# US 10,502,858 B2 · Method and system for formation texture and rock type identification

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- Number: US 10,502,858 B2
- Document ID: US10502858B2
- Status: Granted
- Kind: B2
- Application number: 15/333,835
- Filed: 2016-10-25
- Published: 2017-06-08
- Granted: 2019-12-10
- Earliest claimed: 2015-12-04
- Assignees: Schlumberger Technology Corporation
- Applicants: Schlumberger Technology Corporation
- Inventors: Tianhua Zhang; Yong-Hua Chen; Robert Laronga
- Web page: https://patentgrep.com/patent/US10502858B2

## CPC

- G01V 3/20: operating with propagation of electric current
- E21B 47/002: by visual inspection
- E21B 47/0025: {generating an image of the borehole wall using down-hole measurements, e.g. acoustic or electric}
- 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: 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

In one embodiment, a method includes receiving, via a processor, data from a plurality of imaging buttons disposed on a downhole tool within a borehole, generating, via the processor, a resistivity image, a permittivity image, a standoff curve, a rugosity index curve, a high-resolution image of a relationship between resistivity and permittivity of a section of a geological formation measured by the downhole tool, or some combination thereof based on the data, characterizing, via the processor, one or more vugs, one or more fractures, or some combination thereof based at least on the resistivity image, the permittivity image, the standoff curve, the rugosity index curve, the high-resolution image of the relationship between resistivity and permittivity, or some combination thereof, and identifying, via the processor, one or more rock types based at least on the high-resolution image of the relationship between resistivity and permittivity.

## Claims

### Claim 1

A method comprising:
receiving, via a processor, data from a plurality of imaging buttons disposed on a downhole tool within a borehole;
generating, via the processor, a set of parameters relative to the formation, wherein the set of parameters comprises one or more of a resistivity image, a permittivity image, a standoff curve, a rugosity index curve, a high-resolution image of a relationship between resistivity and permittivity of a section of a geological formation measured by the downhole tool and wherein the set of parameters comprises at least the high-resolution image of a relationship between resistivity and permittivity;
characterizing, via the processor, one or more vugs, one or more fractures, or some combination thereof based at least on the set of parameters; and
identifying, via the processor, one or more rock types based at least on the high-resolution image of the relationship between resistivity and permittivity,
wherein the set of parameters includes the rugosity index curve, wherein the rugosity index curve is calculated in accordance with the following relationship:
bore
⁢
⁢
oleRugosityIndex
=
∑
i
=
1
n
⁢
(
A
ij
⁢
⁢
1
+
A
ij
⁢
⁢
2
)
∑
i
=
1
n
⁢
(
l
i
d
j
)
where dj is the depth sampling interval between log points and li is the distance between neighboring imaging buttons, li dj is the square surface area of an image pixel, and Aij1 and Aij2 are the two projected triangular surface areas on the generally curved borehole surface calculated from the standoff variation.

### Claim 2 (depends on 1)

The method of claim 1, wherein the method comprises characterizing one or more vugs, wherein characterizing one or more vugs comprises:
characterizing whether the one or more vugs are open to a surface of the borehole or are closed to the surface; and
characterizing a filling material of the one or more vugs.

### Claim 3 (depends on 1)

The method of claim 1, wherein the method comprises characterizing one or more fractures, wherein characterizing one or more factures comprises characterizing whether the one or more fractures are horizontal or vertical.

### Claim 4 (depends on 1)

The method of claim 1, wherein the high-resolution image of the relationship between resistivity and permittivity is generated by calculating a Hayman factor for each pixel of an image of the section of a geological formation, wherein the Hayman factor is calculated in accordance with the following relationship:
HF
=
Permittivity
a
+
b
freq
c
Resistivity
d
where Permittivity is permittivity of the formation surround the borehole, freq is a frequency of measurement, Resistivity is a resistivity of the formation surround the borehole and coefficients a, b, c and d can be determined from laboratory measurements.

### Claim 5 (depends on 1)

The method of claim 1, wherein the received data is in a megahertz range of frequency.

### Claim 6 (depends on 1)

The method of claim 1, wherein the set of parameters includes at least one of the resistivity image, the permittivity image and the standoff image, wherein the at least one of the resistivity image, the permittivity image, and the standoff image is generated using inversion.

### Claim 7 (depends on 1)

The method of claim 1, comprising:
receiving, via the processor, subsequent data including a relationship of resistivity and permittivity measured in a lab; and
comparing the subsequent data to the high-resolution image of the relationship between resistivity and permittivity to identify the one or more rock types.

### Claim 8 (depends on 1)

The method of claim 1, wherein the set of parameters includes the standoff image, the method comprising measuring the total impedance of material in front of the imaging buttons when generating the standoff image.

### Claim 9

A system, comprising:
a downhole tool comprising a plurality of imaging buttons; and
a data processing system comprising a processor configured to:
receive data from the plurality of imaging buttons;
generate a high-resolution image of a relationship between resistivity and permittivity of a section of a geological formation measured by the plurality of imaging buttons; and
identify one or more rock types based at least on the high-resolution image of the relationship between resistivity and permittivity,
wherein the processor is configured to generate at least a rugosity index curve and a high-resolution image of a relationship between resistivity and permittivity and to characterize one or more vugs based at least on the rugosity index curve and the high-resolution image of the relationship between resistivity and permittivity, wherein characterizing one or more vugs includes :
characterizing whether the one or more vugs are open to a surface of the borehole or are closed to the surface based on the rugosity index curve; and
characterizing a filling material of the one or more vugs based on the rugosity index curve and the high-resolution image of the relationship between resistivity and permittivity.

### Claim 10 (depends on 9)

The system of claim 9, wherein the processor is configured to characterize one or more fractures, wherein characterizing one or more fractures includes characterizing whether the one or more fractures are horizontal or vertical.

### Claim 11 (depends on 9)

The system of claim 9, wherein the plurality of imaging buttons are configured to obtain measurements at megahertz frequencies.

### Claim 12 (depends on 9)

The system of claim 9, wherein the rugosity index curve indicates a smoothness of a surface of the section of the geological formation.

### Claim 13 (depends on 9)

The system of claim 9, wherein the processor identifies one or more rock types based on different vug filling materials visualized in the high-resolution image by different colors.

### Claim 14

A tangible, non-transitory computer-readable medium storing instructions that, when executed by a processor, cause the processor to:
receive data from a plurality of imaging buttons disposed on a downhole tool, wherein the data comprises megahertz range frequency measurements and the imaging buttons are measuring a section of a borehole;
generate at least a rugosity index curve and a high-resolution image of a relationship between resistivity and permittivity; and
characterize one or more vugs based at least on the rugosity index curve and the high-resolution image of the relationship between resistivity and permittivity, wherein characterizing the one or more vugs comprise :
characterize whether the one or more vugs are open to a surface of the section or are closed to the surface based on the rugosity index curve; and
characterize a filling material of the one or more vugs based on the rugosity index curve and the high-resolution image of the relationship between resistivity and permittivity.

### Claim 15 (depends on 14)

The computer readable medium of claim 14, wherein the instructions, when executed by the processor, cause the processor to identify one or more rock types based at least on the high-resolution image of the relationship between resistivity and permittivity.