Electrical Properties (Induction) Logging
Resistivity, an electrical property, was the first rock property logged in a well, and it is still one of the most important properties logged. Recall from Chapter 3 that most water saturation calculations are based on establishing a ratio of resistivities. If we compare a rock’s resistivity to the resistivity it would have at 100% water saturation, we can calculate the water saturation from Archie’s equation. Then we can infer that the balance of the pore spaces are occupied by hydrocarbon. However, we must resist the temptation to draw the apparently logical conclusion that the resistivity curves recorded on a log are saturation curves. A low resistivity does not by itself mean there is a high water saturation. We must still compare the resistivity to the value it would have if saturated with water. This requires knowledge of the rock’s porosity as well as its resistivity.
KeywordsApparent Resistivity True Resistivity Ground Loop Deep Induction Undisturbed Zone
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- 1.Hubert Guyod, Guyod’s Electrical Well Logging, a reprint of 16 articles that appeared in various issues of the Oil Weekly between August 7, 1944 and December 4, 1944 ©1944 by Welex, a division of Halliburton Company, Houston, Texas, 1944.Google Scholar
- 2.Ibid.Google Scholar
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