In electrical well logging, ...

In electrical well logging, two electrical properties are measured in the borehole: potential and resistivity. It has been observed that in a borehole, the electrical potential varies according to the nature of the beds traversed. For example, salt water sands and brackish water sands are usually more negative than the associated shale or clay. On the other hand, fresh water sands may either be more negative or more positive than the associated formation. Demang, this method is not very expensive it is used very commonly these days. Best.