7th May, 2019 Page 1

AN INTEGRATED FORMATION EVALUATION APPROACH TO CHARACTERIZE A

TURBIDITE FAN COMPLEX: CASE STUDY, FALKLAND ISLANDS

Graham DavisDEVEX May 2019

Co-authors: Rob Newbould, and Aldo Lopez, Premier Oil

Hamid Hadibeik, Zunerge Guevara, Bob Engelman, Ron Balliet, Sandeep Ramakrishna, and Andrew Imrie, Halliburton

7th May, 2019

Outline

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• Introduction - North Falkland Basin and Sea Lion Field

• The 14/15b-5 Zebedee Exploration Well

• Formation Evaluation - Objectives

• Results:• Image Log Facies Recognition

• Facies Properties

• Impact on Evaluation

• Conclusions

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North Falklands Basin: Sea Lion Area History

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1990’s

• Seismic Acquired• 6 exploration wells, no commercial hydrocarbons

2004/05• RKH awarded blocks PL023/32 and 33

2008• Desire awarded 3 blocks

2010

• April: 14/10-2 spudded• September: Sea Lion discovery declared: 69m reservoir, medium gravity crude

2011• May-November: PL032 appraisal; 6 wells and 1 sidetrack. 14/10-9, 9z declared a discovery (Casper)

2012• Premier farm in for 60% of RKH’s Falkland Islands interest

2013• Premier and RKH acquire PL004 from FOGL. RKH acquire FOGL

2015

• Premier led exploration campaign• Zebedee and Isobel Oil Discoveries made

Present• Phase 1 Development DEFINE phase

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Area Location

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• Located in the southern ocean on the Falkland Plateau

• 220km North of the Falkland Islands in the North Falkland basin.

• Water Depth ca. 450m

Zebedee

Isobel

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Northern Rift Basin Generalised Stratigraphy

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• The Northern Rift Basin is filled by Cretaceous and Tertiary clastics

• Cretaceous - fluvial / lacustrine

• Tertiary - marine

• Lacustrine claystones are organic rich source rocks with high TOC

• Potential Reservoirs • Syn-rift fluvial sandstones

• Early post-rift lacustrine turbidite sandstones

• Late post rift fluvial deltaic sandstones

• Lacustrine turbidite sandstones • Sourced from the shelf areas in the east

through canyons and feeder channels

• Accumulate to form deep water fans

• Hydrocarbon accumulations in multiple fans many of which are overlapping

Sea Lion

Isobel Area

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Zebedee Well Opportunity

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14/15-4z

14/15b-5

14/15-3

Geobody extraction Zebedee fan - EEI-70 Amplitude

AA’

A A’

Flatttened on AAOM

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14/15b-5 (Zebedee) Objectives

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• Extend F2 Sea Lion / “Satellite” discovered resource further south within PL004b & evaluate F3 potential

• Primary Target• F2 Zebedee

• Secondary Targets• F1 Jackie

• F2 Hector

• F3B Parker

• F3E Catriona

• F3G Orinoco North

• Core primary target reservoir, • RSWC in secondary targets

• Log entire open hole interval

• Acquire pressure data

• Acquire representative fluid samples

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Wireline Logging Programme

• GR-CSNG-DSN-SDL-AST-ALAT-MSFL-SP

• GR-MRIL-XL (NMR)

• GR-XRMI (Imaging Tool)

• GR-RDT (Pressures and Sampling)

• GR-HRSCTB (Rotary Cores)

• GR-VSP (Seismic)

14/15b-5 (Zebedee) - Integrated Results

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7th May, 2019

Wireline Logging Programme

• GR-CSNG-DSN-SDL-AST-ALAT-MSFL-SP

• GR-MRIL-XL (NMR)

• GR-XRMI (Imaging Tool)

• GR-RDT (Pressures and Sampling)

• GR-HRSCTB (Rotary Cores)

• GR-VSP (Seismic)

14/15b-5 (Zebedee) - Integrated Results

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Results Summary

• Hector Interval• NtG = 0.72• Avg Ø = 20.3% • Avg Vsh = 8.1%• Avg Sw = 19.5%

• Zebedee Interval• NtG = 0.95• Avg Ø = 24.5% • Avg Vsh = 6.7%• Avg Sw = 25.5%

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14/15b-5 (Zebedee) - Integrated Results – Main Sand

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14/15b-5 (Zebedee) - Integrated Results – Main Sand

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Evaluation Highlights

• Hole Conditions good (WBM)

• Log quality generally good

• Clear invasion profile across porous sands, good +ve SP deflections

• RDT: 55 pressures (25 good, 12 tight, 17 SC, 1 repeat)

• Good formation samples obtained

• 7 Samples:• Jackie - Water (x1)• Hector - gas (x 2) • Ninky Oil - (x1)• Zebedee - Oil (x 2)• Pre Zebedee - Water /tr oil (x1)

• Pressure Gradients coincident with Sealion

• Image quality excellent

• Image Facies identified………

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14/15b-5 (Zebedee) - Integrated Results – Main Sand

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Evaluation Highlights

• Hole Conditions good (WBM)

• Log quality generally good

• Clear invasion profile across porous sands, good +ve SP deflections

• RDT: 55 pressures (25 good, 12 tight, 17 SC, 1 repeat)

• Good formation samples obtained

• 7 Samples:• Jackie - Water (x1)• Hector - gas (x 2) • Ninky Oil - (x1)• Zebedee - Oil (x 2)• Pre Zebedee - Water /tr oil (x1)

• Pressure Gradients coincident with Sealion

• Image quality excellent

• Image Facies identified………

Good NMR

Med. NMR

Poor NMR

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14/15b-5 (Zebedee) – Image Facies Recognition: Facies A

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Facies A

Coupled debrites or coarse-tail graded basal lag

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14/15b-5 (Zebedee) – Image Facies Recognition: Facies B

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Clean, very fine to fine-grained, well-sorted sands

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14/15b-5 (Zebedee) – Image Facies Recognition: Facies C

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Fine-grained sandstone with minor clay content

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14/15b-5 (Zebedee) – Image Facies Recognition: Facies D

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Thin to very thin bedded or laminated, very fine-grained sandstone

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14/15b-5 (Zebedee) Image Facies: Core Validation - Facies ALL

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2.6%<0.001mD

26.8%360 mD

24.7%85 mD

15.0%2.9 mD

Increasing quality

A

B

C

D

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14/15b-5 (Zebedee) – Image Facies: Core & NMR Comparison

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Facies D

Facies C

Facies B

CT Scan ImageXY Plane

Laminated very fine to fine grained sandstone and mudstone

Clean very fine grained sandstone, minor clay content with some discontinuous clay laminae

Uniformly clean very fine to fine grained sandstone.

Core Description

0 1000mD (Linear)

Permeability Contrast

- Predicted Perm- NMR PermK Core PermM RDT Mob

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Reservoir Quality from Nuclear Magnetic Resonance (NMR)

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• Ratio of Free Fluid (Good Reservoir) to Bound Fluid (Poor Reservoir)FF

I to

BVI R

atio

??

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Rock Quality Index (RQI) and Turbidite Facies

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In “Good” Facies B & C we can obtain mobilitiesand formation pressures at RQI’s <1

In “Poor” Facies A & D RQI’s generally have to be >>1 to obtain mobilitiesand formation pressures

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14/15b-5 (Zebedee) – Formation Testing Programme

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Mostly Water

GAS & OIL

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14/15b-5 (Zebedee) – Formation Testing Programme

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Facies C &D

Facies B & C

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Conclusions

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• Using an integrated workflow, the combination of conventional, image and NMR logs can be processed for basic reservoir properties, facies interpretation, and Reservoir Quality Index (RQI), which allows optimization and real-time adjustments to the formation pressure and fluid sampling programme.

• RQI cut-off for successful pressure testing/sampling potentially varies by facies, pressures can be obtained at lower RQI in good quality facies than in their poorer facies counterparts.

• The difference in properties between the two best Facies is not readily observed in conventional visual core description, or carried in current subsurface modelling, however these Operational insights may be utilised in future reservoir property investigation & characterisation.

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Acknowledgements

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• The Authors would like to acknowledge Rockhopper Exploration Plc for their co-operation and permission to publish this Paper.