Determination of Resistivity of Rocks from Various Parts of Kenya when Soaked in Different Types of Water







The objective of the study was to determine trends in resistivity of 6 different rocks when soaked in types of water of varying salinity. Resistivity refers to resistance of a substance per unit volume. Resistance refers to the opposition to flow of electric charge in a material. Salinity refers to the number of free ions in a solution and depends on amount of dissolved salts in that solution. Conduction in water saturated rocks is largely electrolytic and depends on number of ions in water and on petrophysical factors especially porosity.


A mineral is a naturally occurring solid chemical substance that is formed from geological processes while a rock is a mixture of minerals. 6 Rock samples from various parts of Kenya were obtained from the department of mines and geology and cut into blocks of equal sizes.


Different types of water were obtained including deionized water, distilled water, tap water and water from Nairobi River. The samples were then soaked in the various types of water for 24 hours and the voltage and current measured by use of a 30Volts DC voltmeter and an analog microammeter. The salinity of samples was measured using an Exstick 2 conductivity meter.


The resistivity of all the rocks reduced with increase in salinity of water. It was found that river water was the most saline with deionized water being the least saline. A clear trend of the most resistive rocks and the least resistive rocks when under water saturation was also found. The method used could be applied in analysis of rocks and building blocks for stress fractures. It could also be used in geothermal well prospecting, in well logging and in groundwater assessment.

Fourth Year Project - 2011-2278.pdf69.39 KB