ises 2013 day 2 - malin torsæter (arctic researcher, sintef) - arctic drilling

Technology for a better society

International Student Energy Summit (ISES), June 14th 2013

Malin Torsæter, PhDResearch ScientistDept. of Drilling and WellsSINTEF Petroleum [email protected]

Preparing for Safe Arctic Well construction

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Photo: Stockbyte/Getty Images


Preparations for crossing the "final frontier"

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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 requiredfor 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


Summary:Challenges ofArctic wells

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Freezing/thawingof 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 constructionneeded, less time for repairs

Minimal emissionsDrill cutting & water disposal?

Well abandonment procedures?

Operations thatminimize CO2 em.?

New monitoringtechnologies?

Technology for a better society 5


Extra slides to be brought up ifnecessary during discussion

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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


15 year old well in GoM: 50% probability to leak

United States Mineral Management Service (MMS) survey on sustainedcasing pressure (SCP) of 15500 wells in the Gulf of Mexico.

Brufatto et al. (2003), "From Mud to Cement ‐ Building Gas Wells", Oilfield Review.


38% of temporarily abandoned wells on NCS have issues

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2 defect barriers1 defect barrier1 reduced barrierNo 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.


#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


Gap along casing‐cement interface

Cementporosity

Degraded casing

Cracks in cement

Gap along cement‐formation interface

Based on: Celia et al., Quantitative Estimation of CO2Leakage from Geological Storage, ICGGCT (2004)

#2: Placement and integrity of well barriers


There are several ways to define "the Arctic"

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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"


Challenges escalate with water depth

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Source: Imperial Oil (Canada)


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


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).


Challenging subsurface conditions

Permafrost

G. Cherkashov, "Russian studies on subsea permafrost and gas hydrates in the Arctic", VNIIOkeangeologia, St. Petersburg

Gas hydrates

Source: AAPG

? ?


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


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


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/freezingA 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 temperaturegradient in Arctic wells


What does cold "top hole" mean?

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IKU News 1988: Målinger av temperatur igrunne brønner sør for Svalbard

Beaufort Sea = Worst case?

South of Svalbard = Best case?

Xie et al. (2011), "Methodology to Assess Thaw Subsidence Impacts on theDesign and Integrity of Oil and Gas Wells in Arctic Regions", SPE 149740.


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!


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


• Drilling muds are chosen with respect to e.g. weight and hole cleaning properties.

• Their effect on the sealing ability of cementwas 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.

ises 2013 day 2 - malin torsæter (arctic researcher, sintef) - arctic drilling

Business

abandonment source

howstuffworks source

firstarcticwave source

petersburg gashydrates

years of production

wells o

casing pressure scpof

subsurface temperature