taurus libra north idku - slope channel 3d seismic modelling, egypt

Seismic Conditioned 3D Reservoir Modelling: Examples from Gas-Bearing Pliocene Slope

Channel/Canyon Complexes, Offshore Nile Delta, Egypt

27-28 April 2003

SEISMIC DATA

STATIC MODEL

DYNAMIC MODEL

Seismic Conditioned 3D Reservoir Modelling:

Examples from Gas-Bearing Pliocene Slope

Channel/Canyon Complexes

Offshore West Nile Delta

Egypt

Presented by

Richard D. Vaughan

RWE Dea Egypt



27-28 April 2003

Agenda

Modelling Objectives

Modelling Assumptions and Workflow

– Data Analysis

– Seismic Conditioned Reservoir Modelling Parameters

Parameters 3D Modelling as a E & P Risk Reduction tool

– Taurus Prospect Evaluation

– Libra Prospect Evaluation

– North Idku Slope Channel Evaluation

Conclusions



27-28 April 2003


To create seismic conditioned 3D static modelling grids to assist with:

• 3D reservoir characterisation of slope canyon & channel turbidite systems

• Understand 3D distribution reservoir architecture and heterogeneity

• Pre-drill Independent assessment of GIIP

• Up-Scaling & Forward modelling

Well location optimisation

Minimum compartment size/well

Estimate Well deliverability

Evaluate various development plan strategies



27-28 April 2003

Inc

rea

sin

g s

inu

os

ity

Inc

rea

sin

g la

tera

l m

igra

tio

n

Inc

rea

sin

g w

idth

-de

pth

ra

tio

Co

nfi

ned

Un

co

nfi

ned

Increasing rate of sediment accumulation

Channel stacking patterns related to sinuosity, rate of sediment accumulation,

sand/mud ratio of sediment supplied (net to gross) and degree of channel confinement

After Pickering & Clark, 1998

What type of turbidite reservoir architecture are we exploring for and/or trying to develop?



27-28 April 2003

Overbank Shales

Channel sands Levee Heterolithics

Positive & negative amplitudes show

vertical – lateral stacking patterns

consistent with laterally offset stacked

submarine channel-levee deposits

“Negative Amp”

channels

Flooding Surface

Base Channel Complex

Taurus-1X

“Positive Amp”

channels

“East Taurus Complex”

“West Taurus Complex”



27-28 April 2003

Agenda



– Data Analysis






Conclusions



27-28 April 2003


• The inherent 3D distribution of seismic amplitude and extracted attributes

can be interpreted geologically (seismic facies analysis)

• Meaningful relationship between data at the well scale (cm to metre-scale)

and seismic scale (12.5m x 25m bins)

• Calibration wells are correctly located within the grids

• Top depth converted map surface and internal model layers are

chronostratigraphically consistent



27-28 April 2003

North Idku-4X Canyon Complex

25 Layer grid = 3D Model

3D volume

attribute (10ms

window) inserted

as 2D Trend

3D Grid: 25 x 25x (10msec) = c. 9.5m

Depth converted time

map 250msec below top

Depth Structure Maps

Artificial Base

Top

Chronostratigraphic Flooding surface



27-28 April 2003

Base Slope

Channel

Depth map

25242322212019181716151413121110987654321Top Taurus Slope Channel depth map

4 Km

Taurus-1X

Note: East and West Taurus

Slope channel complexes



27-28 April 2003

Proroportional grid of Route Mean Squared of Amplitude

Cell Size X = 12.5m & Y = 25m

Top grid surface

= layer 6

826 rows

(Y)25 layers

(Z)

1778Columns

(X)

2000 mTaurus-1X



27-28 April 2003

Data Analysis

• Derive relationship between seismic attributes at the well location and facies

types and petrophysical properties

• Condition and threshold attribute data with well data /rock type

• Generate facies, net:gross and porosity models (multiple realisations)



27-28 April 2003

Seismic Conditioned Reservoir

Modelling Parameters

• Facies Model

• Net:gross Model

• Porosity Model

• Gas expansion factor

• Water saturation

• GWC

Fixed -

seismic conditioned

by multiple realisations

Variable

(p10 – p50 – p90)

• Cap Press, Rel Perm, PVcomp – Data Conditioned



27-28 April 2003

RMS Amplitude thresholds and Seismic facies types

Shale Hete

rolit

hic

Sand

Non Res Net reservoir

3000 4500

Data source: migrated 16 bit data



27-28 April 2003

RMS amplitude threshold 1800-3000



Too little sand and heterolithic facies

Too much sand and heterolithic facies

Sand and heterolithic facies constrained at well location

Facies Model Realisations – Threshold Sensitivity

Column 890: oblique dip section



27-28 April 2003

Seismic Crossline 18825

Final Facies Model cross section

Taurus-1X

Taurus-1X

“East Taurus Complex”“West Taurus Complex”



27-28 April 2003

Interpolated Porosity

Interpolated

well porosities

Sand = 0.3

Heterolithic = 0.2

3D Model Parameters

Net to gross

Deterministic Porosity

Facies



27-28 April 2003

500m range

3000m rangeFinal Stochastic Porosity Realisation

2000m range parallel

to channel belt orientation

Stochastic Porosity Realisations (controlled by variograms)



27-28 April 2003

Agenda



– Data Analysis






Conclusions



27-28 April 2003

3D Modelling as a E & P Risk Reduction tool:

• Optimisation of exploration well locations

• Multiple scenarios for development/production well locations to assess

effective well drainage and deliverability

• Up-scaled models for forward dynamic simulation predictions



27-28 April 2003

Taurus Prospect Evaluation



27-28 April 2003

1

2

3

4

5

A

Proximal levee-channel

Channel

sand

Proximal levee

heterolithics

Layer 5: Slice through a sinuous laterally and vertically

amalgamated channel complex

50metres

Can

yo

n F

ill–

sta

cked

ch

an

nel

levee

co

mp

lex

(pro

xim

al

–d

ista

l re

lati

on

sh

ips

reco

rde

db

y w

ell

pa

th)

300 metres

A A’

WELL

A’

Distal levee-

Overbank

Outcrop analogue

Bell Canyon Formation, West Texas

Well

Taurus-1X

From Kendrick, 2000

Post w

ell

Pre

dic

ted

Seis

mic

Fa

cie

s

H-p

ela

gic

slo

pe

DST – 1A

Pign

RMS Amp



27-28 April 2003

Max GWC 1980m TVDSS

DST–1A recorded rapid buildup due to lateral communication

between heterolithic levee-overbank thin beds with adjacent channel

N SW NES

Min GWC 1950m TVDSS

DST-1A

Taurus-1X

Channels connected to

Levees



27-28 April 2003

Libra Prospect Evaluation



27-28 April 2003

1700m TVDss

2000m TVDss

1900m TVDss

GWC’s

Sensitivity

Libra Prospect canyon / channel complex – dip section

Confined canyon feeder

Ponded fan complex

Change in slope angle across faults



27-28 April 2003

Libra Prospect canyon / channel complex – strike section

1700m TVDss

2000m TVDss

1900m TVDss

GWC’s

Sensitivity



27-28 April 2003

FaciesRMS Amp

Pre-drill facies predictions Well Libra-1X3D Model Layers

Dip section through 3D facies model

Strike section through 3D facies model

Libra-1X

Libra-1X

K- Libra

Canyon 3D

Reservoir model

Results

ELAN Interpretation

Post Drill

Adjustment

-12m Shift

6

7

8

9

10

11

12

13

14

GDT

GDT

Main Findings

• Model predicts

main pay interval

• Over-estimates

net-to-gross

Confined canyon feeder

Ponded fan complex

Libra-1x

Change

in slope

angle

across

fault

GDT

WUT

6

7

8

9

10

11

12

13

14

6

7

8

9

10

11

12

13

14



27-28 April 2003

North Idku Slope Channel

Evaluation



27-28 April 2003

NI-2x NI- 4x

Cut off in

gas-bearing

sequence

Cut off in

water-bearing

sequence

High RMS

amplitude

associated

with

gas-bearing

sequence

RMS

AMP

Seismic

Facies



27-28 April 2003

North Idku LeaseWest Med

Deep Marine

North Alex.

Block B

North Abu Qir Dev. Lease

North Idku-4x

Discovery

North Idku

Lease

ARMADILLO

Prospect

North Idku-2X

Discovery

7.5 Km

2.5 Km

Depth Map

&

Static

Model(25m x 25m x c. 9.5m grid)



27-28 April 2003

Depth Map

&

Static

Model

North Idku-4x

N 2.5 km

Reservoir below

1511.5m TVDss

Reservoir above

GWC @ 1511.5m TVDss

North Alex B North Idku Concession

C.I =10m

1530

Seismic Facies“Sand”

>6000 RMS AMP

“Heterolithic”

>4500<6000

“Non-Reservoir”

<4500



27-28 April 2003

Simgrid: 100 x 100 x c. 9.5m

GWC

Projected

through model

Depth Map &

Simulation

Model

Connected volume

in red



27-28 April 2003

Dynamic Simulation Model with 4 “Virtual” wells and a discovery well

Well V1Well V2

GWC @ 1511.5m TVDss

based on NI-4x results

Initial Gas Saturation

Well V3

Well NI - 4x

discovery

Initial Gas Saturation

Armadillo

Viper Canyon

Including NI-4x

NI-2x

Dynamic Simulation

Model

400m

Well V4



27-28 April 2003

Up-scaled

simulation modelProduced Gas over 25 years

Cell Size

100 x 100 x 9.5m



27-28 April 2003

Agenda



– Data Analysis






Conclusions



27-28 April 2003

Conclusions

• Static models allow visualisation of reservoir complexity

(architecture & heterogeneity – connected / drainable volumes)

• Multiple realisations can be modelled rapidly, testing sensitivities

to different rock and fluid parameters

• Independent check of GIIP

• Dynamic simulation studies

• Various development plans can be evaluated



27-28 April 2003

Acknowledgements

The author would like to thank RWE Dea, bp Egypt and EGAS

for permission to present this material

EGAS

taurus libra north idku - slope channel 3d seismic modelling, egypt

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