Triassic and Jurassic reservoir development in the Barents · PDF file13:00 Gustafsson L.E. (ENI Norge) - Realgrunnen Sub-group reservoir development in the Goliat Field: updated results

Abstract Volume Stavanger, 9th – 10th June 2015

Organizing committee:

Terje Hellem, Idemitsu

Domenico Chiarella, Rocksource

Eirik Rosseland Knutsen, BP

Alf Eivind Ryseth, Statoil

Morten Bergan, Bayerngas

Tone Mydland, NPD

Triassic and Jurassic reservoir development

in the Barents Sea FORCE workshop arranged by the Sedimentology Stratigraphy network

The workshop has been sponsored by

Organizing committee: Terje Hellem (Idemitsu) Domenico Chiarella (Rocksource) Eirik Rosseland Knutsen (BP) Alf Eivind Ryseth (Statoil) Morten Bergan (Bayerngas) Tone Mydland (NPD)

Triassic and Jurassic reservoir development in the Barents Sea Valhall, NPD in Stavanger, 9th -10th June 2015

9th June - Triassic Sassendalen Group and Storfjorden Sub-group

08:00 Registration and coffee

08:30 Welcome: Terje Hellem (Idemitsu) and Morten Bergan (Bayerngas)

09:00 Keynote speaker - Mørk, A. & Lundschien, B.A. (SINTEF, NPD) - The Triassic Svalbard Hydrocarbon Play Model: A prospective model for the Barents Shelf

09:45 Lord, G.S., Solvi, K.H., Klausen, T.G. & Mørk, A. (NTNU, UNIS, UiB) - Triassic channel bodies on Hopen, Svalbard: Their facies, stratigraphic significance and spatial distribution

10:15 Knutsen, E.R. (UNIS/UiB, now at BP) - Sedimentology of the offshore- to tide-dominated Upper Triassic De Geerdalen Formation on central Spitsbergen and examples of comparable facies in the equivalent Snadd Formation

10:45 Coffee/Tea break

Chairs: Alf Eivind Ryseth (Statoil) and Domenico Chiarella (Rocksource)

11:00 Arrigoni, V. et al. (ENI Norge) - Kobbe Fm reservoir development in the Goliat Field

11:30 Norina, D.A. (Total S.A. France) – Triassic of the Barents Sea shelf: depositional environments and hydrocarbon potential (Russian Barents sector)

12:00 Lunch break

Chairs: Morten Bergan (Bayerngas) and Eirik Rosseland Knutsen (BP)

13:00 Net, L.I., Ochoa, M., McDougall, N.D. & Pestman, P. (Repsol) - Occurrence and distribution of coating cements in the Snadd Formation sandstones (Triassic), Barents Sea, Norway: impact on reservoir quality

13:30 Buckley, S., Braathen, A. et al. (Uni Research CIPR) – State of-the-art of digital outcrop mapping methods: application to the Triassic of Edgeøya, Svalbard

14:00 Olaussen, S. (UNIS) & Rismyhr, B. (UNIS/UiB) (on behalf of ENI Norge) – Core presentation (7122/7-6, Kobbe Fm – Goliat field)

14:15 Stinson, P. (Total E&P Norge) – Core presentation (7225/3-1 and 7225/3-2 - Norvarg)

14:30 Ryseth, A.E. (Statoil) – Core presentation (7222/6-1S – and 7222/11-1)


Core workshop

15:00 Core workshop with:

Olaussen, S. (UNIS) & Rismyhr, B. (UNIS/UiB) (on behalf of ENI Norge) – well 7122/7-6 (Goliat field)

Stinson, P. (Total E&P Norge) – well 7225/3-1 and 7225/3-2 (Norvarg)

Ryseth, A.E. (Statoil) – well 7222/6-1S (Obesum) – and 7222/11-1 (Caurus)

17:00 End of day 1

19:00 Dinner at Hall Toll, ice breaker drink at 18.00


Triassic and Jurassic reservoir development in the Barents Sea Valhall, NPD in Stavanger, 9th -10th June 2015

10th June - Jurassic Realgrunnen Sub-group

08:30 Coffee/Tea

Chairs: Alf Eivind Ryseth (Statoil) and Eirik Rosseland Knutsen (BP)

09:00 Keynote speaker - Olaussen, S., Rismyhr, B. et al. (UNIS) - Uppermost Triassic to «mid» Jurassic basin fill in the Western Barents Sea and Svalbard; are influence of larger tectonic movements underestimated in sequence stratigraphic and facies analysis?

09:45 Alsen, P., Bjerager, M., Guarnieri, P., & Hovikoski, J. (GEUS) - The Triassic-Jurassic tectono-sedimentary evolution of the Wandel Sea Basin (North Greenland): implications for the understanding of the western Barents Sea

10:15 Rismyhr, B. & Olaussen, S. (UiB - UNIS) - Facies characteristics and sequence stratigraphy of the condensed Upper Triassic-Middle Jurassic succession on eastern Spitsbergen


Chairs: Terje Hellem (Idemitsu) and Eirik Rosseland Knutsen (BP)

11:00 Wærum, G. (Statoil) - Snøhvit area: 8 years of production and injection in the Realgrunnen reservoir

11:30 Watt, J. (Statoil) - Field Development Geology from Johan Castberg

12:00 Lunch break

Chairs: Morten Bergan (Bayerngas) and Domenico Chiarella (Rocksource)

13:00 Gustafsson L.E. (ENI Norge) - Realgrunnen Sub-group reservoir development in the Goliat Field: updated results based on recent wells

13:30 Kurz, T., Buckley, S., Howell, J. & Naumann, N. (Uni Research CIPR) - Hyperspectral analysis of core material: a case study from the Barents Sea (Finnmark Platform)

14:00 Olaussen, S. (UNIS) & Rismyhr, B. (UNIS/UiB) (on behalf of ENI Norge) – Core presentation (7122/7-3 and 7122/7-6, Realgrunnen Subgroup – Goliat field)

14:15 Ryseth, A. (Statoil) – Core presentation (7120/6-2S Snøhvit field and 7220/7-1 Johan Castberg field - Realgrunnen Sub-group)


Core workshop

15:00 Core workshop with:

Olaussen, S. (UNIS) & Rismyhr, B. (UNIS/UiB) (on behalf of ENI Norge) – well 7122/7-3 and 7122/7-6 (Goliat field)

Ryseth, A. (Statoil) – well 7120/6-2S (Snøhvit field) and 7220/7-1 (Johan Castberg field)

17:00 Wrap up and end of the workshop


The Triassic Svalbard Hydrocarbon Play Model; A prospective model for the Barents Shelf

Atle Mørk1,2 and Bjørn Anders Lundschien3

1SINTEF Petroleum Research 2Department of Geology and Mineral Resources Engineering, Norwegian university of science and technology (NTNU) 3Norwegian Petroleum Directorate (NPD)

With contributions from: Ingrid B. Hynne, Tore Høy, Tore Klausen, Gareth S. Lord, Mai Britt E. Mørk, Rita S. Rød, Kristoffer H. Solvi & Marina A. Tugarova

The up to 700 m thick Lower and Middle Triassic Sassendalen Group is shale dominated although it also contains minor sandstones. The upper part, mainly the Botneheia Formation, is very organic rich and contains mixed type II and III kerogen. The Upper Triassic to mid. Jurassic Kapp Toscana Group is rich in sandstones representing fluvial, deltaic and shallow marine deposits (up to 500 m thick in exposures but 700 m thick including the near subsurface on Svalbard). Both groups sediments continue southwards in the Barents Shelf where they form a prospective hydrocarbon play model.

These groups outcrop on all major islands of the Svalbard Archipelago and we have visited numerous localities to study facies variations as well as organic and reservoir properties. Between Svalbard and the southern part of the Barents shelf, where hydrocarbon exploration has taken place since 1980, NPD has carried our extensive seismic studies and drilled 12 shallow stratigraphic coreholes penetrating the Triassic succession, while IKU/SINTEF have drilled similar stratigraphic coreholes in the southern part of the Barents Sea. Together with exploration wells this gives a good data coverage to extrapolate interpretations for understanding the northern Barents Sea which is still not open for exploration.

Major parts of the Barents shelf display Triassic and Jurassic sediments under a thin Quaternary cover, implying that these rocks form the upper part of the sedimentary succession. It also implies that hydrocarbon accumulations may be relatively shallow making restrictions for source rock maturation and possibility for tight seals; the post Triassic time may thus be critical for filling and unfortunately emptying of any possible reservoirs.

After the Permian formation of the Pangea Supercontinent by fusing Laurentsia with Siberia forming the Uralian Mountain chain a large shallow shelf bay was formed on the northern coast of Pangea facing Panthalassa. This bay, mainly around 400 m deep, was filled by sediment during the Triassic. We have mapped parallel clinoform-belts, representing sedimentation in front of prograding rivers down to the shelffloor starting in the late Permian-Induan close to the Norwegian mainland ending in the late Carnian northeast of Svalbard.

Organic rich mudstones, similar to the Botneheia Formation on Svalbard, occur all the way down to southern Barents shelf, however the organic rich facies started earlier (in the


Olenekian) in the areas most restricted and distal to the Panthalassa sea. It is also possible that similar organic rich accumulations occurred in the deeper areas in front of the clinoform belts. The northwestward prograding clinoforms that during the late Triassic fills the Barents shelf bay leaves behind an extensive delta system rich in sand filled channels which rests in fine-grained delta top sediment. Such channels are nicely displayed in the steep cliffs of Hopen, the southeasternmost island of Svalbard, and similar channels systems are mapped throughout the Barents shelf. Sandstone properties, a result of primary mineralogy and the transport processes control reservoir properties. When the Barents shelf was finally filled by sediment in the latest Triassic extensive reworking of these sediments during the early to mid. Jurassic resulted in maturation of the sandstones improving reservoir properties.


Triassic channel bodies on Hopen, Svalbard: Their facies, stratigraphic significance and spatial distribution

Gareth S. Lord1,2, Kristoffer H. Solvi1, Tore G. Klausen3 and Atle Mørk1,4

1Department of Geology and Mineral Resources Engineering, Norwegian University of Science and Technology (NTNU), NO-7491 Trondheim, Norway. e-mail: [email protected] 2The University Centre in Svalbard (UNIS), Longyearbyen, Norway. 3University of Bergen, Norway. 4 SINTEF Petroleum Research, Trondheim, Norway. 4SINTEF Petroleum Research, Trondheim, Norway

Channelized deposits are observed in the steep cliff sections on the island of Hopen in SE Svalbard. This presents a unique opportunity to study the geometry and spatial distribution of these channel bodies within the paralic depositional environment of the Carnian aged De Geerdalen Formation. In this study we have combined field observations with a 3D geological model of the island.

Utilising PhotoModeler™ software, with an extensive photo database of the study area, it has been possible to identify the presence of 25 channel bodies on the island. 12 have been observed directly in the field, with the remainder being identified with photo mosaics and by implementing the 3D geological model. Analysis has shown that the channels were deposited in three different depositional environments; fluvial, tidal and estuarine. Channel deposits that have not been observed in the field are interpreted based on their geometries and visible internal architectures seen within high resolution outcrop photographs.

Channel bodies are seen to be confined to discrete stratigraphical intervals within the De Geerdalen Formation, defined as channel zones. Three zones are described, based upon the concentration of channels within each interval. These intervals are categorised as a lower fluvial zone, a middle tidal zone and an upper fluvial zone.

These zones are subsequently overlain by a marine flooding event represented by the Hopen Member. An overall paralic depositional environment for the De Geerdalen Formation on Hopen is maintained, however the nature of channels clearly shows a greater influence of fluvial deposition for the formation in this region of Svalbard. This indicates deposition in a more proximal position relative to the source area, than elsewhere on Svalbard.

Figure - Schematic overview of stratigraphical logs recorded on the island of Hopen by the Hopen Geology Project. Log locations are marked on the map and are flattened along the base of the Hopen Member in the correlation. A simplified interpretation of depositional environment is given and those channels which have been logged in the field are highlighted by their channel type. The approximate position of the zones is denoted based on the position of depositional environments within the log correlation. In addition the approximate position of all identified channels is presented in the cross section. Logs are provided by the Hopen Geology Project, whilst map, cross section and facies interpretations is adapted after Mørk et al. (2013).



Sedimentology of the offshore- to tide-dominated Upper Triassic De Geerdalen Formation on central Spitsbergen and examples of comparable facies in the

equivalent Snadd Formation

Rosseland Knutsen, Eirik - UNIS/UiB, now at BP Norge

New sedimentological data from the upper De Geerdalen Formation on central Spitsbergen contributes to increased understanding of depositional mechanisms and paleogeography during the Late Triassic on Svalbard. A detailed outcrop study has been carried out along a beach located close to Deltaneset in the southern Isfjorden. The studied succession is 70 meters thick and characterized by an allover shallowing upward trend. The lower part of the succession is interpreted to have accumulated in an offshore to offshore-transition zone environment, based on marine trace and body fossils, allover fine grained lithology and predominance of wave- and storm-generated sedimentary structures. A glauconitic and fossiliferous condensed section situated within these deposits reflects a period with restricted detrital sediment supply. A tidal ravinement surface separates the lower part of the succession from overlying estuary fill deposits. The estuarine strata are dominated by vertically stacked marginal marine deposits, including tidal bar, crevasse splay, paleosol, tidal flat and lagoonal facies. It is suggested that the vertical variations reflect lateral migration of adjacent sub-environments within a mainly aggrading estuary complex. Additionally, a comparison of similar facies in the De Geerdalen Formation and equivalent offshore Snadd Formation is conducted. The sedimentological data from the Snadd Formation were obtained by logging of well cores from four wells in the southwestern Barents Sea. The well cores predominately contain continental to marginal marine deposits, in addition to one interval showing a shallowing upward sequence from offshore-transition zone to middle shoreface facies. Most of the facies identified in the De Geerdalen Formation are comparable with those recognized in the Snadd Formation, although the well cores contain significantly thicker sandstone bodies.


Kobbe Fm. reservoir development in the Goliat Field: updated results based on

recent wells

Veronica Arrigoni - Eni Norge AS

The Goliat field is part of PL229, located in block 7122/7 in the SW part of the Barents

Sea. The field is located on the SE margin of the Hammerfest Basin and banked to the

Troms-Finnmark Fault complex. Goliat is the first field to produce oil in the Barents Sea

with production start-up scheduled in the 2nd half of 2015. The field consists of two

separate siliciclastic reservoirs, the Middle Triassic Kobbe Formation and the Middle

Jurassic Realgrunnen Subgroup both contain oil with an overlaying gas cap.

The Kobbe formation represents a WSW-ENE prograding deltaic system with mouth bars

and tidal influenced lobes. In its lower section, the system shifts to a more proximal,

heterogeneous fluvial setting. At PDO stage, in 2010, 3 exploration wells and one sidetrack

had penetrated the Kobbe reservoir. To today, approaching production start-up, one

appraisal well, 5 oil producers, 4 water injectors and 2 gas injectors have been drilled into

the reservoir. The development wells have greatly contributed to better define the

complex hydraulic framework of the reservoir and constrain the distribution of the

sedimentary facies across the several reservoir units. The collection of data to today has

confirmed the sedimentological model for Kobbe across the entire field characterized by

a relatively high NTG Upper Sequence (Kobbe 9-8) of fluvial sands and tidal lobes

overlapping the more shaly heterogenous fluvial and deltaic facies of the Lower Kobbe

(Kobbe 7-2).

Exception to this otherwise established sedimentary setting was showed in the appraisal

well 7122/7-6, drilled in 2012 in the Main segment. The well found a shallower HC contact

and also the presence of unexpected poor reservoir properties in the Upper Kobbe of this

segment. 28m of reservoir cores were retrieved in the well and sedimentological analysis

performed by Eni HQ in Milan; the study suggests that Kobbe 9 has there developed as a

low-energy coastal lagoon, partially open to the sea. The extent of this more shaly facies

remains uncertain in the area. The reservoir zonation and facies proportions and

distributions have been optimized according to this and all other well observations.

The structural framework of Goliat, originally involving 4 separate compartments, has

proved to be more challenging than expected: the development wells have seen a more

complex vertical and horizontal compartmentalization of the Kobbe reservoir and a

several revisions of the hydrocarbon contacts have been done since development drilling

started. The reservoir is now separated into 5 hydraulic compartments: Central, Main,

South3, South4 and South16. The gas and water gradient are aligned across the field,

while the pressure regime of the oil ring varies from North to South and, in S3 and S4

compartments, between Upper and Lower Kobbe.


To date the Goliat field, which went into the development phase realizing major

uncertainties, confirms to be a heterogeneous and structurally complex field. The drilling

schedule and the designed data acquisition have successfully targeted the main

uncertainties in the early phase and have established the best possible basis for the

imminent production start-up.

M0 C5A

S16

S4

S3


Triassic of the Barents Sea shelf: depositional environments and hydrocarbon

potential

Darya A. Norina - TOTAL (Paris, France)

The work is a part of PhD thesis conducted in Petroleum Department, Geological faculty of Lomonosov MSU

(Moscow, Russia)

Presented evaluation of structure, depositional environments, cyclicity and hydrocarbon

potential of Triassic complex in the Barents Sea shelf is based on interpretation of 2D

seismic lines, well log data for 17 wells, descriptions of well sections and outcrops, source

rock geochemical analysis and 2D basin modeling.

Triassic clastic complex reaches the maximum thickness of 10.5-12 km within the South

Barents basin and pre-Novaya Zemlya foredeep. Its lower boundary is represented by

Permian-Triassic erosion unconformity in the south-eastern margin of the basin and

marked by the downlap of Induan clinoforms. Upper boundary corresponds to the Rhaetian

erosion unconformity best pronounced in the pre-Novaya Zemlya foredeep, Kola

monocline and Pechora Sea. Interpreted Triassic reflectors – top Induan, top Olenekian, top

Ladinian – are correlated with sequence boundaries in wells.

Triassic sediments of the Barents Sea were deposited in deltaic, shallow-marine to deep

shelf environments in the large epicontinental basin. Up to 8 transgressive-regressive

sequences were identified in the well sections of the Eastern Barents Sea. Deltaic sediments

coming from the main south-eastern (Timan-Pechora) and eastern (Novaya Zemlya and

Kara land) provenances compensated the steady subsidence of the South- and North

Barents basins and pre-Novaya Zemlya foredeep in Early and Middle Triassic. Progradation

of Induan clinoforms is well-traced across the South-Barents basin towards the area of non-

compensated deep shelf deposition in the west and north-west. Since Olenekian the

clinoform break persisted in the western shelf; no clinoforms are observed in the Eastern

Barents shelf where deltaic environments had prevailed. Periodic marine transgressions

led to significant lateral shift of the shoreline: the delta plain was flooded and more shaly

packages were deposited forming transgressive system tracts. In the Late Triassic the non-

compensated area in the north-west was progressively filled with sediments.

Cyclicity of Triassic section controls the alternation of marine shales containing a mix of

marine and terrestrial organic matter (type II-III) and deltaic sediments with type III of

organic matter. The proportion of marine organic matter (type II) as well as total organic

matter content increases towards the west and north-west of the Barents Sea shelf where

Lower and Middle Triassic source rocks have high oil and gas generation potential. Triassic

source rocks in the Eastern Barents shelf contain predominantly type III of organic matter

and have variable gas generation potential, except for the shales deposited during marine

transgressions and capable of liquid hydrocarbons generation.

Main Triassic source rock kitchens are situated within the South and North Barents basins,

Saint Anna through and basins within the Western Barents shelf. Prospective zones of gas


accumulation are related to these basins, where Triassic source rocks have high maturity.

Zone of possible oil accumulations is situated in the north-west of the shelf. Zones of oil-

gas accumulations are predicted on the basins margins and within the saddles.

Figure - Triassic seismostratigraphic complex of the Eastern Barents Sea shelf on seismic data and Triassic transgressive-regressive sequences in wells with results of source rock


Occurrence and distribution of coating cements in the Snadd Formation sandstones

(Triassic), Barents Sea, Norway: impact on reservoir quality

Laura I. Net, Ochoa, M., McDougall, N.D. and Pestman, P.

Repsol Exploración S.A. Calle Méndez Álvaro 44, 28045 Madrid, Spain ([email protected], [email protected], [email protected], [email protected])

The Triassic Snadd Formation was regionally studied in the Norwegian Barents Sea in order to identify the main factors controlling its reservoir quality. Integration of conventional logs, seismic, core descriptions, petrographic and petrophysical data allowed the unit to be informally subdivided into two members: a) the Lower Snadd, dominated by lower shoreface and inner shelf deposits, and b) the Upper Snadd, which also includes fluvial and fluvio-tidal deposits. Also, a detailed sequence stratigraphic framework was built, which recognized shelf margin (SMST), transgressive (TST) and highstand (HST) system tracts. Petrographic analysis of 41 sandstone samples taken from full cores in 10 wells revealed variations in texture and composition. Whereas Lower Snadd is mostly made up of fine-grained, relatively quartz-rich feldspathic litharenites and sublitharenites (avg. QFR = 63-15-22; n = 8), Upper Snadd include very fine- to coarse-grained, relatively quartz-poor feldspathic litharenites and litharenites (avg. QFR = 48-21-31; n = 33) containing common volcanic rock (VRF) and chert (Ch) fragments. Some diagenetic processes had a fundamental role on preserving the reservoir quality of these sandstones: 1) early precipitation of pore lining/filling siderite cement straightened the rock fabric and impeded further mechanical compaction; 2) development of chlorite coatings inhibited quartz cement precipitation. Early microcrystalline, pore lining siderite is rarely present, mostly in SMST sandstones of both Lower and Upper Snadd. QEMSCAN® mapping revealed that this microcrystalline siderite can be associated to pore lining phosphate cement in sandstones close to a flooding surface (FS). More common siderite as pore filling cement later precipitated with well-developed botryoidal texture, or as macrocrystalline mosaics with “saddle” extinction. High values of intergranular volumes (IGV) and evidences of cement compaction confirmed the early character of the siderite precipitation. Also, the Mn2+-enriched character of the siderite revealed by XRD, as well as the spherulitic texture, are typical of deposition in transitional environments, in agreement with an observed peak of abundance within coastal plain sandstones, either within SMSTs of the Upper Snadd (up to 24%vol), or within TSTs of the Lower Snadd (up to 5%vol). Chlorite as coating cement is a widespread phase in the Snadd Formation, although its distribution is markedly heterogeneous (0-17%, avg. 5,6%). High values of chlorite (>10%) correspond to sandstones from fluvial or freshwater-influenced marine settings, suggesting a potential formation mechanism involving the iron being transported by fluvial systems, and later being remobilized into a reducing shallow marine environment. Chlorite coatings are thick and continuous within SMSTs and TSTs (avg. Chl_pl 4.8% and 3.0%, respectively), but thin and discontinuous within the HSTs (avg. Chl_pl 0.8%) (Figure 1). However, the inverse relationship of chlorite coatings to quartz cement is partially masked (avg. Qtz Cmt 2.1% in SMSTs, 9.6% in TSTs, and 5.0% in HSTs) due to the presence of other cements also contributing to inhibit quartz cementation in HST sandstones, e.g.,


calcite (avg. 8.3%). The abundance of chlorite as coating cement directly correlates to core porosity (avg. PHI = 26,7% in SMSTs, 21,6% in TSTs, and 19,5% in HSTs), and it is a key factor to understand the overall distribution of reservoir quality in the unit. A combination of the above described depositional and diagenetic characteristics help to explain best reservoir quality characteristics are found within SMST sandstones of the Upper Snadd (avg. PHI = 26,5%, avg. K = 538,2 mD).

Figure - Different thickness and continuity of chlorite coating cement in sandstones of Snadd Formation is strongly related to sequence stratigraphy, and help to explain different reservoir quality characteristics.


State of-the-art of digital outcrop mapping methods: application to the Triassic of

Edgeøya, Svalbard

Simon J. Buckley1, Benjamin Dolva1, Alvar Braathen2, Ingrid Anell2, Mark Mulrooney3

and Isabelle Lecomte2,4

1Uni Research CIPR, Postboks 7810, 5020 Bergen 2University of Oslo, Postboks 1047 Oslo 3Unis, Postboks 156, 9171 Longyearbyen 4NORSAR, Gunnar Randers vei 15, 2007 Kjeller Digital outcrop mapping methods have become increasingly common across geoscience

research and industry over the last decade, allowing detailed spatial data to be used as

the geometric framework for analysis. In the petroleum industry, the study of geological

outcrops is vital for understanding the geometries and distributions of e.g. architectural

elements and structural features, and how they affect reservoir models between core and

seismic scales. The introduction of lidar scanning has been the catalyst for increased

quantification in outcrop studies. By acquiring highly accurate, georeferenced 3D point

clouds, with co-registered digital images, high resolution photorealistic models can be

generated for interpretation, visualisation and communication of project data. More

recently, a renewed interest in photogrammetric (image-based) modelling – calculation

of 3D models from overlapping image sets – has been driven by advances in digital

cameras, automatic algorithms coming from computer vision, and innovative camera

platforms, such as unmanned aerial vehicles (UAVs/drones). This lower-cost approach

has broadened the scope of digital outcrop modelling and now has the potential to be

utilized by field geologists. This presentation will showcase the state-of-the-art in digital

outcrop mapping, from lidar scanning to the use of photogrammetry from drones, and

integrated hyperspectral imaging for mineralogical mapping. A case study from onshore

Triassic exposures at Kvalpynten, Edgeøya demonstrates the workflows and possibilities

of this digital geometric framework. Here, photogrammetric images were captured from

a boat for cliff sections >25 km in length and up to 400 m in height, and 3D models

generated as the basis for interpretation. The outcrop section is representative of the

subsurface Barents Shelf, and work is ongoing to model the exposed geology as synthetic

seismic sections. This will facilitate the link between outcrop and subsurface, enhancing

our understanding of this important region.

Figure 3D textured model of Kvalpynten, Edgeøya rendered and interpreted in LIME (length of section ~ 8 km)


Uppermost Triassic to mid-Jurassic basin fill in Svalbard and the western and northern Barents Sea – is the influence of larger tectonic movements

underestimated in sequence stratigraphic and facies analysis?

Snorre Olaussen1; Rismyhr, B., 1,2; Dalen, G.3; Lars Erik Gustafson3; Johannessen, E.P.4; Larssen, G.B.5; Leutscher, J.3

1The University Centre in Svalbard 2University in Bergen 3Eni Norge, 4Statoil 5Lundin Norway In the western margin of the Barents Sea Platform, the Realgrunnen Subgroup (Norian-?Early Bathonian) was deposited in an active tectonic regime, partly within the incipient extensional phase of the Upper Jurassic to Lower Cretaceous North Atlantic rift system. In contrast, contemporary sedimentation in the north-eastern part of the Norwegian Barents Sea and on Svalbard (i.e. the Wilhelmøya Subgroup) occurred in a slowly subsiding intracratonic basin, but with wide deeper sag basins showing differential subsidence. No Upper Jurassic extensional tectonics is recorded in this area. On the contrary in the north- eastern part of the Norwegian Barents Sea, the Late Jurassic and Early Jurassic experienced weak compressional tectonics in the form of large and wide anticlinal and synclinal structures. Even within this different tectonic regime, the depositional environment, petrography and major sequence boundaries are remarkably similar in the two areas. Similar to the North Sea and Norwegian Sea basins, the Barents Sea and Svalbard experienced high overall sedimentation rates in the Early Triassic to Carnian, while the Norian to Bathonian consists of thinner units suggesting an upward decrease in accommodation space caused by a gradual decrease in subsidence rates. In this setting, even small regional changes in relative sea-level will induce condensation, hiatuses, incised valleys and subaerial unconformities. This can be demonstrated in the north-eastern part of the Norwegian Barents Sea including Svalbard, and along the western margins of the Barents platform. In both areas highs and terraces either show condensed units or remnants from erosive events while basinal areas have more complete successions. Basin margins are characterized by more proximal facies, coarser fluvial deposits and incised valleys. Along the Troms-Finnmark Fault Complex in the south-western Barents Sea Lower to Middle Jurassic units are either eroded or not deposited (e.g. the Goliat structure). On the rotated fault block of the Nucula discovery only remnants of the units are preserved. A similar change from condensed or eroded units on highs or terraces to a more complete succession basinward can also be demonstrated by dip sections on the Bjørnøyrenna/Ringvassøy- Loppa fault complexes. North of Loppa High; on the terrace Fingerdjupet Subbasin the Realgrunnen Subgroup is approximately 200 m thick. Rhaetian, Hettangian and Sinemurian units are missing, and Lower to Middle Jurassic units reach only a few tens of meters in thickness. Basin-ward the Lower to Middle


Jurassic units are up to 300 m thick, and the Realgrunnen Subgroup reaches a total thickness of more than 900 m along the western margin of south-western Barents Sea. This trend is also seen in another tectonic regime; in Svalbard. In Kong Karls Land, the Norian to Bathonian consists of a 250 m thick, sandstone-dominated succession deposited in estuarine, shoreline and paralic to inner shelf environments (Flatsalen, Svenskøya and Kongsøya formations). In western Spitsbergen, the Wilhelmøya Subgroup is only approximately 25 m thick. Norian, Pliensbachian to Toarcian and Aalenian units are capped by Early Bathonian remanie conglomerates with older reworked fossils. The differences in thickness and preservation from west to east suggest syn-depositional, differential tectonic movements. While eastern Svalbard experienced a slow continuation of subsidence during latest Triassic and Early Jurassic, western Spitsbergen must periodically have acted as a structural high, probably slightly tilted towards the north east. By Toarcian-Aalenian times, these differences levelled out and the Middle Jurassic occurs as thin, condensed or remnant units all over Svalbard, indicating a common and stable structural high with periodic subaerial exposure and erosion. On Svalbard four 2nd order T-R sequences are defined, which we propose to be correlative with the western margin of the Barents Platform. But also partly into basins in East Barents Sea, East Greenland, Norwegian Sea and Arctic Canada suggesting larger tectonic control on the Norian to Bathonian basin-fill (i.e. the Early Kimmerian tectonic phase). The purpose of this presentation is to compare the sequences with more local tectonic movements and the larger regional pan-Arctic, and even global tectonic events. We will try to use the onshore - offshore link to improve the prediction of stratigraphic and facies development.


Figure - Outcropping Lower Jurassic to Lower Cretaceous succession in the Kong Karls Land (KKL) Archipelago and a NW-SE seismic line south of KKL. Upper right shows panorama and geological succession of the mountainside at Hårfagrehaugen, Kongsøya. Width: ca. 1.3 km, mountaintop: 304m. Yellow: unconsolidated (friable) sandstone, light and bright green: heterolithic sand/mudstone, blue-green: fossiliferous sand/mudstone, dark green: mudstone, violet: Lower Cretaceous basalt lava. : The seismic line is from Grogan et al 1999. Insert shows scale of the KKL outcrop which is also partly comparable in size and rock volume to some of the smaller recent discoveries in the south-western Barents Sea. Location of outcrop and seismic line are marked on the Svalbard geological index map.


The Triassic-Jurassic tectono-sedimentary evolution of the Wandel Sea Basin (North Greenland): implications for the understanding of the western Barents Sea

P. Alsen, M. Bjerager, P. Guarnieri and J. Hovikoski - GEUS

The Wandel Sea Basin, eastern North Greenland, contains a ~3.5 km-thick Mesozoic sedimentary succession. Due to the very remote and inaccessible position, only limited, pioneering field work has been carried out in the area. Accordingly, the understanding of its sedimentary and structural evolution and stratigraphy is limited. Three recently initiated GEUS-projects, The Triassic of the Wandel Sea Basin, The Jurassic–Cretaceous of the Wandel Sea Basin and The tectonic evolution of the Wandel Sea Basin are based on field work carried out in 2012 and 2013, which resulted in the collection of a large amount of new data (incl. e.g. fossils, rock samples, 3D geological photos, a shallow drill core, logged sections, structural geological measurements etc.). The ongoing studies have already resulted in a much better stratigraphic and structural geological framework that will improve the interpretation of the basin development and the correlation to Svalbard and the western Barents Sea.

The succession includes coarse grained units that are potential analogues for reservoirs, and mudstone units that are equivalent to other known source rock intervals in the Arctic. Due to its position an improved understanding of the geological development of the Wandel Sea Basin will have important implications for the petroleum geology of the western Barents Sea and Danmarkshavn Basin.


Facies characteristics and sequence stratigraphy of the condensed uppermost Triassic-Middle Jurassic succession on eastern Spitsbergen

Bjarte Rismyhr1,2 and Snorre Olaussen2

1 Department of Earth Science, University of Bergen, N-5020 Bergen, [email protected] 2 Department of Arctic Geology, University Centre in Svalbard, N-9171 Longyearbyen,

[email protected]

The latest Triassic-Middle Jurassic in the western Barents Sea and Svalbard was

characterised by low subsidence and sedimentation rates reflected by the deposition of

thin Norian-Bathonian sedimentary units. Differential subsidence patterns are indicated

by the marked thinning from basinal areas onto highs and terraces of the region, where

either condensed units or remnants from erosive events occur.

In Svalbard, the Wilhelmøya Subgroup (Norian-Bathonian; Fig 1) which represents the

onshore counterpart to the Realgrunnen Subgroup (Norian-Bajocian) in the south-

western Barents Sea, is represented by increasingly condensed units toward the west. The

subgroup thins from 250 m in Kong Karls Land in the east to less than 25 m in western

Spitsbergen. Well-exposed outcrops along the east coast of Spitsbergen reveal a 35 m

thick sandstone-dominated succession deposited in shoreface, inner shelf and estuarine

environments (Flatsalen, Svenskøya and Kongsøya formations; Error! Reference source

not found.). The succession is characterised by complex and abrupt internal facies

transitions, reflecting intermittent deposition, partly within incised valleys, in the Norian,

Late Pliensbachian-Toarcian and Bathonian during relative sea-level highstands (Fig 2).

Deposition was punctuated by major erosional and/or non-depositional hiatuses in the

Rhaetian-Early Pliensbachian and the Aalenian-Bajocian suggesting prolonged, periodic

exposure.

The purpose of this presentation is to document the temporal facies variations and

sequence stratigraphic surfaces observed within the thin Norian-Bathonian succession in

central eastern Spitsbergen. The complexity of the sequence stratigraphic surfaces, the

preserved sandstone bodies and the main biostratigraphic hiatuses as recorded on

Spitsbergen are here suggested to be valid analogues for the Realgrunnen Subgroup on

internal basin highs and terraces in the Greater Barents Sea.


Figure 1 - Uppermost Triassic-Middle Jurassic stratigraphy of Svalbard and the Barents Sea. Modified from Mørk et al. (1999)

Figure 2 - Correlation panel and sequence stratigraphic interpretation of the outcrops in Agardhbukta, central eastern Spitsbergen.


Snøhvit area: 8 years of production and injection in the Realgrunnen reservoir

Gard Ole Wærum – Statoil, Harstad

Snøhvit, located in the Barents Sea at 71º north, is the first major offshore development

on the Norwegian continental shelf with no surface installations. The field was discovered

in 1984 and came on stream in August 2008. The installations are all sub-sea in 250–350m

of water depth. The field produces gas and condensate from the Stø and Nordmela

formations in the Realgrunnen Subgroup. The main reservoir, the Stø Formation (Early

Jurassic to Middle Jurassic age), consists of shallow marine deposits dominated by

sandstones. The Nordmela Formation (Early Jurassic age) consists of tidal and coastal

plain deposits while the Tubåen Formation (Late Triassic to Early Jurassic age) consists

of fluvial dominated delta plain deposits with marine influence. Currently gas is produced

from 9 wells and transported in 150km pipeline to the onshore, Melkøya LNG plant. Since

the start-up more than 30 GSm3 gas has been produced. The gas is processed on the shore

and CO2 is separated from the sales gas, transported back to the field and injected through

a single well into the CO2 storage reservoir.

Originally CO2 was injected into the Tubåen Formation, after approximately one year of

production gradual pressure increase was observed in the injection well. Most likely this

was related to a near well reservoir limitation that could not receive the necessary

injection rate. Therefore, the Tubåen CO2 injection was abandoned in April 2011. All CO2

is now injected into the aquifer of the Stø reservoir, down dip from the gas zone. The

injection is as expected and no pressure increase in the injector is observed. 4D seismic

together with continuous pressure readings in the injector well are actively used as the

key parameters to understand the injection process and monitor the CO2 distribution

with time. The reservoir simulation model is continuously history matched as soon as new

information is available.


Field Development Geology from Johan Castberg

Jeremy Watt, Simon Knight and Birgit Dietrich - Statoil, Harstad

The Johan Castberg discoveries of Skrugard and Havis in 2011/2012 increased focus on

the Barents Sea after a period of lower optimism.

Most of the volumes in the field occur in the Jurassic/ Triassic Tubåen, Nordmela and Stø

formations, which will be the focus of this talk. Moving from upwards from base Tubåen

there is an overall transgressive system continuing until the end of Stø times. The base

of the Tubåen Formation is a sequence boundary, with high NTG fluvial sandstones

being deposited on top of bayfill and mouthbar deposits of the upper Fruholmen

(Krabbe Member). There is a greater marine influence towards the top of Tubåen with

mouthbars appearing, before a switch into a more freshwater lacustrine environment at

the base of Nordmela. Nordmela is dominated by deltaic mouthbar and bayfill

environments with an increasing marine influence upwards. An unconformity occurs at

the base of Stø with the lower part of Stø dominated by major sheet-like sand dominated

mouthbars. The upper part of Stø is a possible forced regression interpreted as a

shoreface environment, with coarsening up cycles ranging from the offshore transition

zone to upper shoreface deposits.

A combination of the varying reservoir environments, properties and depths have

resulted in different field development challenges to understanding the best

development for the area. The understanding of the stratigraphy has been used to

develop robust reservoir models for optimizing the Johan Castberg drainage strategy.

New results from 6 wells during the 2013/2014 exploration campaign have shown the

general geological understanding to be consistent across the area, as well as providing

approximately 10% extra oil volumes from the Drivis (7220/7-3 S) discovery.


Realgrunnen Sub-group reservoir development in the Goliat Field: updated

results based on recent wells.

Lars-Erik Gustafsson - Eni Norge AS

The Goliat field is part of the production licence 229, which was awarded in May 1997. It

is located in block 7122/7 in the SW part of the Barents Sea, 85km NW of Hammerfest.

The licensees in the current Production Licences PL229/229B are Eni Norge AS (operator,

65%) and Statoil Petroleum AS (35%). The Goliat field will be the first oil producing field

in the Barents Sea, and production start-up is scheduled for the 2nd half of 2015.

The field consists of two separate reservoirs; the Kobbe Formation at approximately 1800

meters depth and the Realgrunnen Subgroup, at approximately 1000 meters depth. Both

reservoirs contain oil with an overlaying gas-cap and are strongly compartmentalized by

faults. The Realgrunnen reservoir consists of the Late Triassic (Norian-Rhaetian) Tubåen

and Fruholmen formations in the Goliat area.

Appraisal well 7122/7-6 was drilled in December 2012 in the Main segment. The primary

objective of the well was to determine the oil water contact in the undrilled M0 segment

of Kobbe reservoir. One of the secondary objectives was to give facies information from

the Realgrunnen reservoir. The well found an unexpected thick (~ 30m) sandstone

sequence with excellent reservoir properties in the upper section and a deeper oil-water

contact than previously interpreted for the Realgrunnen in the Main Segment.

37m of Realgrunnen cores were retrieved in the well; the cores were interpreted and

included in a sedimentological study performed by Eni HQ in Milan.

The result of the study suggests that the coarse sandstones found in the uppermost

section of Realgrunnen belong to the Tubåen Fm. (Late Rhaetian to early Hettangian)

rather than the more heterogeneous Fruholmen Fm. (Norian to Rhaetian). The study also

suggests that the coarse sandstones in Realgrunnen South segment found in well 7122/7-

3 which has been interpreted as alluvial fan deposits also belongs to Tubåen Fm. This was

previously thought to belong to the Fruholmen Fm.

The results from the five development wells drilled through Realgrunnen after appraisal

well 7122/7-6 has confirmed the updated sedimentological model for Realgrunnen.


Hyperspectral analysis of core material: a case study from the Barents Sea

(Finnmark Platform).

Tobias Kurz, Simon Buckley, John Howell and Nicole Naumann - Uni Research CIPR, Bergen

Hyperspectral imaging is a novel, non-destructive method for analysing the material

content and distribution of rocks. Utilising the unique spectral response of minerals and

rocks at different light wavelengths allows both identification and quantification of

mineralogy on the core’s surface. With high spatial and spectral sampling, hyperspectral

imaging allows continuous, mm-scale coverage of material in a well. This contribution

describes the workflow, including data collection, processing of the hyperspectral

imagery and the generation of mineral distribution maps. Sample data from the Barents

Sea and from different geological formations will be presented. Hyperspectral imaging

provides an innovative technique for first-pass interpretation of core, and allows

separation of minerals of key importance for reservoir characterisation and drilling.

Figure - Well 7128/6-1, Barents Sea, visualisation of material

differences.


C o r e s e s s i o n

Norvarg 7225/3-1 and 7225/3-2 Patrick Stinson - Total E&P Norge

Well 7225/3‐1 is a vertical exploration well drilled in 2011 on the Norvarg Dome structure, which is located in the Norwegian Barents Sea, roughly 300km NE of Snøhvit. The main objective was to prove hydrocarbons in Triassic sandstones of the Snadd and Kobbe Fms, with secondary objectives in the Stø and Havert Fms and the Bjarmeland Gp. Three cores were retrieved, one in the Snadd (Intra-Carnian), one in the Kobbe and one in the Upper Havert sandstone. A fourth coring attempt in the Permian limestone failed. Well 7225/3‐2 is a vertical delineation/exploration well drilled in 2013 on the NE part of Norvarg Dome. The main objective was to drill the distributary channels seen on the seismic in the Kobbe Formation (not intersected in the first well) and to evaluate the productivity of these channels. Two intervals in the Kobbe Fm were cored. Core descriptions and sedimentological interpretation were performed by Total sedimentologists François Lafont, Jonathan Pelletier, and Elodie Marcheteau based in Pau, France. The Kobbe Formation was deposited in a low energy shallow marine platform, with almost no wave action and weak tides. Most of the Kobbe Fm is made up of stacked heterolithic tidal bars or tide-reworked mouth-bars deposited downstream of a very low gradient mature fluvial system. Reservoir properties are poor overall, in particular due to the heterolithic nature, and to the abundance of shale at all scales, which is typical of low energy mixed tidal/fluvial systems. Sideritic cement is observed frequently. The reservoirs are expected to be heterogeneous and poorly interconnected. Improvement of reservoir quality and connectivity requires the presence of large channels cutting the tidal bar complexes. Unfortunately, the static and dynamic well results in the channels at Norvarg 2 did not show better productivity compared to tidal bars tested in Norvarg 1. The Upper Havert Sandstone represents coastal deposition, as documented by the intervals with shallow marine burrows and intertidal flat deposits. Most of it is made up of stacked unconfined flow deposits and interpreted as a broad outwash lobe or sheet flood delta in a semi-arid to arid setting. The Intra-Carnian Sandstone was deposited in a flood plain to delta plain landward of a likely wave-dominated coast. The main sandstone accumulations correspond to very large point bars deposited by a major sandy meandering river system. Numerous small low sinuosity ribbon channels seen on the seismic, but not calibrated on cores, are interpreted as small deltaic distributaries.

Documents

Triassic and Jurassic reservoir development in the Barents · PDF file13:00 Gustafsson L.E. (ENI Norge) - Realgrunnen Sub-group reservoir development in the Goliat Field: updated results