Norske, Norway
Norske, Norway

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Rupke L.H.,Leibniz Institute of Marine Science | Schmid D.W.,University of Oslo | Schmid D.W.,GeoModelling Solutions GmbH | Perez-Gussinye M.,Royal Holloway, University of London | And 2 more authors.
Geochemistry, Geophysics, Geosystems | Year: 2013

The conditions permitting mantle serpentinization during continental rifting are explored within 2-D thermotectonostratigraphic basin models, which track the rheological evolution of the continental crust, account for sediment blanketing effects, and allow for kinetically controlled mantle serpentinization processes. The basic idea is that the entire extending continental crust has to be brittle for crustal scale faulting and mantle serpentinization to occur. The isostatic and latent heat effects of the reaction are fully coupled to the structural and thermal solutions. A systematic parameter study shows that a critical stretching factor exists for which complete crustal embrittlement and serpentinization occurs. Increased sedimentation rates shift this critical stretching factor to higher values as sediment blanketing effects result in higher crustal temperatures. Sediment supply has therefore, through the temperature-dependence of the viscous flow laws, strong control on crustal strength and mantle serpentinization reactions are only likely when sedimentation rates are low and stretching factors high. In a case study for the Norwegian margin, we test whether the inner lower crustal bodies (LCB) imaged beneath the Møre and Vøring margin could be serpentinized mantle. Multiple 2-D transects have been reconstructed through the 3-D data set by Scheck-Wenderoth and Maystrenko (2011). We find that serpentinization reactions are possible and likely during the Jurassic rift phase. Predicted thicknesses and locations of partially serpentinized mantle rocks fit to information on LCBs from seismic and gravity data. We conclude that some of the inner LCBs beneath the Norwegian margin may be partially serpentinized mantle. Key Points Thermotectonostratigraphic basin model resolves mantle serpentinization Sedimentation controls strength of lower crust and the onset of serpentinization LCBs beneath the Norwegian margin may be partially serpentinized mantle ©2013. American Geophysical Union. All Rights Reserved.


Rupke L.H.,GeoModelling Solutions GmbH | Schmid D.W.,GeoModelling Solutions GmbH | Schmid D.W.,University of Oslo | Hartz E.H.,Det Norske Oljeselskap | And 2 more authors.
Petroleum Geoscience | Year: 2010

This study explores the structural and thermal evolution of the Ghana transform margin. The main objective is to explore how the opening of the Atlantic Ocean and subsequent interaction with the Mid-Atlantic Ridge (MAR) has affected the margin's structural and thermal evolution. Two representative evolution scenarios are described: A reference case that neglects the influence of continental breakup and a second scenario that accounts for a possible heat influx during the passage of the MAR as well as magmatic underplating. These two scenarios have further been analysed for the implications for the hydrocarbon potential of the region. The scenario analysis builds on a suite of 2D realizations performed with TECMOD2D, modelling software for automated basin reconstructions. As the observed stratigraphy is input, the structural and thermal evolution of the basin is automatically reconstructed. This is achieved through the coupling of a lithosphere scale forward model with an inverse algorithm for model parameter optimization. We find that lateral heat transport from the passing MAR in combination with flexure of the lithosphere can explain the observed uplift of the margin. These results were obtained for a broken plate elasticity solution with a relative large value for the effective elastic thickness (Te=15) and necking level (15 km). Lateral heat flow from oceanic lithosphere is clearly visible in elevated basement heat flow values up to 50 km away from the ocean-continent transition (OCT). This influx of heat does not seem to have affected the maturation history along the margin significantly. Only the deepest sediments close to the OCT show slightly elevated vitrinite reflectance in simulations that account for the passage of the MAR. In conclusion, it appears that that lateral heat transport from the oceanic lithosphere is instrumental in shaping the Ghana transform margin but seems to have only limited control on the maturation history. © 2010 EAGE/Geological Society of London.


Bruton D.L.,University of Oslo | Gabrielsen R.H.,University of Oslo | Larsen B.T.,Det Norske Oljeselskap
Norsk Geologisk Tidsskrift | Year: 2010

In geological terms, the Oslo region is a graben structure containing downfaulted fossiliferous, Lower Palaeozoic rocks in a belt 40-70 km in width and extending 115 km north and south of the city of Oslo. Shelly, graptolitic and early vertebrate faunas together with microfaunas and -floras offer a detailed biostratigraphy and time scale for the Caledonide tectonics and associated events. The provided correlation charts reflect a preferred Baltoscandian terminology for the Cambrian and Ordovician successions and a standard British system for the Silurian. Reference to recent biostratigraphic and sedimentological studies allows speculation on changes in sedimentary rates having both global and local causes based on the fact that the Oslo Region occupied an intermediate position between the stable platform to the east and the developing orogen to the west. Sedimentary rates, were high with dominantly mudstones and limestones and local thicknesses up to 1 km in the Ordovician and nearly twice this amount in the Silurian where siliceous rocks in a red-bed facies first appear around the Wenlock-Ludlow boundary. Caledonian tectonics in the Oslo Region activated the Osen-Røa detachment along which the major displacement was to take place. This structure underlies the entire Oslo Region, but dies out to the south in the Skien-Langesund area. In the Oslo Region, the Osen-Røa detachment lies within the late Cambrian Alum Shale and is developed as an intensely deformed thrust plane, from which numerous faults splay up-section into the Ordovician and Silurian strata, forming a duplex structure. Although the strain intensity decreases towards the south and towards the upper part of the Cambro-Silurian section, three major structural levels, in addition to the basal Osen-Røa detachment are identified. These are partly associated with flats of semi-regional significance in the nappe pile. The bulk transport is towards the south-southeast, but areas of southerly (Klekken area) and southeasterly transport (southern Ringerike) are also prominent. The detailed timing of the deformation is not well established, but the first sedimentary response to the growing mountain chain to the northwest is believed to be the fine-grained sandstones and siltstones of the Elnes Formation of late Middle Ordovician (Darriwilian) age, whereas the first siliciclastic sediments of more significant thickness date to the latest Ordovician. Finally, it is evident that the up to 1250 m-thick, Upper Wenlock-Lower Ludlow sandstones of the Ringerike Group have been affected by the contractional deformation, defining a maximum age for the latest Caledonian (Scandian) orogenic movements.


Ytrehus J.D.,Sintef | Taghipour A.,Sintef | Golchin A.,Lulea University of Technology | Prakash B.,Lulea University of Technology | Saasen A.,Det Norske Oljeselskap
Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE | Year: 2015

A very important aspect in highly inclined wellbores is the mechanical friction. For extended reach drilling (ERD) and through tubing extended reach drilling (TTERD) this can be a limiting factor. Friction caused by the contact between the drill string and the well casing or borehole is dependent to the drilling weight and fluid properties. Drilling fluids play an important role on mechanical friction and using oil based drilling fluids with higher lubricity can reduce torque and drag behavior and minimize stick and slip. Reducing mechanical friction will improve drilling efficiency in general, and will in particular enable longer reach for ERD wells. This paper presents results from experimental laboratory tests where mechanical friction has been investigated. The experiments have been conducted as part of a project in the Tribolab at Lulea University of Technology in cooperation with Det norske Oljeselskap. Friction behavior has been investigated for different drilling fluids; water based and oil based drilling fluids both with and without solid particles. A pin on disc setup was used for these experiments where a spherical steel pin was sliding on a rotational disc made of granite. Friction force has been measured in constant sliding speed and in presence of particles in wet condition. The test results show that mechanical friction in general is smaller with oil based than water based drilling fluids in the presence of solid particles. In addition, the friction coefficient increases when solid particles were added to the lubricants. Such experiments in a tribology laboratory are important to identify the effect of drilling fluids on mechanical friction from a basic point of view and isolated from all other wellbore parameters. It is interesting to monitor if the results from this setup can have quantitative relevance also for field situations and such comparison should be done as follow up. Test results and the experimental approach could therefore be of value for any one working with drilling and well construction. © 2015 by ASME.


Taghipour A.,Sintef | Ytrehus J.D.,Sintef | Lund B.,Sintef | Saasen A.,Det Norske Oljeselskap
Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE | Year: 2014

Mechanical friction is one of the most important aspects in highly inclined wellbores such as extended reach drilling (ERD) and through tubing extended reach drilling (TTERD). Friction caused by the contact between the drill string and the well casing or borehole is dependent to the drilling weight and fluid properties. Drilling fluids play an important role on mechanical friction and using oil based drilling fluids with higher lubricity can reduce torque and drag and minimize stick and slip concerns. Reducing mechanical friction will improve drilling efficiency in general, and will in particular enable longer reach for ERD wells. This paper presents results from experimental laboratory tests where mechanical friction has been investigated in non-circular wellbore geometry. The experiments have been conducted as part of a research project in the tribology lab in Technical University of Luleå. The project was sponsored by the Research Council of Norway and four oil companies. Friction behavior has been investigated for two different drilling fluids; water based and oil based drilling fluids both with and without solid particles. A pin on disc setup was used for these experiments where a spherical steel pin was sliding on a rotational disc made of granite. Friction force has been measured in constant sliding speed and in presence of particles in wet condition. The test results show that mechanical friction is smaller with oil based than water based drilling fluids in the presence of solid particles. In addition, the friction coefficient depends to the particle types and is higher when solid particles were added to the lubricants. Such experiments in a tribology laboratory are important to identify the effect of drilling fluid on mechanical friction from a basic point of view isolated from the other wellbore parameters. Test results and the experimental approach could therefore be of value for any one working with drilling and well construction. Copyright © 2014 by ASME.


Ytrehus J.D.,Sintef | Taghipour A.,Sintef | Sayindla S.,Norwegian University of Science and Technology | Lund B.,Sintef | And 2 more authors.
Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE | Year: 2015

One important requirement for a drilling fluid is the ability to transport the cuttings out of the borehole. Improved hole cleaning is a key to solve several challenges in the drilling industry and will allow both longer wells and improved quality of well construction. It has been observed, however, that drilling fluids with similar properties according to the API standard can have significantly different behavior with respect to hole cleaning performance. The reasons for this are not fully understood. This paper presents results from flow loop laboratory tests without and with injected cuttings size particles using a base oil and a commercial oil based drilling fluid. The results demonstrate the importance of the rheological properties of the fluids for the hole cleaning performance. A thorough investigation of the viscoelastic properties of the fluids was performed with a Fann viscometer and a Paar-Physica rheometer, and was used to interpret the results from the flow loop experiments Improved understanding of the fluid properties relevant to hole cleaning performance will help develop better models of wellbore hydraulics used in planning of well operations. Eventually this may lead to higher ROP with water based drilling fluids as obtained with oil based drilling fluids. This may ease cuttings handling in many operations and thereby significantly reduce the drilling cost using (normally) more environmentally friendly fluids. The experiments have been conducted as part of an industry-sponsored research project where understanding the hole cleaning performance of various oil and water based drilling fluids is the aim. The experiments have been performed under realistic conditions. The flow loop includes a 10 meter long test section with 2" OD freely rotating drillstring inside a 4" ID wellbore made of concrete. Sand particles were injected while circulating the drilling fluid through the test section in horizontal position. © 2015 by ASME.


Rdosjo M.,Det Norske Oljeselskap | Akutsu E.,Det Norske Oljeselskap | Morris S.,Halliburton Co. | Mikalsen R.,Halliburton Co.
Society of Petroleum Engineers - SPE Offshore Europe Conference and Exhibition, OE 2013 | Year: 2013

Historically, invert emulsion drilling fluids (IEFs) require organophilic clays to provide viscosity and suspension characteristics. Whilst effective, these chemicals are prone to stratification in certain conditions, slow chemical reaction times, high pressure spikes, and high equivalent circulating densities (ECDs) attributed to the solids contribution and inherent chemistry of the fluid. To help reduce such adverse effects, clay-based chemicals used in IEFs can be replaced with highly sophisticated polymer viscosifiers, filtration agents, and emulsifiers, which provide a strong, stable emulsion, even with low-oil/water ratio (OWR) IEFs. Legislation governing the energy industry's use of chemicals in Norway prohibits use of certain products that are otherwise globally used in drilling fluids. To address such restrictions, extensive research and development has resulted in availability of environmentally acceptable chemicals that produce the unique rheological and suspension characteristics inherent to clay-free IEF systems. This paper describes the first application of clay-free IEFs in the Norwegian continental shelf (NCS) with an emphasis on an impressively low ECD contribution far more consistent than previously recorded in comparable wells. Further, a treatment was developed to allow the IEFs to be used to drill into a section exhibiting temperatures greater than 160°C. Chemical consumption was substantially lower compared to previous wells using traditional IEF systems, thus reducing shipping requirements. Before planning the subject well, the environmentally acceptable chemicals intended for use were approved by governing bodies. Consequently, a vertical exploration prospect was selected as the initial well to be drilled using a clay-free IEF. This well was comparable to a previously drilled high-pressure/high-temperature HP/HT well, allowing direct comparison of several of the metrics. Copyright 2013, Society of Petroleum Engineers.


Aas B.,IRIS | Sorbo J.,IRIS | Stokka S.,IRIS | Saasen A.,Det Norske Oljeselskap | And 4 more authors.
SPE/IADC Drilling Conference, Proceedings | Year: 2016

Well abandonment operations can be very time-consuming and costly, and thousands of wells need to be permanently plugged and abandoned offshore Norway during the upcoming years. One possible way to reduce costs during P&A operations is to leave most of the production tubing in the well, as this would save significant rig time. A major concern with such an approach is, however, whether the cement will properly displace the original fluid, due to lack of tubing centralization and possible unfavorable flow dynamics in the annulus. In this paper, we demonstrate by full-scale experimental tests that it is possible to obtain good cement placement when the tubing is left in the hole, with and without control lines. Full-scale tests have been performed with both conventional and expandable cement to determine the sealing ability of annulus cement when tubing is left in hole. The quality of the cement placement was evaluated by pressure tests with water; where leakage rates and pressure drops over the test sections were recorded, and by visual inspection after cutting the test assemblies at different places. It is seen from the experiments that cement is well placed in the annulus when tubing is left in hole, but some microannuli are detected. Copyright 2016, IADC/SPE Drilling Conference and Exhibition.


Haldan M.M.,University Utrecht | Meijers M.J.M.,University of Nice Sophia Antipolis | Meijers M.J.M.,University of Minnesota | Langereis C.G.,University Utrecht | And 2 more authors.
Geophysical Journal International | Year: 2014

We have performed an extended palaeomagnetic study of the Oslo Graben volcanics, compared to the study of half a century ago by van Everdingen, using modern techniques and a four times larger amount of sites, plus additional rock magnetic experiments.We conclude that the average direction (D = 204.0, I = -37.9, k = 46.9, α95 = 2.0) and associated palaeomagnetic pole (λ = 48.3, ϕ = 155.5, K = 52.2, A95 = 1.9) of the Krokskogen and Vestfold volcanics together are statistically identical to those of the earlier study. This gives confidence in the fact that older palaeomagnetic studies can be reliable and robust, even though methods have improved. Our larger number of samples, and better age constraints, enable us to separate the data into two major intervals: the younger, on average, Krokskogen area and the older Vestfold area. The results show firstly that palaeolatitudes are slightly higher than predicted by the latest apparent polar wander path (APWP) for Eurasia by Torsvik et al. These data support an early Permian Pangaea A configuration and do not necessitate a Pangaea B configuration. The larger data set also allows us to assess the distribution of the characteristic remanent magnetization directions of the Oslo Graben in terms of geomagnetic field behaviour, which were acquired during a long period of dominantly single polarity the Permo-Carboniferous Reversed Superchron (PCRS). The distributions showa significantly lower virtual geomagnetic pole (VGP) scatter at the observed (low) latitudes than expected from a compilation from lavas of the last 5 Myr. The data do however show excellent agreement with the scatter observed both during the Cretaceous Normal Superchron and the PCRS. A comparison of the directional distributions in terms of elongation is less discriminating, since the large errors in all cases allow a fit to the predicted elongation/inclination behaviour of the TK03.GAD model. © The Authors 2014. Published by Oxford University Press on behalf of The Royal Astronomical Society.


Aas B.,IRIS DrillWell | Sorbo J.,IRIS DrillWell | Stokka S.,IRIS DrillWell | Saasen A.,Det Norske Oljeselskap | And 4 more authors.
SPE - International Association of Drilling Contractors Drilling Conference Proceedings | Year: 2016

Well abandonment operations can be very time-consuming and costly, and thousands of wells need to be permanently plugged and abandoned offshore Norway during the upcoming years. One possible way to reduce costs during P&A operations is to leave most of the production tubing in the well, as this would save significant rig time. A major concern with such an approach is, however, whether the cement will properly displace the original fluid, due to lack of tubing centralization and possible unfavorable flow dynamics in the annulus. In this paper, we demonstrate by full-scale experimental tests that it is possible to obtain good cement placement when the tubing is left in the hole, with and without control lines. Full-scale tests have been performed with both conventional and expandable cement to determine the sealing ability of annulus cement when tubing is left in hole. The quality of the cement placement was evaluated by pressure tests with water; where leakage rates and pressure drops over the test sections were recorded, and by visual inspection after cutting the test assemblies at different places. It is seen from the experiments that cement is well placed in the annulus when tubing is left in hole, but some microannuli are detected. Copyright 2016, IADC/SPE Drilling Conference and Exhibition.

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