The Rosebank Discovery A new play type in intra basalt reservoirs ...
Transcript of The Rosebank Discovery A new play type in intra basalt reservoirs ...
DOC ID© Chevron 2009
The Rosebank Discovery
A new play type in intra basalt reservoirs of the North Atlantic volcanic province
DEVEX AECC 13 May 2009
Louise Duncan, Dag HellandHansen, Cliona Dennehy
DOC ID© Chevron 2009
Outline
2
Introduction
Regional geology and play concept
The Rosebank Discovery
Appraisal Program and Results
Development studies:
Use of Analogues
Challenges associated with Volcanic Plays
Conclusions & Acknowledgements
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IntroductionRosebankLochnagar Location
Structural elements map restored back to breakup of N Atlantic (Paleogene)
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Easterly advancing volcanic system of extrusive basalts & volcaniclastics.
Contemporaneous Flett Delta system to the SE prograding in a N/NW direction
Confluence of volcanic and sedimentary interaction
4
Geologic SettingRosebank & Greater Rosebank Area
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Base Tertiary
TWT
1s
2s
3s
4s
5s
Flett Fm.Late Paleocene/Early Eocene
PreRiftsediments
W E
Rift phase(s)
Inversion phases Various pulses throughout Cenozoic
Inversion anticlines
~10km
Pre Tertiary
Corona Ridge
VolcanicComplex
Seabed
Greater Rosebank Area The Play Concept
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RosebankThe prospect in 2001
NW SE
Exploration Target
Volcanics
Reservoir
Hydrocarbon Target
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RosebankLochnagarThe Discovery in 2004
Flett Fm.
Rosebank Discovery
Lochnagar
Rosebank North
Rosebank213/27-1Z
213/271Z
PreTertiary
NW SE
GRIN0 150
HCGRIN0 150
2740
2750
2760
2770
2780
2790
2800
2810
2820
2830
2840
2850
2860
2870
2880
DEPTHMETRES
9000
9050
9100
9150
9200
9250
9300
9350
9400
9450
DEPTHFEET
8850
8900
8950
9000
9050
9100
9150
9200
9250
9300
9350
TVDSSFEET
RHOBG/C31.95 2.95
PEFZB/E0 10
NPHIV/V0.45 -0.15
RXOOHMM0.2 2000
P16HOHMM0.2 2000
P40HOHMM0.2 2000
A28H0.2 2000
A40HOHMM0.2 2000
PHIE_1V/V1 0
VOL_UWAT_LWD_1V/V1 0
BVI_GAS_2V/V1 0
TUFF_50 1
BASALT_30 1
VSHGR_1V/V0 1
SWEARCHV/V1 0
SWEARCHV/V1 0 O
IL_2
GAS
CO
ND
ENSA
TE
FILT
RAT
E_1
SAND3 0
PAY0 3
CH_1V/V0 1
TG_10 2.5
C1C2_1V/V1 1000
BH_1V/V1 1000
C1C3_1V/V1 1000
WH_1V/V1 1000
C1C4_1V/V1 1000
C1C5_1V/V1 1000
350’
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Proven Petroleum PlaysIntra and SubVolcanic Reservoirs
Risk Elements
Reservoir: Intra & Sub basalt: Siliciclastic fluvial and shallowmarine reservoir sandstones
Trap: 4way inversion structure
Source: PreTertiary Source Rock
Seal: Volcanic rocks & shales
Fluvial / Marginal marine
Marginal Marine
Fluvial
VolcaniclasticsBasalt
Basalt - lavaflow
Basalt - lavaflow
Basalt - lavaflow
Fluvial
Volcaniclastics
Flett Fm, PaleoceneEocene, Intravolcanic
Lochnagar,Rona sst, Jurassic
PaleoceneCretaceous, Subvolcanic
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Appraisal Drilling
3 well appraisal campaign carried
out in 2006/2007 aimed at:
Defining field commerciality
Reducing key reservoir uncertainties
Data Acquired:
Log data, SWC & whole core
Production Data: 1DST
Pressure Data: MDT
Seismic Data: VSP
Extensive data acquisition programme provided a comprehensive dataset for field delineation & aid future development decisions
Top Colsay 1 Depth Structure
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Appraisal program DST Results
Press release: Aberdeen, Scotland, 17th July 2007
Chevron North Sea Limited announced today the successful conclusion of a production test of the Rosebank appraisal well 205/11, West of Shetland. The Rosebank discovery is in approximately 3,700 feet of water some 100 miles north west of the Shetland Islands. Rosebankpartners are Chevron as operator, Statoil, OMV and DONG Energy.
During the production test, the well flowed at choked rates of 6,000 barrels of oil per day of good quality light oil (37o API).
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Rosebank Correlation PanelTVDss
11
Colsay 1
Colsay 3
Upper Volcanics
Lower Volcanics
S N
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Appraisal program Results Summary
Reservoir Intra and subvolcanic siliciclastic sandstone reservoir
Fluvial – shallow marine environment Varying thickness, NTG and reservoir quality Medium porosities with very high permeabilities
Fluids Thin gas cap encountered Oil downdip in all zones
~37o API oil
Pressure Independent reservoirs within different fluid contacts
Seismic data VSP
Reprocessing and calibration of seismic Reservoir characterization with seismic
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Development Challenges
Resource Size Benchmark reservoir properties e.g. NTG, reservoir architecture etc against appropriate analogues
Outcrop Analogues
Predicting away from well control Seismic Imaging challenging in intra basalt reservoirs
Multiple attenuation and resolution challenges Attempts to delineate Sand Fairways
Uncertainty Management Size of Accumulation Reservoir Quality and productivity
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Analogs Sites of StudyField Scale Rosebank
West Coast Greenland
East Coast Greenland
West of Scotland
Isle of Skye
Mull
Iceland
Grand Canyon
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Subbasaltfluvial / marine Sandstone
Fluvialshallow marine sandstoneVolcanics
Analogue StudiesEast Coast Greenland
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Braided river deposits gradually filling in surface and burying lava flow
Lava flow
Iceland Present day processes
Iceland Lava topography
Analogue StudiesIceland
Lava flowForms cliff line
Inflation Structures
Fluvial channel feeding a shoreface sand
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Seismic Imaging
Intra and Subvolcanic imaging, a continuous improvement process
Various seismic acquisition and processing techniques have been tested: focus on frequency enhancement, velocity estimation and multiple attenuation
Currently assessing how valuable the seismic is in delineating sand fairways for development planning
3D 1998,Predrilling
3D 2007, Postdrilling
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Seismic ImagingDeriving the geology from seismic
2nd-well
Soft sediment : shale/sand Hard rocks : Volcanics
Structure interpretation
Paleotopography and faults
Amplitudes and seismic stratigraphy
Paleoenvironment
Reservoir quality maps
Discovery1st-well 3rd-well
S NSeismic Coloured Inversion
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Development ChallengesUncertainty Management
5m
Size of HC accumulation Reservoir extent Reservoir thickness Sealing Capacity
Quality of Reservoir Sand poroperm Reservoir architecture Sealing faults Volcanic baffles / barriers to flow
Basalt plug / reservoir baffle
Mineral precipitation along fault planes and
in reservoir?
Intrusives cutting through reservoir
Reservoir architecture / sand distribution dominated by drainage systems and lavaflow barriers
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Reservoir Characterisation
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Volcanoclastic Prodelta Shale
MouthBar
Channel Margin
Channel Axis
20
Build Structural Framework grids
Model Facies
PetrophysicalModeling
OOIP
Uncertainty Analysis& Calculate Volumes
Select Modelsfor simulation
QC / Peer Review
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Conclusions
Rosebank discovery & appraisal programme demonstrates
Working intravolcanic and subbasalt plays
Siliciclastic sands
Seal in volcanic clays
High permeability and productivity
Unconventional challenges and uncertainties
Volcanic petroleum geology systems > Analogs for improved understanding
Seismic imaging challenges
The Rosebank discovery opens up new opportunities for prospectivity along the North Atlantic Volcanic Margin
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Rosebank Partners:
Chevron
Dong Energy
OMV
StatoilHydro
Acknowledgments