Workshop - Challenges in Offshore Geotechnics - Gulin T ...

Geotechnica l considera tions throughout the entire project lifecycle : from perception to executionGülin Yetginer, Equinor Leading Advisor Geotechnics

Open 25 September 20 19

Equinor: sha ping the future of energy«We a im to be the world's most ca rbon-efficient oil a nd ga s producer, a nd a re investing a ctive ly in renewa bles.»

Turning na tura l resources into energy for people a nd progress for society

3 | Geotechnica l considera tions throughout the entire project lifecycle : from perception to execution

Explora tionDevelopment a nd productionRefining a nd processingMa rketing a nd tra ding

Ca na da

Mexico

Colombia

Argentina

USA

Nica ra gua

Ba ha ma s

Surina meVenezue la

Bra zil

Russia

China

Austra lia

Algeria

UKIre la nd

Greenla nd

Norwa y

Denma rk

Belgium

Netherla ndsGerma ny

Turkey Azerba ija n

UAE

Nigeria

Ta nza niaAngola

South AfricaUrugua y

Libya

South Korea

Indonesia

New Zea la nd

Singa pore

Opera tor of a sse tsJ oint venturePresence


How ca n we ensure tha t considera tions do not become cha llenges?

cha llenge = unidentified risk


Open 25 September 20 195 | Geotechnica l considera tions throughout the entire project lifecycle : from perception to execution

Open 25 September 20 196 | Geotechnica l considera tions throughout the entire project lifecycle: from perception to execution


Project Lifecycle : «The Ca pita l Va lue Process»


EngineeringEa rly Pha se

Prospect


• “Memory”: the soil response depends on the geologica l a nd ma n-ma de pa st (ha s it been loa ded before? decrea sed porosity a nd wa ter content)

• “Mood”: the soil response depends on how we trea t it a nd loa d it (how much dra ina ge is expected)

• “Temper”: it is possible to trigger a n unexpected fa ilure if the bigger picture is not well understood (regiona l geology)

• Importa nt to perform a good qua lity soil investiga tion to a ssess the a bove a nd construct a ground model tha t presents the comple te picture

Ea rly Pha se : Understa nding the Soil



Ea rly Pha se : Geoha za rds

• Pore pressure modelling• Slope sta bility• Sha llow ga s a nd other drilling ha za rds• Ea rthqua kes

9 | Geotechnica l considera tions throughout the entire project lifecycle: from perception to execution


Desktop Study

• Informa tion sourcestypica lly a va ila ble during the desktop study pha sefor a new projectdevelopment in a ma turea rea (e .g. North Sea ):

• Geologica l se tting• Prelimina ry

geophysica linforma tion

• Geotechnica linforma tion from thela rger developmenta rea

• Insta lla tion experience



Desktop Study

• Informa tion sourcestypica lly a va ila ble during the desktop study pha sefor a new projectdevelopment in a newa rea (e .g. Ta nza nia ):

• Geologica l se tting• Prelimina ry

geophysica linforma tion



Ea rly Pha se : Soil Investiga tion Scope of Work Definition

12 | Geotechnica l considera tions throughout the entire project lifecycle: from perception to execution

“The scope of work for the ABC Development Area soil investigation consists of:• A detailed soil investigation at TEMPLATE X where geotechnical

information is required for foundation design purposes• Optional soil investigation at an additional template location • Optional soil investigation for an UnMannedWellhead Platform• Pipeline routes between the new template locations and existing

infrastructure to determine pipe soil interaction properties and to assess trenchability”


Ea rly Pha se (a nd beyond): Opera tions

• Selection of geotechnica l drilling equipment: • Remoteness• Wa ter depth• Expected soil conditions• Potentia l geoha za rds

• Design a nd se lection of founda tion concept• All of the a bove• Insta lla tion / penetra tion



Ea rly Pha se : Soil Investiga tion Cha llenges / La b Testing Considera tions

Tjelta , T.I. & Yetginer, A.G. 20 10 . Luva deepwater site investigation programme and findings. Proc. 2nd ISFOG.



Ea rly Pha se : La b Testing

Worldwide Offshore Database Dogger Bank


Loss of memory


Engineering: Na tura l Va ria bility

10 0 9-1 10 0 9-1A Dista nce: 3m



Engineering: Na tura l Va ria bility

• Da ta from boreholes kilometers a pa rt in a comple te ly different geologica l se tting



Pla nned scope of work for the development a rea

A Moving Ta rge t?


Fa cilities la yout upda ted oncethe subsurfa ce informa tion is further ma tured


Execution: Wha t you see is not wha t you get!



Wha t you see is not wha t you get!

• Na tura l e rosion of the sea bed due to scour


Open 25 September 20 1921 | Geotechnica l considera tions throughout the entire project lifecycle: from perception to execution



• Ma nma de erosion of the sea bed due to drilling



ISO 13628-15:20 11 Subsea Structures a nd Ma nifolds



There is however one considera tion which will a lwa ys rema in a cha llenge…


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Gülin Yetginer, Equinor Lea ding Advisor Geotechnics

Geotechnica l considera tions throughout the entire project lifecycle : from perception to execution

Workshop - Challenges in Offshore Geotechnics - Gulin T ...

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