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K17-FA Monotower UBD Stack UBD Flaring

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EBN/TNO Tight Gas workshop, 19Sept 2006, Utrecht K17-FA Tight Gas Development NAM-Shell EPE, Assen K17-FA Monotower UBD Stack UBD Flaring
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Page 1: K17-FA Monotower UBD Stack UBD Flaring

EBN/TNO Tight Gas workshop, 19Sept 2006, Utrecht

K17-FA Tight Gas Development

NAM-Shell EPE, Assen

K17-FA Monotower

UBD Stack

UBD Flaring

Page 2: K17-FA Monotower UBD Stack UBD Flaring

EBN/TNO Tight Gas workshop, 19Sept 2006, Utrecht

Tight Gas in NL/NL Offshore

• Tight gas defined as reservoir properties <1mD average insitu

• TG Volumes mostly contained in Rotliegend reservoir (Slochteren Sst)

– Tight gas properties mainly due to diagenetic impairment of reservoir sandstones by combinations of grain coating and pore-filling clay minerals and carbonates

– Flow during well testing/production logging observed to be derived from few thin zones

– Large lateral and vertical variation of reservoir facies, difficulty to accurately predict presence/location/orientation/ dimensions of high flow features ( fractures/HPS)

– Absence or paucity of open natural fractures

– Unusual combinations occur of low to high porosity and low permeability and limited height gas columns (often ~100m) characterised by thick transition zones and significant Sw

– Compartmentalisation by faults common

• Well bore stability, sand production and risk of water influx are additional complications for TG field development

• Relatively modest in-place-volumes

– Costs a major factor, cost control & reduction are a CSF

– Ageing production systems, rising OPEX

Page 3: K17-FA Monotower UBD Stack UBD Flaring

EBN/TNO Tight Gas workshop, 19Sept 2006, Utrecht

K17-Location• Broad Fourteens Basin

– ~80km west of Den Helder

• Complex structural history, tight reservoir

K17-FA

K17-FA

Page 4: K17-FA Monotower UBD Stack UBD Flaring

EBN/TNO Tight Gas workshop, 19Sept 2006, Utrecht

K17-FA UBD : Background

K17-FA-102

K17-FA-101

Main reservoir units 3 & 4

Thickness ~130m

N/G 80-100%

Porosity 4-26%

Permeability 0.01 - 200mD in-situ

Development – 2 horiz. wells close to existing wells

K17-FA discovered in 1972 (#2 well).

• NAM 60%, EBN 40%

• 1 Exploration and 3 Appraisal wells drilled 1977-1998

• 3D seismic;

– Excellent to good quality. Complex overburden

• Rotliegend reservoir

– Predominantly aeolian,with fluvial sandstones

– Very heterogeneous

– Paleo burial caused severe reservoir deterioration (hairy illite)

– Poor well test results (also fracced wells) – tight reservoir

Page 5: K17-FA Monotower UBD Stack UBD Flaring

EBN/TNO Tight Gas workshop, 19Sept 2006, Utrecht

K17-FA – Location and Geological Setting

Diagenetic setting

K17 FA

Structural setting Depositional setting

At the SW edge of the inverted Broad Fourteens BasinLocated in Erg setting adjacent to major fluvial systemReservoir severely illitised

Fibrous Illites

Page 6: K17-FA Monotower UBD Stack UBD Flaring

EBN/TNO Tight Gas workshop, 19Sept 2006, Utrecht

K17-FA diagenesis

• Key reservoir issue on K17-FA: Reservoir pervasively illitised

– No relation with

• Structural position

• Sedimentology

– Permeability effect largest on poorly sorted fluviatile sands

0.00

0.00

0.01

0.10

1.00

10.00

100.00

0 5 10 15 20 25 30 35

Phi (%)

Kair

(m

D)

Aeolian

Fluvial

Page 7: K17-FA Monotower UBD Stack UBD Flaring

EBN/TNO Tight Gas workshop, 19Sept 2006, Utrecht

Rotliegend SNS analogues Similarities/differences

UK SNS NL SNS

K17 vs Galleon

0.01

0.1

1

10

100

1000

10000

0 5 10 15 20 25

Cpor

Cp

erm

Galleon 48144

Galleon 48205

K17-7A

K17-8

K17 vs UK Rotliegend TGsimilar poroperm distribution

K17 UK SNS analogues

SIMILARITIES

Rotliegend -Slochteren Rotliegend Illite/Fibrous illite Fibrous IllitesCore perm=<0.01-10’smD

Core perm=<0.001-10’smD

Porosity=(5)10-26% Porosity=(5)10-22%

High permeabilitystreaks (from PLT)

Some high permeabilitystreaks (cores & PLT)

?Natural fractures/matrix (Natural) fracs/matrix

DIFFERENCES

Stacked fluvial/dunesets (20-35m)

Same, but thicker dunesequence (45-60m)

Small column (» 165m) Large column (» 250m)UBD only tried in 1997 UBD the norm

Page 8: K17-FA Monotower UBD Stack UBD Flaring

EBN/TNO Tight Gas workshop, 19Sept 2006, Utrecht

K17-FA Main Development Risks

• Project cost

– Drilling operations

– Diving operations (weather risk)

– Concurrent drilling, tie-ins, hookup & commissioning

• Well performance

– Underbalance operations

• Operational execution is critical (experience)

• Relative lack of data ( GR/Dir) and tool reliability

• Well productivity prediction (initial)

– Comparable to UK analogues?

– Sand control required?

– Deployment and cleanup of sand screens

– Reservoir quality

• Pipeline & Facilities

– Minimum facilities

Page 9: K17-FA Monotower UBD Stack UBD Flaring

EBN/TNO Tight Gas workshop, 19Sept 2006, Utrecht

K17-FA RotliegendDevelopment

1

2

5

4

3

-

POROSITY

30 % 0

GAS SAT’

0 % 100mTVDss

2

5

4

3

FWL 2905

POROSITY

30 % 0

GAS SAT’

0 % 100mTVDss

N

FWL

A

SE

N

NW2

NW1

K17-FA

FWL

FWL

2

4

7

8

9

9AA

--K17-FA-102UBD screen

K17-FA-101UBD barefoot

K17-FA-1Monotower

N

• K17-FA-101 plan to develop SE Block via 1700 m sub-horizontal placed in 40 m thick Unit 4

• K17-FA-102: plan to develop NW Block via 1900 m sub-horizontal placed in 40 m thick Unit 4

Z e c h s te in H a lite

U n it -4U n it -3

U n it -5

C a rb o n ife ro u s

U n it -1U n it -2

S lo c h te re n

7 ”B a s a l Z e c h s te in

F W L

Z e c h s te in H a lite

U n it -4U n it -3

U n it -5

C a rb o n ife ro u s

U n it -1U n it -2

S lo c h te re n

7 ”B a s a l Z e c h s te in

F W L

Z e c h s te in H a lite

U n it -4U n it -3

U n it -5

C a rb o n ife ro u s

U n it -1U n it -2

S lo c h te re n

7 ”B a s a l Z e c h s te in

F W L

Page 10: K17-FA Monotower UBD Stack UBD Flaring

EBN/TNO Tight Gas workshop, 19Sept 2006, Utrecht

K17 FA – Vertical facies distribution

Ro

tlie

ge

nd

(22

0-3

10

m)

GWC

Layer 5: 12 to 30 m, fluvio-aeolian,

cemented very poor quality

Layer 4: 29 to 48 m aeolian, main target,

best reservoir at base

Layer 3: 70 to 125 m fluvio-aeolian,

medium quality, best reservoir at top

Layer 2: 19 to 28 m fluvial

very poor to non-reservoir, vertical seal

Layer 1: 65 to 101 m sabkha-aeolian,

medium reservoir, best reservoir at top

Field wide shaly interval at base

Page 11: K17-FA Monotower UBD Stack UBD Flaring

EBN/TNO Tight Gas workshop, 19Sept 2006, Utrecht

• Best reservoir across bottom half Unit 4 in line with E&A

• Difference between PIWD for Leg #1 and Leg #2 illustrates heterogeneity and benefit of long horizontal wells in TG reservoir

• No indications of natural fractures from either drilling or productivity data - but present in core

K17-FA-101 Well Results

K17-FA-101 PIWD vs Depth

02468

1012141618

3400 3600 3800 4000 4200 4400 4600 4800 5000Depth (m AHORT)

PIW

D (

10

E3 m

^3

/d/b

ar)

Leg #1

Leg #2

PIWD = Qgas / (Pres-BHP)

Leg #1 trajectorySteering problems

Leg #2 200m shortSurface erosion problems

Pres = 305 barUB ~ 40 bar

Page 12: K17-FA Monotower UBD Stack UBD Flaring

EBN/TNO Tight Gas workshop, 19Sept 2006, Utrecht

• Unit 4 less clean than expected: NTG 85% vs 98% in E&A wells

• Best reservoir across bottom half Unit 4 in line with E&A data

• No indications of natural fractures from either drilling or production

• PIWD very helpful in steering well

• Shorter well than plan due to drilling difficulties

K17-FA-102 Well Results

K17-FA-102 PIWD vs Depth

0

2

4

6

8

10

12

14

16

18

3100 3300 3500 3700 3900 4100 4300 4500 4700

Depth (m AHORT)

PIW

D (

10

E3

m^

3/d

/ba

r) Hole #1

Hole #2

Pres = 310 bar UB ~ 30 bar

Hole #1 400m short, killed & abandonedTorque & drag limit, sand screen incident

Hole #2 1100m shortPackoff & twistoff

Page 13: K17-FA Monotower UBD Stack UBD Flaring

EBN/TNO Tight Gas workshop, 19Sept 2006, Utrecht

Initial Well Performance

• Very rapid clean-up – typical for UBD wells

• Transient PI about 50% of instantaneous PI due to rapid depletion of thin high perm streaks

– high PI’s 10-20Km3/d/bar

• Initial well performance suggests tortuous communication in reservoir

• Corresponds with heterogeneity of reservoir

• Connected volume increases with time

• Wellbore PI ≠ Reservoir RI

Page 14: K17-FA Monotower UBD Stack UBD Flaring

EBN/TNO Tight Gas workshop, 19Sept 2006, Utrecht

K17-FA Hole Size

K17-FA-101 Solids vs Depth

0

20

40

60

80

100

120

140

160

180

3400 3600 3800 4000 4200 4400 4600 4800 5000

Hole Length Drilled (m)

Cu

mu

lati

ve

So

lid

s (

MT

) Gauge Hole

Actual Leg #1

Actual Leg #2

8.9"

6"8.8"

K17-FA-102 Solids vs Depth

0

20

40

60

80

100

120

140

160

180

200

3100 3300 3500 3700 3900 4100 4300 4500 4700Hole Length Drilled (m)

Cu

mu

lati

ve S

oli

ds (

MT

)

Gauge Hole

Actual Hole #1

Actual Hole #2

9.1"

6"11.5"

+100m ST

Bit trip

Packoff & twistoff

• Average hole size 9” vs6” gauge

• Extreme 12” hole size in K17-FA-102 sidetrack may have caused a drilling trouble spot

• Large volume of “whole grain” solids main cause of erosion of surface equipment

Page 15: K17-FA Monotower UBD Stack UBD Flaring

EBN/TNO Tight Gas workshop, 19Sept 2006, Utrecht

Comparison Against E&A Wells and Model

• Excellent inflow compared to E&A wells: horizontal & UBD success story

• Less inflow than modelled: model optimistic, impact of diagenesis difficult to model

0

0.5

1

1.5

2

2.5

0 5 10 15 20 25 30

PI (10^3 m^3/d/bar)

Init

ial

Gas R

ate

(10^

6 m

^3/d

)

Exploration/Appraisal Well Post-Stimulation 0.4E6 m^3/d

K17-FA-102

1.3E6 m^3/d

K17-FA-101

2.0E6 m^3/d

Exploration/Appraisal Well Pre-Stimulation 0.05E6 m^3/d, S>10

9E

3 m

^3/d

/bar 1

8E

3

m^

3/d

/bar

0.3

E3 m

^3/d

/bar

2.4

E3 m

^3/d

/bar

Mo

del 101

75E

3 m

^3/d

/bar

Mo

del 102

30E

3 m

^3/d

/bar

Reservoir KH

E&A 5-10-14-36 mD.m

Model 52-64 mD.m

Actual 10-15 mD.m

Page 16: K17-FA Monotower UBD Stack UBD Flaring

EBN/TNO Tight Gas workshop, 19Sept 2006, Utrecht

• Biggest gain from drilling horizontals

• UBD enables horizontals in fractured reservoir

• UBD Qi benefit:

– 1.5x-2.5x OK for damage

– 6x-8x due to fractures

• Kill can be worse than drilling OB, in-line with general industry experience

• K17-FA performance in line with UK analogue wells

Current View

Page 17: K17-FA Monotower UBD Stack UBD Flaring

EBN/TNO Tight Gas workshop, 19Sept 2006, Utrecht

Evacuation system

Dry Gas to Den Helder

via K15 block

K14-FB-1

K14-FA-1P/C

K17-FA-1

Monotower

Umbilical

Wet GasTie in to ONEGAS JDA

LoCal evacuation system (WGT)

Page 18: K17-FA Monotower UBD Stack UBD Flaring

EBN/TNO Tight Gas workshop, 19Sept 2006, Utrecht

Novel type of surface facilities: T2 monotower design

minimal facilities, remotely operated, 4 well slots,

boat access, renewables (wind, solar) provide power

Page 19: K17-FA Monotower UBD Stack UBD Flaring

EBN/TNO Tight Gas workshop, 19Sept 2006, Utrecht

Installation Interfacing

Drilling

Installation

Page 20: K17-FA Monotower UBD Stack UBD Flaring

EBN/TNO Tight Gas workshop, 19Sept 2006, Utrecht

K17-FA - Lessons Learned

� Multi-discipline, multi-functional effort with great attention to detail is critical

� To get it right-first-time is difficult

� Subsurface heterogeneity confirmed by drilling, difficult to model

� Minimum facilities - installation successful

� Reproduced success of horizontal drilling in UK offset tight gas fields

� Similar tight reservoir type – ‘horses for courses’ approach

� Maximised well capacity by underbalanced drilling (geosteering, impairment)

� Reaped benefits of oil-based underbalanced drilling fluid

� Installed sand screens underbalanced – but with a lot of difficulties/learnings

X Experienced integrity problems (BOP’s and surface erosion)

X Drilling trouble spots - need further investigation


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