Abstract: A method and apparatus for determining properties of rocks surrounding a borehole in which electrokinetic signals are generated in the rocks is disclosed. For example, the signals may be generated by the vibration induced by the drilling of the borehole or by a seismic source emitting continuous pressure waves. The electrokinetic signals generated are detected and the signal amplified and processed to measure the porous rock properties.

Abstract: Apparatus and method for measuring the properties of rocks such as permeability, porosity and fluid properties downhole around a borehole (3) in which a seismic source (6) which radiates a seismic signal substantially radially within the borehole is lowered down the borehole (3) and the electrical signal generated by the seismic signal within the surrounding rock is detected by detectors (4, 5) mounted above and below the seismic source (6) so that signals are received from substantially all radial directions. Preferably a continuous wave signal is generated and the signal detected whilst the apparatus (1) is raised or lowered. The apparatus (1) gives a much better and more accurate measurement than previous methods.

Abstract: A method and apparatus for detecting underground liquids is disclosed in which the electrical potential generated by a seismic shock is detected and measured with respect to a base point insulated from the earth.