Subsurface Scenarios:  What Are We Trying to
Model?

  Technical Workshop Series:
  Follow-up Discussion on Subsurface Modeling
                     Stephen Kraemer (EPA), George Moridis (LBNL)

                        EPA-Arlington, VA • June 3, 2013
  Office of Research and Development
  National Exposure Research Laboratory
BERKELEY LAB
                                                         United States
                                        LAWRENCE BERKELEY NATIONAL LABORATORY   Environmental Protection
                                                         Agency

-------
EPA Hydraulic Fracturing Study - research questions
      Well Injection
         What are the possible impacts of the
         fracturing process on drinking water
                     resources?
                Disposal
Recycling
"acility

 ^'
                                              Drinking
                                             Water Well
  How effective are current well
   construction practices at
containing fluids (gases, liquids)
   before, during, and after
        fracturing?
                                                      Can subsurface migration of
                                                       fluids (gases, liquids) to
                                                    drinking water resources occur,
                                                    and what local geologic or man-
                                                    made features might allow this?
                                                                 &ER&
                                                                   United States
                                                                   Environmental Protection
                                                                   Agency

-------
           Critical Path for
Subsurface Migration Modeling
           Scenario:
           production
              well
            pathway

           Scenario:
            induced
            fractures
            pathway
Scenario:
   fault
 pathway
         v
          k
Scenario:
offset wells
 pathway
                   Run
                   geo-
                mechanics,
                   flow,
                 transport
                  models
  Factors
influencing
geophysical
likelihood of
 pathway?
                                              Factors
                                           influencing fluid
                                           migration and
                                           potential impact
                                          on drinking water
                                             aquifer ?
                                             &ER&
                                               United States
                                               Environmental Protection
                                               Agency

-------
            Impact assessment
     (not a comprehensive risk assessment!)
For each hypothetical potential failure scenario, we are looking for
combinations of parameters that result in drinking water aquifer
impact or no-impact, in order to assess an estimated "envelope" of
impact
       N
         8
       envelope of
          impact

-------
Reality — Conceptual — Computational
                                                      MeshVoro
                                               Freeman et a. LBNL
              http://sn.wi kipedia.Org/wiki/File:Marcellu
                                          Tetrahedralization of region surrounding
                                          the horizontal well
                         TIGHT RESERVOIR
                                                  &ER&
United States
Environmental Protection
Agency

-------
            Computational Model Selection
           Water
Hydraulic
Fracturing
Water Cycle Acquisitlon
Chemical
Mixing
                      Produced
                      Water
Research
Approach
             Data
             Mining
Conceptual    simple
Model     <

Computational
Solutions
                  Wastewater
                  Treatment
Model
Type
Intellectual
Property
Well
Operations
 Lab
 Studies
         Toxicity
         Assessmen
      Scenario
      Evaluations
                           Case
                           Studies
                          not too
                          simple
                                     complex
               analytical
     semi-analytical
                                 numerical
                                                          first principles
               empirical
             stochastic
                                   deterministic
             public
             domain
                                      trade
                                      secret
open
source
proprietary

-------
  Computational  Model Selection
Property
multidimensional

multiphase
Attributes
2D, 3D

liquid, gas
temporality (time)
transient
multicomponent
non-isothermal

fractured-media
coupling
water, brine, introduced
chemicals
heat

equivalent continuum, dual
porosity, multiple interacting
continua, dual permeability

fully coupled (mass and
energy), fully implicit
                                              &ER&
                                                United States
                                                Environmental Protection
                                                Agency

-------
 Conceptual Models — Scenarios
Geophysical
likelihood of
pathways?

Potential for
fluid migration?
(a)

V

1

p**1

Groundwater Aquifer
	 — J 	 r 	
1 I*- 	 Hydro-Fractures
**(•'• I . \ Shale Gas
	 ^ 	 ^ — " Reservoir
MMI-MB
(b)
1
J
1
V
T

pN^

Groundwater Aquifer
,
:N 	 g f . , S,a,eG,s

(0 ^
1
\
V

v
V

Groundwater Aquifer
^~- Oit/Gas Reservoir
'
V



(d)
(


^4
Fault '
=^

Oroundwater Aquifer

X
\^ 1
V>T— 	 ! 	 —r- 	 ! 	 	 r— ğ V Shal.Gas

E*oĞl-oĞ
W r^^
*
j •

)\ '
"
v\
1
Older Well

i
^ • '
	 L. • '.

Groundwater Aquifer
H
|^
- Hydro -Fracture
^ 	 4- 	 1 — n \ Shale Gas
-0 Reservo-r

Not to
r7^>i ii RFF
.ujiijijjmjyl LAWREN
scale!
IKELEY LAB
CE BERKELEY NATIONAL LABORATORY
&ER&
United States
Environmental Protection
Agency

-------
        Scenario Assumptions
 7 sub-domains for modeling (see diagrams)
Shale        Open wellbore
Overburden   Conventional Petroleum reserve
Aquifer       Fault
Fracture
Each sub-domain has defined flow properties:
 Permeability
 Porosity
 Thermal Properties
And geo-mechanical properties:
 Vertical stress gradient
 Minimum principal horizontal stress
 Young's modulus
 Poisson's ratio
 Fracturing Pressure
 Fault properties
                                              &EPA
                                                United States
                                                Environmental Protection
                                                Agency

-------
         Scenario Assumptions
Properties & Conditions applying to all scenarios:
  Constant bottom hole flowing pressure (at the shale reservoir)
         Reference value: 3.3 MPa (=500 psi);
         Range: 2 MPa to 5 MPa

  Water production rate from aquifer (full penetration)
         Reference value: 50 m3;
         Range: 20 to 100 m3/hr

  Initial pressure
         Reference value: Hydrostatic;
         Range: 1.5*hydrostatic (shale only)
                                                 &EPA
                                                   United States
                                                   Environmental Protection
                                                   Agency

-------
         Scenario Assumptions
Properties & Conditions applying to all scenarios:
   Solute diffusion coefficients in water -
          Reference cases, from CRC
          Salt: 1.5E-9m2/s
          Benzene: 1.1 E-9 m2/s
          Methane: 1.5E-9m2/s
                                                &EPA
                                                  United States
                                                  Environmental Protection
                                                  Agency

-------
          Scenario A:  Migration Along Well Bore
                                     Qw = 50m3/hr (20-100m3/hr)
                                              Groundwater Aquifer
                               100m(20m-200m)
                               970m(100m-3000m)
                                               Hydro-Fractures

                                                  30m(10m-100m)

                                                  Shale Gas
          Constant Bottomhole Pressure = 3MPa (2MPa-5MPa)

          Pressure Distribution: Hydrostatic (1.5 x hydrostatic shale only)
                                                         ESD11-040
                                                                       Not to
                                                                       scale!
&ER&
Note: see supplementary slides for properties associated with zones
   United States
   Environmental Protection
   Agency

-------
Scenario B:  Hydraulically Induced Fracture
                              Qw = 50m3/hr (20-100m3/hr)
     Hydraulically-
                                        Groundwater Aquifer
    Induced Fracture /^
                        100m 20m-200m
                             970m(100m-3000m)
                                             (F2) IGM1

                               '
.
                                            30 m (10m-100m)

                                           Shale Gas
                                            Reservoir
    Constant Bottomhole Pressure = 3MPa (2MPa-5MPa)

    Pressure Distribution: Hydrostatic (1.5 x hydrostatic shale only)
                                                   ESD11-043
Not to
scale!
                                                                &ER&
                                                                   United States
                                                                   Environmental Protection
                                                                   Agency

-------
Scenario C:  Hydraulically Induced Fracture Through Oil/Gas
                                         Qw = 50m3/hr (20-100m3/hr)

Groundwater Aquifer
      F3) (GMU
                                   100m(20m-200m)


                                             Oil/Gas Reservoir
          f
                                                          970m
                                                       (100m-3000m)
                                                F2BIGM1J    I
    30m(10m-10pm)
    Shale Gas
    Reservoir

     (M) (GMI)
jr
i
en
c
e
o
00
Q}
"•6
"rc
y
t:
j
LU
|
               Constant Bottomhole Pressure = 3MPa (2MPa-5MPa)
               Pressure Distribution. Hydrostatic (1.5 x hydrostatic shale only)
                                                             6S011-044
                                                                          Not to
                                                                          scale!
                                                                        &ER&
                                                                           United States
                                                                           Environmental Protection
                                                                           Agency

-------
Scenario D:  Natural Pathway (Fault or Fracture)
                                Qw = 50m3/hr (20-100m3/hr)
                                         Groundwater Aquifer
                                              (F3) (GM1
                              970m(100m-3000m)
                                              30m (10m-10pm)

                                             Shale Gas
                                             Reservoir
c
g
'w

CD
.0

I
LU
o
      Constant Bottomhole Pressure = 3MPa (2MPa-5MPa)

      Pressure Distribution: Hydrostatic (1.5 x hydrostatic shale only)
                                                    ESD11-042
       Not to
       scale!
     &ER&
                                                                   United States
                                                                   Environmental Protection
                                                                   Agency

-------
Scenario E:   Artificial  Pathway (Old Well)
               Older Well
                                        ^D Qw = 50m3/hr (20-100m3/hr)
  Non-Sealed Tubing
    Disintegrating
      Cement
                                970m (100m-3000m)
                             Hydro-Fracture

                                 /W\    30m (10m-100m)
                                         Shale Gas
                                         Reservoir
 Constant Bottomhole Pressure = 3MPa (2MPa-5MPa)

 Pressure Distribution: Hydrostatic (1.5 x hydrostatic shale only)
                                                 ESD11-041
Not to
scale!
                                                                     United States
                                                                     Environmental Protection
                                                                     Agency

-------
                            Publication  Plan
1.  Gas flow tightly coupled geomechanics

2.  3D Voronoi mesh building

3.  RGas and RGasH2O modeling with
TOUGH+
4.  RGasH2OCont modeling with TOUGH+

5.  T+M coupled flow-thermal-geomechanical
Accepted with minor revisions,   SPE Journal
4/8/2013

In preparation

Accepted 6/18/2013 with minor   Computers & Geosciences
revisions
In preparation

Published online as proof,
5/22/2013
Computers &
Geosciences
6. Modeling fault reactivation
Published online, 5/14/2013    Journal of Petroleum
                       Science and Engineering
 7. Fracture propagation in the overburden
 8. Geomechanical failure of well cement
Assessment of impact
 9.   Gas migration pathways

 10.  Contaminant transport pathways
Accepted with minor revisions,
4/18/2013
In preparation



In preparation

In preparation
Int. Journal Rock
Mechanics and Mining
Sciences
                                                                           United States
                                                                           Environmental Protection
                                                                           Agency

-------
   www.epa.gov/hfstudy
Disclaimer:  Mention of trade names or
commercial products does not constitute
endorsement by the EPA.
                                 &EPA
                                   United States
                                   Environmental Protection
                                   Agency

-------
Supplementary Slides
                            &ER&
                              United States
                              Environmental Protection
                              Agency

-------
F1: Flow properties of sub-domain 1 (shale)

Shale permeability
Reference value: 1.0E-18 m2; Range: 1.0E-16 to 1.0E-21 m2

Shale porosity
Reference value: 0.10; Range: 0.05 to 0.15

Thermal properties (invariable)
Saturated thermal conductivity: 4 W/m/K
Dry thermal conductivity: 1 W/m/K
Rock specific heat: 1000 J/kg
                                                    &EPA
                                                      United States
                                                      Environmental Protection
                                                      Agency

-------
F2: Flow properties of sub-domain 2 (overburden)

Overburden permeability:
Reference value: 0.0 m2

Overburden porosity
Reference value: 0.05

Thermal properties (invariable)
Saturated thermal conductivity: 4 W/m/K
Dry thermal conductivity: 1 W/m/K
Rock specific heat: 1000 J/kg
                                                   &EPA
                                                      United States
                                                      Environmental Protection
                                                      Agency

-------
F3: Flow properties of sub-domain 3 (aquifer)

Aquifer permeability
Reference value: 1.0E-12 m2; Range: 1.0E-11 to5.0E-12 m2

Aquifer porosity
Reference value: 0.30;  Range: 0.15 to 0.40

Thermal properties (invariable)
Saturated thermal conductivity: 3.5 W/m/K
Dry thermal conductivity: 0.75 W/m/K
Rock specific heat: 1000 J/kg
                                                    &EPA
                                                      United States
                                                      Environmental Protection
                                                      Agency

-------
F4: Flow properties of sub-domain 4 (fracture)


Fracture permeability: function of aperture b, i.e., k = b2/12 m2
Reference value: b = 1 .OE-3 m; Range: 1 .OE-4 m to 1 .OE-2 m


Fracture porosity
Reference value: 0.70; Range: 0.50 to 1.0
                                                     &EPA
                                                       United States
                                                       Environmental Protection
                                                       Agency

-------
F5: Flow properties of sub-domain 5 (open wellbore)


Permeability
Reference value: 1 .OE-8 m2


Fracture porosity
Reference value: 1.0
                                                    &EPA
                                                      United States
                                                      Environmental Protection
                                                      Agency

-------
F6: Flow properties of sub-domain 6 (conventional
petroleum reservoir)

Permeability
Reference value: 1.0E-14 m2

Porosity
Reference value: 0.20

Thermal properties (invariable)
Saturated thermal conductivity: 4 W/m/K
Dry thermal conductivity: 1 W/m/K
Rock specific heat: 1000 J/kg
                                                   &EPA
                                                      United States
                                                      Environmental Protection
                                                      Agency

-------
F7: Flow properties of sub-domain 7 (fault)

Fault permeability
Reference value: 1.0E-16 m2; Range: 1.0E-14 to 1.0E-19 m2

Fault porosity
Reference value: 0.30; Range: 0.15 to 0.40

Thermal properties (invariable)
Saturated thermal conductivity: 3.5 W/m/K
Dry thermal conductivity: 0.75 W/m/K
Rock specific heat: 1000 J/kg
                                                    &EPA
                                                      United States
                                                      Environmental Protection
                                                      Agency

-------
GM1: Geomechanical property set 1

Vertical stress gradient (maximum principal stress)
26487 Pa/m, corresponding to an overburden density of about
2700 kg/m3.
Minimum principal horizontal stress
Reference value: 0.6*Vertical stress; Range:  0.5 to 0.7*Vertical
stress

Young's Modulus (Marcellus shale and overburden)
Reference value: 30 GPa; Range: 10-50 GPa

Poisson's ratio
Reference value: 0.2; Range: 0.15 to 0.25
                                                   &EPA
                                                     United States
                                                     Environmental Protection
                                                     Agency

-------
GM2: Geomechanical property set 2

Tensile strength  - Reference cases
Casing-to-cement: 2 MPa
Cement: 5.0 MPa
Shale: 8.0 Mpa

Young's modulus - Reference cases
Casing-to-cement: 10 GPa
Cement: 10.0 GPa
Shale: 30 GPa (4-50 GPa)

Poisson's ratio - Reference cases
Casing-to-cement: 0.18
Cement: 0.18
Shale: 0.35

Fracturing pressure
Depends on depth, up to 150 MPa; extreme case up to 28 GPa
                                                  Environmental Protection
                                                  Agency

-------
GM3: Geomechanical property set 3 (fault)

Fault properties - Cohesionless fault with coefficient of friction
Reference value: 0.6; Range: 0.5 to 0.7

Fault properties - residual friction (after slip) in a slip-
weakening model
Reference value: 0.2
                                                      &EPA
                                                        United States
                                                        Environmental Protection
                                                        Agency

-------
Important references used as data sources

Agrawal, A., Wei, Y, Cheng, K., and Holditch, S.A. 2010. A Technical and Economic Study of Completion Techniques in Five Emergin
US Gas Shales. SPE paper 135396 presented at the SPE Annual Technical Conference and Exhibition held in Florence, Italy 19-22
September.

Cipolla, C.L., Lolon, E.P, Erdle, J.C., and Rubin, B. Reservoir Modeling in Shale-Gas Reservoirs. SPEREE (August 2010) 638-653.

Eseme, E., Urai, J.L., Krooss, B.M. and Littke, R. 2007.  AReview of Mechanical Properties of Oil Shales: Implications for Exploitation
and Basin Modelling.  Oil Shale, (24) 2.

Fisher, K., and Warpinski, N. 2011. Hydraulic Fracture-Height Growth: Real Data. SPE paper 145949 presented at the SPE Annual
Technical Conference and Exhibition held in Denver, Colorado 30 October-2 November.

Gottschling, J.C. 2009. Horizontal Marcellus Well Cementing in Appalachia. SPE paper 125985 presented at the 2009 SPE Eastern
Regional Meeting held in Charleston, West Virginia, 23-25 September.

Lee, D.S., Herman, J.D., Elsworth, D., Kim, H.T., and Lee, H.S. A Critical Evaluation of Unconventional Gas Recovery from the
Marcellus Shale, Northeastern United States. KSCE Jrounal of Civil Engineering (2011) 15(4):679-687.

Li, Y.  1973. Diffusion of ions in sea water and deep-sea sediments. Geochimica et Cosmochimica Acta, Volume 38, Issue 5, May 1974,
Pages 703-714, ISSN 0016-7037, 10.1016/0016-7037(74)90145-8.

Soeder, DJ. 1988.  Porosity and Permeability of Eastern Devonian Gas Shales. SPEFE (March 1988) 116-124.

Yeager, B.B., and Meyer,  B.R. 2010. Injection/Fail-off Testing in the Marcellus Shale: Using Reservoir Knowledge to Improve
Operational Efficiency. SPE paper 139067 presented at the SPE Eastern Regional Meeting held in Morgantown, West Virginia 12-14
October.
                                                                                                       &ER&
                                                                                                           United States
                                                                                                           Environmental Protection
                                                                                                           Agency

-------