DEVEX 2010 Moving in the Right Direction; Realising Upside...

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;


Agenda

2

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


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


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


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


Challenges imaging and mapping top reservoir

n  Strong Base Chalk reflector obscures Top UCS seismic response

SW NE


Key uncertainties in the Captain field

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n Main uncertainty:

n Top Reservoir depth

n Top Reservoir surface – high rugosity

DOC ID © Chevron 2005 8

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


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


Dip section across northern wedge of field

n  Most northerly well in field – step out from nearest wells (~100m)


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)


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


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


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


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


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


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


QUESTIONS ?

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Backup slides


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


Captain Dynamics - Coning

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5

Yrs

Water Coning Producers Injector

INFILL INFILL

Infill well opportunities


Strike section along well

n  Producer hole – proved TOP UCS follows P90 model n  Pilot hole proved up a future second target

DEVEX 2010 Moving in the Right Direction; Realising Upside...

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