HYDROCARBON HABITATS Quaternary Processes in NCS Petroleum Systems October 24th 2013
www.geologi.no/konferanser
HYDROCARBON HABITATS -03 Norsk Geologisk Forening Abstracts and Proceedings of the Geological Society of Norway No. 3, 2014 Hydrocarbon Habitats: Quaternary Processes in NCS Petroleum Systems Oslo, October 24th 2014
Quaternary Processes in NCS Petroleum Systems Oslo Kongressentere Folkets Hus 24th October 2013
Program 10:00
Registration
11:00
Lunch
12:00
Welcome
12:05
Keynote: Fridtjof Riis, Norwegian Petroleum Directorate
Relations between Quaternary Processes and Dynamic Trapping of Hydrocarbons. Examples from the Norwegian Shelf
12:30
Willy Fjeldskaar, Tectonor
The Effects of Glaciations on the Petroleum Systems in the Barents Sea
13:00
Coffee
13:30
Hans Petter Sejrum, University of Bergen
Glacial-influenced Basins – Industrial Challenges and Potential
13:55
Odleiv Olesen, Geological Suvey of Noway
Neotectonics in Nordland: Implications for Petroleum Exploration
14:20
Fridtjof RIis, Norwegaian Petroleum Directorate
Uplift in the Barents Sea and its Influence on the Petroleum Systems
14:45
Coffee
15:15 Keynote: Daniel Stoddart, Lundin Norway 15:45
Helge Løseth, Statoil
16:10 Martin Hovland, Professor Emeritus 16:35
Ola Kaas Eriksen, P-Cable 3D Seismic AS
17:00
End
The Utsira High – Understanding its Oil Charge/ Leakage History in Relation to Recent Glacial Events Gigantic Quaternary Sand Volcano above the Snorre Field Effects of Migrating Hydrocarbons on Seafloor Acoustics (noise) High-resolution P-Cable 3D Seismic Imaging of the Peon Gas Discovery
Effects of Glaciations on Petroleum Systems and Dynamic Trapping of Hydrocarbons in the Norwegian Continental Shelf Fridtjof Riis, NPD In this study a petroleum system is geologically described in terms of four distinct environments where different chemical and physical processes take place: • • • •
The mature source rock, where hydrocarbons are generated and primary migration (ex pulsion) takes place. The permeable carrier beds, where hydrocarbons migrate and spill from the source to wards the traps. The trap, with accumulation and retention of hydrocarbons. The cap rock, where hydrocarbons seep to shallower traps and the sediment surface.
The development of the petroleum system depends on the development of temperature, pore pressure and stress in the subsurface, as well as the physical and chemical properties of the rocks. The oil and gas accumulations in the Norwegian offshore belong to several petroleum systems. Many of those systems developed or were strongly modified during the Quaternary glaciations in the last 2.8 Ma. Important effects of the glaciations are listed below. Erosion and sedimentation The most obvious effects of glaciations are an increased rate of erosion and deposition of sediments, and changes in the mechanisms of sediment transport. In the basinal areas of the northern North Sea and the Halten Terrace (fig. 1), sedimentation rates were typically more than 10 times the rates of the pre-glacial deposition. Due to the high subsidence rates, the rate of temperature increase in the buried Jurassic source rocks was in the order of 10 deg/Ma and large volumes of source rocks passed into the oil window. It is likely that most of the hydrocarbons in the fields in these prolific areas were generated in the Quaternary. In the Barents Sea, Svalbard and in Scandinavia including the near-coastal offshore, glacial erosion prevailed (fig. 1). Particularly rapid erosion took place in the Barents Sea, which was covered by mainly soft Cretaceous and Paleogene sedimentary rocks prior to the glaciations. Cooling rates due to erosion were typically in the order of 5 deg/Ma. In the platform areas, generation of hydrocarbons in the Triassic and Jurassic source rocks appears to have terminated, while the deeper basins are still active. Loading and unloading Loads imposed by thick sedimentary deposits and ice caps with large areal extent create depressions and forebulges. Isostasy may in some areas have influenced the spill of hydrocarbons, e.g. Troll and Hammerfest Basin. In periods of deglaciation, release of stress built up during glaciations leads to increased seismicity and increased risk of slide and leakage events, e.g. the Storegga slide. It is likely that glacial processes caused reactivation of salt structures in the regions with net uplift.
Permafrost and gas hydrates Thick, continuous permafrost represents an impermeable seal. In a sedimentary basin covered by permafrost, the aquifer systems and their pore pressures may be significantly changed (e.g. the Longyearbyen test site). In the Norwegian continental shelf there is presently no permafrost due to the water depth. Gas hydrates occur in the Norwegian Sea slope and in several locations in the Barents Sea. It is likely that extensive gas hydrate deposits were formed in the shelf areas during glacial maxima and may have played an important role in the development of gas seepage systems. Time scales and trapping In the time scale of exploration and production, a hydrocarbon accumulation can be regarded as static. In a static trap, the top and bottom seal are regarded as impermeable, and segments with different hydrocarbon contacts are separated by barriers. In a static trap, there will be no significant supply or leakage of hydrocarbons, unless the accumulation is influenced by depletion of other fields in the same aquifer. Conversely, in a dynamic trap, the top, bottom and side seals are regarded as low permeability baffles which allow a slow fluid flux. In the Norwegian offshore, pressure gradients and segmentation in aquifers are common, overpressured fields are actively seeping fluids, and in the eroded basins traps are filled to spill only if the rate of migration into the trap is equal to or greater than the rate of leakage out of the trap. Temperatures, pressures and isostatic subsidence in many areas have not reached equilibrium. Studies of the paleocontacts of the Troll, Albatross and Ormen Lange fields give insights into the rates of migration, seepage, leakage and tilt of large hydrocarbon accumulations. It is suggested that in a basin with rapid subsidence rates caused by glaciations, an accumulation could be regarded as dynamic in a time scale of 100 000 to 1 million years. In conclusion, knowledge of the Quaternary history is important to understand and predict the pressure and temperature history and describe the dynamic trapping of hydrocarbons both in the regions with subsidence and in the regions with net uplift. Figure
Figure: The bathymetry of the Norwegian shelf reflects the large amount of erosion in the Barents Sea, the troughs which were formed by ice streams, and the trough mouth fans where thick sections of Quaternary sediments were accumulated. Hydrocarbon accumulations (red lines) occur on both sides of the black line which marks the boundary between the region where maximum burial occurs today (petroleum systems heating up) and the regions with net uplift (petroleum systems cooling down). Major trough mouth fans are indicated (NS – North Sea, Sk Sklinnadjupet, B – Bjørnøyrenna and S – Storfjorden). Red arrows indicate drainage directions in major troughs.
The Effects of Glaciations on the Petroleum Systems in the Barents Sea
Glacial-influenced basins – industrial challenges and potential
Willy Fjeldskaar, Tectonor
Hans Petter Sejrup, Department of Earth Science, University of Bergen
Glacial climate changes over the last million years have influenced the distribution of oil and gas reserves, mainly in high latitude and arctic basins. Hydrocarbon exploration in the Norwegian part of the Barents Sea has been rather unsuccessful so far; numerous glaciations during the last 3 million years are regarded to be a major cause for this. Rapid erosion and subsequent differential uplift and tilting is commonly envisioned to have led to spillage of hydrocarbons, phase transition from oil to gas, expansion of gas, seal failure, and cooling of source rocks. In addition to glacial erosion, repeated ice and sediment loading had great influence on and the temperature history, i.e. hydrocarbon maturation hydrocarbon and migration routes. Detailed control on the glacial history, glacial erosion and sediment deposition is therefore an important factor for identification of the remaining hydrocarbon resources in the Barents Sea. The effects of glaciations on the temperature regime in a sedimentary basin can be significant. Glaciations affect the thermal conductivities of the sediments and the surface temperatures. Both will also influence the reservoir temperatures. A typical glacial period cycle lasts for 100 000 years, which is sufficient time to lower reservoir temperatures to depths of 5 km by reductions in mean surface temperatures. Ten glacial periods could lower the reservoir temperature by up to 10°C. Increased thermal conductivities due to frozen pore water will also contribute to the cooling of the subsurface. Subsurface temperatures during a cold (permafrost) glaciation could be as much as 25°C lower than the subsurface temperatures in a non-glaciated case. Glaciers, sediments and erosion act as loads on the Earth’s surface – positive or negative. Both glaciers and glacial erosion will lead to significant isostatic tilting of the reservoirs. Glacial erosion leads to significantly lower sub-surface temperatures, and will thus deactivate source rock hydrocarbon generation. Changes in local stresses and associated fluid pressures in petroleum reservoirs generated by glaciers and/or rapid glacial erosion may reactivate or initiate faults and other fractures, allowing oil and gas to escape from reservoirs.
During the last decade there has been a grooving interest on how the onset of glaciations dramatically changed the rate and style of sedimentation in mid and high latitude Northern Hemisphere offshore sedimentary basins. This interest has partly been driven by the importance of understanding the history and processes linked with the development of marine based parts of the large late Cenozoic ice sheets and what this can tell us about the function of the climate system. However, investigation of such sequences on the north-western European continental margin has also been driven by industrial interest. These efforts include research focusing on themes such as glaciers direct and indirect influence on the deeper hydrocarbon systems, CO2 storage, gas hydrates, shallow reservoirs and geological hazards. With examples from the North Sea/southern Norwegian margin the current state of knowledge on this subject will be elucidated and major knowledge gaps will be discussed.
Neotectonics in Nordland: Implications for Petroleum Exploration Odleiv Olsen, Geological Survey of Norway One of the most significant exploration problems in the Helgeland and Ribban basins relates to the severe uplift and erosion of the area that occurred during the Cenozoic. The coastal area of Nordland, northern Norway, is a region with increased seismic activity relative to other parts of Fennoscandia (Fig. 1). There is a parallel and shallow zone of increased seismicity along the coast largely reflecting extensional stress conditions. Below the Pleistocene wedge - along the continental edge to the west - there is another seismic zone with deeper compressional events. The amount of sediments deposited along the continental margin within the Pleistocene Naust Formation has recently been estimated by Dowdeswell et al. (2010) to be ~0.24 m ky–1 over the ice age, with bedrock lowering of ~500 m in the ice-sheet catchment. The mean sediment delivery is 2–3 times higher for the most recent 600 ky than for the period 0.6-2.7 My. The coinciding patterns of sediment loading/unloading and compressional/extensional earthquakes indicate that there is a causal relationship between the two phenomena. Several independent datasets in the outer Ranafjorden region indicate that this coastal area is under WNW-ESE present day extension. This deformation can constitute a part of the present day tectonic deformation along the cost of Nordland. A six-station seismic network established by NORSAR in this region detected during a two-year period (1997-1999) c. 300 earthquakes, often occurring as swarms (Hicks et al. (2000). Fault plane solutions indicate E-W extensional faulting. The outer Ranafjorden district is also the location for the largest earthquake recorded in Fennoscandia in historical times, i.e. the c. 5.8 magnitude in 1819. Three measurements of uplift of acorn barnacle and bladder wrack marks on the islands of Hugla and Tomma in the outer Ranafjorden area (Fig. a2) show anomalous low land uplift from 1894 to 1990 (0.00.07m) compared with the uplift recorded to the north and south (0.23-0.30 m) (Olesen et al. 1995). An irregular subsidence pattern in the order of c. 1 mm/year is also observed on DInSAR permanent scatterer data in the same area (Dehls et al. 2002). The relatively low seismicity occurring at a depth of 2-12 km could therefore create the observed irregular subsidence pattern at the surface. Benchmarks for GPS measurements have been established along three 15-20 km-long profiles across outer, central and inner Ranafjorden. GPS campaign measurements in 1999 and 2008 indicate that the bench marks along the western profile have moved c. 1 mm/ year to the NW and W relative to the stations along the two eastern profiles (Olesen et al. in prep). Weathered bedrock can be found up to an altitude of c. 500 m above sea level along the coast of Nordland (Figs. 1 & 2) and is most likely exhumed during Pleistocene erosion. These observations support the conclusion of Dowdeswell et al. (2010) of a young basement exhumation along the coast. The unloading of the crust along the coastal areas of Nordland resulted most likely in flexuring and accompanying fracture extension and seismicity. The pressure decrease associated with removal of sedimentary overburden may have caused expansion of gas and resulted in expulsion of oil from the offshore traps. Where uplift and tilting result in local extension, seal breaching and spillage may also occur. The cooling of the source rocks owing to vertical movement may also cause hydrocarbon generation to decrease.
An improved understanding of the processes of uplift and erosion in time and space will be an important piece of information in the petroleum exploration of the northeastern Nordland area. NGU has therefore in collaboration with NORSAR, Kartverket, NORUT and the universities in Bergen and Luleå established a research project to monitor the present stress and strain in the Nordland region. We want further to study how these phenomena can relate to the loading/ unloading process along the coast (NEONOR2 - Neotectonics in Nordland - Implications for Petroleum Exploration). The study is sponsored by ten petroleum companies and PETROMAKS2.
Figure 1
Figure 1: Map of the Nordland margin, including source catchment area of glacial erosion (green dashed line) and area of offshore deposition (isopach map of thickness of the Naust Formation in milliseconds of two-way travel time, where 1 ms is ~1 m). Blue line marks present shelf edge. Adapted from Dowdeswell et al. (2010). Zones of deep weathering up to 100 m thick and more than 1 km wide occur within the eroded area indicating that the present landscape is to a large degree of Mesozoic age. Subcrop units (modified from Sigmond 2002) underlying the Naust Formation are mainly Tertiary, Cretaceous, and Jurassic sedimentary rocks (hatched pattern). Earthquakes from the period 1989–2011 provided by Norwegian National Seismic Network at the University of Bergen are shown in yellow and the size of the circles reflects the magnitude on the Richter scale. The red frame depicts the location of Figure 2.
The Utsira High – Understanding its Oil Charge/Leakage History in Relation to Recent Glacial Events Daniel Stoddart, Arlid Jørstad and Hans Chr. Rønnevik, Lundin Norway
Figure 2a
Figure 2b
Figure 2: Results from a detailed neotectonics study in southern Nordland . a) The observed 19981999 seismicity in the outer Ranafjord area occurs along NNW-SSE trending clusters. Fault-plane solutions indicate N-S compression and E-W extensional faulting (Hicks et al. 2000). The NNW-SSE trending earthquake clusters coincide with mapped fractures and faults with pronounced escarpments. GPS stations to the west of the earthquake clusters have moved c. 1 mm/year to the W relative to the stations on the eastern side during the period from 1999 to 2008. (The velocities are relative to station ne08). The zones of deep weathering have been mapped by Gjelle et al. (1985) and Wilberg (1989). b) The observed 1998-1999 seismicity occurs along NNW-SSE trending clusters. Fault-plane solutions indicate N-S compression and E-W extensional faulting (Hicks et al. 2000). The shallow and NNW-SSE trending earthquake clusters coincide with mapped fractures and faults with pronounced escarpments. GPS stations show relative east-west movement of 1mm/year during the period from 1999 to 2008. The uplift data in colours are acquired using the DInSAR permanent scatterer method (Dehls et al. 2002) and height measurements of acorn and bladder marks (Olesen et al. 1995). The irregular relative subsidence pattern (blue areas) seems to coincide with elongate clusters of small and shallow earthquakes. The contoured green isolines of the acorn barnacle and bladder marks likewise reveal a relative subsidence of the seismically active area. References Dehls, J.F., Basilico, M. & Colesanti, C. 2002: Ground deformation monitoring in the Ranafjord area of Norway by means of the Permanent Scatterers technique, Geoscience and Remote Sensing Symposium, 2002. IGARSS ‘02. 2002 IEEE International, Volume 1: Toronto, 203-207. Dowdeswell, J.A., Ottesen, D. & Rise, L. 2010: Rates of sediment delivery from the Fennos candian Ice Sheet through an ice age. Geology 38, 3–6. Gjelle, S., Gustavson, M., Qvale, H. & Skauli, H. 1985: Berggrunnsgeologisk kart Melfjord 19283, 1:50000, foreløpig utgave. Norges geologiske undersøkelse. Hicks, E., C., Bungum, H. & Lindholm, C.D. 2000: Seismic activity, inferred crustal stresses and seismo tectonics in the Rana region, northern Norway. Quaternary Science Reviews 19, 1423-1436. Olesen, O., Gjelle, S., Henkel, H., Karlsen, T.A., Olsen, L. & Skogseth, T. 1995: Neotecton ics in the Ranafjorden area, northern Norway (Extended abstract). Norges geologiske undersøkelse Bul letin 427, 5-8. Olesen, O., Kierulf, H.P., Brönner, M., Dalsegg, E., Fredin, O. & Solbakk, T. in prep: Deep weathering, neotectonics and strandflat formation in Nordland, northern Norway. Submitted to Norwegian Journal of Geology. Wilberg, R. 1989: Data for malmsonering for Bordvedåga-forekomsten, analyser fra Be-mineraliseringer og regional geologi i Høgtuva-området. NGU Rapport 89.097, 67 s.
Recent drilling and appraisal on the Southern Utsira High has proved several large discoveries, including the giant Johan Sverdrup, Edvard Grieg, Draupne, Ragnarrock and Apollo, making this a prolific petroleum area. The Southern Utsira High contains a variety of GOR fluids and gases found at several stratigraphic levels illustrating the compartmentalized nature of accumulations and charge history. The Southern Utsira High has been in a position to receive an oil/gas charge for a considerable period of time, with the basin towards the west most likely generating petroleum from early Eocene (50MMabp) to its maximum present day burial depth. However, reservoir temperatures on the Southern Utsira High are just above the threshold for biodegradation (80°C). The Southern Utsira High oils are non-biodegraded suggesting that the majority of the oil charged relatively late – ca.1 million years ago to present day. The effects of the glaciation on the filling history of the Southern Utsira High are currently being assessed. It is clear that several erosional surfaces in the Pliocene can be identified, as well as glacial channels and moraine deposits, indicating that significant deposition and erosion occurred in the last five million years. Importantly, the effects of glacial rebound mean that the Southern Utsira High more than likely underwent tilting and possible leakage, not just once, but several times in the last 1 million years. The effects of tilting/leakage of geological areas on oil migration have been recognized by several authors. However, the detailed integration of geological mapping and geochemical evidence has not previously been published. The implications of a detailed assessment of tilting of a ‘’high’ through time are; 1) opening up areas where oil migration is thought to be high risk or impossible; 2) identify possible paleo-oil columns aiding the de-risking of discovery appraisal strategies. The evidence of tilting/leakage of oil accumulations through time can be recognized in several oil fields on the Utsira High. The Johan Sverdrup discovery oil columns contain paleoOWC, residual oil zones/paleo-oil columns, and oil shows considerably deeper than the current OWC or residual oil columns. Lundin has performed detailed mapping of the seabed and water column in the Alvheim/ Utsira High areas in order to identify areas of gas leakage and its geological manifestations on the seabed and ultimately resulting in the collection of high quality samples. Results shows that gas leakage is prominent over the Alvheim and Utsira High areas and the implications of this to oil exploration will be discussed. In summary, Lundin’s approach to oil migration is to better understand the fluid/gas movement throughout the whole basin through time. The talk will focus on the timing of charge from the South Viking Graben, fill-spill directions on the Southern Utsira High, the effects of late tilting/leakage on the charge/re-distribution of oil, and seabed / water column characterization and sampling. All placed in the context of oil exploration.
Gigantic Quaternary sand volcano above the Snorre Field Helge Løseth, Nuno Rodrigues and Peter Cobbold, Statoil Using 3D seismic and well data from the northern North Sea, we describe a large (10 km3) body of sand and interpret it as extrusive. To our knowledge, this is the world’s largest such sandbody. It would bury Oslo under 22 m of sand, or the whole of London, UK (1579 km2), under 6 m of sand. This sand vented to the seafloor when it was more than 500 m deep, during the Pleistocene glacial period. The sandbody (1) covers an area of more than 260 km2, (2) is up to 125 m thick, (3) fills low areas around mounds, which formed when underlying sand injectites lifted the overburden, (4) wedges out, away from a central thick zone, (5) is locally absent along irregular ditches, 20 km long and up to 50 m deep, which overlie feeders on the flanks of the mounds, and (6) consists of fine-grained to medium-grained, sub-rounded to rounded grains. We compare the distribution of the sand with the results of scaled physical experiments. In our interpretation, high fluid pressure fractured the regional Hordaland Group seal in the study area, so that fluidized sand moved rapidly to the seafloor through fissures on the flanks of underlying mounds, mixed with seawater, and formed lateral gravity currents. These transported the sand as much as 8 km away from the blow-out fissures and formed extruded sand sheets. We interpret that rapid burial below a 500 m tick prograding shelf caused pressure build-up in underlying Tertiary parent sands. This is the first time large volume of extrusive sand is described. Such sands represent a new type of economically interesting reservoir and are a new play concept.
‘Carbonoacoustics’ and ‘Seepology’: - Understanding Quaternary Marine Geophysical ‘Anomalies’ Dr Martin Hovland, Ambio Tech Team, Stavanger, Prof. emeritus, Center for Geobiology, University of Bergen, Bergen Marine seismic, sonar, and geomorphologic ‘anomalies’ commonly occur in Quaternary sediments on the NCS and elsewhere. They are represented by features such as 1) pockmarks, mounds, and ridges (geomorphology); 2) ‘bright spots’, ‘acoustic blanking’ (‘wipeouts’), ‘bottom simulating reflectors’ (BSRs), and ‘chimneys’ (seismics); and 3) ‘hydroacoustic plumes’ (‘flares’) and ‘high-reflective patches’ (sonar). Over the last 30 years, such marine geophysical anomalies have been studied visually (by ROVs) and by coring and sampling. Currently, we have a relatively good idea of how movement of hydrocarbons may cause most of these anomalies. Thus, pockmarks are caused by migration of porewater and free gas and the compressible action of sub-surface gas accumulations. Mounds and ridges may be formed by the accumulation of organisms (mussels, tubeworms, etc), by precipitation of methane derived authigenic carbonates (MDACs), and by shallow gas hydrates (‘pingoes’). Therefore, the tertiary migration of hydrocarbons not only causes physical and chemical changes in the sub-surface, but also alterations to the seafloor morphology (Figure).
Figure
Figure: A good carbonoacoustic and seepology data example from offshore mid-Norway (Hovland, 1990, p. 272). The upper image is from the port channel of a side-scan sonar (sss) record, which corresponds to the lower image, which is from the simultaneously acquired sub bottom profiler (sbp) record. The seafloor ridges named A-D correspond to each other (sss and sbp). Note the acoustically high-reflective zones, about 15 m below seafloor. These ‘bright spots’ are suspected gas-charged sediments. Note how their ‘edges’ correspond to the seafloor ridges and to the highly reflective zones on the sss data. There is suspected to be seepage of hydrocarbons from these edges.
Fertilization: However, there is also a growing awareness of the interaction between seeping hydrocarbons from depth, into shallow sediments and the above water column (Boetius and Wenzhöfer, 2013). The migrating hydrocarbons, thus, fertilize and stimulate the growth of micro-organisms (first trophic stage), which further stimulates the higher trophic stages of life forms in the marine and lacustrine environments (Hovland et al., 2012). Data: This presentation uses published high-resolution data examples, not only from Norwegian offshore fields and locations (Veslefrikk, Gullfaks, Troll, Tommeliten, and Nyegga), but also from other parts of the world (Adriatic Sea). Both of the themes ‘Carbonoacoustics’ (e.g., the study of how and why hydrocarbons affect marine seismic and sonar data) and the related theme ‘Seepology’ (e.g., the study of how and why marine and lacustrine fluid flow (seepage) affects the local environment) can be regarded as emergening scientific themes. Potentially, further development of these two fields will improve our understanding of physical and chemical processes affecting hydrocarbon molecules, water, and other minerals, as they migrate, accumulate, precipitate, and dissipate in the sub-surface and the water column. Not least, it is expected that the themes will aid in the further improvement of hydrocarbon exploration and understanding the marine life-web, in general. References Boetius, A., Wenzhöfer, F., 2013. Seafloor oxygen consumption fuelled by methane from cold seeps. Nature Geoscience 6, 725-734. Hovland, M., 1990. Suspected gas-associated clay diapirism on the seabed off Mid Norway. Mar. and Petrol. Geol., 7, 267-276. Hovland, M., Jensen, S., Fichler, C., 2012. Methane and minor oil macro-seep systems – Their com plexity and environmental significance, Marine Geology 332-334, 163-173.
High-Resolution P-Cable 3D Seismic Imaging of the Peon Gas Discovery Ola.K. Eriksen, S. Planke, F.N. Eriksen, E. Planke, S. Vadakkepuliyambatta & S. Buenz, P-Cable 3D Seismic AS Glacial sediments in the North Sea may contain major gas accumulations. The Peon gas field in the northern North Sea was discovered in 2005 in Pleistocene sediments approximately 165 m below the seafloor (GEO 07/2005; «Fra problem til mulighet»). The reservoir covers an area of 250 km2 and consists of up to 35 m thick unconsolidated, homogenous sandstone. The gas column is 0-25 m thick, and the gas is almost entirely methane. The Peon field is very well suited for high-resolution 3D seismic imaging due to the large water depth, ca. 380 m, and shallow target. The P-Cable2 seismic system was partly developed in a Joint Industry Project between StatoilHydro and VBPR from 2006 to 2009. The P-Cable2 system consists of 24 digital streamers each with a length of 25 m. The streamer separation is typically 10-15 m, giving an in-line spacing of 5-7 m. Two high-resolution 3D P-Cable cubes have been acquired over the Peon field, a small test cube in 2007 and a ca. 180 km2 cube in 2009. The data has a dominant frequency of about 100 Hz and a bin size of 6.25x6.25 m. The P-Cable cubes provide a detailed image of the regional unconformity URU, the topreservoir, and the glacial sediments above reservoir. Intra-reservoir reflections, including a possible gas-water contact, are imaged on the high-resolution data. Horizon attribute maps reveal deep plough marks and shallow gas accumulations in a much better detail than on conventional 3D data. There is no evidence of current fluid leakage on the seafloor. However, one buried prod mark has been identified.
Figure 1
Figure 1: The heart of the P-Cable system is the cross cable where up to 24 short streamers are attached. This configuration allow for a very short in-line spacing, typically 3 to 6 m.
Deltakere
Figure 2
Figure 2: Comparison of top reservoir amplitude maps between P-Cable 3D (top) and conventional 3D (bottom) data. Important small structures such as deep plough marks are only visible on the PCable data. Data from Statoil.
Figure 3
Alejandro Amilibia Alexey Deryabin Amer Hafeez Anders Foss Andreas Aarnes Anne Grethe Bretting Arild Skjervøy Arna Aase Kleiven Artem Rabey Arve Næss Asgeir Bang Audun Kjemperud Aurelien van Welden Axel Lundin Bart Hendriks Bartosz Goledowski Beathe Heggen Benedict Reinardy Benjamin Bowlin Bernt Olav Korsfur Birger Dahl Bjarte Hellevang Bjørn Helge Sætersmoen Bjørn Tore Larsen Camilla Fjeldheim Hovelsrud Catherine Holter Clara Plagnol Dan Han Daniel Stoddart Dirk van der Wel Dwarika Maharjan Egil Bergsager Eirik Graue Elisabet Malmquist Enric Leon Erlend Morisbak Jarsve Erling Frantzen Erling Rykkelid Fridtjof Riis Geir Elvebakk Geir Hansen Geir Lunde Gustav Aagenes Ersdal Gustav Pless Guy de Caprona Halfdan Carstens Halvor Bulkholt Hanne Øines Hans Martin Helset Hans O Augedal Hans Petter Sejrup Helge Løseth Idar Horstad Ingeborg Verstad Inger F. Strass Ingrid Gjendem Fæstø Jan Erik Lie Jan Erik Rudjord Jan Inge Faleide Janne Johannesen John Clark Jon H. Pedersen Jørn Olsen
Statoil ASA NPD Tullow Oil Norge AS Talisman Energy Norge Norske Shell Wintershall Norge AS ConocoPhillips Geo Surveys AS Lukeoil Overseas North Shelf AS Statoil Marathon Oil Norge AS Idemitsu Petroleum Norge CGG Lundin Norway Statoil Dong E&P Norge AS Statoil University of Bergen Dong E&P Norge AS Idemitsu Petroleum Norge AS Bayerngas Norge AS Petrolia Norway Bridge Energy Norge AS Det norske oljeselskap ASA Bayerngas Norge AS Bayerngas Norge AS Wintershall Norge AS Acona AS Lundin Norway Concedo ASA VBPR Lukeoil Overseas North Shelf AS Rocksource Concedo ASA Concedo ASA CGG Services Norway AS CGG Svenska Petroleum NPD Det norske oljeselskap ASA APT Concedo ASA CGG MCS&NV Statoil Lime Petroleum Norway AS GeoPublishing Statoil Statoil Wintershall Norge AS Lundin Norway Universitetet i Bergen Statoil CGG Det norske oljeselskap ASA Wintershall Norge AS Ithaca Petroleum Norge AS Lundin Norway RWE Dea Norge AS Universitetet i Oslo Esso Norge AS RWE Dea Norge AS Lundin Norway North Energy
aaca@statoil.com alexey.deryabin@npd.no amer.hafeez@tullowoil.com afoss@talisman-energy.com andreas.aarnes@shell.com anne-grethe.bretting@wintershall.com arild.skjervoey@cop.com post@geosurveys.no artem.rabey@lukoil-overseas.com arvn@statoil.com abang@marathonoil.com avk@idemitsu.no aurelien.vanwelden@cgg.com axel.lundin@lundin-norway.no bahen@statoil.com barto@dongenergy.no beaheg@statoil.com benedict.reinardy@geo.uib.no benbo@dongenergy.no bok@idemitsu.no birger.dahl@bayerngas.com bjarte.hellevang@petrolia.no bjorn.saetersmoen@bridge-energy.com bjorn.tore.larsen@detnor.no camilla.hovelsrud@bayerngas.com catherine.holter@bayerngas.com clara.plagnol@wintershall.com dan.han@acona.com danielstoddart@hotmail.com dirk.vanderwel@concedo.no dwarica@vbpr.no eibe@online.no eirik.graue@rocksource.com elisabet.malmquist@concedo.no enric.leon@concedo.no erlendmorisbak.jarsve@cgg.com erling.frantzen@cgg.com erling.rykkelid@svenska.com fridtjof.riis@npd.no geir.elvebakk@detnor.no gh@aptec.no geir.lunde@concedo.no Gustavaagenes.Ersdal@CGG.com gple@statoil.com guy.de.caprona@limepetroleum.com halfdan@geo365.no hbsa@statoil.com hanneoines@hotmail.com hans-martin.helset@wintershall.com hans-oddvar@lundin-norway.no sejrup@geo.uib.no heloe@statoil.com idar.horstad@cgg.com ive@detnor.no inger.strass@wintershall.com ifasto@ithacaenergy.com janerik.lie@lundin-norway.no jan-erik.rudjord@rwe.com j.i.faleide@geo.uio.no janne.johannesen@exxonmobil.com john.clark@rwe.com jon-halvard.pedersen@lundin-norway.no jorn.olsen@northenergy.no
Julien Champroux Kai Xue Karsten Eig Kjersti Hagland Hansen Kjetil Broberg Kristian Angard Krzysztof Chwesiuk Krzysztof Jan Zieba Lars Lorenz Laszlo Buko Marchesi Sebastian Marit Stokke Bauck Martin Hovland Matthias Daszinnies Matthias Forwick Mette Eliassen Mikal Trulsvik Monica Vaksdal Morten Bergan Morten E Lindbæck Morten Krogh Nadine Friese Najibur Rahman Nicola Møller Nigel Mills Nils Nolde Odleiv Olesen Ola Kaas Eriksen Oluwatobi Olobayo Päivi Heiniö Per Varhaug R. John Ancock Richard Olstad Ronny Setså Rune Mattingsdal Rune Olsen Shutaro Hasegawa Sidsel Haug Silje Rogne Stein Åsheim Sunil Vadakkepuliyambatta Svein Johansen Svein Roar Østmo Sven Hvoslef Terje Endresen Thomas Harris Tom Bugge Tom Wolden Tommi Rautakorpi Tor O. Sømme Torbjørn Throndsen Tord Pedersen Tormod Sæther Torodd Nordlie Trond Christoffersen Vegard Gunleiksrud Vitaliy V. Yurchenko Wiebke Andrea Olsen Willy Fjeldskaar Yngve Rundberg
LIME Petroleum Norway EMGS North Energy Det norske oljeselskap ASA E.ON E&P Tullow Oil Norge AS EMGS ASA NTNU EMGS ASA Bridge Energy Idemitsu Petroleum Norge CGG Services Norway AS Ambio Tech Team Migris AS Universitetet i Tromsø VNG Norge AS Dana Petroleum Rocksource Bayerngas Norge AS Fondsfinans Statoil Wintershall Norge AS Svenska Petroleum Exploration AB Statoil APT EMGS ASA Geological Survey of Norway P-Cable 3D Seismic AS Tullow Oil Norge AS ST-FV B3494A, Statoil ASA Wintershall Norge AS Aker Geo AS Tullow Oil Norge AS Geoforskning Oljedirektoratet Explora Petroleum Idemitsu Petroleum Norge AS Bayerngas Norge AS CGG CGG Universitetet i Tromsø North Energy Geo Surveys AS Bayerngas Norge AS Det norske oljeselskap ASA Wintershall Norge AS NGF MultiClient Geophysical ASA Concedo ASA Statoil ASA Torena AS Core Energy GEO-TOS RWE Dea Norge AS Spec Partners Ltd Tullow Oil Norge ORG Geophysical Bayerngas Norge AS Tectonor Svenska Petroleum Exploration AB
julien.champroux@limepetroleum.com kxue@emgs.com karsten.eig@northenergy.no kha@detnor.no kjetil.broberg@eon.com kristian.angard@tullowoil.com kchwesiuk@emgs.com krzysztof.zieba@sintef.no llo@emgs.com laszlo.buko@bridge-energy.com sebastian.marchesi@idemitsu.no maritstokke.bauck@cgg.com martin.hovland@ambio.no matthias.daszinnies@migris.no matthias.forwick@uit.no mette.eliassen@vng.no mikal.trulsvik@dana-petroleum.com monica.vaksdal@rocksource.com morten.bergan@bayerngas.com morten@lindbaeck.no mok@statoil.com nadine.friese@wintershall.com najibur.rahman@svenska.com nimol@statoil.com nm@aptec.no nnolde@emgs.com odleiv.olesen@ngu.no ola@pcable.com tobi.olobayo@tullowoil.com phei@statoil.com per.varhaug@wintershall.com john.ancock@akersolutions.com richard.olstad@tullowoil.com ronny@geo.as rune.mattingsdal@npd.no rune.olsen@explorapetroleum.no shurtao.hasegawa@idemitsu.no sidsel.haug@bayerngas.com silje.rogne@cgg.com stein.aasheim@cgg.com sunil.vadakkepuliyambatta@uit.no svein.johansen@northenergy.no post@geosurveys.no sven.hvoslef@bayerngas.com terje.endresen@detnor.no thomas.harris@wintershall.com tom.bugge@detnor.no tom.wolden@mcg.no tommi.rautakorpi@concedo.no tooso@statoil.com torbjorn.throndsen@torena.no tp@coreenergy.no tormods2@broadpark.no torodd.nordlie@rwe.com tc@specpartners.net vegard.gunleiksrud@tullowoil.com vyu@orggeophysical.no wiebke.olsen@bayerngas.com wf@tectonor.com yngve.rundberg@svenska.com