Lapponi F.,StatoilHydro Research Center |
Swennen R.,StatoilHydro Research Center |
Casini G.,StatoilHydro Research Center |
Amilibia Cabeza A.,StatoilHydro Research Company |
And 7 more authors.
2nd Arabian Plate Geology Workshop 2010: Albian/Cenomanian/Turonian Carbonate-Siliciclastic Systems of the Arabian Plate | Year: 2010
Late burial dolomite of hydrothermal origin replaces Cretaceous carbonate shelf sediments of Albian to Turonian age (Sarvak Formation) in the NW closure of the Anaran Anticline, Zagros Mountains, Simply Folded Belt, Iran. The outcrops, spectacularly exposed along deep river canyons, offer the possibility for a 3D reconstruction of the geobodies, combining both field data (sedimentary logs, cross sections and samples for diagenetic and petrophysical studies) and LIDAR derived photorealistic model of the most representative dolomite bodies. The aim is to quantify the impact of hydrothermal dolomitisation on the reservoir quality. The hydrothermal origin of the dolomitising fluids will be discussed integrating different geochemical data (fluid inclusions, stable and radiogenic isotopes, minor and trace elements). Dolomite replaces carbonate rocks characterised by different facies, showing different geometries: 1) massive plus stratabound (Lower Sarvak); 2) pipes (Upper Sarvak). Dolomite distribution decreases vertically with at least three discrete breaks corresponding to two main aquitard intervals: 1) Ahmadi Shales, separating massive dolomite form from plume-like bodies; 2) Turonian Mudstones; 3) Surgah Fm., above, which no dolomite has been observed. Fractures and faults play a major role in controlling the distribution of the dolomite bodies, in particular the ENE-WSW and WNW-ESE conjugate fault systems, which are often associated with dolomitic halos. A geological conceptual model is built taking into account different fracture and matrix porosity models for limestone and dolomite.
Marsh N.,Durham University |
Imber J.,Durham University |
Holdsworth R.E.,Durham University |
Brockbank P.,Statoil |
Ringrose P.,StatoilHydro Research Center
Basin Research | Year: 2010
Tectonic subsidence in rift basins is often characterised by an initial period of slow subsidence ('rift initiation') followed by a period of more rapid subsidence ('rift climax'). Previous work shows that the transition from rift initiation to rift climax can be explained by interactions between the stress fields of growing faults. Despite the prevalence of evaporites throughout the geological record, and the likelihood that the presence of a regionally extensive evaporite layer will introduce an important, sub-horizontal rheological heterogeneity into the upper crust, there have been few studies that document the impact of salt on the localisation of extensional strain in rift basins. Here, we use well-calibrated three-dimensional seismic reflection data to constrain the distribution and timing of fault activity during Early Jurassic-Earliest Cretaceous rifting in the Åsgard area, Halten Terrace, offshore Mid-Norway. Permo-Triassic basement rocks are overlain by a thick sequence of interbedded halite, anhydrite and mudstone. Our results show that rift initiation during the Early Jurassic was characterised by distributed deformation along blind faults within the basement, and by localised deformation along the major Smørbukk and Trestakk faults within the cover. Rift climax and the end of rifting showed continued deformation along the Smørbukk and Trestakk faults, together with initiation of new extensional faults oblique to the main basement trends. We propose that these new faults developed in response to salt movement and/or gravity sliding on the evaporite layer above the tilted basement fault blocks. Rapid strain localisation within the post-salt cover sequence at the onset of rifting is consistent with previous experimental studies that show strain localisation is favoured by the presence of a weak viscous substrate beneath a brittle overburden. © 2009 The Authors. Journal Compilation © Blackwell Publishing Ltd, European Association of Geoscientists & Engineers and International Association of Sedimentologists.
Larsen J.,Agder Natural History Museum and Botanical Garden |
Appleby P.G.,University of Liverpool |
Christensen G.N.,Akvaplan Niva |
Berg T.,StatoilHydro Research Center |
Eide I.,StatoilHydro Research Center
Water, Air, and Soil Pollution | Year: 2010
Sediment cores collected from 12 lakes and eight marine sites along the Norwegian and Svalbard coast as part of a project investigating polycyclic aromatic hydrocarbons (PAH) in sediments were dated radiometrically using 210Pb, 137Cs and 241Am fallout radionuclides. In all lake cores, except on Svalbard, the 137Cs activity versus depth profile appears to have been significantly modified by post-depositional migration within the sediment column. The relatively low 137Cs inventories suggest that these sites were not significantly impacted by fallout from the 1986 Chernobyl accident. All the marine cores have 137Cs inventories that are substantially lower than in lake sediments almost certainly due to leaching of 137Cs from the marine sediments due to higher solubility in the seawater. In the marine surface sediments, the unsupported 210Pb concentrations are up to an order of magnitude lower than in the corresponding lake sediments reflecting the higher (dry mass) sedimentation rate at the marine sites. Five of the cores including marine sites and lakes have unusual high 210Pb flux most likely due to sediment focusing. Most of the irregularities in the 210Pb records seem to be due to slump events but some patterns are also due to possibly increased accumulation rates. Three of the marine cores show systematic increase in their sedimentation rate from c.1960 towards the present while only one lake shows the same systematic increase. © 2009 Springer Science+Business Media B.V.
Kane I.A.,University of Leeds |
Catterall V.,University of Manchester |
McCaffrey W.D.,University of Leeds |
Martinsen O.J.,StatoilHydro Research Center
AAPG Bulletin | Year: 2010
Lateral tilting is a common deformation style in extensional basins; its influence on subaerial channels is, to a degree, understood and may be significant, controlling the style of channel development and the resultant sand-body architecture. Growth faulting and lateral tilting in turbidite channel systems have been demonstrated from three-dimensional seismic data, but the resultant architecture of channels within these settings has not yet been documented. In the Carboniferous of northern England, a sand-rich slope channel, developed within a basin undergoing late-stage extension, underwent progressive and unidirectional migration toward a topographic low on a laterally tilting block. The resultant sandstone body is wedge shaped in cross section and composed dominantly of sigmoidal lateral accretion deposits. The channel returned to an axial course before undergoing lateral migration in the same direction, creating a multistory, multilateral channel sandstone body. The repeated unidirectional migration combined with evidence of syndepositional deformation suggests that active tectonism strongly influenced channel evolution and deposition. A model of submarine channel evolution in extensional basins is presented; in systems where large displacements occur, the channel system may avulse, creating isolated sand ribbons, which are connected updip; where the lateral dip is always more influential than the regional dip, the system may pond in the hangingwall syncline. The model is compared to a subsurface channel within the Pliocene of the Nile Delta slope, which was influenced by syndepositional fault movement; application of the outcrop-derived model allows some simple architectural interpretations to be made. Copyright © 2010. The American Association of Petroleum Geologists. All rights reserved.
Grip H.F.,Norwegian University of Science and Technology |
Johansen T.A.,Norwegian University of Science and Technology |
Imsland L.,Norwegian University of Science and Technology |
Imsland L.,Cybernetica |
Kaasa G.-O.,StatoilHydro Research Center
Automatica | Year: 2010
We consider a class of systems influenced by perturbations that are nonlinearly parameterized by unknown constant parameters, and develop a method for estimating the unknown parameters. The method applies to systems where the states are available for measurement, and perturbations with the property that an exponentially stable estimate of the unknown parameters can be obtained if the whole perturbation is known. The main contribution is to introduce a conceptually simple, modular design that gives freedom to the designer in accomplishing the main task, which is to construct an update law to asymptotically invert a nonlinear equation. Compensation for the perturbations in the system equations is considered for a class of systems with uniformly globally bounded solutions, for which the origin is uniformly globally asymptotically stable when no perturbations are present. We also consider the case when the parameters can only be estimated when the controlled state is bounded away from the origin, and show that we may still be able to achieve convergence of the controlled state. We illustrate the method through examples, and apply it to the problem of downhole pressure estimation during oil well drilling. © 2009 Elsevier Ltd. All rights reserved.
Akselsen O.M.,Norwegian University of Science and Technology |
Fostervoll H.,Norwegian University of Science and Technology |
Ahlen C.H.,StatoilHydro Research Center
International Journal of Offshore and Polar Engineering | Year: 2010
In the present investigation, hyperbaric welding has been simulated by laboratory welding in a pressure chamber as part of the development programme for fully remote controlled GMA welding. The welding trials of x65 pipeline steel were carried out at pressures of 12, 25 and 35 bar, using one metal cored tubular low-alloy steel and one solid Inconel 625 wire. All welds were characterized by macrographs, hardness measurements, and tensile and impact testing, in addition to metallurgical inspection through light microscopy and microprobe analysis. It is demonstrated that both welding wires can be used to provide high-quality welds under the prevailing conditions, satisfying current requirements set to hyperbaric welding. Copyright © by The International Society of Offshore and Polar Engineers.
Strimbeck G.R.,Norwegian University of Science and Technology |
Kjellsen T.D.,StatoilHydro Research Center
Forest Ecology and Management | Year: 2010
In experiments with needles of Picea abies, we tested the specific hypothesis that a single night of freezing acts as a signal that triggers a rapid increase in low temperature (LT) tolerance, and the more general hypothesis that repeated or prolonged freezing stimulates increased LT acclimation. In three growth chamber experiments involving acclimation under early- to mid-autumn light and temperature conditions followed by one or more freezing treatments, we found no significant effect of a single night of freezing on LT tolerance, and only limited and inconsistent effects of repeated and prolonged freezing. We also tested the effect of prolonged storage at -5 °C on LT tolerance on samples of three boreal and three temperate conifer species during acclimation under field conditions, and again found no consistent enhancement of LT tolerance attributable to freezing in either group. In agreement with our own and others' anecdotal observations that some species can attain nearly maximal LT tolerance in the absence of freezing under field conditions, we conclude that freezing is neither required nor a major influence in LT acclimation, at least in well-studied boreal conifer species, while the effects of freezing on temperate conifers are not as well-documented. We conclude that freezing treatment of conifer seedlings to ensure sufficient hardiness for late planting seems to offer little practical advantage. © 2010 Elsevier B.V. All rights reserved.
Kumara W.A.S.,Telemark University College |
Elseth G.,Telemark University College |
Elseth G.,StatoilHydro Research Center |
Halvorsen B.M.,Telemark University College |
And 3 more authors.
Flow Measurement and Instrumentation | Year: 2010
In this work, a comparison of Particle Image Velocimetry (PIV) and Laser Doppler Anemometry (LDA) measurement methods was made applied to oil-water two-phase flow in a horizontal pipe. The experiments were conducted in a 15 m long, 56 mm diameter stainless steel pipe using Exxsol D60 oil (density 790 kg/m3 and viscosity 1.64 mPa s) and water (density 996 kg/m3 and viscosity 1.0 mPa s) as test fluids. The experiments were performed at different mixture velocities and water cuts. Mixture velocity and water cut vary up to 1.06 m/s and 0.75, respectively. The instantaneous local velocities were measured using PIV and LDA, and based on the instantaneous local velocities mean velocities and turbulence profiles are estimated. The measurements are performed in the vertical plane through the pipe center. A double-pulsed Nd:yttrium aluminium garnet (YAG) laser and a high-speed camera with 1260×1024 px resolution (1.3 Mpx) were used for the PIV measurements. The LDA set-up is a two-colour backscatter system with 3 W Argon-Ion Laser. The time averaged cross-sectional distributions of oil and water phases were measured with a traversable gamma densitometer. The measured mean axial velocity and turbulence profiles using PIV were observed to compare favourably well with LDA measurements. Nevertheless, the PIV measurements are more sensitive for optical disturbances in the dispersed region close to the oil-water interface. Hence, this region cannot be confidently analyzed using PIV, whereas LDA offers full-field measurements even at higher mixture velocities. © 2010 Elsevier Ltd.
Ulleberg O.,Institute for Energy Technology of Norway |
Nakken T.,StatoilHydro Research Center |
Ete A.,University of Strathclyde
International Journal of Hydrogen Energy | Year: 2010
An autonomous wind/hydrogen energy demonstration system located at the island of Utsira in Norway was officially launched by Norsk Hydro (now StatoilHydro) and Enercon in July 2004. The main components in the system installed are a wind turbine (600 kW), water electrolyzer (10 Nm3/h), hydrogen gas storage (2400 Nm3, 200 bar), hydrogen engine (55 kW), and a PEM fuel cell (10 kW). The system gives 2-3 days of full energy autonomy for 10 households on the island, and is the first of its kind in the world. A significant amount of operational experience and data has been collected over the past 4 years. The main objective with this study was to evaluate the operation of the Utsira plant using a set of updated hydrogen energy system modeling tools (HYDROGEMS). Operational data (10-min data) was used to calibrate the model parameters and fine-tune the set-up of a system simulation. The hourly operation of the plant was simulated for a representative month (March 2007), using only measured wind speed (m/s) and average power demand (kW) as the input variables, and the results compared well to measured data. The operation for a specific year (2005) was also simulated, and the performance of several alternative system designs was evaluated. A thorough discussion on issues related to the design and operation of wind/hydrogen energy systems is also provided, including specific recommendations for improvements to the Utsira plant. This paper shows how important it is to improve the hydrogen system efficiency in order to achieve a fully (100%) autonomous wind/hydrogen power system. © 2009 Professor T. Nejat Veziroglu.
Toxopeus G.,Technical University of Delft |
Thorbecke J.,Technical University of Delft |
Petersen S.,StatoilHydro Research Center |
Wapenaar K.,Technical University of Delft |
Slob E.,Technical University of Delft
Computers and Geosciences | Year: 2010
An earth model is used in a collaborative environment in which some members provide information for its construction and others utilize the result. Validating an earth model by simulating a migration image is an important step. However, the high computational cost of generating 3D synthetic data, followed by the process of migration, limits the number of scenarios that can be validated. To overcome this computational cost, a novel strategy is used where a migration image is simulated by filtering a model with a spatial resolution filter. One of the key properties of this approach is that the model that describes a target-zone is decoupled from the macro-velocity model that is used to compute the spatial resolution filters. Consequently, different models can be filtered with the same resolution filter. For a horizontally layered medium, the Gazdag phase-shift operators are used to construct a common-offset spatial resolution filter to simulate the phase of 2D primary reflection data. To approximate a spatial resolution filter in a laterally variant medium, ray trace information is used as an illumination constraint. Additionally, the influence of seismic uncertainties on the shape of a spatial resolution filter and the resulting migration image are simulated. These filters enhance an iterative earth modeling approach. © 2009 Elsevier Ltd. All rights reserved.