# US 2010/0164500 A1 · Method for quantitative separation of electromagnetic induction and induced polarization effects

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- Number: US 2010/0164500 A1
- Document ID: US20100164500A1
- Status: Published application
- Kind: A1
- Application number: 12/588,507
- Filed: 2009-10-19
- Published: 2010-07-01
- Earliest claimed: 2008-10-23
- Assignees: Siberian Geophysical Research and Production Company, LLC.
- Inventors: Petr Yuryevich Legeydo; Yevgeny Valeryevich Ageyenkov; Ivan Yuryevich Pesterev; Sergey Aleksandrovich Ivanov; Svetlana Yuryevna Garina; Elena Olegovna Kudriavtseva; Yury Aleksandrovich Davydenko
- Web page: https://patentgrep.com/patent/US20100164500A1

## CPC

- G01V 3/38: Processing data, e.g. for analysis, for interpretation, for correction
- G01V 3/083: {Controlled source electromagnetic [CSEM] surveying}
- G01V 3/12: operating with electromagnetic waves {(operating with millimetre waves G01V8/005)}
- G01V 2003/086: {Processing}
- G01V: GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS (means for indicating the location of accidentally buried, e.g. snow-buried, persons A63B29/02)

## Abstract

The invention relates to the field of electrical exploration and to the methods of determination of subterranean formations properties by means of electric parameters of subterranean formations measuring and separating of the parameters measured. The invention can be applied both in surface and marine electrical exploration using controlled sources of electromagnetic field, and is used in gas and oil exploration for searching and delimitation of oil and gas reservoirs basing on segregation of response from stratum, secondarily changed due to hydrocarbons migration, to split the measured signal to available components. The invention provides for a set of techniques that enable a layer-by-layer determination of geoelectrical parameters values, as well as process characteristics of induced medium polarization and electromagnetic induction.

## Claims

### Claim 1

A method for quantitative separation of electromagnetic induction and induced polarization effects, comprising: measuring of the process of transient over a polarizable medium, modeling of electromagnetic measurements within a horizontally stratified polarizable medium, segregating of an electrodynamic component from transient process, segregating of a galvanic component of induced polarization from transient process, evaluating of changes of the induced polarization galvanic component by area and its geological interpretation,
characterized in
setting of several input functions dependent on medium parameters and measured on the medium surface, forming of these functions in the way that ensures different manner of their dependence on the electromagnetic induction field and induced polarization field, wherein one of these functions is made to increase an electromagnetic induction and induced polarization ratio as compared to DU(t), the second of these functions is made to decrease the electromagnetic induction and induced polarization ratio as compared to DU(t), and the third of these functions is made as a combination of time and spatial derivatives of the transient field, and further in simultaneous inversion of all the input functions and obtaining of a geoelectrical model of the section, meanwhile the number of the medium parameters which characterize induced polarization is deliberately redundant, so that the obtained medium model is not single, but lies within a certain range of equivalence, then the obtained model polarizability is set to nil for all layers, and through solving the direct problem the electromagnetic induction field (EM) is calculated, simultaneously the wave numbers of the said model are set to nil, and through solving the direct problem the field of the induced polarization (IP) galvanic component is calculated.

### Claim 2 (depends on 1)

The method for quantitative separation of effects according to claim 1, characterized in that the several input functions are formed, where one of the functions is Ps, calculated to increase the electromagnetic induction and induced polarization ratio as compared to DU(t), the second is P1, calculated to decrease the electromagnetic induction and induced polarization ratio as compared to DU(t), and the third is Dφ, calculated as a combination of time and spatial derivatives of the transient field.

### Claim 3 (depends on 1)

The method for quantitative separation of effects according to claim 1, characterized in that the parameter P1 is formed as a filter that increases the induced polarization and electrodynamics ratio as compared to ΔU(t), the said parameter P1 is defined as a ratio of the second axial potential difference of the transient field Δ2U(t) and first axial potential difference of the transient field ΔU(t) under a condition of current cut-off according to the equation P1(t)=Δ2U(t)/ΔU(t)/time off.

### Claim 4 (depends on 1)

The method for quantitative separation of effects according to claim 1, characterized in that the parameter Ps is formed as a filter that decreases the induced polarization and electrodynamics ratio as compared to ΔU(t), the said parameter Ps is defined as a ratio of the second axial potential difference of the transient field Δ2U(t) and first axial potential difference of the transient field ΔU(t) under a condition of current switched on according to the equation Ps(t)=Δ2U(t)/ΔU(t)/time on.

### Claim 5 (depends on 1)

The method for quantitative separation of effects according to claim 1, characterized in that the parameter Dφ(t) is formed as a difference of parameters It(t) and P1(t) according to the equation Dφ(t)=It(t)−P1(t), where the It(t) is calculated according to the equation It(t)=Δt(Δ2U(t))/Δt(ΔU(t)) as a ratio of the time derivatives Δ2U(t) and ΔU(t).

### Claim 6 (depends on 1)

The method for quantitative separation of effects according to claim 1, characterized in that the simultaneous minimization of the input parameters determined at the same measure point is performed through inputting the following parameters to a minimization program:
DU(t)=ΔU(t)/ΔU0, where ΔU0 is a potential difference ΔU measured during a current passing,
P1(t)=Δ2U(t)/ΔU(t), calculated under a cut-off current condition,
Ps(t)=Δ2U(t)/ΔU(t), calculated under a switched on current condition,
Dφ(t)=It(t)−P1(t), where It(t)=Δt(Δ2U(t)/Δt(ΔU(t)),
and performing their inversion within a horizontally stratified polarizable medium under conditions of the deliberately redundant number of the model geoelectrical parameters describing its polarization properties.

### Claim 7 (depends on 1)

The method for quantitative separation of effects according to claim 1, characterized in that the induced polarization field IP is determined as a result of solving the direct problem of the model obtained after its minimization with the wave numbers set to nil.

### Claim 8 (depends on 1)

The method for quantitative separation of effects according to claim 1, characterized in that the electromagnetic induction field EM is determined as a result of solving the direct problem of the model obtained after its minimization with polarizability set to nil.

### Claim 9 (depends on 1, 2, 3, 4, 5, 6, 7, 8)

The method for quantitative separation of effects according to claims 1-8, characterized in that verification of reproducibility of the solution is performed.