Probing the Influence of Thermally Induced Structural Changes on the

Subscriber access provided by Kaohsiung Medical University

Fossil Fuels

Probing the Influence of Thermally Induced Structural Changes on the Microstructural Evolution in Shale using Multi-Scale X-ray Scattering Measurements Meishen Liu, and Greeshma Gadikota Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.8b01486 • Publication Date (Web): 17 Jul 2018 Downloaded from http://pubs.acs.org on July 25, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

1 2 3

6

Probing the Influence of Thermally Induced Structural Changes on the Microstructural Evolution in Shale using Multi-Scale X-ray Scattering Measurements

7

Meishen Liu and Greeshma Gadikota1,*

4 5

8 9

1

Department of Civil and Environmental Engineering

10

Environmental Chemistry and Technology Program, Geological Engineering Program

11

Grainger Institute for Engineering

12

University of Wisconsin-Madison, Madison, WI 53706

13 14 15 16 17 18 19 20 21 22 23 24 25 26

1

Corresponding Author. Phone: +1 608-262-0365. E-mail: [email protected]

1 ACS Paragon Plus Environment

Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 30

1

Abstract

2

Various pathways to accelerate the recovery of hydrocarbons from unconventional subsurface

3

environments have been proposed including the use of high-temperature fluids. However, the

4

influence of temperature on the structural and microstructural changes in complex subsurface

5

materials characterized by compositional and morphological heterogeneity are not very well

6

understood. In this study, in-operando ultra-small angle, small angle, and wide angle X-ray

7

scattering (USAXS/SAXS/WAXS) were performed to link the structural and morphological

8

changes in shale when heated from 30 °C to 1150 °C. The structural changes observed from the

9

wide angle X-ray scattering (WAXS) measurements were complimented by the changes in the

10

porosity, particle size, and surface morphology. Overall, the combined USAXS/SAXS

11

measurements showed enhanced smoothness in the pore-solid interface on heating. The

12

dehydroxylation of illite and calcination of calcium carbonate were noted prior to the formation

13

of denser and sintered silicate and alumino-silicate phases such as Mg2SiO4 (forsterite),

14

Fe0.3Mg0.7(SiO3) (enstatite), and Al2.35Si0.64O4.82 (mullite).

15 16

Keywords: shale, morphology, multi-scale X-ray scattering, crystal structure, dehydroxylation,

17

calcination, heat treatment

18


Page 3 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

1

Energy & Fuels

1.

Introduction

2

The development of novel pathways for recovering energy resources from the subsurface

3

environments is essential for sustainable energy and environment. Several approaches have been

4

proposed including the use of in-situ heating methods from 200 °C to as high as 800 °C,1–11

5

novel working fluids such as CO2 foams,12,13 and non-aqueous fracturing technologies.14 In

6

particular, in-situ heating approaches were found to be effective in stimulating heavy oil

7

reservoirs with low injectivity.1–7 However, our understanding of how the structural changes at

8

the sub-nano scale influence the morphology of shales in extreme thermal environments is

9

limited. Developing this fundamental understanding is complicated by the compositional and

10

morphological heterogeneity of these materials.

11

Shales are complex heterogeneous materials with varying compositions of carbonates,

12

clays, quartz, feldspar15,16 and considerable morphological heterogeneity. While few studies

13

investigated the influence of mineralogy on the self-heating retorting of oil shale,17,18 the

14

morphological changes in unconventional subsurface environments on heating are not as well

15

understood. However, there has been considerable interest in estimating the organic porosity and

16

water accessibility in shales19 and the relationship between porosity and total organic carbon

17

(TOC).20

18

Recent attempts have focused on combining several complementary techniques to

19

develop link the structural and morphological changes in shales. Examples include using atomic-

20

force microscopy (AFM) for gas-shale characterization,21 combining FIB-SEM and NMR

21

cryoporometry to understand shale structures,22 combined ultra-small-angle and small-angle

22

neutron scattering techniques (USANS/SANS) measurements,23-26 ultra-small and small angle X-


Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 4 of 30

1

ray scattering (USAXS/SAXS),27,28 small and wide angle X-ray scattering (SAXS/WAXS)29

2

complemented by BET gas adsorption, mercury intrusion porosimetry, and electron microscopy

3

measurements as needed. Regardless, a substantial understanding of reaction-driven structural

4

and microstructural changes in shales is essential.

5

With the development of novel scattering techniques which encompass ultra-small-angle,

6

small-angle, and wide-angle X-ray scattering (USAXS/SAXS/WAXS), connecting the

7

microstructures and structures of materials across four orders of magnitude in spatial scale30-33

8

i.e., from the subnano-to-micrometer scales is now possible. Further. the reaction-driven

9

evolution of the pore-solid interface in shale can be determined from the USAXS/SAXS analyses.

10

A holistic understanding of the microstructural changes is developed by using complementary

11

characterization measurements such as the particle size analysis, electron microscopy

12

measurements, and pore size and surface area analyses. In this study, the structural changes in

13

shale on heating are linked to the morphological changes on heating to temperatures as high as

14

1150 oC.

15

2.

Experimental Methods

16

A combination of laboratory-scale and synchrotron characterization methods were used

17

to link the microstructural and structural changes in shales on heating. The ground shale sample

18

was procured from Ward Scientific (Henrietta, NY). To determine the changes in the

19

morphology, shale was heat treated at 350 °C, 650 °C, and 900 °C for 3 hours. Changes in the

20

pore and particle sizes were determined using the BET technique (Quantachrome Autosorb1

21

Analyzer) and a laser diffraction method (Beckman Coulter, Inc., LS 13 320 MW), respectively.

22

Using these techniques, the cumulative pore volume, surface area, and the mean particle size

23

were determined to be 0.19 ml/g, 117 m2/g, and 38.87 µm, respectively. The morphological 4 ACS Paragon Plus Environment

Page 5 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

1

changes were imaged using Scanning Electron Microscopy (SEM, Hitachi High Technologies

2

America, Hitachi S3400-N).

3

Wavelength

Dispersion

X-Ray

Fluorescence

(WD-XRF,

Pananalytical

Axios)

4

measurements were performed to determine the chemical composition of the unreacted shale

5

listed in Table 1. The weight changes in shale on heating were determined using

6

Thermogravimetric Analysis (TA Instruments, TGA550) at a heating rate of 5°C /min and flow

7

rate of 40 mL/min. The structural changes were determined from the Wide Angle X-Ray

8

Scattering (WAXS) regime (1 nm – 0.2 Å) and the corresponding changes in the pore-solid

9

interface were determined using the combined Ultra-Small and Small Angle X-Ray Scattering

10

(USAXS/SAXS) measurements.

11

The in-operando USAXS/SAXS/WAXS measurements were performed in a Linkam

12

TS1500 heating stage (Linkam Scientific Instruments Ltd., Tadworth, UK). As noted in previous

13

studies,30,31 materials containing alumino-silicate and silicates are compacted into pellets with a

14

thickness of 1 mm (± 0.2 mm) to reduce multiple scattering at the larger length scales. After

15

mounting the Linkam heating stage, the measurements were performed at increments of 10 °C

16

from 30 °C to 50 °C. Starting from 50 °C, data were collected at time intervals of 25 °C up to a

17

maximum temperature of 1150 °C. The temperature controls were programmed and the

18

associated scattering measurements were performed at the USAXS facility at Sector 9-ID at

19

Advanced Photon Source (APS) in Argonne National Laboratory (ANL), Argonne, IL.

20

The ability to probe spatial scales that range from Angstrom to the micrometer scales in a

21

single measurement is one of the prime advantages of using this facility.40,41 This Bonse-Hart

22

USAXS instrument is composed of a pair of collimating crystals, ion chamber, guard slits,


Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 6 of 30

1

analyzer crystals, and a photodiode detector. The total X-ray flux, X-ray energy and

2

corresponding wavelengths were 10-13 photon s-1, 21.0 keV, and 0.59 Å, respectively. Reference

3

materials such as the silver behenate and the NIST standard reference material, SRM 640d (Si)

4

were used as calibration standards. IgorPro (Wavemetrics, Lake Oswego, OR) software

5

containing the Irena and Nika packages was used to reduce and analyze the data.42,43

6

3.

Results and Discussion

7

3.1

Thermally Induced Structural Changes in Shale

8

Shales are complex heterogeneous materials composed of clays, carbonates, and other

9

minerals such as quartz. Detailed analyses of the X-ray diffraction pattern of the shale sample

10

showed that (K,H3O)(Al,Mg,Fe)2(Si,Al)4O10[(OH)2,(H2O)] (illite), CaCO3 (calcite), and SiO2

11

(silica) constitute 33 wt %, 17 wt %, and 34 wt %, respectively (Table 2). The major phases

12

were identified as calcite,34 quartz,35 illite,36 chamosite,37 ankerite,38 and pyrite39 as shown in

13

Figure 1. Clays constituting illite, chlorite, kaolinite, and mixed layer illite and smectite account

14

for 37 wt% of shale. Carbonates including calcite and dolomite account for 40 wt%. Other

15

minerals including quartz, plagioclase, and marcasite account for 23 wt% of shale (Table 2).

16

Given the abundance of clay, carbonate and quartz phases, the structural changes of these

17

materials were evaluated as a function of temperature. The peak shifts to larger d spaces

18

correspond to the thermal expansion of the materials as noted in previous publications.23,24,26

19

Illite is a non-swelling clay constituent of shale that has a hierarchical structure composed

20

of interlayer nanopores. The d (0 0 1) reflection which corresponds to the interlayer basal

21

spacing is a characteristic feature of hierarchical materials such as illite.44 The integrated

22

intensity of this characteristic peak represents the quantity of interlayer nanopores, and the peak


Page 7 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

1

position indicates the interlayer basal distance. The changes in the integrated intensity of the d (0

2

0 1) peak and the interlayer basal distance are shown in Figure 2(a). The observed interlayer

3

basal distance of illite of 10 Å at 25 °C is consistent with previously published data.45 The

4

normalized integrated peak intensity reduces by about 30% on heating to 600 °C. About 60%

5

reduction in the integrated peak intensity of the d (0 0 1) reflection is noted on heating to 900 °C.

6

Further, the disappearance of the characteristic interlayer basal distance is noted when the

7

temperature is increased to 1150 °C. The disappearance of the characteristic interlayer basal peak

8

is indicative of the loss of microporosity in shale.

9

Further, the effect of temperature on the structural changes in calcite was determined.

10

Our studies showed that the d (0 1 -4) reflection of calcite decreased in intensity on increasing

11

the temperature above 800 °C which is consistent with the calcination behavior of calcite at these

12

temperatures (Figure 2(b)).46 Unlike illite and calcite phases which disappear on heating above

13

1000 °C, the quartz peak at d = 3.04 Å remains on heating despite a 30% loss in the integrated

14

peak intensity on heating above 1000 °C (Figure 2(c)). The structural changes of the key

15

constituents of shales are supported by thermally induced changes in the weight of the samples

16

as shown in Figure 3. The change in the weight of unreacted shale is contrasted with shales

17

thermally treated at 350 °C, 650 °C and 900 °C. No significant changes in the weight of the

18

sample were noted on heating shales at 350 °C. In shale heated to 650 °C, about 14% weight loss

19

is noted. One of the contributing factors to the loss in the weight of the sample is the

20

dehydroxylation of illite.44 In shale heat treated to 900 °C, no weight loss was noted which is

21

consistent with illite dehydroxylation44 and calcination of calcium carbonate46 on heating to

22

900 °C.


Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 8 of 30

1

On heating shale beyond 700 °C, the formation of denser, crystalline phases was

2

observed (Figure S1). The onset of mullite (Al2.35Si0.64O4.82), forsterite (Mg2SiO4) and enstatite

3

(Fe0.3Mg0.7(SiO3)) phases was noted in the temperature range of 700 °C - 800 °C in the WAXS

4

regime.47-51 Progressive growth of mullite and forsterite phases was observed (Figures 4(a) and

5

4(b)). On heating above 900 °C, the intensity of the enstatite phase decreased (Figure 4(c)).

6

Phase transitions in enstatite on heating have been reported previously.52,53 It was also interesting

7

to note a significant difference in the densities of the high temperature phases compared to shale.

8

The estimated density of shale is 2.7 g/cm3 compared to those of forsterite, mullite, and enstatite

9

which are 3.3, 3.15, and 3.3 g/cm3, respectively.54-58 The progressive changes in WAXS patterns

10

of shale on heating are represented in Figure S2. The influence of these structural changes on the

11

microstructural changes in shale is described in the following section.

12

3.2

Thermally Induced Morphological Changes in Shale

13

One of the challenges in recovering fluids from the subsurface environments is

14

characterizing the fundamental phenomena leading to changes in the permeability. In this study,

15

we focus on developing a structural and microstructural basis for potential bulk scale behaviors

16

observed in the subsurface with specific emphasis on understanding the role of heat on shale.

17

Specifically, the structural changes discussed previously are linked to the morphological changes

18

in this section.

19

Shale samples were heated to 350 °C, 650 °C, 900 °C, and 1150 °C to quantify the

20

morphological changes in shale. To understand field scale observations of enhanced fluid

21

recovery on heating, the changes in the pore volume of shale were determined using BET

22

measurements on unreacted shale and shale heated to 650 °C and 900 °C. Significant increases in


Page 9 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

1

the cumulative pore volume from 0.19 cm3/g to 0.76 cm3/g and surface area from 117 m2/g to

2

536 m2/g were noted on heating shale to 650 °C compared to the unreacted material (Figure 5

3

and Table 3). However, a reduction in the cumulative pore volume and surface area to 0.26

4

cm3/g and 196 m2/g, respectively were noted on heating shale to 900 °C. The reductions in the

5

cumulative pore volume and surface area are attributed to the formation of denser crystalline

6

phases (Figure 4). These data suggest an enhancement in the porosity and surface area on

7

heating to 650 °C, which in turn may enhance the permeability of the subsurface for enhanced

8

fluid recovery.

9

The changes in the porosity were complemented by detailed particle size analyses of the

10

heat-treated shale samples. The mean particle size of the unreacted shale sample is 39 µm. On

11

heating to 650 °C, a small reduction in the particle size to 35 µm is noted (Table 2 and Figure 6).

12

A significant increase in the particle size from 70 µm and 139 µm is noted on heating from

13

900 °C and 1150 °C (Table 3) which is attributed to the formation of denser and sintered silicate

14

and alumino-silicate phases such as Mg2SiO4 (forsterite), Al2.35Si0.64O4.82 (mullite), and

15

Fe0.3Mg0.7(SiO3) (enstatite) (Figure 4). Scanning electron microscopy images show the

16

formation of less dense shale on heating to 650 °C (Figure 7(b)) compared to unreacted shale

17

(Figure 7(a)). The formation of a denser, less porous material on heat treating shale to 1150 °C

18

is evident in Figure 7(c). However, there is a limited understanding of how the formation of

19

denser phases at elevated temperatures influences the changes in the pore-solid interface (Figure

20

8). At the nano-scale, the changes in the interlayer basal distance corresponding to the d (0 0 1)

21

reflection of illite are determined Figure 2(a). This nano-scale porosity is progressively lost on

22

heating illite above 500 °C. Detailed changes in the characteristic interlayer basal distance


Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 10 of 30

1

corresponding to the d (0 0 1) reflection of illite are shown in Figure 2(a) and discussed in the

2

previous section.

3

Unlike the interlayer basal spacing, significant changes in the USAXS/SAXS curves are

4

not evident on heating shale from 35 °C to 700 °C in the q range smaller than 0.001 Å-1. These

5

data are in agreement with the small changes in the particle size of shale when heated from 25 °C

6

to 650 °C. However, significant changes in the pore size distributions are shown by the BET

7

measurements reported in Figure 5. It is also feasible to determine the pore size distributions by

8

applying the correct scattering contrast factors in the q-range of 0.001 Å-1 - 0.5 Å-1.24, 26, 30-33, 59

9

Significant increases in the scattering intensity were noted on heating shales in the

10

temperature range of 600 °C to 900 °C (Figure 8(b)). This temperature range corresponds to the

11

decomposition of calcium carbonate, illite, and the onset of the formation of denser crystalline

12

phases as shown in Figures 2 and 4 and discussed in the previous section. The growth of denser

13

crystalline phases corresponds to the reduction in the scattering intensity (Figure 8). The

14

influence of these denser phases on the changes in the pore-solid interface are determined from

15

the Porod Slope calculated from the USAXS/SAXS data.65, 66

16

Previous studies reported the fractal character of pores in sandstones and limestones

17

using microscopy techniques.59-64 With the advancements in small angle scattering techniques,

18

the quantification of the fractal structure is now possible. In this paper, the fractality of the local

19

structure is probed in the q region of 0.01 – 0.3 Å-1. The relationships between porod slope, n and

20

the scattering intensity, I (q) are represented below.

21

= +

(Equation 1)


Page 11 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

1

log − = log − log

2

As summarized in a previous publication,66 porod slopes between 3 and 4 and, 2 and 3 are

3

indicative of the degree of interfacial roughness, and branched networks, respectively.65 Porod

4

slope of 4 represents a smooth surface.65 In heterogeneous and complex materials such as shales

5

comprising rough interfaces, the porod slopes are in the range of 3.4 and 3.5 on heating up to

6

temperatures of 700 °C. Enhanced smoothness of the pore-solid interface is noted on further

7

heating from 700 °C to 900 °C. Further, a transition in the porod slope is noted on heating from

8

800 °C to 1000 °C. Various studies starting with pure material precursors (e.g., kaolinite, illite)

9

report this temperature range as the transition regime for forming spinel structures which is

10

consistent with this observation.44,

11

crystallites yielding increasingly smoother pore-solid interfaces (Figure 9).

12

4.

13

51, 67, 68

(Equation 2)

Further heating increases the size of the denser

Conclusions By

combining

various

complementary

characterization

techniques

with

14

USAXS/SAXS/WAXS measurements, we link the thermally induced structural changes to the

15

microstructural changes in shale. Heating shale to temperatures up to 650 oC increased the

16

surface area and the cumulative pore volume that corresponded to the dehydroxylation of illite.

17

On further heating to 900 oC, an increase in the particle size and a reduction in cumulative pore

18

volume was noted. These morphological changes corresponded to the onset of denser crystalline

19

phases (e.g., mullite, forsterite, and enstatite), the decomposition of calcite and dehydroxylation

20

of illite. The formation of denser, crystalline phases corresponded to smoother pore-solid

21

interfaces. These findings provide detailed insights into the influence of structure on the

22

morphology of complex materials such as shales for tuning the subsurface environments for

23

enhanced hydrocarbon recovery using in-situ thermal methods. 11 ACS Paragon Plus Environment

Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 12 of 30

1

Acknowledgements

2

The authors gratefully acknowledge the experimental support provided by Dr. Jan Ilavsky and Dr.

3

Ivan Kuzmenko at the USAXS facility, X-ray Science Division, Argonne National Laboratory.

4

The use of the Advanced Photon Source, an Office of Science User Facility operated for the U.S.

5

Department of Energy (DOE) Office of Science by Argonne National Laboratory, is supported

6

by the U.S. DOE under Contract DE-AC02-06CH11357. Financial support for this research was

7

provided by the Wisconsin Alumni Research Foundation and the College of Engineering at the

8

University of Wisconsin, Madison

9 10

References

11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36

(1) (2) (3) (4)

(5) (6) (7) (8)

(9) (10) (11) (12)

(13)

Fredrik, L. Method of Recovering Oil and Gases from Non-Consolidated Bituminous Geological Formations by A Heating Treatment In Situ. U. S. Patent 2,780,450, 1957. Lynn, D. J. Recovery of Petroleum Products from Oil Shale. U. S. Patent 3,241,611, 1966. Sahni, A.; Kumar, M.; Knapp, R. B. Electromagnetic Heating Methods for Heavy Oil Reservoirs; Livermore, CA, 2000. Hakala, J. A.; Stanchina, W.; Soong, Y.; Hedges, S. Influence of Frequency, Grade, Moisture and Temperature on Green River Oil Shale Dielectric Properties and Electromagnetic Heating Processes. Fuel Process. Technol. 2011, 92 (1), 1–12. Nielson, D. H. Method and Apparatus for Shale Gas Recovery. U. S. Patent 4,928,765, 1990. Leaute, R. P. Recovery and Upgrading of Hydrocarbon Utilizing In Situ Combustion and Horizontal Wells. U.S. Patent 5,339,897, 1994. Hendrick, R. P. Recovery of Hydrocarbons by In Situ Thermal Extraction. U. S. Patent 3,954,140, 1976. Van Meurs, P.; De Rouffignac, E. P.; Vinegar, H. J.; Lucid, M. F. Conductively Heating A Subterranean Oil Shale to Create Permeability and Subsequently Produce Oil. U. S. Patent 4,866,118, 1989. Vogel, J. V. Thermal Oil Recovery. U. S. Patent 3,294,167, 1966. Parker, H. W. Recovery of Oil from Oil Shale. U. S. Patent 3,528,501, 1970. Elkins, L. F. Shale Oil Recovery. U. S. Patent 4,265,307, 1981. Espinoza, D. A.; Caldelas, F. M.; Johnston, K. P.; Bryant, S. L.; Huh, C. NanoparticleStabilized Supercritical CO2 Foams for Potential Mobility Control Applications. In SPE Improved Oil Recovery Symposium; Society of Petroleum Engineers, 2010. Prigiobbe, V.; Worthen, A. J.; Johnston, K. P.; Huh, C.; Bryant, S. L. Transport of Nanoparticle-Stabilized CO2 Foam in Porous Media. Transp. Porous Media 2016, 111 (1), 265–285. 12 ACS Paragon Plus Environment

Page 13 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46

Energy & Fuels

(14) (15) (16) (17) (18) (19)

(20)

(21) (22)

(23)

(24)

(25) (26)

(27)

(28)

(29)

(30)

Rogala, A.; Krzysiek, J.; Bernaciak, M.; Hupka, J. Non-Aqueous Fracturing Technologies for Shale Gas Recovery. Physicochem. Probl. Miner. Process. 2013, 49 (1), 313–321. Allix, P.; Burnham, A.; Fowler, T.; Herron, M.; Kleinberg, R.; Symington, B. Coaxing Oil from Shale; 2011. Bai, B.; Elgmati, M.; Zhang, H.; Wei, M. Rock Characterization of Fayetteville Shale Gas Plays. Fuel 2013, 105, 645–652. Guo, H.; Lin, J.; Yang, Y.; Liu, Y. Effect of Minerals on the Self-Heating Retorting of Oil Shale: Self-Heating Effect and Shale-Oil Production. Fuel 2014, 118, 186–193. Na, J. G.; Im, C. H.; Chung, S. H.; Lee, K. B. Effect of Oil Shale Retorting Temperature on Shale Oil Yield and Properties. Fuel 2012, 95, 131–135. Gu, X.; Mildner, D. F. R.; Cole, D. R.; Rother, G.; Slingerland, R.; Brantley, S. L. Quantification of Organic Porosity and Water Accessibility in Marcellus Shale Using Neutron Scattering. Energy and Fuels 2016, 30 (6), 4438–4449. Sun, M.; Yu, B.; Hu, Q.; Zhang, Y.; Li, B.; Yang, R.; Melnichenko, Y. B.; Cheng, G. Pore Characteristics of Longmaxi Shale Gas Reservoir in the Northwest of Guizhou, China: Investigations Using Small-Angle Neutron Scattering (SANS), Helium Pycnometry, and Gas Sorption Isotherm. Int. J. Coal Geol. 2017, 171, 61–68. Javadpour, F.; Moravvej Farshi, M.; Amrein, M. Atomic-Force Microscopy: A New Tool for Gas-Shale Characterization. J. Can. Pet. Technol. 2012, 51 (4), 236–243. Tong, S.; Dong, Y.; Zhang, Q.; Elsworth, D.; Liu, S. Quantitative Analysis of Nanopore Structural Characteristics of Lower Paleozoic Shale, Chongqing (Southwestern China): Combining FIB-SEM and NMR Cryoporometry. Energy and Fuels 2017, 31 (12), 13317– 13328. Mastalerz, M.; He, L.; Melnichenko, Y. B.; Rupp, J. A. Porosity of Coal and Shale: Insights from Gas Adsorption and SANS/USANS Techniques. In Energy and Fuels; 2012; Vol. 26, pp 5109–5120. Clarkson, C. R.; Solano, N.; Bustin, R. M.; Bustin, A. M. M.; Chalmers, G. R. L.; He, L.; Melnichenko, Y. B.; Radliński, A. P.; Blach, T. P. Pore Structure Characterization of North American Shale Gas Reservoirs Using USANS/SANS, Gas Adsorption, and Mercury Intrusion. Fuel 2013, 103, 606–616. Gu, X.; Cole, D. R.; Rother, G.; Mildner, D. F.; Brantley, S. L. Pores in Marcellus Shale: A Neutron Scattering and FIB-SEM Study. Energy & Fuels 2015, 29 (3), 1295–1308. Bahadur, J.; Radlinski, A. P.; Melnichenko, Y. B.; Mastalerz, M.; Schimmelmann, A. Small-Angle and Ultrasmall-Angle Neutron Scattering (SANS/USANS) Study of New Albany Shale: A Treatise on Microporosity. Energy & Fuels 2015, 29 (2), 567–576. Lee, S.; Fischer, T. B.; Stokes, M. R.; Klingler, R. J.; Ilavsky, J.; McCarty, D. K.; Wigand, M. O.; Derkowski, A.; Winans, R. E. Dehydration Effect on the Pore Size, Porosity, and Fractal Parameters of Shale Rocks: Ultrasmall-Angle X-Ray Scattering Study. Energy & Fuels 2014, 28 (11), 6772–6779. Okolo, G. N.; Everson, R. C.; Neomagus, H. W. J. P.; Roberts, M. J.; Sakurovs, R. Comparing the Porosity and Surface Areas of Coal as Measured by Gas Adsorption, Mercury Intrusion and SAXS Techniques. Fuel 2015, 141, 293–304. Leu, L.; Georgiadis, A.; Blunt, M. J.; Busch, A.; Bertier, P.; Schweinar, K.; Liebi, M.; Menzel, A.; Ott, H. Multiscale Description of Shale Pore Systems by Scanning SAXS and WAXS Microscopy. Energy and Fuels 2016, 30 (12), 10282–10297. Gadikota, G.; Zhang, F.; Allen, A. In Situ Angstrom-to-Micrometer Characterization of 13 ACS Paragon Plus Environment

Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46

(31)

(32)

(33)

(34) (35) (36) (37) (38) (39) (40) (41)

(42) (43) (44) (45)

(46)

(47) (48)

Page 14 of 30

the Structural and Microstructural Changes in Kaolinite on Heating Using UltrasmallAngle, Small-Angle, and Wide-Angle X-Ray Scattering (USAXS/SAXS/WAXS). Ind. Eng. Chem. Res. 2017, 56, 11791-11801. Gadikota, G.; Zhang, F.; Allen, A. J. Towards Understanding the Microstructural and Structural Changes in Natural Hierarchical Materials for Energy Recovery: In-Operando Multi-Scale X-Ray Scattering Characterization of Na- and Ca-Montmorillonite on Heating to 1150 °C. Fuel 2017, 196, 195–209. Gadikota, G.; Allen, A. J. Microstructural and Structural Characterization of Materials for CO2 Storage Using Multi-Scale X-Ray Scattering Methods. In Materials and Processes for CO2 Capture, Conversion, and Sequestration; Li, L., Wong-Ng, W., Eds.; Wiley Books, 2018. Gadikota, G. Connecting the Morphological and Crystal Structural Changes during the Conversion of Lithium Hydroxide Monohydrate to Lithium Carbonate Using Multi-Scale X-Ray Scattering Measurements. Minerals 2017, 7 (9). Maslen, E. N.; Streltsov, V. A.; Streltsova, N. R. X‐ray Study of the Electron Density in Calcite, CaCo3. Acta Crystallogr. Sect. B 1993, 49 (4), 636–641. Levien, L.; Prewitt, C. T.; Weidner, D. J.; Prewir, C. T.; Weidner, D. J. Structure and Elastic Properties of Quartz at Pressure. Am. Mineral. 1980, 65 (9–10), 920–930. Kübler, B.; Jaboyedoff, M. Illite Crystallinity. Comptes Rendus l’Academie Sci. - Ser. IIa Sci. la Terre des Planetes 2000, 331 (2), 75–89. Walker, J. R.; Bish, D. L. Application of Rietveld Refinement Techniques to a Disordered IIb Mg-Chamosite. Clays Clay Miner. 1992, 40 (3), 319–322. Ross, N. L.; Reeder, R. J. High-Pressure Structural Study of Dolomite and Ankerite. Am. Mineral. 1992, 77 (3–4), 412–421. Bayliss, P. Crystal Structure Refinement of a Weakly Anisotropic Pyrite. Am. Mineral. 1977, 62 (11–12), 1168–1172. Bonse, U.; Hart, M. Tailless X-Ray Single-Crystal Reflection Curves Obtained by Multiple Reflection. Appl. Phys. Lett. 1965, 7 (9), 238–240. Ilavsky, J.; Jemian, P. R.; Allen, A. J.; Zhang, F.; Levine, L. E.; Long, G. G. Ultra-SmallAngle X-Ray Scattering at the Advanced Photon Source. J. Appl. Crystallogr. 2009, 42 (3), 469–479. Ilavsky, J.; Jemian, P. R. Irena: Tool Suite for Modeling and Analysis of Small-Angle Scattering. J. Appl. Crystallogr. 2009, 42 (2), 347–353. Ilavsky, J. Nika: Software for Two-Dimensional Data Reduction. J. Appl. Crystallogr. 2012, 45 (2), 324–328. Gualtieri, A. F.; Ferrari, S. Kinetics of Illite Dehydroxylation. Phys. Chem. Miner. 2006, 33 (7), 490–501. Drits, V. A.; Eberl, D. D.; Srodon, J. XRD Measurement of Mean Thickness, Thickness Distribution and Strain for Illite and Illite-Smectite Crystallites by the Bertaut-WarrenAverbach Technique. Clays Clay Miner. 1998, 46 (1), 38–50. Beruto, D. T.; Searcy, A. W.; Kim, M. G. Microstructure, Kinetic, Structure, Thermodynamic Analysis for Calcite Decomposition: Free-Surface and Powder Bed Experiments. Thermochim. Acta 2004, 424 (1–2), 99–109. Angel, R. J.; Prewitt, C. T. Crystal Structure of Mullite: A Re-Examination of the Average Structure. American Mineralogist. 1986, pp 1476–1482. Dove, M. T.; Craig, M. S.; Keen, D. A.; Marshall, W. G.; Redfern, S. A. T.; Trachenko, 14 ACS Paragon Plus Environment

Page 15 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46

Energy & Fuels

(49) (50) (51) (52)

(53) (54) (55)

(56) (57) (58) (59) (60) (61) (62) (63) (64) (65) (66) (67) (68)

K.; Tucker, M. G. Crystal Structure of the High-Pressure Monoclinic Phase-II of Cristobalite, SiO2. Mineral. Mag. 2000, 64 (3), 569–576. Hazen, R. M. Effects of Temperature and Pressure on the Crystal Structure of Forsterite. Am. Mineral. 1976, 61 (l), 1280–1293. Smith, J. V. The Crystal Structure of Proto-Enstatite, MgSiO3. Acta Crystallogr. 1959, 12 (7), 515–519. Rodriguez-Navarro, C., Cultrone, G.; Sanchez-Navas, A.; Sebastian, E. TEM Study of Mullite Growth after Muscovite Breakdown. Am. Mineral. 2003, 88 (5–6), 713–724. Yang, H.; Ghose, S. High Temperature Single Crystal X-Ray Diffraction Studies of the Ortho-Proto Phase Transition in Enstatite, Mg2Si2O6 at 1360 K. Phys. Chem. Miner. 1995, Physics an (1995), 300–310. Foster, W. R. High‐Temperature X‐Ray Diffraction Study of the Polymorphism of MgSiO3. J. Am. Ceram. Soc. 1951, 34 (9), 255–259. Ismail, M. G. M. U.; Nakai, Z.; Sōmiya, S. Microstructure and Mechanical Properties of Mullite Prepared by the Sol-Gel Method. J. Am. Ceram. Soc. 1987, 70 (1). Barzegar Bafrooei, H.; Ebadzadeh, T.; Majidian, H. Microwave Synthesis and Sintering of Forsterite Nanopowder Produced by High Energy Ball Milling. Ceram. Int. 2014, 40 (2), 2869–2876. Downs, R. T.; Palmer, D. C. The Pressure Behavior of Alpha Cristobalite. Am. Mineral. 1994, 79, 9–14. Ahrens, T. J.; Gaffney, E. S. Dynamic Compression of Enstatite. J. Geophys. Res. 1971, 76 (23), 5504–5513. Viti, C.; Hirose, T. Thermal Decomposition of Serpentine during Coseismic Faulting: Nanostructures and Mineral Reactions. J. Struct. Geol. 2010, 32 (10), 1476–1484. Radlinski, A. P. Small-Angle Neutron Scattering and the Microstructure of Rocks. Rev. Mineral. Geochemistry 2006, 63 (1), 363–397. Katz, A.; Thompson, A. H. Fractal Sandstone Pores: Implications for Conductivity and Pore Formation. Phys. Rev. Lett. 1985, 54 (12), 1325. Jacquin, C. G.; Adler, P. M. Fractal Porous Media II: Geometry of Porous Geological Structures. Transp. Porous Media 1987, 2 (6), 571–596. Hansen, J. P.; Skjeltorp, A. T. Fractal Pore Space and Rock Permeability Implications. Phys. Rev. B 1988, 38 (4), 2635. Krohn, C. E. Fractal Measurements of Sandstones, Shales, and Carbonates. J. Geophys. Res. Solid Earth 1988, 93 (B4), 3297–3305. Thompson, A. H. Fractals in Rock Physics. Annu. Rev. Earth Planet. Sci. 1991, 19, 237. Porod, G., X-Ray Low Angle Scattering of Dense Colloid Systems, Part I. Kolloid Z., 1951, 124, 83–114. Liu, M.; Gadikota, G. Chemo-Morphological Coupling during Serpentine Heat Treatment for Carbon Mineralization. Fuel 2018, 227, 379–385. Leonard, A. J. Structural Analysis of the Transition Phases in the Kaolinite‐Mullite Thermal Sequence. J. Am. Ceram. Soc. 1977, 60 (1–2), 37–43. Grim, R. E.; Bradley, W. F. Investigation of the Effect of Heat on the Clay Minerals Illite and Montmorillonite. J. Am. Ceram. Soc. 1940, 23 (8), 242–248.


Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 16 of 30

1 2 3 4 5 6 7 8

Table 1. Composition of Shale Components SiO2 Al2O3 Fe2O3 MgO CaO Na2O

Weight % 40.30 9.50 4.10 1.70 19.40 0.80

Components K2 O TiO2 LOI* Total Carbon (%C) Total Inorganic Carbon (%C) Total Organic Carbon (%C)

Weight % 2.10 0.50 19.40 6.50 2.50 4.00

9 10 11 12 13 14 15 16 17 18 19 20 21 16 ACS Paragon Plus Environment

Page 17 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

1 2 3 4 5 6 7

Table 2. Mineralogical composition of shale (Tr indicates trace levels which constitute less than 1% of the total composition)

8

Composition Components (wt%) 37

Clays Illite/Mica (K,H3O)(Al,Mg,Fe)2(Si,Al)4O10[(OH)2,(H2O)]

34

Chlorite ((Mg,Fe)3(Si,Al)4O10(OH)2·(Mg,Fe)3(OH)6)

1

Kaolinite (Al2Si2O5(OH)4)

Tr

Mixed layer Illite/Smectite ((K,H3O)(Al,Mg,Fe)2(Si,Al)4O10[(OH)2,(H2O)] & (Na,Ca)0.33(Al,Mg)2(Si4O10)(OH)2. nH2O

2 40

Carbonates Calcite (CaCO3)

33

Dolomite ((CaMg(CO3)2)

7 23

Other Minerals Quartz (SiO2)

17

Plagioclase (CaAl2Si2O8 - NaAlSi3O8)

3

Pyrite (FeS2)

2

Rutile (TiO2)

-

Marcasite (FeS2)

1


Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 18 of 30

1 2 3 4 5 6 7 8 9

Table 3. Surface area of samples at 25°C, 350°C, 650°C, and 900°C. Estimated error of surface area and cumulative pore volume is based on double analysis. Estimated error of average mean of particle size is based on triple analysis. Sample Temperature (°C) Cumulative Pore Volume (cc/g) Surface Area (m2/g)

25

650

900

1150

0.19 ± 0.03

0.76 ± 0.07

0.26 ± 0.01

-

117 ± 31

536 ± 86

196 ± 6

-

38.87 ± 3.02

34.79 ± 1.41

70.52 ± 2.32

139.43 ± 2.20

Average Mean of Particle Size (µm)

10 11 12 13 14 15 16 17 18 19 18 ACS Paragon Plus Environment

Page 19 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

1 2 3 4 5 6

Captions for Figures

7 8

Figure 1. Identification of unreacted shale peak composition. Peak identification is based on the crystallographic data reported for calcite,27 quartz,28 illite,29 chamosite,30 ankerite,31 and pyrite.32

9 10 11 12 13 14

Figure 2. Changes in the characteristic peaks of illite (d = 10.02 Å, q = 0,63 Å-1, h k l: (0 0 1)29) (a-1), calcite (d = 3.04 Å, q = 2.07 Å-1, h k l: (0 1 -4)27) (b-1), and quartz (d = 3.34 Å, q = 1.88 Å1 , h k l: (0 1 -1)28) (c-1) on heating from 30 °C to 1150 °C. The relative integrated intensity of illite (a-2), calcite (b-2), and quartz (c-2) is the integrated intensity of the characteristic peak at a given temperature normalized to the integrated intensity at 40 °C. Vertical bars in (b) represent estimated 5% standard deviation uncertainties.

15 16

Figure 3. Changes in the weight of shale heat-treated to 350 °C, 650 °C, and 900 °C with respect to untreated shale at 25 °C determined using thermogravimetric analysis.

17 18 19 20 21 22

Figure 4. Changes in the characteristic peaks of mullite (d = 2.88 Å, q = 2.18 Å-1, h k l: (0 0 1) 49) (a-1), forsterite (d = 1.10 Å, q = 5.70 Å-1, h k l: (8 1 2)44) (b-1), and enstatite (d = 1.72 Å, q = 3.65 Å-1, h k l: (2 5 3)43) (c-1) on heating from 30 °C to 1150 °C. The relative integrated intensity of mullite (a-2), forsterite (b-2), and enstatite (c-2) is the integrated intensity of the characteristic peak at a given temperature normalized to the integrated intensity at 40 °C. Vertical bars in (b) represent estimated 5% standard deviation uncertainties.

23 24 25

Figure 5. Changes in the cumulative pore volume (a) and pore volume distributions (b) in bituminous shale heat treated at 350 °C, 650 °C, and 900 °C with respect to untreated bituminous shale at 25 °C.

26 27

Figure 6. Changes in the particle size distributions of bituminous shale heat treated at 350 °C, 650 °C, and 900 °C with respect to untreated bituminous shale at 25 °C.

28 29

Figure 7. Comparison of morphological changes of untreated shale at 25 °C (a) with shale heattreated at 650 °C (b) and 1150 °C (C) using scanning electron microscopy images.

30 31 32 33 34 35

Figure 8. Changes in the combined slit-smeared USAXS/SAXS data on heating shale to a nominal temperature of 1150 °C. An increase in the scattering intensity is noted on heating to 700 °C at q larger than 0.03 Å-1. This transformation corresponds to the change in the morphology of bituminous shale at ambient temperature to a pseudo-amorphous structure. Further heating to 1150 °C results in the formation of denser phases (see Figure 4) and is accompanied by a reduction in the scattering intensity at q larger than 0.03 Å-1. 19 ACS Paragon Plus Environment

Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

1 2 3 4 5

Page 20 of 30

Figure 9. Changes in porod slopes for q in the range of 0.01 Å-1 to 0.3 Å-1. The slopes are determined after desmearing the USAXS/SAXS data shown in Figure 8. The roughness of the pore-solid interfaces increases on calcite decomposition. Interfaces become smoother on the formation of high temperature phases such as Al2.35Si0.64O4.82 (mullite), Mg2SiO4 (forsterite), Fe0.3Mg0.7(SiO3) (enstatite).

6 7

8 9 10

Figure 1. Identification of unreacted shale peak composition. Peak identification is based on the crystallographic data reported for calcite,27 quartz,28 illite,29 chamosite,30 ankerite,31 and pyrite.32

11 12 13


Page 21 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

1

2

3

4 5


Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

1 2 3 4 5 6

Page 22 of 30

Figure 2. Changes in the characteristic peaks of illite (d = 10.02 Å, q = 0,63 Å-1, h k l: (0 0 1)29) (a-1), calcite (d = 3.04 Å, q = 2.07 Å-1, h k l: (0 1 -4)27) (b-1), and quartz (d = 3.34 Å, q = 1.88 Å1 , h k l: (0 1 -1)28) (c-1) on heating from 30 °C to 1150 °C. The relative integrated intensity of illite (a-2), calcite (b-2), and quartz (c-2) is the integrated intensity of the characteristic peak at a given temperature normalized to the integrated intensity at 40 °C. Vertical bars in (b) represent estimated 5% standard deviation uncertainties.

7 8


Page 23 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

1 2 3

Figure 3. Changes in the weight of shale heat-treated to 350 °C, 650 °C, and 900 °C with respect to untreated shale at 25 °C determined using thermogravimetric analysis.

4


Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 24 of 30

1

2

3

4


Page 25 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

1 2 3 4 5 6

Energy & Fuels

Figure 4. Changes in the characteristic peaks of mullite (d = 2.88 Å, q = 2.18 Å-1, h k l: (0 0 1) 49) (a-1), forsterite (d = 1.10 Å, q = 5.70 Å-1, h k l: (8 1 2)44) (b-1), and enstatite (d = 1.72 Å, q = 3.65 Å-1, h k l: (2 5 3)43) (c-1) on heating from 30 °C to 1150 °C. The relative integrated intensity of mullite (a-2), forsterite (b-2), and enstatite (c-2) is the integrated intensity of the characteristic peak at a given temperature normalized to the integrated intensity at 40 °C. Vertical bars in (b) represent estimated 5% standard deviation uncertainties.

7 8


Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 26 of 30

1

2 3 4 5 6

Figure 5. Changes in the cumulative pore volume (a) and pore volume distributions (b) in bituminous shale heat treated at 350 °C, 650 °C, and 900 °C with respect to untreated bituminous shale at 25 °C.

7 8 9


Page 27 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

1 2 3

Figure 6. Changes in the particle size distributions of shale heat treated at 350 °C, 650 °C, and 900 °C with respect to untreated shale at 25 °C.

4 5


Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 28 of 30

1 2 3

Figure 7. Comparison of morphological changes of untreated shale at 25 °C (a) with shale heattreated at 650 °C (b) and 1150 °C (C) using scanning electron microscopy images.

4


Page 29 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

1 2 3 4 5 6 7

Energy & Fuels

Figure 8. Changes in the combined slit-smeared USAXS/SAXS data on heating shale to a nominal temperature of 1150 °C. An increase in the scattering intensity is noted on heating to 700 °C at q larger than 0.03 Å-1. This transformation corresponds to the change in the morphology of bituminous shale at ambient temperature to a pseudo-amorphous structure. Further heating to 1150 °C results in the formation of denser phases (see Figure 4) and is accompanied by a reduction in the scattering intensity at q larger than 0.03 Å-1.

8 9 10 11 12 13 14 15 16 17 18 19


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Porod Slope

Energy & Fuels

Page 30 of 30

Growth of denser crystalline phases

Decomposition of calcite, illite and onset of denser crystalline phases

1 2 3 4 5 6 7 8

Q (Å-1)

Figure 9. Changes in porod slopes for q in the range of 0.01 Å-1 to 0.3 Å-1. The slopes are determined after desmearing the USAXS/SAXS data shown in Figure 8. The roughness of the pore-solid interfaces increases on calcite decomposition. Interfaces become smoother on the formation of high temperature phases such as Al2.35Si0.64O4.82 (mullite), Mg2SiO4 (forsterite), and Fe0.3Mg0.7(SiO3) (enstatite).


Probing the Influence of Thermally Induced Structural Changes on the

Recommend Documents