outlined as follows. The data required include the SP, the invaded zone resistivity, the formation temperature, and the mud and mud filtrate resistivities at the given formation temperature.

Jan 22, 2025 · Self-potential (SP) borehole logging is an electrical wireline method that passively measures naturally occurring voltage anomalies along the length of an open, fluid-filled borehole.

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. Collection of spontaneous-potential logs is limited to water- or mud-filled open holes.

Mar 15, 2021 · It can be seen that with the SP, gamma ray, and old neutron logs it is best to normalize all of the logs. For curves like the sonic and induction it is best just to go through the dataset and select only those wells which are anomalous and set them aside for later study.

Sep 16, 2016 · Spontaneous potential (SP) is one of the oldest logging techniques. It employs very simple equipment to produce a log whose interpretation may be quite complex, particularly in freshwater aquifers.

Sep 7, 2018 · SP log measures the potential difference in the borehole due to the electrochemical and electrokinetic processes taking place in the formation. SP log can therefore be obtained in only conductive media.