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¹ EBN, the Netherlands. E-mail: exploration@ebn.nl² PanTerra Geoconsultants³ Utrecht University

Marloes Kortekaas¹, Ulf Böker², Cas van der Kooij³, Bastiaan Jaarsma¹ and Eveline Rosendaal¹

Mesozoic Resource Potential in the Southern Permian Basin, 8-9 Sept 2016, London

The Triassic Main Buntsandsteinplay – New prospectivity in the Dutch northern offshore

Top RBMVL (mTVD)

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Introduction

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Terracube

Currently no Triassic fields in Dutch northern offshore

General perception:• Thick ZE prevents HC migration into Trias• Thinning/shaling out of sst packages

towards north

Only 20 wells have been drilled in studyarea (17000 km2) with MBU as primary/secondary target.

11 of these wells: invalid tests of theplay

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Introduction – northern provenance?

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?

Source: Southern Permian Basin Atlas

Well locations with Sollingfluvial sands sourced fromRingkøbing-Fyn High (Olivarius et al., 2015)

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Presentation outline

• Regional geology 5 countries-area Indications for local sediment provenance (DK and UK)

• New data: biostratigraphy, heavy minerals, grain size analyses

• New Triassic prospectivity away frommain fairway

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Stratigraphic subdivision of the Triassic

Source: van der Kooij, 2016

Main BuntsandsteinSubgroup (MBU)

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Northern Early Triassic sands: local provenance?

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RB_BArfai et al., 2014

RBMVL_TEBN, 2015

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Where are the structural highs?

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OGA 2D seismic lines couldhelp define outline in UK

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Northern reservoir provenance?

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Fluvial sands withnorthern provenance mayhave developed as reservoir in thenorthwestern area.

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Southern provenance(thick RBMVL, high N/G)

D12-04-S1

A15-01

A05-01

Southern provenance(thin RBMVL, low N/G)

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B13-01

Southern provenance(‘classic’ RBMVL, high N/G)

F15-01

Southern provenance(‘classic’ RBMVL, low N/G)

F04-01

GR DT RHOB

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Early Triassic thickening: depocentre at A15-01?

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TWT

TWT

van der Kooij, MSc-thesis 2016

A15-01A15-01

A18-01 A18-01

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A05-01, Bertel-1: potential for Keuper Schilfsst?

Bertel-01 (1992)

• Inconsistencies in biostrat. analysis reported

• Trias-/Jurassic boundary doubted

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Bertel-1

A15-01

A05-01

A05-01 (1999 – Amerada Hess)

Limited info on nlog

• 2016: Biostrat analyses by TNO: Late Jurassic/Early Cretaceousstrata present as well as (Carnian?) Triassic strata

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TNO, 2016: biostratigraphical analysis

RB_BArfai et al., 2014

RBMVL_TEBN, 2015

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A05-01, A15-01, A18-01: grainsize analysis

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Bertel-1

A15-01

A05-01

Bezemer, BSc-thesis 2016

A18-01

RB_BArfai et al., 2014

RBMVL_TEBN, 2015

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Intermediate results heavy mineral analyses

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Vonk, BSc-thesis 2016

Fennoscandian?

Shetland Islands?

MNSH?

A05-01 A15-01 A18-01

Variscan?

Variscan?

Variscan?

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Top Lower Volpriehausen Sst depth map - Prospectivity

Three types of leads:

1) “classic” leads with proven types of trap, source, seal andreservoir

2) leads which may be sourcedwith HC’s via Tertiary volcanicdykes

3) leads with local reservoir provenance area1

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3RB_B (depth) from Arfai et al., 2014

RBMVL_T (EBN)

UK Triassic gas fields that are sourcedfrom the Carboniferous via Tertiaryvolcanic dykes. The dykes extend intothe Dutch sector with leads lining up along their strike.

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Charge mechanisms

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Three charge mechanisms:

• Salt windows (ZE thickness)

• Faults

• Volcanic dykes

Analysis per lead is required

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MBU gas fields UK charged via fractures near volcanic dykes (a.o. Underhill, 2009).

Tertiary dyke trend UK (Kirton and Donato, 1985)

Tertiary dyke trend UK (Underhill, 2009)

Charge via volcanic dykes

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Amplitude extraction at base Tertiary

A

A’

A A’

15

25 km

• Thick ZE: charge bypassed ZE via volcanic dykes

• Significant lateral HC migration

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Source Rock potential (Lower Carboniferous coals)

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30 m coal23 m coal

8 m coal

Coals• N-ward increase in Lower

Carboniferous coal content (Scremerston Fm.)

• Yoredale Fm and Namurian alsocontain coal; up to 7.5 m encountered in wells.

2 m coal

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Leads• 53 structures

• P50 GIIP of ~87 BCM (unrisked)

• Closures also located in open acreage

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Conclusions

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Work in progress…We welcome any suggestions:

marloes.kortekaas@ebn.nl

• New prospectivity away from themain fairway

• Local reservoir development

• Potential for Upper Triassicreservoirs?

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Thank you for your attention

More information? Contact us:

exploration@ebn.nl

Acknowledgements:Fugro and Spectrum ASA, for giving permission to show data from the DEF survey

EBN Colleagues, students Utrecht University: Aike Vonk (heavy mineral analysis) and GioiaBezemer (grain size analysis)

References:Southern Permian Basin atlas (2010)

Geology of the Netherlands (2007)

Arfai et al. (2014), Late Palaeozoic to Early Cenozoic geological evolution of the Entenschnabel, NJG.

Olivarius et al. (2015), Provenance of the Lower Triassic Bunter Sandstone Formation, Basin Research.

Van der Kooij, C. (2016), Triassic sand development in the northern Dutch offshore (MSc thesis Utrecht University)

Vonk, A. (2016), Provenance of Lower Triassic sands in the northern Dutch offshore (BSc thesis, Utrecht University)

Bezemer, G. (2016), Grain size analysis of the Triassic Main Buntsandstein Subgroup in the northern Dutch offshore (BSc thesis, Utrecht University)

TNO, 2016: biostratigraphical analysis carried out for EBN.

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