Method of analyzing fines migration in multiphase flow in sediment layer using X-ray computed tomography image

Patent metadata

Field	Value
Publication number	US-10508997-B1
Application number	US-201916390249-A
Country	US
Kind code	B1
Filing date	Apr 22, 2019
Priority date	May 28, 2018
Publication date	Dec 17, 2019
Grant date	Dec 17, 2019

Abstract

A method of analyzing fines migration in a multiphase flow in a sediment layer using X-ray computed tomography (CT) image includes, preparing an X-ray CT image analysis sample; analyzing an X-ray CT image during a depressurization process; calibrating and calculating a fines content; and estimating a fines migration analysis result.

First claim

What is claimed is:

1. A method of analyzing fines migration in a multiphase flow in a sediment layer using X-ray computed tomography (CT) image, comprising,
preparing an X-ray CT image analysis sample;
analyzing an X-ray CT image during a depressurization process;
calibrating and calculating fines content; and
estimating a fines migration analysis result.

2. The method of claim 1 , wherein the preparing the X-ray CT image analysis sample comprises,
obtaining an X-ray CT image after gas injection prior to gas hydrate production and performing a voxel-scale based analysis.

3. A non-transitory storage medium storing a computer program for implementing a method disclosed in claim 2 .

4. The method of claim 1 , wherein the preparing the X-ray CT image analysis sample is premised on,
a first assumption that water and the fine particles are homogeneously distributed throughout the sample, and
a second assumption that mass of sand per voxel (M sand ) is constant during the depressurization process.

5. A non-transitory storage medium storing a computer program for implementing a method disclosed in claim 4 .

6. The method of claim 1 , wherein the analyzing the X-ray CT image during the depressurization process comprises,
classifying positions of gas bubbles based on threshold values obtained through a histogram analysis to calculate only the volume of the gas bubbles, and
calculating the volume of fine particles that take up space within a constant volume as a volume of water divided by a number of voxels having gas therein of the entire sample, which is considered as a volume of each voxel, to calculate mass of the fine particles in each of the gas voxels.

7. A non-transitory storage medium storing a computer program for implementing a method disclosed in claim 6 .

8. The method of claim 1 , wherein the calibrating and calculating the fines content comprises,
comparing the calculated fines content with a result of sampling after an experiment, to calculate a calibration coefficient, and finally calculating the fines content by applying the calibration coefficient.

9. A non-transitory storage medium storing a computer program for implementing a method disclosed in claim 8 .

10. The method of claim 1 , wherein the estimating the fines migration analysis result comprises,
estimating a change in the fines content at each position of the sample in each step of the depressurization process by using calculation results of the calculated fines content.

11. A non-transitory storage medium storing a computer program for implementing a method disclosed in claim 9 .

12. The method of claim 1 , wherein the preparing the X-ray CT image analysis sample further comprises,
calculating Equation b-11 to Equation b-14, and
M total0 =M sand +M fines0 +M water   [Equation b-11]

wherein, M total0 : total mass per voxel, M sand : mass of sand per voxel, M fines0 : mass of fine particles per voxel, M water : mass of water per voxel,
w=M water /( M sand +M fines0 )  [Equation b-12]

wherein, w: water content, M water : mass of water per voxel, M sand : mass of sand per voxel, M fines0 : mass of fine particles per voxel,
FC ini =M fines0 /( M sand +M fines0 )  [Equation b-13]

wherein FC ini : initial fines content, M fines0 : mass of fine particles per voxel, M sand : mass of sand per voxel,
M sand =(1−FC ini )· M total0 /(1+ w )  [Equation b-14]

wherein, M sand : mass of sand per voxel, FC ini : initial fines content, M total0 : total mass per voxel, w: water content.

13. A non-transitory storage medium storing a computer program for implementing a method disclosed in claim 12 .

14. The method of claim 1 , wherein the analyzing the X-ray CT image during the depressurization process comprises, calculating Equation b-21 to Equation b-26, and
M total_J =M sand +M fines_J +M water_J   [Equation b-21]

wherein, M total_J : total mass per voxel after depressurization, M sand : mass of sand per voxel, M fines_J : mass of fine particles per voxel after depressurization, M water_J :
mass of water per voxel after depressurization,
M′ total_J =M total_J +ρ w ·V gas   [Equation b-22]

wherein, M total_J : total mass per voxel after depressurization, M′ total_J : total mass per voxel after water replaces gas by volume after depressurization, ρ w : bulk density of voxel, V gas : volume of gas per voxel,
M′ total_J −M sand =M void_J   [Equation b-23]

wherein, M′ total_J : total mass per voxel after water replaces gas by volume after depressurization, M sand : mass of sand per voxel, M void_J : void mass per voxel after depressurization,
M void_J =M fines_J +M water_J   [Equation b-24]

wherein, M void_J : void mass per voxel after depressurization, M fines_J : mass of fine particles per voxel after depressurization,
V sand =M sand /G s ·ρ w   [Equation b-25]

wherein, V sand : volume of sand per voxel, M sand : mass of sand per voxel, G s : specific density of sediment particle, ρ w : bulk density of voxel,
V void =V total −V sand   [Equation b-26]

wherein, V void : void volume per voxel, V total : total volume per voxel, V sand : volume of sand per voxel.

15. A non-transitory storage medium storing a computer program for implementing a method disclosed in claim 14 .

16. The method of claim 1 wherein the calibrating and the calculating the fines content comprises,
calculating Equation c-1 to Equation c-5, and
Δ M=M void_J −M void   [Equation c-1]

wherein, M void : void mass per voxel, M void_J : void mass per voxel after depressurization, ΔM: difference of void mass per voxel before and after depressurization,
M fines_J =ΔM·G s /( G s −1)  [Equation c-2]

wherein, M fines_J : mass of fine particles per voxel after depressurization, ΔM: difference of void mass per voxel before and after depressurization, G s : specific density of sediment particle,
FC J =M fines_J /( M fines_J +M sand )  [Equation c-3]

wherein, FC J : fines content after depressurization, M fines_J : mass of fine particles per voxel after depressurization, M sand :
mass of sand per voxel,
FC J =( M′ total_J −V total ·ρ w )· G s /( G s −1)− M sand   [Equation c-4]

wherein, FC J : fines content after depressurization, M′ total_J : mass per voxel after depressurization, V total : total volume per voxel, ρ w : density of water, G s : specific density of sediment particle, M sand : mass of sand per voxel,
FC J_calibrated =α·FC J +β  [Equation c-5]

wherein, FC J_calibrated : calibrated fines content, α:
calibration parameter, FC J : fines content after depressurization, β: offset parameter.

17. A non-transitory storage medium storing a computer program for implementing a method disclosed in claim 16 .

18. A non-transitory storage medium storing a computer program for implementing a method disclosed in claim 1 .

19. An apparatus for analyzing fines migration in a multiphase flow in a sediment layer using X-ray computed tomography (CT), comprising,
a high pressure cell provided with, a body part in which a center sample is located, a fluid injection port on one side of the body part, and a fluid discharge port on an opposite side of the body part;
a temperature sensor and a pressure sensor provided in the fluid injection port and the fluid discharge port; and
a server configured to:
prepare an X-ray CT image analysis sample;
analyze an X-ra

Assignees

• Korea Inst Geoscience & Mineral Resources

Inventors

• Lee Joo-Yong
• Lee Min-Hui
• Han Gyeol
• Kwon Tae-Hyuk

Classifications

• G01N2223/635

  fluids, granulates · CPC title

• G01N2223/616

  earth materials · CPC title

• G01N2223/605

  phases · CPC title

• G01N2223/419

  computed tomograph · CPC title

• G01N33/24 Primary

  Earth materials (G01N33/42 takes precedence) · CPC title