K17-FA Monotower UBD Stack UBD Flaring
Transcript of 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
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
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
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
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
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
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Phi (%)
Kair
(m
D)
Aeolian
Fluvial
EBN/TNO Tight Gas workshop, 19Sept 2006, Utrecht
Rotliegend SNS analogues Similarities/differences
UK SNS NL SNS
K17 vs Galleon
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Cpor
Cp
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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
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
EBN/TNO Tight Gas workshop, 19Sept 2006, Utrecht
K17-FA RotliegendDevelopment
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POROSITY
30 % 0
GAS SAT’
0 % 100mTVDss
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FWL 2905
POROSITY
30 % 0
GAS SAT’
0 % 100mTVDss
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FWL
A
SE
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NW2
NW1
K17-FA
FWL
FWL
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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
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
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
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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
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
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Depth (m AHORT)
PIW
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E3
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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
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
EBN/TNO Tight Gas workshop, 19Sept 2006, Utrecht
K17-FA Hole Size
K17-FA-101 Solids vs Depth
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Hole Length Drilled (m)
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mu
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lid
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Actual Leg #1
Actual Leg #2
8.9"
6"8.8"
K17-FA-102 Solids vs Depth
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Cu
mu
lati
ve S
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ds (
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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
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
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PI (10^3 m^3/d/bar)
Init
ial
Gas R
ate
(10^
6 m
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)
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
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/bar
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E3 m
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/bar
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Mo
del 101
75E
3 m
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/bar
Mo
del 102
30E
3 m
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/bar
Reservoir KH
E&A 5-10-14-36 mD.m
Model 52-64 mD.m
Actual 10-15 mD.m
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
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)
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
EBN/TNO Tight Gas workshop, 19Sept 2006, Utrecht
Installation Interfacing
Drilling
Installation
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