US 2006/0136135 A1 · Method of evaluating fluid saturation characteristics in a geological formation

Abstract

In one aspect of the present invention, a method of evaluating water saturation characteristics is provided. The method is applicable to a geological formation that is penetrated by a borehole and includes injection fluid introduced into the formation by an external process performed upon the borehole. The method includes conducting electromagnetic induction measurements indicative of resistivity values of the formation. A value of total porosity for the formation is also obtained. Then, the method calls for defining fractional volumes for each of clay bound water, free water, and irreducible water in the formation, wherein the free water volume accounts for injection fluid introduced into the formation. The method also calls for defining values of conductivity for each of clay bound water, free water, and irreducible water, wherein the free water conductivity is determined from the conductivity of the injection fluid. Finally, water saturation in the formation is determined from a relationship between total porosity and conductivity values for the formation, and conductivities and fractional volumes for each of clay bound water, free water, and irreducible water. This relationship is preferably provided by the Triple Water Equation.

Claims25

Dependent claims

-24. (canceled)

A method of evaluating differential saturation levels in a reservoir from an initial state of production to a later state of production existing after performance of an external fluid injection process whereby new injection fluid is introduced into a reference region of the reservoir, said method comprising the steps of:

conducting electrical resistivity measurements at a reference region in the reservoir during the initial state;
and
deriving from the electrical resistivity measurements, an evaluation of initial total water saturation at the reference region;
performing a fluid injection process on the reservoir, whereby injection fluid is introduced into the reference region of the reservoir;
conducting a second set of electrical resistivity measurements at the reference region during the later state;
driving from the second electrical resistivity measurements, an evaluation of later total water saturation at the reference region, whereby total water saturation is obtained from a relationship accounting for fractional volumes of each of irreducible water, free water, and clay-bound water, wherein the free water is considered to have different conductive properties from the irreducible water and the clay bound water;
and
comparing the later total water saturation with the initial total water saturation, thereby evaluating the differential water saturation at the reference region between the initial state and the later state.

5 more elements

A method of interpreting electromagnetic tomography measurements conducted in a geological formation penetrated by a borehole and including fluids introduced into a reference region of the formation by an external injection process performed upon the formation, to obtain water and hydrocarbon saturation characteristics of the reference region in the formation, said method comprising the steps of:

conducting electromagnetic tomography measurements of the formation in the vicinity of the borehole, the measurements being indicative of resistivity values of the reference region of the formation;
obtaining a value of total porosity for the reference region of the formation;
defining values of conductivity for each of clay bound water, free water, and irreducible water in the reference region of the formation;
defining fractional volumes for each of the clay bound water, the free water, and the irreducible water in the reference region of the formation;
and
determining total water saturation in the reference region of the formation, including employing a triple water model to obtain a value for total water saturation, whereby the total water saturation value is obtained from a relationship in which values are entered for total porosity, conductivity of the formation, conductivity of clay bound water, conductivity of free water, and conductivity of irreducible water.

3 more elements

Dependencies are inferred from the claim text.

Method of evaluating fluid saturation characteristics in a geological formation

Life of this patent

Method of evaluating fluid saturation characteristics in a geological formation

Life of this patent

Abstract

Claims25