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Organic and Inorganic Pore Structure Analysis in Shale Rocks with Superposition

MethodDr. Chenchen Wang

Prof. Zhangxing (John) Chen

University of Calgary

06/14/2014

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Results and Discussions

Methodology

1

2

3

4 Conclusions

5 Future Research

Introduction

Outline

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1. Introduction

Typical shale matrix SEM image with organic and inorganic pores

Shale rocks are inherently heterogeneous and the shale matrix pores can

be divided into organic and inorganic pores. The organic and inorganic

pores are distributed with each other in the shale matrix.

Shale matrix(Organic pores + few inorganic pores)Organic matter: 3%-15%

Inorganic matter(Inorganic pores)

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1. Introduction

While the organic pores and inorganic pores in shale rocks are at different scales,

and the transport mechanisms of shale gas in organic and inorganic pores are

different, it is necessary to describe the nanoscopic organic and inorganic pore

characteristics of shale rocks with a method, such as superposition, based on a

digital rock analysis technology.

Different Scale Resolution Images Digital Rock Analysis Technology

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Results and Discussions

Methodology

1

2

3

4 Conclusions

5 Future Research

Introduction

Outline

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2. Methodology

2.1 Image analysis and 3D digital rock reconstruction

Low resolution inorganic pore image High resolution organic pore image

SEM images

Binary images

Inorganic pore binary image Organic pore binary image0: skeleton (white)1: pore (black)

Resolution: 25nm Resolution: 5nm

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2. Methodology

Markov Chain Monte Carlo (MCMC) Method

Inorganic pore digital rock216×216×216

Organic pore digital rock500×500×500

2.1 Image analysis and 3D digital rock reconstruction

xy

yz

xz

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2. Methodology

2.2 Shale matrix digital rock superposition method

1 2 1 2

1 2

1 2

1 2

skeleton skeleton skeleton

organic pore skeleton pore

inorganic pore pore skeleton

inorganic pore pore pore

Superposition algorithm:

Step 1. Superposition of representative shale organic matter digital rocks

Ω: shale organic matter digital rockΩ1: inorganic pore digital rockΩ2: organic pore digital rock

The sectional inorganic pore digital rock100×100×100

The sectional inorganic pore digital rock500×500×500

Inorganic pore digital rock216×216×216

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2. Methodology

2.2 Shale matrix digital rock superposition method

Step 1. Superposition of representative shale organic matter digital rocks

The sectional inorganic pore digital rock500×500×500

Representative shale organic matter digital rock

500×500×500

Organic pore digital rock500×500×500

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2. Methodology

2.2 Shale matrix digital rock superposition method

Step 2. Integration of representative shale matrix digital rocks

The remaining inorganic pore digital rock

Representative shale organic matter digital rock

Representative shale matrix digital rock

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Results and Discussions

Methodology

1

2

3

4 Conclusions

5 Future Research

Introduction

Outline

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3. Results and Discussions

Organic pore digital rock Representative shale matrix digital rockInorganic pore digital rock

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Inorganic Pore Digital Rock

Organic Pore Digital Rock

Shale Matrix Digital Rock

Rock Size 5.4μm×5.4μm×5.4μm 2.5μm×2.5μm×2.5μm 5.4μm×5.4μm×5.4μm

Pores Number 5,158 92,226 96,541

Throats Number 7,182 154,848 160,096

Average Connection Number 2.7644 3.34573 3.99445

Net Porosity 0.0783 0.192 0.102

Absolute Permeability (nD) 19.6 135 61.2

3. Results and Discussions

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The representative shale matrix digital rock with the superposition method has a

bimodal pore volume distribution; the first mode reflects the inorganic pores with

relatively larger pore sizes, while the second mode reflects the organic pores with

relatively smaller pore sizes.

Pore size distribution Pore size volume distribution

3. Results and Discussions

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3. Results and Discussions

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Results and Discussions

Methodology

1

2

3

4 Conclusions

5 Future Research

Introduction

Outline

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4. Conclusions

(1) A two-step superposition method is introduced to construct the

representative shale matrix digital rock, and a comparison of the pore structure

properties among the three digital rocks shows that the superposition shale

matrix digital rock can characterize the inorganic pore and organic pore

properties simultaneously.

(2) This method provides a research platform for the study of different pore

structure characteristics in shale rocks, and it can also be used as input for the

nanoscopic flow simulation in pores with different wettability.

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Results and Discussions

Methodology

1

2

3

4 Conclusions

5 Future Research

Introduction

Outline

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5. Future Research

5.1 Wettability Analysis

Organic Pore: Oil-wetInorganic Pore: Water-wet

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5. Future Research

5.2 Fracture Description

Aperture

Regular Fracture-Digital Rock

Number DipOccurrence

Orientation

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5. Future Research

5.2 Fracture Description Regular Fracture-Pore Network

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