Determination of porosity and permeability of a geological formation based on the electrofiltration phenomenon

摘要

The pressure waves (11,13) generator is placed against the inner wall of a trial drilling (1) in a medium (2). Two electrodes (14,15) made of graphite, platinum, or silver chloride are also in close contact with the wall and their output is received by an amplifier (16) and electronic data capture unit (18). The electrical signal representing the potential difference between the two electrodes due to electro-filtration varies with varying frequency of the applied sound wave and when it is at a maximum the frequency is resonant. This resonant frequency enables the porosity and permeability of the medium (2) to be determined.