US 2008/0306692 A1 · Method and Apparatus for Determining the Permeability of Earth Formations

Abstract

A method and apparatus for determining the fluid permeability of an earth formation is described. An instrument comprising an acoustic source and acoustic and electrokinetic sensors is located in a borehole at a site of interest. The acoustic source is fired and the resulting variations in pressure and electric field generated are measured and recorded. The Biot equation, and an equation for the streaming potential coupled to fluid displacement terms, is solved using finite element analysis to give an expected pressure waveform and electrokinetic waveform based on estimated earth formation properties. By comparison of the measured waveforms and those calculated from the equations, the actual permeability of the earth formation can be deduced.

Claims26

Dependent claims

A method of determining the permeability of a downhole earth formation, comprising the steps of:

generating an acoustic signal at a first point in a borehole;
detecting, as an acoustic response at a second point in the borehole, variations in pressure resulting from the acoustic signal;
detecting as an electric response at the second point in the borehole, variations in the electric field resulting from the acoustic signal;
determining the permeability of the earth formation using the detected acoustic and electric responses, and by solving the Biot equation and an expression for the streaming potential given in terms of the fluid and solid displacement.

1 more element

Dependencies are inferred from the claim text.

Method and Apparatus for Determining the Permeability of Earth Formations

Life of this patent

Method and Apparatus for Determining the Permeability of Earth Formations

Life of this patent

Abstract

Claims26