# US 2025/0085449 A1 · Determining Invaded Zones In Resistivity Logging

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- Number: US 2025/0085449 A1
- Document ID: US20250085449A1
- Status: Published application
- Kind: A1
- Application number: 18/244,125
- Filed: 2023-09-08
- Published: 2025-03-13
- Earliest claimed: 2023-09-08
- Assignees: Halliburton Energy Services, Inc.
- Applicants: Halliburton Energy Services, Inc.
- Inventors: Xusong Wang; Baris Guner; Ahmed Fouda
- Web page: https://patentgrep.com/patent/US20250085449A1

## CPC

- G01V 3/20: operating with propagation of electric current
- E21B 49/00: Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells
- G01V 3/26: operating with magnetic or electric fields produced or modified either by the surrounding earth formation or by the detecting device (with electromagnetic waves G01V3/30)
- G01V 3/38: Processing data, e.g. for analysis, for interpretation, for correction
- E21B 2200/20: Computer models or simulations, e.g. for reservoirs under production, drill bits
- G01V: GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS (means for indicating the location of accidentally buried, e.g. snow-buried, persons A63B29/02)
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS

## Abstract

A method comprising: disposing a tool into a borehole, wherein the tool comprises: one or more guard electrodes configured to transmit a current into at least a formation surrounding the borehole; and one or more monitor electrodes configured to obtain one or more measurements from at least the formation surrounding the borehole. The method may be further configured to perform a first and second inversion on the one or more measurements to form a first inversion set; forming a misfit of the first inversion and a misfit of the second inversion based at least on the first inversion set and second inversion set; determining a weighting inversion coefficient based at least on the misfit of the first inversion and the misfit of the second inversion; and combining the first invasion set, the second invasion set, and/or weighting inversion coefficient to form one or more inversion products.

## Claims

### Claim 1

A method comprising:
disposing a tool into a borehole, wherein the tool comprises:
a survey electrode and one or more guard electrodes configured to transmit a current into at least a formation surrounding the borehole; and
one or more monitor electrodes configured to obtain one or more measurements from at least the formation surrounding the borehole;
performing a first inversion on the one or more measurements to form a first inversion set;
performing a second inversion on the one or more measurements to form a second inversion set;
forming a misfit of the first inversion and a misfit of the second inversion based at least on the first inversion set and second inversion set;
determining a weighting inversion coefficient based at least on the misfit of the first inversion and the misfit of the second inversion; and
combining the first invasion set, the second invasion set, and weighting inversion coefficient to form one or more inversion products.

### Claim 2 (depends on 1)

The method of claim 1, wherein one or more inversion products are borehole diameter dbh, mud resistivity Rm, invasion diameter dxo invasion resistivity Rxo, and/or formation resistivity Rt.

### Claim 3 (depends on 1)

The method of claim 1, wherein the first inversion comprises a step radial model without invasion.

### Claim 4 (depends on 3)

The method of claim 3, wherein the second inversion comprises a step radial formation model with invasion.

### Claim 5 (depends on 4)

The method of claim 4, further comprising forming a misfit ratio as a ratio between the misfit of the first inversion and the misfit of the second inversion.

### Claim 6 (depends on 5)

The method of claim 5, further comprising forming a first decision boundary and a second decision boundary.

### Claim 7 (depends on 6)

The method of claim 6, wherein the first decision boundary is formed by an adjustable threshold based on the misfit ratio and the second decision boundary is greater than the first decision boundary.

### Claim 8 (depends on 7)

The method of claim 7, wherein determining the weighting inversion coefficient is performed by:
winv
=
{
0
if
⁢
Ratio
misfit
<
Thres
⁢
1
Ratio
misfit
-
Thres
⁢
1
Thres
⁢
2
-
Thres
⁢
1
if
⁢
Thres
⁢
1
≤
Ratio
misfit
≤
Thres
⁢
2
1
if
⁢
Ratio
misfit
>
Thres
⁢
2
wherein Thres1 is the first decision boundary, Thres2 is the second decision boundary, and Ratiomisfit is the misfit ratio.

### Claim 9 (depends on 8)

The method of claim 8, further comprising calculating a final inversion result for an invasion diameter by:
dxo
final
=
winv
×
dxo
inv
wherein dxofinal is the final inversion result for the invasion diameter, winv is the weighting inversion coefficient, and dxoinv is an invasion diameter result of the first second inversion.

### Claim 10 (depends on 8)

The method of claim 8, further comprising calculating a final inversion result for an invasion zone resistivity by:
Rxo
final
=
winv
×
Rxo
inv
+
(
1
-
winv
)
×
Rt
n
-
inv
wherein Rxofinal is the final inversion result for the invasion zone resistivity, winy is the weighting inversion coefficient, Rxoinv is the invasion zone resistivity result of the second inversion, and Rtn-inv is a formation resistivity result of the second-first inversion.

### Claim 11 (depends on 8)

The method of claim 8, further comprising calculating a final inversion result for the formation resistivity by:
Rt
final
=
winv
×
Rt
inv
+
(
1
-
winv
)
×
Rt
n
-
inv
wherein Rtfinal is the final inversion result for the formation resistivity, winv is the weighting inversion coefficient, and Rtinv is a formation resistivity result of the second inversion.

### Claim 12 (depends on 1)

The method of claim 1, further comprising performing a statistical analysis on the one or more inversion products, wherein a statistical analysis may comprise a median, a mean filter or any other statistical data operation to remove one or more spikes from the one or more inversion products.

### Claim 13

A non-transitory storage computer-readable medium storing one or more instructions that, when executed by a processor, cause the processor to:
obtain one or more measurements of current or voltage acquired by a tool;
perform a first inversion on the one or more measurements to form a first inversion set;
perform a second inversion on the one or more measurements to form a second inversion set;
form a misfit of the first inversion and a misfit of the second inversion based at least on the first inversion set and second inversion set;
determine a weighting inversion coefficient based at least on the misfit of the first inversion and the misfit of the second inversion; and
combine the first invasion set, the second invasion set, and/or weighting inversion coefficient to form one or more inversion products.

### Claim 14 (depends on 13)

The non-transitory storage computer-readable medium of claim 13, wherein the first inversion comprises a step model without invasion and the second inversion comprises a step radial formation model with invasion.

### Claim 15 (depends on 14)

The non-transitory storage computer-readable medium of claim 14, wherein the one or more instructions, that when executed by the processor, further cause the processor to form a misfit ratio as a ratio between the misfit of the first inversion and the misfit of the second inversion.

### Claim 16 (depends on 15)

The non-transitory storage computer-readable medium of claim 15, wherein a first decision boundary is formed by an adjustable threshold based on the misfit ratio.

### Claim 17 (depends on 16)

The non-transitory storage computer-readable medium of claim 16, wherein a second decision boundary is greater than the first decision boundary.

### Claim 18 (depends on 17)

The non-transitory storage computer-readable medium of claim 17, wherein the determining weighting inversion coefficient is calculated by:
winv
=
{
0
if
⁢
Ratio
misfit
<
Thres
⁢
1
Ratio
misfit
-
Thres
⁢
1
Thres
⁢
2
-
Thres
⁢
1
if
⁢
Thres
⁢
1
≤
Ratio
misfit
≤
Thres
⁢
2
1
if
⁢
Ratio
misfit
>
Thres
⁢
2
wherein Thres1 is the first decision boundary, Thres2 is the second decision boundary, and Ratiomisfit is the misfit ratio.

### Claim 19 (depends on 18)

The non-transitory storage computer-readable medium of claim 18, wherein the determining weighting inversion coefficient is calculated by:
dxo
final
=
winv
×
dxo
inv
wherein dxofinal is the final inversion result for the invasion diameter, winv is weighting inversion coefficient, and dxoinv is an invasion diameter of the second inversion.

### Claim 20 (depends on 13)

The non-transitory storage computer-readable medium of claim 13, wherein the one or more instructions, that when executed by the processor, further cause the processor to perform a statistical analysis on the one or more inversion products, wherein a statistical analysis may comprise a median, a mean filter or any other statistical data operation to remove one or more spikes from the one or more inversion products.