Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.
Yifeng Wang, Yongliang Xiong, Louise Criscenti, Tuan Anh Ho, Philippe Weck, Edward Matteo, Jessica Kruichak
Sandia National Laboratories, Albuquerque, New Mexico
Fundamental Understanding of Methane-Carbon Dioxide-Water (CH4-CO2-H2O) Interactions in Shale Nanopores under Reservoir Conditions
Acknowledgments DOE NETL for financial support Bruce Brown, Adam Tew, Joe Renk, Henry Stephen, Jared
Ciferno, (NETL) for management support MSEEL for shale samples Mei Ding (LANL) for neutron scattering experiments
2
Shale gas production: A multi-scale problem
SPE 124253 (2009)
JCPT 46, 55 -61 (2007)
Kerogen
1.0E-13
1.0E-11
1.0E-09
1.0E-07
1.0E-05
1.0E-03
1.0E-01
1 10 100 1000f(
r) (n
m-1
)
Pore radius (r) (nm)
Fractal distribution
Barnett Shale
Nanopore confinement and emergent properties
Bulk phase fluids (Unconfined or pore size >
~100 nm)
EOS = f(P, T, composition)
Nanofluids(Confined in nanopores, pore
size < ~100 nm)
EOS = f(P, T, composition, pore size, surface chemistry)
Nanoconfinement
0
0.1
0.2
0.3
0.4
0.5
0 0.1 0.2 0.3 0.4 0.5(T
c-Tcp
)/T c
σ/rp
Ar
Ar
O2
Xe
CO2
CO2
C2H4
N2
Wang (2014); Zarragoicoechea and Kuz (2004)
Akkutlu, 2013
Overall goal: (1) Obtain a fundamental understanding of CH4-CO2-H2O (or other fluid component) interactions in shale nanopores under high-pressure and high temperature reservoir conditions, and (2) integrate this understanding into reservoir engineering for efficient resource recovery and subsurface carbon sequestration.
Capabilities for Nanogeochemical Studies at Sandia National Laboratories
Gas disposition & release• Gas in place (GIP)• Gas migration from matrix
into fractures• Stimulated volume• Gas for secondary recovery
Material characterization• Pore structures: SANS, BET,
TEM, SEM, etc• Chemistry & mineralogy: XRD,
XRF, etc
Sorption/desorption measurements• Methane sorption/desorption
on model materials• Methane sorption/desorption
under high P & high T• Chemical/physical
stimulations
Field observations• Core/outcrop sample
collection• Quantification of
heterogeneities
Column experiments• Diffusive fluxes• Advective fluxes
Nanoscience• Effects of nanopore
confinement on fluid thermodynamic properties
• Effects of nanoporeconfinement on methane transport (microfluidics in shale)
Molecular dynamic (MD) modeling• Binding energies of methane
sorption• Diffusion rates
Upscaling• Percolation theory• Fractal representation• Lattice Boltzmann modeling
Predictive models• Constitutive relationships• Continuum models• Reactive transport modeling
Synthesis of nanoporousmaterials
Isolation of kerogen from Mancos shale Density functional theory (DFT)
modeling
High pressure/high temperature sorption/desorption measurements
TRAMANTO: Classical Density Functional Theory
http://www.pflotran.org/applications.html
PFLOTRAN: Reactive transport modeling
Pore structure characterization
Pioneering work in nanogeochemistry. Access to DOE Center of Integrated Nanotechnology
Pore structure characterization (FIB)
Material preparation & characterization
About 10 shale core samples obtained Focus on Mancos, Marcellus &
Woodford
Pure kerogen isolated from Mancos, Woodford & Marcellus shale
About 5 model materials synthesized or purchased
Major material characterization completed (BET, SANS, FTIR)
Synthesis of nanoporousmaterials
Gas sorption measurements
Model Substances Temp, oC Gas Mixture, volume percent Pressure, PSI Sorption Capacity (mixture)
mg/g
Sorption Rate,
mg/g min-1
Illite, <75 mm 50 90% CH4 + 10% CO2 300 190 1.5
Kerogen
8
DensitySample 1: 1.172g/cm3
Sample 2: 1.287g/cm3
Average :1.22±0.04 g/cm3
Experiment: 1.28±0.3g/cm3
Stankiewicz A, et al. (2015) Kerogen density revisited –lessons from the Duvernay Shale. In: Paper URTeC2157904 at the Unconventional Resources Technology Conference, San Antonio, Texas, July 2015
Pore size distribution
Pore Diameter (Å)0 2 4 6 8 10 12 14 16
Prop
abili
ty D
ensi
ty0.0
0.2
0.4
0.6
0.8
1.0
1.2
21
Method: Bhattacharya S & Gubbins KE (2006) Langmuir 22:7726-7731 AAPG 96 (2012), 1099-1119
Over-mature kerogen molecules
Ho et al, Scientific Reports 28053
Methane sorption and extraction from kerogen
Time (ps)0 200 400 600 800 1000Ex
trac
tion
rate
(# m
olec
ules
/ps)
0.0
0.2
0.4
0.6
0.8
1.0
Pres
sure
(atm
)
0
50
100
150
200
250
47% 50%Sample 1
Sample 2 30% 35% 35%
Fast Slow Unrecoverable
Pressure (atm)0 50 100 150 200 250 300
Tota
l upt
ake
(mm
ol/g
)
0
1
2
3
4
CO2CH4
10
Gas adsorption Scenario 1: Pure CH4 and pure CO2
Pressure (atm)0 50 100 150 200 250 300
Tota
l upt
ake
(mm
ol/g
)
0
1
2
3
4
5
CO2
CH4
Scenario 2: 1:1 binary mixture CH4 and CO2
Pore specific effects on enhanced gas recovery
11
CH4
CO2
0.814 nm CNTPore is too small for the invasion of CO2
1.085 nm CNTPore is big enough for the invasion of CO2
Pore size effect
Pore specific effects on enhanced gas recovery
12
Water effect
Assume that water thin films block the pore entrance.
CO2 invades through water and replaces CH4 in the nanopore.
Model Molecular Structure of kerogen
Ungerer et al. (2015)
Weck et al, Scientific Reports (2017)
Kerogen Models
Comparison of DFT results with measurements
Activated carbon: pH titration, surface functional groups, gas sorption and metal sorption and release
Wang et al. (2007)
New kerogen models?
17
Bousige et al. (2016)
New structural models
Nanoconfinement & emergent transport properties
Slip flow Knudsen diffusion
𝑘𝑘𝑎𝑎𝑎𝑎𝑎𝑎 = 2𝑟𝑟3𝑅𝑅𝑅𝑅
8𝑅𝑅𝑅𝑅𝜋𝜋𝜋𝜋
1/2+ 1 + 8𝜋𝜋𝑅𝑅𝑅𝑅
𝜋𝜋
1/2 𝜇𝜇𝑎𝑎𝑟𝑟
2𝛼𝛼− 1 𝑐𝑐𝑟𝑟2
8𝜇𝜇
SPE 124253 (2009)
Conventional reservoir
Shale formation
M - Molecular weight
Mass dependent transport
Wang (2017)
Nanoconfinement & emergent transport properties: isotope fractionation Chemical species confined in
nanopores behave differently from those in a bulk system.
Interaction of chemical species with pore surfaces is much enhanced due to a high surface/fluid volume ratio.
Nano-confinement also manifests the discrete nature of fluid molecules in transport, therefore enhancing mass-dependent isotope fractionations.
All these effects combined lead to a distinct set of tracer signatures that may not be observed in a conventional hydrocarbon reservoir or highly permeable groundwater aquifer system.
-10.2
-10.0
-9.8
-9.6
-9.4
-9.2
-9.0
-8.8
-8.6
-8.4
0 50 100 150 200
δ18O
(‰)
Total filtrate (ml)
Residual solution
Filtrate
Isot
ope
frac
tiona
tion
Data from Coplen & Hanshaw (1973)
Isotope fractionation of water by ultrafiltration across a compacted clay membrane (Coplen and Hanshaw, 1973)
-70
-65
-60
-55
-50
-45
-40
-35
-30
-25
-20
-10 -9 -8 -7 -6 -5 -4δ
D (
‰)
δ18O (‰)
Waters extracted from Opallinus Clay at Benken (Switzerland) (Mazurek et al., 2009)
Wang (2017)
Chaotic behavior of gas migration in compacted clay
FORGE Report D4.17 (Harrington, 2013)
Bubble migration under a pressure gradient
𝜆𝜆1 =𝑘𝑘𝑢𝑢0𝑃𝑃𝑢𝑢 + 𝑘𝑘𝑑𝑑0𝑃𝑃𝑑𝑑 𝑅𝑅𝑅𝑅
𝑉𝑉 𝜆𝜆2 =𝑘𝑘𝑢𝑢0 + 𝑘𝑘𝑑𝑑0 𝑅𝑅𝑅𝑅
𝑉𝑉𝐾𝐾 =
𝜆𝜆1𝜆𝜆2
𝑑𝑑𝑃𝑃𝑑𝑑𝑑𝑑
= 𝜆𝜆1 1 −𝑃𝑃𝐾𝐾
�−∞
𝑡𝑡𝛼𝛼𝑒𝑒 )−𝛼𝛼(𝑡𝑡−𝑠𝑠 𝑝𝑝 𝑠𝑠 𝑑𝑑𝑠𝑠
𝑑𝑑𝑃𝑃𝑑𝑑𝑑𝑑
= 𝜆𝜆1 1 −𝑃𝑃𝐾𝐾
�−∞
𝑡𝑡𝐺𝐺 𝑑𝑑 − 𝑠𝑠 𝑝𝑝 𝑠𝑠 𝑑𝑑𝑠𝑠
Delay logistic equation
M P V
Dilated zone
𝑘𝑘𝑢𝑢𝑘𝑘𝑑𝑑
𝑃𝑃𝑢𝑢 𝑃𝑃𝑑𝑑
Fracture healingFracture opening
)𝑝𝑝𝑛𝑛+1 = 𝜆𝜆𝑝𝑝𝑛𝑛(1 − 𝑝𝑝𝑛𝑛
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1 5 9 13 17 21 25 29 33 37 41 45 49 53 57 61 65 69 73 77 81 85 89 93 97
P
n
λ = 2.5 3.2 3.6
0.0E+002.0E-094.0E-096.0E-098.0E-091.0E-081.2E-081.4E-081.6E-081.8E-08
66 67 68 69 70 71 72
Out
flow
Day
Logistic map
Chaotic behavior of well production?
22
https://www.shaletec.com/files/Production-below-decline-curve.png
Future work Performing additional high pressure and high temperature sorption
measurements on crushed shale samples. Perform sorption measurements more on multicomponent systems to clarify the
interactions among different components (CH4-CO2-H2O). Develop new structural models for kerogen that correctly account for both atom
correlations and functional group distributions. Understand the effects of surface functional groups on gas sorption and release in
kerogen. Perform MD (or MC) simulations for understanding CH4-CO2-H2O interactions in
nanoporous clay matrix. Extend the research to include other hydrocarbon components. Develop a nanofluidic model for gas transport and isotope fractionation in shale. Based on the existing experimental and modeling results to formulate new gas
disposition and release model for well-borehole production. Collaboration on kerogen study: Schlumberger, MIT
23