Michael Byrne Maria Jimenez Juan Carlos Chavez

Outline

!   Background and Motivation

!  Detailed Numerical Model of Well Inflow

!  Applications – Added Value

!  Final comments

Background and Motivation

Analytical Solutions

3D Sector models Finite Differences

Computational Fluid Dynamics (CFD) - Finite Volumes

Semi- Analytical Solutions

Background and Motivation

Analytical and Semi-Analytical Solutions

!  Derived from general differential equations with specific boundary conditions and geometry. May include some numerical aid

!  Good for high level answers but limited for optimisation and decision making, unless the case is very similar to the model

! Multiphase flow complexities and

non-Darcy effects are usually neglected

! Case adapted to the model and not the model adapted to the case

Background and Motivation

3D sector models in finite differences (traditional reservoir modelling)

!  Good and more realistic but limited for detailed completion representat ion. The mesh cannot adapt to all completion geometries

!  The well is not coupled with the porous media…important for medium to long horizontal wells

Discretisation of governing differential equations

Background and Motivation

IPR models in finite volumes CFD – Computational Fluid Dynamics

!  Flexible meshing. Complex geometries can be represented

with detail. !  It handles multiphase flow

!  It handles steady state and

transient situations !  M o d e r n / o p t i m i s e d c o d e s

together with modern computer power al lows running big

models

!  Allows the coupling of the porous media and the well

Discretisation of governing control- volume equations

!   Numerical simulation technique

!   Approximate numerical solutions to both the momentum and energy governing equations of fluid flow based on space and time

!   It is based in finite volumes

What is CFD?

!   Flexible, comprehensive !   Near-wellbore area, including damaged

zones, perforations at real scale, screens, horizontal wells, hydraulic fractures, open hole, naturally fractured reservoirs

!   Coupled well-porous media modelling !   Steady state cases !   Transient cases

Why CFD?

!   Evaluation of drilling techniques for a naturally fractured reservoir

1)  Overbalanced?

2)  MPD?

3)  Underbalanced?

Applications – Drilling Technique selection

AAAAA BBBBB

Undamaged reservoir

Damaged Zone

Wellbore

A: matrix permeability zone

B: enhanced permeability zone

Horizontal well with natural fractures and damage

Applications – Drilling Technique selection

Horizontal well with natural fractures and damage – Pressure Profiles

Applications – Drilling Technique selection

!   Asymmetric damage – horizontal well Well

Well

Well

Formation Damaged Zone

Mud Cake

Undamaged Reservoir

Preservoir= 4.47E07 Pascal

Pwf=4.42E07 Pascal

K= 1000 mD

K= 10 mD K= 1000000 mD

K= 100 mD

Applications – Asymmetric Damage

Mesh

Applications – Asymmetric Damage

Well

Well

Velocity Profile – Approach 1

Applications – Asymmetric Damage

!   Deviated well !   Other fracture options

Applications – Hydraulically Fractured Well

!   Perforations+ Fracture @ S3 layer. !   Fracture & one of the perfs planes

Pressure Profile (Pas)

Applications – Hydraulically Fractured Well

Pressure Profile (Pas)

Applications – Hydraulically Fractured Well

Mesh for coupled well-porous media case

Applications - others

Mesh for cased-

perforated 90 deg phasing

Pressure contours-perforations

Applications - others

Stress-deformation modelling using FEM

Well inflow modelling using CFD

Equivalent Plastic Strain

Pressure

Applications – others – Sand Management

Velocity magnitude

Failed area

Velocity magnitude

Pressure

Applications – others – Sand Management

Cost / expertise / specialised data requirements

Acc

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y of

ans

wer

/

glo

bal a

pplic

abili

ty Numerical modelling

Analytical

!   Reservoir characterization uncertainties !   No model is 100% reliable !   Better Prediction = Better Production

Final comments

Final comments