Sand Injectites in the North Sea and the Atlantic margin Giant fields - Infill targets - Drilling hazards - Migration paths

Mads HuuseWith unpublished interpretation input from Tobi Olobayo (PhD 2015)Basin Studies and Petroleum Geoscience Group, University of Manchester, UK

mads.huuse@manchester.ac.uk

FORCE Conference: Underexplored Plays, NPD, Stavanger 8-9 April 2015

Stratigraphic and geographic occurrence of sand injection in the North Sea

– Northeast Viking Graben• Late Cretaceous (Måløy slope), Late Paleocene / Early Eocene

– North Viking Graben• Mid Eocene, Late Eocene, mid/late Miocene/Pliocene, Plio-Pleistocene

– South Viking Graben & Utsira High• Paleocene/Eocene boundary, Early Eocene, Mid Eocene, Oligo-Miocene

– Outer Moray Firth• Mid-Eocene, Late Eocene / early Oligocene, Miocene, ?Plio-Pleistocene

– Northern Central Graben• Early Eocene

– Norwegian-Danish Basin (Siri Canyon)• Late Eocene / early Oligocene, mid Miocene

– Ringkøbing-Fyn High • Late Oligocene

– ?Southern North Sea• ?Pliocene

– Faroe-Shetland Basin• Early Eocene, mid/late Miocene

– Møre Basin• Paleocene?, Miocene

– Barents Sea (Sørvestnaget Basin)• Eocene

– San Joaquin Valley (California)• Late Cretaceous, Paleocene, Eocene

– Watch this space: Uruguay, Angola, Baffin Bay, Tanzania, New Zealand…

JotunBalder

GraneSleipner

MarinerGryphonHarding

AlbaChestnut

Catcher

? ? ?

Porosity and permeability 30-40%, 1-10 D @ 1.6-2.0 km depth

Alba Field (Eocene Outer Moray Firth) Balder Field (Paleocene Utsira High)

Duranti et al. 2002: Pet Geosci

Briedis et al. 2007: AAPG Mem 87

Analogues for crestal sand injectites in Californian outcrops: Santa Cruz (a, b), San Joaquin Valley (c, d)

Eocene Alba Field (Grid sst): 1B bbl field discovered by mistake..

Wing-producers doubled production on Gryphon (UK 9/18b)

Jackson et al. 2011: AAPG BulletinProduction data courtesy of Maersk Oil UK

Seismic stratigraphic recognition of depositional, remobilised and fully injected sandstones

Depositional sandstone(no remobilisation)

Mound (turbidite or extrudite)

Channel fill (truncation, onlap fill)

Remobilised sand(in situ)

Remobilised mound

Remobilised channel fill

100% injected sand(saucer-shaped injectites)

Laccolith and marginal dykes (+ extrudite)

Conical injectite

Huuse et al. 2012: EAGE

Submarine fans, lobes etc, in a sequence stratigraphic framework - are they all primary depositional sandstones?

Den Hartog Jager et al 1993: PGC4

Paleocene sand injectites: NCS 35/11 (NE North Sea)

Dmitrieva et al. 2012: Petroleum Geoscience

North Viking Graben injectites, extrudites and mudstone diagenesis

Huuse 2008: WorldOil

Structural-stratigraphic setting of large-scale sand injectites in the South Viking Graben & Utsira High

3D visualizations of injected sands reservoirs: South Viking Graben

South Viking Graben: sand injectite heaven

Isolated massive sandstone mounds in the South Viking Graben:Balder (earliest Eocene) thickness and TWT structure

Gamma – Volund: Early and Middle Eocene episodes

Wing-like reflections emanate from massive Balder-age sandstone on a scale similar to Alba and other remobilized fields (>200 m vertical)

Total sandstone volume ~ 2.5 km3 (all injected)

View looking North

24/9-3 24/9-4

Volund Field: Balder sand with marginal ‘wings’

Regional Top Balder

OWC

Frigg

Balder

Sele

Jack up

Discordant ‘wings’

Volund: 3D morphology

Chestnut / Alba fairway: mid and Late Eocene episodes

Outer Moray Firth: sand injectite reservoirs, migration paths and drilling hazards

Huuse et al. 2005: Petroleum Geology Conference

Sand injectites as reservoirs or conduits is not a new concept!

AAPG Bulletin 1930:

UKCS Q22: lower Eocene (Caran) sst intrusions:

• Migration paths• Thief sands• Reservoirs

Murphy & Wood 2011

Ringkøbing-Fyn High Oligocene: a spitting image of Mariner (Paleocene, East Shetland Platform)

Andresen & Clausen 2014: Basin Research

BCU depth map with selected sand injectite field locations

28/9: Catcher

29/6: Danica

22/2: Chestnut

15/30: Alba

24/9-7: Volund

Loseth et al. 2013

35/11: Dmitrieva et al 2012

35/3,6,9, 36/1,4,7: Jackson et al. 2012

9/11: Mariner

Modified from Fraser et al. 2003 (Millennium Atlas)

And overall injectite province outline

Kimmeridge Clay oil & gas expulsion vs sand injectite locations

Modified from Kumala et al. 2003 – Millennium Atlas

North Sea overpressure (Jurassic, Cenozoic) vsSand Injection Province: mutually exclusive

Overpressure in the North Sea (modified from Kumala et al. 2003 – Mill Atlas)

Cretaceous Late Paleocene/ Early Eocene mid Eocene

Late Eocene/Early Oligocene Oligocene mid/late Miocene

Central Graben transect, overpressure and main injectite locations. Modified from Moss et al. 2003 Millennium Atlas

SUMMARY..• At least 7 sand injection events in the North Sea

• 8-10 Myr interval• some 3-500 m of sedimentation between each episode

• Mutually exclusive relationship between SI and present-day overpressures (long term conduits!)

• Only a handful of exploration wells targeting injectites• wells targeting injectites are aiming at thick ‘wings’ updip of

proven oil within jack-up/differential compaction anticlines

• Most larger fields located along basin margins • charge control

• Origin of North Sea injectites still poorly understood• Likely multiple causes

• Current work focused on regional 3D stratigraphic framework & detailed characterization and modelling (IS Phase 3 JIP)

Silica diagenesis and sand injectites: Viking Graben, Faroe-Shetland and Møre Basins

Davies et al. 2006: Geology

Ormen Lange Miocene above opal A/CT

Huuse et al. 2014: EAGE Conference Abstracts

Faroe-Shetland Basin (NE Atlantic): Conical intrusions below and 1km above Eocene fan

Barents Sea: middle Eocene sand injectites (Safronova PhD 2013)

E&P implications of sand injectition• ‘Unconventional’ sandstone occurrence

• ‘Unconventional’ reservoir geometry

• Excellent reservoir properties (30-40% ϕ, 1-10 D)

• Long-term conduits for fluid flow- Migration paths, thief sands, connectivity

• Drilling hazards..

mads.huuse@manchester.ac.uk