DOC ID © Chevron 2008
DEVEX 2010 Moving in the Right Direction; Realising Upside Potential in a Mature Field Using Real Time 3D Geo-Steering Technology
Authors: Lisa Chisholm, Chevron Upstream Europe David Holbrough, Baker Hughes Co-Authors: Haakon Dahle-Smith, Chevron Upstream Europe; Mandy Ponton, Chevron Upstream Europe; Mike Unger, Chevron Upstream Europe;
DOC ID © Chevron 2005
Agenda
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n Introduction to the Captain field
n Chevron well objectives
n AziTrak™ tool specifics
n Case example using AziTrak™
n Results and discussion
n Questions
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Captain Field Location
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n LOCATION – 80 miles NE of Aberdeen, UK Northern North Sea n EQUITY – 85% CVX, 15% KCCL n FIRST OIL – 1997 n Upper Captain Sand Reservoir ~ 700 MMbbls STOIIP n Development – water flood through horizontal wells and pumps
Block 13/22a
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Captain field geological cross-section
n Upper Captain Sand reservoir
Ø Main producing interval Ø Shallow, low relief structure Ø Combined structural and stratigraphic closure
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Reservoir characterisation
Upper Captain Sand reservoir n Unconfined Turbidite sheet system n Massive sands n Unconsolidated n 98% average N:G n 32% average Porosity n 5500mD average Permeability
n Top seal = Rodby/Carrack shale
n Heavy oil of 19 – 20° API gravity n High viscosity crude 49 – 150 cp
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Challenges imaging and mapping top reservoir
n Strong Base Chalk reflector obscures Top UCS seismic response
SW NE
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Key uncertainties in the Captain field
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n Main uncertainty:
n Top Reservoir depth
n Top Reservoir surface – high rugosity
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Captain field - drilled well location
n 180 well penetrations n Well located in NW of field targeting attic oil NW of existing producer and above OWC
Top Upper Captain Sand depth map
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Well objectives
n Drill safely
n Geosteer for attic oil – place well in an optimal location
n Target unswept reserves between abandoned producer and the northern wedge above the OWC
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Dip section across northern wedge of field
n Most northerly well in field – step out from nearest wells (~100m)
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AziTrak™ - Tool specifics
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§ Directional § Near Bit Inclinometer § Gamma ray imaging § Annular Pressure § Multiple Propagation Resistivity (MPR)
– 8 compensated resistivities – Rv / Rh inversion
§ Deep azimuthal propagation resistivity – Real-time deep image – Real-time distance to remote boundary inversions – Directionality of detected boundary (s)
§ AziTrak™ used on four wells – six boreholes, within Captain field
§ Provides a deep reading azimuthal resistivity measurement for Reservoir Navigation applications (bed boundary detection)
§ Distance to bed varies with the conductivity contrast of reservoir
§ Captain reservoir allows depth of detection of up to 14 ft (4 m)
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Communication lines when drilling using AziTrak™
Rig site
OPERATIONS TEAM
RNS SUPERVISOR
Onshore RNS Team
WellLink Display
RNS Software
RNS Software
OFFICE TEAM
RIGSITE TEAM
WellLink Display
n Integration and communication are key
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Real time geosteering decisions
n Recent improvements in visual aids enable easy interpretation and faster decision making
Up Down
Model surface curtain
Signal amplitude
Resistivity
GR
APR image GR image
Up Down
Steering Rose
Up Down
Left Right
Steering Rose
DOC ID © Chevron 2005
Final AziTrak™ data through producer hole
Dip in well = KOP for pilot hole
Tracking very close to roof down to TVD limit
TD in roof – very shallow dip
Dip information on shales helps us make geosteering decision – hold angle or drop
Drilled above (>32ft TVD)
above planned well path
Signal amplitude
Resistivity
GR
APR image GR image
Model surface curtain
Up Down
Left Right
Distance to Bed (%)
0.0 5.0 10.0 15.0 20.0 25.0 30.0
shale
0-2ft
2 - 4ft
4 - 6ft
6 - 8ft
8 - 10ft
10 - 12ft
12 - 14ft
> 14ft
Dis
tanc
e to
Bed
Percentage of Lateral (%)
Lateral (C44)Lateral (C44z)
§ Followed roof on average 7ft below
§ Average height above plan = 23ft
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Seismic section along the well
Drilled well path
Planned well path
SW NE
Base Chalk
OWC
bulk shift 21ft down to tie chalk at heel
~5Km
Production interval 5309ft MD
n Poor seismic tie n Difference between planned and drilled wellpaths
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Schematic cross-section highlighting results and discussion
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n Significant difference between planned and drilled wellpaths n Drilled on average 7ft TVD below Top UCS (reservoir) n Achieved 98% N:G n Completion interval ~ 5000ft MD n Well came on production above the P90 estimates
OWC = -2982ft TVDSS
TD in Sola Rodby shale 11049ft MD
UCS
R/C
Chalk
Production interval 5605 – 10914ft MD
*Azi Trak modeled Top
UCS
Planned well path
drilled
Top UCS 12ft low to
prognosis
60ft from OWC 9 5/8” shoe 71ft
from OWC
Dip in well = pilot sidetrack
location Original Top UCS surface
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Conclusions
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n Drilling in a mature field requires a flexible approach to well placement
Ø Have tools that enable team to make informed decisions
Ø Integrate the real time data and incorporate /update the geological model in real time
n Ability to think in 3D
Ø Consider lateral steering options
n Flexible and integrated drilling team
Ø Good fast turn around on drilling pilot for upside
Ø Good strong communication links set up between onshore and offshore plus BHI and Chevron
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QUESTIONS ?
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Backup slides
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Resistivity plot – depth of detection
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Resistivity contrasts
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Wet SST = 2.5 ohmm Oil SST = 140 ohmm Shale = 3 – 5 ohmm Chalk = 10 – 15ohmm
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Captain Dynamics - Coning
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5
Yrs
Water Coning Producers Injector
INFILL INFILL
Infill well opportunities
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Strike section along well
n Producer hole – proved TOP UCS follows P90 model n Pilot hole proved up a future second target