Determination of the porosity and permeability of a geological formation from an electrofiltering phenomenon
AssigneeCommissariat a l'Energie Atomique
InventorsMarcel Locatelli, Jean Berthier, Henri Glenat
Life of this patent
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Abstract
The porosity and permeability of a geological formation (2) are determined on the basis of an electrofiltering phenomenon by exploiting the existence of non-linear electrofiltering phenomena. One or two pressure generators (11 ) are used to propagate a pressure wave in the formation. Electrodes (14, 15) applied against the wall of the formation pick up the electric response of the formation. The detection of a resonance frequency or a phase shift corresponding to an extremum of the electric response of the formation makes it possible to calculate the porosity or permeability of the formation or find their values from charts.
Claims16
Method for determining the porosity and/or permeability of a geological formation likely to generate non-linear electrofiltering phenomena from an electrofiltering effect generated in the formation and including stages consisting of:
- --mechanically and repeatedly exciting a fluid of said formation so as to propagate a pressure wave with suitable characteristics for generating an electrofiltering effect in the formation,
- --measuring a variable representative of an electrofiltering potential generated in the formation by said pressure wave, wherein it further includes stages consisting of:
- --determining a critical frequency of propagation of the pressure wave by varying a mechanical excitation frequency of the formation and following up the corresponding variation of the variable representative of the non-linear electrofiltering phenomenon,
- --determining the porosity and/or permeability of the formation on the basis of the relation linking them to said critical frequency.
Method for determining the porosity and/or permeability of a geological formation likely to generate non-linear electrofiltering phenomena from an electrofiltering effect generated in the formation and including stages consisting of:
- --mechanically and repeatedly exciting a fluid of said formation so as to propagate a pressure wave with suitable characteristics for generating an electrofiltering effect in the formation,
- --measuring a variable representative of an electrofiltering potential generated in the formation by said pressure wave, wherein:
- --as the pressure wave is produced by two sources supplying waves of a given frequency and making it possible to channel the excited fluid and as the waves provided by the two sources are shifted with a phase jump between the two sources being adjustable, the variable representative of the electrofiltering potential measured is determined for this phase jump value and passes through an extremum at a critical frequency,
- --the porosity and/or permeability of the formation are determined on the basis of the relation linking them to said phase jump value or from charts.
Method for determining the porosity and/or permeability of a geological formation likely to generate non-linear electrofiltering phenomena from an electrofiltering effect generated in the formation and including stages consisting of:
- --mechanically and repeatedly exciting a fluid of said formation so as to propagate a pressure wave with suitable characteristics for generating an electrofiltering effect in the information,
- --measuring a variable representative of an electrofiltering potential generated in the formation by said pressure wave, wherein it further includes stages consisting of:
- --determining the critical frequency of propagation of the pressure wave by varying a mechanical excitation frequency of the formation and following up the corresponding variation of the variable representative of the non-linear electrofiltering phenomenon,
- --determining the porosity and/or permeability of the formation from charts.
Dependencies are inferred from the claim text.