NMR logging interpretation of solid invasion

Patent metadata

Field	Value
Publication number	US-10197696-B2
Application number	US-201314081218-A
Country	US
Kind code	B2
Filing date	Nov 15, 2013
Priority date	Nov 15, 2013
Publication date	Feb 5, 2019
Grant date	Feb 5, 2019

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.

First claim

What is claimed is:

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 solid particles comprising fine particles of formation material produced from drilling the borehole, 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.

2. 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.

3. 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.

4. 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.

5. The method according to claim 4 , wherein quantifying comprises using the following relationship:

T

2
,
SI

surf

=

T
2
surf

⁢

ϕ

lo
⁢

⁢
g

ϕ

where T 2,SI surf is the surface transverse relaxation time constant with solid invasion, T 2, surf is the surface transverse relaxation time constant without solid invasion, ϕ log is the porosity determined from the NMR measurement, and ϕ is the actual porosity of formation.

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

7. The method according to claim 6 , further comprising calculating a surface relaxation time constant for pores having the invasion of solid particles.

8. The method according to claim 7 , 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

lo
⁢

⁢
g

where T 2,SI surf is the surface transverse relaxation time constant of the invaded solid particles, ϕ log is the porosity determined from the NMR measurement, ϕ s is the porosity occupied by the solid particles, ρ s is the surface relaxivity of the solid invasion particles, and A s /V s represents the surface area-to-volume ratio of the solid particles.

9. The method according to claim 8 , wherein at least a portion of the solid particles are modeled as a sphere and A s /V s is 3/r where r is the radius of the sphere.

10. 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.

11. The method according to claim 10 , wherein the formation property is at least one of porosity, permeability, and hydrocarbon typing.

12. 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; and
quantifying, using a processor, an 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;
wherein quantifying comprises solving:

1

T

2
,
SI

surf

=

1

T
2
surf

⁢

1

1
-

R
SI

+

ρ
s

⁢

A
s

V
s

⁢

Assignees

• Chen Jinhong
• Baker Hughes A Ge Co Llc

Inventors

• Chen Jinhong

Classifications

• G01V3/32 Primary

  operating with electron or nuclear magnetic resonance · CPC title

• G01V11/00

  Prospecting or detecting by methods combining techniques covered by two or more of main groups G01V1/00 - G01V9/00 · CPC title

• G01V3/38

  Processing data, e.g. for analysis, for interpretation, for correction · CPC title

• G01V3/18

  specially adapted for well-logging · CPC title

• G01N24/081

  Making measurements of geologic samples, e.g. measurements of moisture, pH, porosity, permeability, tortuosity or viscosity · CPC title