1. Technology for a better society
International Student Energy Summit (ISES),
June 14th 2013
Malin Torsæter, PhD
Research Scientist
Dept. of Drilling and Wells
SINTEF Petroleum Research
malin.torsater@sintef.no
Preparing for Safe
Arctic Well construction
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Photo: Stockbyte/Getty Images

2. Technology for a better society
Preparations for crossing the "final frontier"
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3. Technology for a better society
Varying:
• Ice conditions (sea, subsurface)
• Temperature (air, seafloor)
• Ocean currents
Everywhere:
• Darkness, remoteness, sensitive area
• Short operational windows
• Unknown geology, ground in motion
• Poor wellbore position accuracy
• Cold "tophole" of well and stronger
temperature cycling (on/off production)
Not "one Arctic"
‐ Different well solutions are required
for different Arctic locations
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J. Bang and T. Torkildsen (2011), "Wellbore Anti‐
Collision Safety: Separation Distances Must Be
Increased Due To Degraded Positioning Accuracy
In Northern Areas", SPE 149699.
Source: AAPG
Arctic ice cap Onshore & offshore permafrost

4. Technology for a better society
Summary:
Challenges of
Arctic wells
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Freezing/thawing
of formations
Barrier isolation/
lifetime challenges
More wax/
hydrate formation
Freezing of water‐
based fluids
Cold top section of well
Less possibilities for shipping
fluids/equipment from shore
Same season well control?
Less time for drilling
Short operational time windows
More robust well construction
needed, less time for repairs
Minimal emissions
Drill cutting & water
disposal?
Well abandonment
procedures?
Operations that
minimize CO2 em.?
New monitoring
technologies?

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6. Technology for a better society
Extra slides to be brought up if
necessary during discussion
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7. Technology for a better society
The life of a hydrocarbon well
Well integrity:
"Application of technical, operational
and organizational solutions to reduce
risk of uncontrolled release of formation
fluids throughout the life cycle of a well."
NORSOK D‐010 Standard
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Drilling
• Drill string & bit
• Mud (closed loop)
• Cuttings
Source: Chief Council's Report
Casing &
completion
• "Save" progress
• Stabilize wellbore
• Make ready for
production
Source:Chief Council's Report
• Cut casing and set
cement plugs.
• Zonal isolation for
eternity.
Abandonment
Source: Indian Oil&Gas Canada
Production
• Controlled flow
of hydrocarbons
• Remediation
Source: Indian Oil&Gas Canada

8. Technology for a better society 8
15 year old well in GoM: 50% probability to leak
United States Mineral Management Service (MMS) survey on sustained
casing pressure (SCP) of 15500 wells in the Gulf of Mexico.
Brufatto et al. (2003), "From Mud to Cement ‐ Building Gas Wells", Oilfield Review.

9. Technology for a better society
38% of temporarily abandoned wells on NCS have issues
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2 defect barriers
1 defect barrier
1 reduced barrier
No WI issues
PSA, SINTEF & Wellbarrier study of 193 temporarily abandoned wells
O. K. Helgesen (2011), "Stor fare for lekkasje fra forlatte oljebrønner", Teknisk Ukeblad, 3. Oct.

10. Technology for a better society
#1: Wells are often not properly
designed/operated
• Ex: Gas‐Lift wells
– SINTEF study on NCS
– Average time for WI problems after
conversion to gas‐lift: 2 years.
Average life of gas
lift wells
Wells operated outside their design envelope:
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• Understand critical design factors:
– Casing depth selection
– Length of annular cement sheath
– Centralizer placement
– Designing wells with plans for P&A

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Gap along casing‐
cement interface
Cement
porosity
Degraded casing
Cracks in
cement
Gap along cement‐
formation interface
Based on: Celia et al., Quantitative Estimation of CO2
Leakage from Geological Storage, ICGGCT (2004)
#2: Placement and integrity
of well barriers

12. Technology for a better society
There are several ways to define "the Arctic"
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13. Technology for a better society
Arctic drilling is not a new topic
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First "Arctic wave"
Source: Wood Mackenzie
• 1970s & 1980s: 176 wells (85 offshore) were drilled only in the Canadian Arctic.
• There is a strong relation between the oil prize and drilling activity in the Arctic
• We seem to be seeing the start of a second "Arctic wave"

14. Technology for a better society
Challenges escalate with water depth
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Source: Imperial Oil (Canada)

15. Technology for a better society
Source: animal.discovery.comSource: my.opera.com
Photo: Mossavis.no
The Arctic environment
Sensitive nature/ wildlifeRemote locations
Challenging subsurface conditionsHarsh topside conditions
Photo: UNODA
Cold "tophole"
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Source: Howstuffworks
Source: presstv.ir
Close to north pole

16. Technology for a better society
Harsh topside conditions
• Short operational windows
• Speed up operations
• Less frequent repairs
• On/off production
• Need to protect top section of the well
• Iceberg scours down to 400 m water depth
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Photo: www.123rf.com
C. Teff (Royal Dutch Shell), "Mud Line Cellar Construction for Arctic Wells", Alaska Exploration (2009).

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Challenging subsurface conditions
Permafrost
G. Cherkashov, "Russian studies on subsea permafrost and gas
hydrates in the Arctic", VNIIOkeangeologia, St. Petersburg
Gas hydrates
Source: AAPG
? ?

18. Technology for a better society
Why avoid thawing
of frozen soil?
Xie et al. (2011), "Methodology to Assess Thaw Subsidence Impacts on the Design and Integrity of Oil and Gas Wells in Arctic Regions", SPE 149740.
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Ca. 20 m radial thaw after
10 years of production
• Up to 9% volume reduction
• Can lead to:
– (local) subsidence that imposes severe
loads on casing and wellhead/BOP.
– Caving that compromises zonal isolation

19. Technology for a better society
Why avoid thawing of
gas hydrates?
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• Trapped gas molecules (often methane)
in a solid framework of water molecules
– Under permafrost
– Beneath sea in outer continental margins
• During thawing, trapped gas is released*
– Pressure build‐up
– Mud gasification
– Poor cement jobs
• Reported consequences**
– Catastrophic subsidence
– Uncontrolled gas release
– Collapsed casings
** Yakushev et al. (1992), "Gas hydrates in Arctic regions: risk to drilling and production", Int. Offshore and Polar Eng. Conf. 1:669‐673
*Tan et al. (2005), "Mechanical and Petrophysical Characterisation and Wellbore
Stability Management in Gas Hydrate‐Bearing Sediments", ARMA/USRMS 05‐833
Image: NOC
Photo: softpedia

20. Technology for a better society
Cold "tophole"
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(2) Boyer and Szakolczai (2011), "Well Architecture and Well Operating Procedures on Kharyaga Field, Russia", OTC 22133
Suppression of temperature gradient down to
600 m at Kharyaga Field(2)
(1) Punase et al. (2011), "Soybean slurry – a new effective, economical and environmental friendly solution for oil congealing", SPE 142658
(3) Singh et al. (2007), "An application of vacuum‐insulated tubing for wax control in an Arctic environment", SPE 111006
 Functioning of BOP/safety valves(1‐3)
– Plugging/freezing
A typical
wax plug(3)
Gas hydrate plug
(SINTEF)
 Frequent flow assurance issues(1‐3)
– Freezing of produced water
– Wax forming
– Gas hydrates forming
 Difficulties during on/off operations
– Freezing of water based well fluids
• Suppression of normal temperature
gradient in Arctic wells

21. Technology for a better society
What does cold "top hole" mean?
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IKU News 1988: Målinger av temperatur i
grunne brønner sør for Svalbard
Beaufort Sea
= Worst case?
South of Svalbard
= Best case?
Xie et al. (2011), "Methodology to Assess Thaw Subsidence Impacts on the
Design and Integrity of Oil and Gas Wells in Arctic Regions", SPE 149740.

22. Technology for a better society
Cold well barrier materials
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*Reinås et al. (2011), "Hindered Strength Development in Oil Well Cement due to Low Curing Temperature", SPE 149687.
**Limaye et al. (2011), "Contamination Resistante Phosphate Ceramic Cement for Arctic Applications", Int.Offshore and Polar Eng. Conference.
• New environment
= new predicted lifetime
• Cement in the Arctic:
• Freezing of water before setting
• Enhanced permeability
• Poor bonding to formation
• Lower compressive strength*
• Proposed solution: new sealant types**
• Steels in the Arctic:
– Brittle at low temperatures
– Stress‐based design
– Proposed solution: other materials***
***M. Y. Gelfgat et al. (2009), "Aluminium pipes – a Viable Solution to Boost Drilling and Completion Technolgy", IPTC 13758.
Surface casing failure, Alaska
(Anders et al. (2008), "Prudhoe
Bay Well P2‐15 Surface Casing
Failure", SPE 116771)
Cement and steel are
weakest where the
loads are largest!

23. Technology for a better society
Wellbore Position Accuracy
J. Bang and T. Torkildsen (2011), "Wellbore Anti‐
Collision Safety: Separation Distances Must Be
Increased Due To Degraded Positioning Accuracy
In Northern Areas", SPE 149699.
• Wellbore trajectory defined by depth, inclination
and azimuth.
• Magnetic instruments: azimuth uncertainty dep. on
horizontal component of geomagnetic field.
• Gyroscopic instruments:
azimuth uncertainty dep. on
horizontal component of the
earth rotation.
• Important for:
– well collision avoidance
– safety margins with respect
to e.g. faults
– Planning/drilling relief wells
– required size of a target

24. Technology for a better society
• Drilling muds are chosen with respect to
e.g. weight and hole cleaning properties.
• Their effect on the sealing ability of cement
was recently investigated by SINTEF.
Ex. Choices made during drilling
affect long‐term well integrity
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Interface porosity: sandstone Interface porosity: shale
No mud WBM OBM No mud WBM OBM
N. Opedal et al. (2013), "Leakage of CO2 along cement‐formation interfaces in wellbores", Energy Procedia.

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