Assessment of deep subsurface hydro-mechanical processes ... · Assessment of deep subsurface hydro-mechanical and transport processes for reducing the environmental footprint of

This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 640979

Assessment of deep subsurface hydro-mechanical and transport processes for reducing the

environmental footprint of shale gas development.

Speaker: Dr. habil C. I. McDermott

FracRisk


Overview of talk

• 13 Partners, only a brief overview.

• Objectives

• Conceptual approach of FracRisk

• Variety of work in progress

• Some Highlights


Objectives

1) Assessment of the environmental impact (footprint) expressed in seismic activities and released substances in the environment. 2) Forward computer modelling based on six focused exemplary scenarios to predict the effect of the migration of chemicals and gases, predict mechanical effects (seismics), and to support risk and uncertainty assessment. 3) Develop and test a framework for risk assessment to be used both by regulators and industry. 4) Development of criteria for appropriate monitoring strategies. 5) Provision of scientific recommendations and a knowledge base for best practices for shale gas development with direct application and relevance to the provision of consistent regulation.


Key aspects of FracRisk

• Geomechanical facies approach, provides the basis of comparison of different sites

• Multiscale baseline data sets from USA and Europe

• Risk analysis – scenario based quantification of

risks involved – Bottom up and top down

approaches

• Numerical modelling – directed by risk analysis – process oriented approach – forward modelling approach – integration of relevant components

• Experimental investigation – Geochemical changes – Actual lab scale fracking

experiments – Mitigation experiments

• Monitoring and mitigation – Risk and impact reduction – Comprehensive summary of

techniques – Development of new techniques

• Legislation – Science based recommendations – Unifying


WP2

WP3

WP4

WP5 WP6

WP7

Project Structure


Source Pathway Target


Focused Modelling Scenarios to Delimit Possible Threats, Prevention Methods, Recovery Methods and

Consequences

• Geomechanics of frack development • Hydro-mechanics and geo-seismicity • Driving forces (e.g. gravity, capillarity, diffusion, initial pressure, pressure gradient). • Time scale (2h for the fracking process, 100 years for methane migration). • Spatial scale (near field and far field). • Fluid (fracking fluids or methane).

Subdivided according to processes


Dealing with Uncertainties

• “Structural” or “Systemic” Uncertainty

– Which scenario is most relevant?

• Parametrical Uncertainty

– Subsurface heterogeneity

• Engineering (+-5%)

• Geological (+-5 orders of magnitude)


The SG-RBCA Tier 3 Tier 2 Tier 1

advanced specific site assessment information

specific site assessment information

general site assessment information

risk based analysis that involves a significant incremental effort over the Tier 2, in order to develop site-specific corrective action goals.

risk based analysis that involves an incremental refinement of the Tier 1, in order to develop site-specific corrective action goals. monitoring data

risk based analysis utilizing non-site-specific corrective action goals for complete & potentially complete direct & indirect human exposure, ecological receptors & habitats


RCBA Platform to Make Project Results Accessible

Development of consistent protocols in a software platform to make project work accessible to wide audience


Tier 1 Assessment Tools, Available on FracRisk website

• Geomechanical Facies Reports

– Operational parameters from seven key shale gas basins within Europe

• FEP analysis, top down and bottom up for different scenarios. Ranked per scenario for risk, being probability X impact

• Source // Pathway // Target

• Chemical Limits

• Multiple relevant baseline & experimental data sets


Data sets available

1. Hydro-geo-chemo-mechanical facies

characterisation of seven main EU shale

basins (D2.3)

2. Marcellus Shale Water and Air Quality Data Sets (on website)

3. UK Coal Bed Methane Composition (from Dart

Energy’s Airth field) (D2.2)

4. UK Shale Gas Composition from

Cuadrilla’s Bowland shale (D2.3)

5. UK Produced water composition (from Dart

Energy’s Airth field)

6. USA Produced water data sets from CBM &

shale gas (D2.3)

7. Batch reaction experiments to replicate

base line conditions (D2.4)

8. Batch reaction experiments to replicate produced water (D2.4)

9. Hydro mechanical and geometrical data

from experimental fracking – (D2.6 due

May 2017)

10. Mine water data sets (on website)

11. Passive seismic data from the UK (D2.5)

12. Gas production data (D2.7 due May 2017)


Subtask 3.1: FEP Database Construction. List of Events and Processes

Slide 13

1 Operational Events 1.1. Multiple well drilling from same platform 1.2. Initial drilling to given below water table (Open Hole) 1.2.1. Casing emplacement 1.2.2. Cementation with wiper plug 1.2.3. Drilling through wiper plug and casing shoe 1.2.4. Additional cementation 1.3. Logging Borehole 1.4. Drilling horizontal borehole 1.4.1. Casing horizontal borehole 1.4.2. Cementation 1.4.3. Perforation 1.5. Hydraulic fracturing 1.5.1. Out of zone / beyond pumping 1.6. Plugging & drilling out of plugs 1.7. Flow back 1.7.1. Production 1.8. Abandonment 1.9. Seal failure

2 Natural events 2.1. Earthquakes 2.2. Large scale erosion 2.3. Hydrological and hydrogeological response to geological changes 2.4. Cap rock failure 2.5. Unexpected large scale scenario

3 Accidents and unplanned events 3.1. Surface chemical spills 3.2. Overpressuring 3.3. Poor site characterization 3.4. Incorrect chemical mix released into fracking fluid 3.5. Cementation poorly undertaken (spaces left) 3.6. Well lining too limited, open hole left 3.7. Inappropriate management of drill cuttings and spent drilling muds. 3.8. Unlikely significant event

Events Processes

1 Thermal effects on the borehole 1.1. Thermal effects on borehole and seal integrity. 1.2. Thermal effects on the injection point

2 Hydraulics / Fluid Pressure Dominated 2.1. Fluid pressure exceeds rock fracking pressures generating new fractures 2.2. Fluid exceeds fault sealing pressures 2.3. Fluid pressure exceeds stability of part of the plant construction. 2.4. Displacement of surrounding formation fluids 2.5. Buoyancy-driven flow 2.6. Advection and co-migration of other gas 2.7. Formation of Gas hydrates 2.8. Water mediated transport 2.8.1. Advection 2.8.2. Dispersion 2.8.3. Diffusion 2.9. Hydraulic and production fluids and the associated contaminants release processes

3 Chemical 3.1 Corrosive mixture attacks plant 3.2 Corrosive mixture attacks geology 3.3 Sorption and desorption 3.4 Mineral dissolution 3.5 Heavy metal release

4 Mechanical 4.1 Soil and rock deformation around boreholes

4.1.1 Subsidence of ground related to gas extraction 4.2 Propagation of fractures beyond the target zone 4.3 Fluid exceeds fault sealing pressures 4.4 Fault valving 4.5 Generation of excavation disturbed zone around well 4.6 Micro-cracking in the casing cements

Results:


Features (1/3)


D3.2 Characterization of key FEP risk scenarios

Slide 15

1 Least Critical

2

3

4

5 Most Critical

List of FeaturesOverall Importance In

Risk Analysis

1 Hydrogeology S1 S2 S3 S4 S5 S6

1.1. Hydrocarbon bearing formation (Source)

1.1.1. Type of the hydrocarbon bearing formation 5 5 5 3 3 3 4

1.1.2. Geometry of the hydrocarbon bearing formation 4 2 4 1 3 4 3

1.1.2.1 Thickness 4 1 4 1 3 3 3

1.1.3. Rock / Petrophysical properties of the hydrocarbon bearing formation 4 3 4 2 3 4 4

1.1.3.1 Lithology 5 3 5 3 4 5 5

1.1.3.2 Diagenesis 4 2 2 4 4 4 2

1.1.3.3 Pore architecture 4 2 4 2 3 2 3

1.1.3.4 Mineralogy 4 1 3 4 3 4 3

1.1.3.5 Kerogen type 5 1 2 5 4 3 3

1.1.3.6 Thermal maturation of source rock 4 1 2 4 3 3 3

1.1.3.7 Porosity 3 2 3 3 3 2 3

1.1.3.8 Intrinsic permeability 4 3 4 2 4 4 2

1.1.3.9 Relative permeability 5 1 3 2 5 4 2

1.1.3.10 Entry pressure 5 2 2 1 5 2 2

1.1.3.11 Residual saturation 2 1 1 1 2 1 2

1.1.3.12 Hysteresis 2 1 1 1 2 2 2

1.1.4. Stress and Mechanical properties 4 3 4 1 1 1 1

1.1.5. Heterogeneity of the hydrocarbon bearing formation 3 2 3 2 3 3 2

1.1.6. Fractures and faults within the hydrocarbon bearing formation 4 3 4 2 4 4 2

1.1.6.1 Porosity of the fracture 3 2 3 1 3 3 3

1.1.6.2 Intrinsic permeability of the fracture 4 3 4 1 4 4 2

1.1.6.3 Relative Permeability of the fractures 5 1 3 1 5 5 2

1.1.6.4 Fracture geometry 5 2 4 1 4 5 3

1.1.7. Undetected features within the hydrocarbon bearing formation 5 2 5 3 5 4 3

1.1.8. Vertical geothermal gradient of the hydrocarbon bearing formation 3 1 2 3 3 2 3

1.1.9. Formation pressure of the hydrocarbon bearing formation 2 2 2 2 2 2 2

1.2. Fluids1.2.1. Hydrocarbons 4 2 2 4 3 3 3

1.2.2. Natural formation water 5 2 3 5 4 3 3

1.2.3. Production fluids 4 3 4 4 3 2 3

1.2.4. Pore fluid composition within the fracking reservoir 4 2 3 4 3 2 2

1.2.5. Reservoir fluids 4 2 2 4 3 2 2

1.2.6. Other fluids 4 2 2 4 2 2 2

1.3. Overburden

1.3.1. Geometry of the overburden 3 2 3 1 3 3 3

1.3.1.1 Thickness 4 2 3 1 3 3 4

1.3.2. Rock / Petrophysical properties of the overburden 3 2 3 1 3 3 3

1.3.2.1 Lithology 4 2 4 3 4 4 4

1.3.2.2 Diagenesis 5 1 2 4 5 3 2

1.3.2.3 Pore architecture 3 1 3 2 2 3 3

Relevance to ScenarioA. Features of the Natural System

List of key parameters for

modelling (UEDIN, EWRE)

FEP Database (D3.1)

Ranked FEP

Database(D4.1)

Provide models with

reference ranges,

boundary conditions

Chemical Database D4.2 M 5.1: Generic modelling

scenarios S1 to S6

Hydro-geo-chemical facies

characteristics (D2.3)

04.12.2015


Tier 2 Assessment: Generic Modelling Scenarios

Recommendations

Identification of key threats during exploration, operation and closure through TIER 1 assessment

TIER 2: Selection of generic scenario Selection of parameter sets f(a,b,c,d,e) Generation of likely outcomes Identification of key risks

Significant computational power required -> development of a response surface allows the detailed modelling results to be accessed


Tier 2 Assessment Tools

• Definition of key parameter sets for each scenario based on FEP, GM & other data sets

• Multiple numerical simulations

• Focus on the PATHWAY

Dimensions Symbol Parameter Medium

Depth to strata

Thickness Lateral Consistency

(heterogeneity) Extent (for faulting)

Surface

Overburden Shale

Underburden Faulting

Geology

& Geometry

𝐿2 𝑘𝑥 ,𝑘𝑦 Horizontal Permeability Hydraulic properties

Rock

𝐿2 𝑘𝑧 Vertical Permeability

𝑛 Porosity

𝐿−1 𝑆0 Specific Storativity

𝑀𝐿−1𝑇−2 𝜎𝑣′ Vertical In-Situ stresses

𝑀𝐿−1𝑇−2 𝜎ℎ𝑚′ Minimum Horizontal

𝑀𝐿−1𝑇−2 𝜎ℎ𝑀′ Maximum Horizontal

𝑀𝐿−1𝑇−2 𝐸 Young modulus Elastic constants

𝜈 Poisson ratio

degrees 𝜙 Friction angle Plastic Parameters

𝜓 𝜓 Dilation angle

𝑀𝐿−1𝑇−2 𝐸𝑙𝑜𝑎𝑑𝑖𝑛𝑔 Loading Modulus

𝑀𝐿−1𝑇−2 𝜎𝑐 Initial unconfined compressive

strength (UCS)

𝑀𝐿−3 𝜌 Density Density Fluid

𝑀𝐿−1𝑇−1 𝜇 Viscosity Viscosity

𝑀𝐿−3 𝑐𝑐𝑙 Chloride concentration Quality

…..

𝑀𝐿−1𝑇−1 𝜇 Viscosity Fluid parameters Fracturing

𝑀𝐿−3 𝜌 Density

𝑐𝑖 , 𝑖 = 1,𝑁𝑐 Chemical composition

𝐿3𝑇−1 𝑄 Flowrate

𝑀𝐿−1

2 𝑇−2 𝐾𝐼𝐶 Fracture toughness

𝑀𝐿−1𝑇−2 𝜎𝑇 Tensile strength



Computational demand

• To parameterise one scenario can take several thousand computer simulations

– Use of analytical models

– Use of standard numerical models

– Use of state of the art tools & development

• Development of PCT to fit numerical results with response surfaces which can then be used in the SG-RBCA program for predictive modelling


Model Data, Tier 2

% , , , , , , , , ,f a b c d e f g h i j

X

Y

Thre

sho

ld

Some generic parameters for all scenarios, and some scenario specific


Model Data Interpreted Using Polynomial Functions (Emulator)

% , , , , , , , , ,f a b c d e f g h i j

X

Y

Thre

sho

ld



Interpreted Surface for RBCA

% , , , , , , , , ,f a b c d e f g h i j

X

Y

Thre

sho

ld



What do we do with the information?

• Critical Chemical Threshold data base (available)

• Geophysical monitoring techniques review and new interpretation techniques developed.

• Ongoing investigation of mitigation & well sealing techniques


Combining FEP’s, Top Down Hazard Assessment and Bow Tie Diagrams


Experimental Work for Validation

• Geochemistry

• Isotope comparison

• Mechanics


Batch scale experimental data on water quality

• Deliverable 2.4 - Report on reactive experimental data

1 – Mix formation shale with synthetic fracturing fluid.

Formations: • Marcellus Shale - USA • Bowland Shale - UK • Kimmeridge Clay - UK

2 – Pressurise to 1500psi (103 bar) to replicate in-situ formation conditions.

3 – Heat to 65oC in oven to simulate formation temperature.

Analyse: Liquid reactants & products Solid reactants & products

Quantify change in geochemistry of system


Isotopic data from source identification

• Gas composition and isotopic data has been obtained from UK Coal Bed Methane (from Dart Energy’s Airth field) and shale gas (from Cuadrilla’s Bowland shale operations)

• The isotopic tracers are 12, 13, 14C and 1,2H and the diverse noble gas isotopes of He, Ar, Ne, Kr and Xe.

Slide 27

4He concentration ~29,000 to 47,500 times higher than groundwater

Helium will be an excellent tracer of migrated gas

C&H isotopes show thermogenic origin


Experimental fracking of large scale samples

Slide 28

Anisotropic stress field mechanical tests in the GREAT cell

Unconfined fracking exp. on resin samples

Anisotropic stress field

Anisotropic strain response

Sample size


Subtask 3.3: Source compartment characterization using seismological techniques: microseismicity and mechanical processes

29

Results:

(Davies et al. 2013)

(Shapiro and Dinske, 2009) (Caffagni et al. 2016)

D3.4 Report on spatio-temporal distribution of microseismicity compared with other baseline data during fracking (due 31st May 2017)

Source Characterisation


Subtask 3.5: Source compartment characterization by tracer methods (UGOE)

Typical tracer spreading patterns in conjunction with the Decision

Matrix defined by Table #1, suggesting which parameters are

best determined from each time stage (transport regime). This

approach requires the use of dual-reactive tracer pairs.

D3.5 Multiple-injection design and parameter sensitivity analyses regarding the use of artificial tracers (conservative, partitioning-dual-reactive; with time- or process-steered in-situ release; detectable uphole during flowback and production) for characterizing the hydrogeology of ‘Source’ compartments (due 30st Sept. 2017 M28)

Results:



Subtask 3.6: Storage, release and transport in shale matrix

Motivation: reliable evaluation of gas resources and mechanisms/kinetic of extraction is critical to evaluate risks if leakage occurs. Objective: determine how C1-C5 gas molecules can be stored in the shale matrix and the mechanisms of release in relation with fracking. Method: develop a molecular modeling approach to determine the thermodynamic and physical stability of C1-C5 gas molecules in nanometer aperture dislocation and cleavage plains



Modelling Developements

• Review of Capabilities of Existing Industry and Research Codes – Potential applicability of the reviewed codes

– Criteria (among others): simulated processes, numerical solution techniques, available constitutive laws

– Special focus on codes for flow in fractured media and for mechanical effects

• Report on developments for DFN models and multi-continua models – Recent implementations as required for the focused scenarios S2 and S4

– Discrete fracture model extended to 3D and for flexible use with different ‘’physics’’

– 2pminc model extended to 3D


• Scaling Laws for hydrogeologic parameters – Statistical model for interpretation of hydrological properties with non-

Gaussian behavior

– Model formulation, procedure and algorithms, first applications

• Parameter and model uncertainty quantification – Developments related to Maximum Likelihood and model identification

criteria

– Data-assimilation and uncertainty quantification framework for application to plumes of dissolved chemicals in heterogeneous aquifers

Modelling Developements


Domino effect


Regional scale methane migration

Scenario 5 (University of Göttingen)


Task 6.1 Monitoring D6.1 Report on existing (geophysical) monitoring techniques (due 15th Feb. 2016)


Mitigation Objective: Investigate injectable self-healing fluids for leakage mitigation both in the well and in fractures Method: Use of Si-solgel Developing an Al-B doped Si-solgel formulation that becomes a chemically stable hard-gel after curing in water. Laboratory testing of the efficiency and emplacement protocols Results:

Solgel optimization

Syringe

VALV-SYR VALV-VAC

Rock core Vacuum pump

Permeability tests

Carbonate

Silica gel

~ 0,5 mD


Legal Interim Review

A review of EU primary legislation relating to the Exploration and Exploitation of Shale Gas and other Unconventional Fossil Fuels (UFF)

A literature review of devolved Member States legislation

The results were summarised and presented in an Interim Report in the November 2016 submission

Ongoing analysis with respect to its effectiveness in regulating Geohazards and Risks


Achievements

Achievements - 23 deliverables submitted ~ on time - Dec 2016 the project had produced ~12 peer reviewed articles and

presented ~40 times at various national and international conference levels.

- Consistent conceptual approach including multi-scales of data through complex modelling to RBCA-SG approach developed.

- Geomechanical Facies Modelling of Different Basins - FEP data base for Shale Gas, Chemical and Seismic Data Bases - Generic Modelling Scenarios S1 to S6, conceptual models

completed, numerical modelling underway - Geophysical monitoring techniques review and new interpretation

techniques developed. - Legal review and initial recommendations.

Documents

Assessment of deep subsurface hydro-mechanical processes ... · Assessment of deep subsurface hydro-mechanical and transport processes for reducing the environmental footprint of