Dynardo Technology and Applications to Well Completion ... · PDF fileto Well Completion Optimization for Unconventionals ... • because of bedding plane and natural ... assumption

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© Dynardo GmbH 2015

Dynardo Technology and Applications to Well Completion Optimization for Unconventionals

Johannes Will, Dynardo GmbH Taixu Bai, Ed Lake Shell Exploration and Production Company

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Dynardo • Founded: 2001 (Will, Bucher,

CADFEM International) • More than 50 employees,

offices at Weimar and Vienna • Leading technology companies

Daimler, Bosch, E.ON, Nokia, Siemens, BMW are supported

Software Development

Dynardo is your engineering specialist for CAE-based sensitivity analysis,

optimization, robustness evaluation and robust design optimization

• Mechanical engineering • Civil engineering &

Geomechanics • Automotive industry • Consumer goods industry • Power generation

CAE-Consulting


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Hydraulic fracturing In general the profitable production of unconventional shale oil & gas requires stimulation of the reservoir rock. Hydraulic fracturing is used to create a large and complex network of fractures which connects the production wells with the greatest possible volume of reservoir rocks:

• A horizontal wellbore is driven into the reservoir layer

• Fluid is pumped into the wellbore • The Fluid pressure is fracturing

(enhancing natural fractures and creating new fractures) the jointed rock (shale).

• Sand (proppant) is added to keep fractures open after fluids have been removed and pressure has been subsided.


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The Dynardo workflow

DYNARDO • © Dynardo GmbH 2015

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Challenge of modeling hydraulic fracturing • Shale is a jointed rock having joints • because of bedding plane and natural fracture system anisotropic strength

behavior dominate fracture growth • Therefore a truly 3D modeling including all strength anisotropies is

mandatory Isotropic mechanical material models will fail 2D or pseudo 3D (2.5D) models will fail Porous flow approach is inadequate

• Rock mechanical challenge or the question: “Discrete or homogenizied modeling of joints” Discrete joint modeling in 3D results in

computational and parameter overkill Therefore a homogenized continuum

approach for seepage flow in jointed rock which was established for 3D FEM simulation from Wittke and others in jointed rock in dam engineering in 1980’/90’s is the method of choice


Wittke, W.: Rock Mechanics, Theory and Application with Case Histories, ISBN/EAN: 3540527192

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Homogenized continuum approach does not model joints discrete. Jointed rock will be modelled as volume having “intact rock” and oriented sets of strength anisotropies (joints).

homogenized continuum approach mechanics

Major fault

Joint sets: joint set 1, joint set 2, Joint set 3

Major faults will be modelled “discrete” with a layer of volume elements, having plane of weakness and “matrix” material.


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multiPlas – material law for jointed rock • joints are modeled with their discrete effects on strength,

stress, conductivity at material point level • multiPlas = multi-surface plasticity: combination of isotropic

Mohr-Coulomb and Rankine yield surfaces for intact rock (material between joints) and anisotropic Mohr-Coulomb and tension cut-off yield surfaces for up to 4+2 joint sets

isotropic Mohr-Coulomb yield surface for intact rock

anisotropic Mohr-Coulomb tension cut-off yield surfaces for joints

• The joint is represented by a plane x’-y’ (red) • The joint orientation with respect to the global

coordinate system (WCS) is defined by two orientation angles alpha (strike angle) and beta (dip magnitude)


+ USERMAT

APDL

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Simulation of fluid flow in jointed rock • Hydraulic model is based on assumption of laminar flow

(Darcy flow) in multiple (parallel) joints • Superposition of fluid flow in initial jointed rock mass and fluid flow in up to

4+2 joint sets results in anisotropic hydraulic conductivity matrix Dynardo provides an anisotropic hydraulic finite element for ANSYS (USER300)

+ USERELEM

APDL

thSR s ∂∂

=+⋅∇− q

• Flow equation (mass balance):

• Darcy’s law (momentum balance): h∇⋅−= Kq

thSR

zhK

zyhK

yxhK

x szzyyxx ∂∂

=+

∂∂

∂∂

+

∂∂

∂∂

+

∂∂

∂∂

• Transient seepage equation (ground water flow equation):


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• the stress-independent hydraulic joint conductivity KJ0 covers joint opening based on plastic strain

KJ0(emax)

K

Max. hydraulic conductivity

e

Update of hydraulic joint conductivity & discrete joint opening • the stress-dependent hydraulic joint

conductivity KJ covers joint closure


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Parametric modeling of reservoir, well, fracture design

N

reference points

[XX6,YY6]

[XX5,YY5]

[XX3,YY3]

ST6

ST5

ST4

ST3

Stage 3 with 4 perforations

Well position


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Dynardo’s hydraulic fracturing simulator • Tool for 3D simulations of hydraulic fracturing based on coupled

hydraulic–mechanical finite element analysis • Non-linear mechanical analysis using multi-surface plasticity material

library multiPlas • Anisotropic hydraulic element USER300 • APDL code for HM coupling, parametric modeling and post processing

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USERMAT USERELEM

APDL


Predefined Results/Outputs

Input parameters

FE-model

Initial pore pressure

Initial effective stresses

Main loop

Mechanical analysis

Transient hydraulic analysis

fluid material properties update

stress state update

Tamino Post-processor

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Tamino - Dynardo’s hydraulic fracturing post-processor Connected proppant accepting elements – layer colors


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Hydraulic fracturing needs calibration • Because of the uncertain jointed rock and reservoir parameter

the reservoir model needs calibration • optiSLang is used for calibration of important model

parameters with measurements (ISIP, slurry rate, bottom hole pressure, and seismic fracture measurements)

+

USERMAT USERELEM

APDL +

Outputs

Input parameters

FE-model

Initial pore pressure

Initial effective stress

Main loop

Mechanical analysis

Transient hydraulic analysis

fluid material properties update

stress state update


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Dynardo‘s Hydraulic fracturing Toolbox

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The Dynardo workflow

DYNARDO • © Dynardo GmbH 2015 Thank you for your attention!

Documents

Dynardo Technology and Applications to Well Completion ... · PDF fileto Well Completion Optimization for Unconventionals ... • because of bedding plane and natural ... assumption