# US 2014/0191762 A1 · System and Method for Imaging Properties of Subterranean Formations

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- Number: US 2014/0191762 A1
- Document ID: US20140191762A1
- Status: Published application
- Kind: A1
- Application number: 14/210,385
- Filed: 2014-03-13
- Published: 2014-07-10
- Earliest claimed: 2010-11-15
- Assignees: Schlumberger Technology Corporation
- Applicants: Schlumberger Technology Corporation
- Inventors: Yong-Hua Chen; Dzevat Omeragic; Tarek M. Habashy; Richard J. Bloemenkamp
- Web page: https://patentgrep.com/patent/US20140191762A1

## CPC

- 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 3/24: using AC
- G01V 3/088: {operating with electric fields (G01V3/082 takes precedence)}
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- 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

A system and method for imaging properties of subterranean formations in a wellbore is provided. The system comprises a formation sensor for collecting currents injected into the subterranean formations, the formation sensor positionable on a downhole tool deployable into the wellbore. The system comprises a controller for controlling the formation sensor and a formation imaging unit. The formation imaging unit comprises a current management unit for collecting data from the currents injected into the subterranean formations, the currents having at least two different frequencies. The formation imaging unit comprises a drilling mud data unit for determining at least one drilling mud parameter, a formation data unit for determining at least one formation parameter from the collected data, and an inversion unit for determining at least one formation property by inverting the at least one formation parameter.

## Claims

### Claim 1

A formation imaging unit for imaging properties of at least one subterranean formation in a wellbore at a wellsite, the formation imaging unit comprising:
a current management unit for collecting data from at least two currents injected into the at least one subterranean formation, the at least two currents having at least two different frequencies;
a drilling mud data unit for determining at least one drilling mud parameter;
a formation data unit for determining at least one formation parameter from the collected data; and
an inversion unit for determining at least one formation property by inverting the at least one formation parameter.

### Claim 2 (depends on 1)

The formation imaging unit of claim 1, wherein the at least one formation property is determined by inverting the drilling mud parameter and the at least one formation parameter.

### Claim 3 (depends on 1)

The formation imaging unit of claim 1, wherein the inversion unit is configured to implement forward modeling to determine at least one formation property.

### Claim 4 (depends on 3)

The formation imaging unit of claim 3, wherein the inversion unit is configured to implement forward modeling according to the equation:
Z
=
V

/

I
=
K
mud

Δ


R
mud
1
+
jωɛ
0

ɛ
mud

R
mud
+
K
rock

R
rock
1
+
jωɛ
0

ɛ
rock

R
rock
.

### Claim 5 (depends on 3)

The formation imaging unit of claim 3, wherein the inversion unit is configured to implement forward modeling using a polynomial fitting process.

### Claim 6 (depends on 3)

The formation imaging unit of claim 3, wherein the inversion unit is configured to perform inversion in conjunction with interpolation from a look-up table.

### Claim 7 (depends on 1)

The formation imaging unit of claim 1, wherein the inversion unit is configured to implement analytic Jacobian calculations.

### Claim 8 (depends on 1)

The formation imaging unit of claim 1, wherein the current management unit is configured to measure amplitude and phase data, and wherein the inversion unit is configured to calibrate the amplitude and phase data.

### Claim 9

A system for imaging properties of at least one subterranean formation in a wellbore at a wellsite, the system comprising:
a formation sensor for collecting at least two currents injected into the at least one subterranean formation, the formation sensor positionable on a downhole tool deployable into the wellbore;
a controller for controlling the formation sensor; and
a formation imaging unit, the formation imaging unit comprising:
a current management unit for collecting data from the at least two currents injected into the at least one subterranean formation, the at least two currents having at least two different frequencies;
a drilling mud data unit for determining at least one drilling mud parameter;
a formation data unit for determining at least one formation parameter from the collected data; and
an inversion unit for determining at least one formation property by inverting the at least one formation parameter.

### Claim 10 (depends on 9)

The system of claim 9, further comprising a mud sensor for collecting at least one current injected into a borehole mud fluid.

### Claim 11 (depends on 9)

The system of claim 9, wherein the inversion unit is configured to determine at least one formation property based on multiple log points.

### Claim 12 (depends on 9)

The system of claim 9, wherein the inversion unit is configured to determine at least one formation property based on multiple inversions run on the at least one formation property.

### Claim 13 (depends on 9)

The system of claim 9, wherein the inversion unit is configured to perform inversions in periodic, relatively smaller zones and use interpolation to determine at least one formation property in a relatively larger zone based on the inversion of the relatively smaller zones.

### Claim 14

A method for imaging properties of at least one subterranean formation in a wellbore at a wellsite, the method comprising:
deploying a downhole tool into the wellbore, the downhole tool having a formation sensor thereon;
collecting at least two currents sent through the at least one subterranean formation from the formation sensor;
sending formation data from the at least two currents to a formation imaging unit;
using the formation imaging unit, performing an inversion on the formation data; and
determining at least one formation property with the formation imaging unit.

### Claim 15 (depends on 14)

The method of claim 14, wherein performing the inversion comprises:
determining at least one drilling mud parameter from the formation data;
determining at least one formation parameter from the formation data; and
inverting the at least one formation parameter to determine the at least one formation property.

### Claim 16 (depends on 14)

The method of claim 14, wherein performing the inversion comprises performing a calibration from the formation sensor based on estimated errors in an amplitude data and a phase data measured at the formation sensor.

### Claim 17 (depends on 14)

The method of claim 14, wherein performing the inversion comprises performing a forward modeling based on the equation:
Z
=
V

/

I
=
K
mud

Δ


R
mud
1
+
jωɛ
0

ɛ
mud

R
mud
+
K
rock

R
rock
1
+
jωɛ
0

ɛ
rock

R
rock
.

### Claim 18 (depends on 14)

The method of claim 14, wherein performing the inversion comprises using the formation data from an individual log point and applying the inversion to multiple log points based on the formation data from the individual log point.

### Claim 19 (depends on 14)

The method of claim 14, wherein performing the inversion comprises performing a plurality of inversions on at least one formation property output and determining an accuracy of the at least one formation property based on results of the plurality of inversions.

### Claim 20 (depends on 14)

The method of claim 14, wherein performing the inversion comprises performing an inversion analysis on a smaller zone of the wellbore and using interpolation to make assumptions on a larger zone of the wellbore, based on the inversion analysis of the smaller zone.