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DEVEX 2014

Checking complex

geomodel and simulation

workflows

Mark Hayes: Head of

Reservoir Engineering RPS

Energy

7th May 2014

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• Introduction

• Reservoir Simulation QC

– Analytical Models

• Field Examples

– Heavy Oil

– Pre & Post Development

– Use of Analogues

– Heterogeneous Producing Fields (Brent)

– Undeveloped Discoveries

• Conclusions

Outline

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Introduction

• Moore's law is the observation that, over the history of computing hardware, the number

of transistors on integrated circuits doubles approximately every two years.

• Seeing impact in subsurface workflows, multiple scenario workflows, very fine grids ….

• BUT ?

M&A short timescale evaluations

Reserves Report / Audit Bank financing ?

Internal corporate assurance

Non operated Working Interest …

VIP vs Eclipse …CMG …

IF I RUN YOUR RESERVOIR MODEL ON MY COMPUTER WHAT AM I DOING ????

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Reservoir Simulation

Simulation

Model

Static Description

• Porosity

• Permeability

• Net-to-Gross

• Compressibility

Fluids

• Oil

• Water

• Gas

Rock/Fluid Interaction

• Relperms

• Capillary Pressure

Initial Conditions

• Fluid contacts

• Initial pressures

• Initial saturations

Pressure Support

• Aquifer

• Formation

Compressibility

Production/Injection

• Well locations

• Perforations, stimulation,

workovers etc

• Production/injection rates

• Well pressures (THP, BHP)

• Well performance tables

Simulation

Model

Static Description

• Porosity

• Permeability

• Net-to-Gross

• Compressibility

Fluids

• Oil

• Water

• Gas

Rock/Fluid Interaction

• Relperms

• Capillary Pressure

Initial Conditions

• Fluid contacts

• Initial pressures

• Initial saturations

Pressure Support

• Aquifer

• Formation

Compressibility

Production/Injection

• Well locations

• Perforations, stimulation,

workovers etc

• Production/injection rates

• Well pressures (THP, BHP)

• Well performance tables

Simulation

Model

Static Description

• Porosity

• Permeability

• Net-to-Gross

• Compressibility

Fluids

• Oil

• Water

• Gas

Rock/Fluid Interaction

• Relperms

• Capillary Pressure

Initial Conditions

• Fluid contacts

• Initial pressures

• Initial saturations

Pressure Support

• Aquifer

• Formation

Compressibility

Production/Injection

• Well locations

• Perforations, stimulation,

workovers etc

• Production/injection rates

• Well pressures (THP, BHP)

• Well performance tables

Simulation

Model

Static Description

• Porosity

• Permeability

• Net-to-Gross

• Compressibility

Fluids

• Oil

• Water

• Gas

Rock/Fluid Interaction

• Relperms

• Capillary Pressure

Initial Conditions

• Fluid contacts

• Initial pressures

• Initial saturations

Pressure Support

• Aquifer

• Formation

Compressibility

Production/Injection

• Well locations

• Perforations, stimulation,

workovers etc

• Production/injection rates

• Well pressures (THP, BHP)

• Well performance tables

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• Applicable in water flood, particularly when heterogeneity and/or mobility is a challenge

• Think about ……

– MOBILITY RATIO

– GRAVITY FORCES

– HETROGENIETY

• Buckley Leveret (homogenous / unfavourable mobility)

– Diffuse & Segregated

• Layered Systems

– Stiles – permeability - flooding order perm dominated

– Vertical Equilibrium – gravity dominated

Fractional Flow

Gravity Heterogeneity

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Best Reference DAKE / Elsever

Best Tool ? Water Drive …

www.petroleumsolutions.co.uk …

OR EXCEL ….!

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Buckley Leveret Stiles (k perm order) Vertical Equilibrium

Fractional Flow Models

10 mD

100 mD

1 mD

10 mD

Fw

Np/N

Increase in Uo

Fw

Np/N

Or Base (hi perm) top

Fw

Np/N

Increase in Uo

Increase in Uo

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Field A – Heavy Oil Development

• Objective

– Validation of ECLIPSE simulation model profiles & reserves using simple Analytical models

– 24 – 48 hr run times on multi processor server

– Every ECLIPSE option in the book !

• Mobility Ratio Critical to estimating Rf

– very unfavourable mobility ratio uo ~ 500 cp M ~ 223

• Buckley Leveret single layer Analysis

– Generic Corey Rel Perm Curves

– Long Drilling Program with phases

– Sector models for phasing…

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0

5000

10000

15000

20000

25000

30000

35000

40000

Oil R

ate

barr

els

per

day

Oil Rate Comparison

Analytical Model Simulation Model

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0

50000

100000

150000

200000

250000

300000

mb

w/d

Water Production

Analytical Simulation

Horizontal

well /

Zonal

Isolation

benefit ?

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• Scope

– Validate satellite discovery forecast

– Main field production history available

• Workflow

– Used available core data

– Digitized from Plot from PDR

– Routine STILES analysis

• Kro = 0.7 krw = 0.3

• Uo = 0.9 Cp

– Matched Fw to offset field performance

– Good match to late field performance given known STOIIP

– Revised STILES model for Discovery

• PVT (higher oil viscosity)

• STOIIP

Field B – Satellite Discovery

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Poor early

wells not

accessing

all STOIIP

Horizontal

well

benefit ?

Good

match

Most PV

contacted

Based on

Known

STOIIP

Match to late field performance

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Discovery Match to Simulation Model

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

Oil Rate

Analytical Simulation

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0

10

20

30

40

50

60

70

1 10 100

RF

%

Viscosity (cp)

field 1

field 2

field 3

Analogues

Stiles -homogenous

Stiles - modhetrogeneous

Field C – Heavy Oil Analog Example

Scope: Benchmark

deepwater heavy

oil development

Limited production

data

Key issue oil

viscosity & mobility

Integrated analog

and simple stiles

flow model using

available core

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Conclusions

• Computing power is leading to many Fine Grid & Complex models

• These can be difficult to Review and QC.

• Still Room for complementary analytical models

– Can given surprisingly accurate results

– Useful in North Sea given strong Waterflood presence

– Particularly when heterogeneity AND/OR mobility level are unfavourable & dominate

– Analytical models may tend to overstate “mid life” water production rates

– Can be linked to facilities constraints

– 1 dimensional model Cannot help with detail

• Development Well location & geometry

• Infill Drilling …

Forecast

An

alo

gu

e