# US 2019/0170893 A1 · Nmr logging interpretation of solid invasion

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- Number: US 2019/0170893 A1
- Document ID: US20190170893A1
- Status: Published application
- Kind: A1
- Application number: 16/266,506
- Filed: 2019-02-04
- Published: 2019-06-06
- Earliest claimed: 2013-11-15
- Assignees: Baker Hughes, A Ge Company, LLC
- Inventors: Jinhong Chen
- Web page: https://patentgrep.com/patent/US20190170893A1

## CPC

- G01V 3/32: operating with electron or nuclear magnetic resonance
- G01N 24/08: by using nuclear magnetic resonance (G01N24/12 takes precedence)
- G01N 24/081: {Making measurements of geologic samples, e.g. measurements of moisture, pH, porosity, permeability, tortuosity or viscosity}
- G01V 3/18: specially adapted for well-logging
- G01V 3/38: Processing data, e.g. for analysis, for interpretation, for correction
- G01V 11/00: Prospecting or detecting by methods combining techniques covered by two or more of main groups G01V1/00 - G01V9/00
- G01V: GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS (means for indicating the location of accidentally buried, e.g. snow-buried, persons A63B29/02)
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

A method for estimating an effect on nuclear magnetic resonance (NMR) measurements of an invasion of solid particles into pores of an earth formation penetrated by a borehole includes conveying a carrier through the borehole and performing an NMR measurement on a volume of interest in the formation to provide a relaxation time constant using an NMR tool disposed at the carrier. The method further includes receiving information describing the solid particles in the pores and quantifying, using a processor, an effect on the measured relaxation time constant due to the invasion of solid particles using the received information.

## Claims

### Claim 1

A method for estimating an effect on nuclear magnetic resonance (NMR) measurements of an invasion of solid particles into pores of an earth formation penetrated by a borehole, the method comprising:
conveying a carrier through the borehole;
performing an NMR measurement on a volume of interest in the formation to provide a relaxation time constant using an NMR tool disposed at the carrier;
receiving information describing the solid particles in the pores, the information comprising a shape property of the solid particles;
quantifying, using a processor, the effect on the measured relaxation time constant due to the invasion of the solid particles using the received information;
correcting the NMR measurement by the processor using the quantified effect to provide corrected NMR output; and
operating drilling or production resources in response to a parameter of the earth formation determined from the corrected NMR output having a value that provides input for operating the drilling or production resources.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the solid particles come from drilling fluid used to drill the borehole.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the relaxation time constant comprises at least one of a transverse relaxation time constant and a longitudinal relaxation time constant.

### Claim 4 (depends on 1)

The method according to claim 1, wherein the information comprises at least one selection from a group consisting of a size of each of the particles, a surface relaxivity of each of the particles, and an amount of space the particles occupy in each of the pores.

### Claim 5 (depends on 1)

The method according to claim 1, wherein the solid invasion particles have negligible surface relaxation compared to the surface relaxation of formation fluid in the pores.

### Claim 6 (depends on 5)

The method according to claim 5, wherein quantifying comprises using the following relationship:
T
2
,
SI
surf
=
T
2
surf

φ
log
φ
where T2,SIsurf is the surface transverse relaxation time constant with solid invasion, T2,surf is the surface transverse relaxation time constant without solid invasion, ϕlog is the porosity determined from the NMR measurement, and ϕ is the actual porosity of formation.

### Claim 7 (depends on 1)

The method according to claim 1, wherein bulk relaxation and pore surface relaxation are negligible compared to the surface relaxation of the solid particles.

### Claim 8 (depends on 7)

The method according to claim 7, further comprising calculating a surface relaxation time constant for pores having the invasion of solid particles.

### Claim 9 (depends on 8)

The method according to claim 8, wherein calculating a surface relaxation time constant for pores comprises using the following relationship:
1
T
2
,
SI
surf
=
ρ
s

A
s
V
s

φ
s
φ
log
where T2,SIsurf is the surface transverse relaxation time constant of the invaded solid particles, ϕlog is the porosity determined from the NMR measurement, ϕs is the porosity occupied by the solid particles, ρs is the surface relaxivity of the solid invasion particles, and As/Vs represents the surface area-to-volume ratio of the solid particles.

### Claim 10 (depends on 9)

The method according to claim 9, wherein at least a portion of the solid particles are modeled as a sphere and As/Vs is 3/r where r is the radius of the sphere.

### Claim 11 (depends on 1)

The method according to claim 1, further comprising using the quantified effect to improve the accuracy in determining a formation property for pores not having solid invasion away from the borehole.

### Claim 12 (depends on 11)

The method according to claim 11, wherein the formation property is at least one of porosity, permeability, and hydrocarbon typing.

### Claim 13

An apparatus for estimating an effect on nuclear magnetic resonance (NMR) measurements of an invasion of solid particles into pores of an earth formation penetrated by a borehole, the apparatus comprising:
a carrier configured to be conveyed through the borehole;
a NMR tool disposed at the carrier and configured to perform a NMR measurement on a volume of interest in the formation to provide a relaxation time constant; and
a processor configured to:
receive information describing the solid particles in the pores, the information comprising a shape property of the solid particles;
quantify an effect on the measured relaxation time constant due to the invasion of solid particles using the received information;
correct NMR measurements using the quantified effect to provide corrected NMR output;
a drilling or production resource configured to be operated in response to a parameter of the earth formation determined from the corrected NMR output having a value that provides input for operating the drilling or production resources.

### Claim 14 (depends on 13)

The apparatus according to claim 13, wherein the solid particles come from drilling fluid used to drill the borehole.

### Claim 15 (depends on 13)

The apparatus according to claim 13, wherein the relaxation time constant comprises at least one of a transverse relaxation time constant and a longitudinal relaxation time constant.

### Claim 16 (depends on 13)

The apparatus according to claim 13, wherein the processor is further configured to calculate a surface transverse relaxation time constant T2,S for pores with invasion of solid particles using T2,SIsurf where T2,SIsurf is the surface transverse relaxation time constant of the invaded solid particles.

### Claim 17 (depends on 16)

The apparatus according to claim 16, wherein the processor is further configured to calculate a transverse relaxation time constant T2 for pores without solid invasion away from the borehole using T2,SIsurf.

### Claim 18 (depends on 13)

The apparatus according to claim 13, wherein the processor is further configured to estimate a formation property with improved accuracy using the quantified effect.