Tor Bjørnstad

• Silva, Mario & Bjørnstad, Tor (2020). Determination of phase-partitioning tracer candidates in production waters from oilfields based on solid-phase microextraction followed by gas chromatography-tandem mass spectrometry. Journal of Chromatography A.  ISSN 0021-9673.  1629 . doi: 10.1016/j.chroma.2020.461508 Fulltekst i vitenarkiv.
• Ould Metidji, Mahmoud; Silva, Mario; Krivokapic, Alexander & Bjørnstad, Tor (2019). Synthesis and Characterization of a Reactive Fluorescent Tracer and its Possible Use for Reservoir Temperature's Data Collection, In  IOR 2019 – 20th European Symposium on Improved Oil Recovery.  European Association of Geoscientists and Engineers.  ISBN 978-94-6282-278-8.  Paper.
• Silva, Mario; Ould Metidji, Mahmoud; Stray, Helge & Bjørnstad, Tor (2019). Alkylpyrazines - from the “Dinner Table” to the Oilfield: A New Class of Partitioning Tracers, In  IOR 2019 – 20th European Symposium on Improved Oil Recovery.  European Association of Geoscientists and Engineers.  ISBN 978-94-6282-278-8.  Paper.
• Silva, Mario; Stray, Helge & Bjørnstad, Tor (2019). Stability assessment of PITT tracer candidate compounds – The case of pyrazines. Journal of Petroleum Science and Engineering.  ISSN 0920-4105.  182 . doi: 10.1016/j.petrol.2019.106269
• Silva, Mario; Stray, Helge & Bjørnstad, Tor (2018). Stability assessment of PITT tracer candidate compounds: the case of benzyl alcohols. Journal of Petroleum Science and Engineering.  ISSN 0920-4105.  167, s 517- 523 . doi: 10.1016/j.petrol.2018.04.027 Fulltekst i vitenarkiv.
• Haukås, Jarle; Madland, Merete Vadla; Flornes, Kristin Margrethe; Hiorth, Aksel; Valestrand, Randi; Viig, Sissel Opsahl; Stavland, Arne; Zimmermann, Udo; Jettestuen, Espen; Mebratu, A.; Bjørnstad, Tor; Klöfkorn, Robert; Skjæveland, Svein Magne & Nævdal, Geir (2017). Integration of IOR Research Projects through Generic Case Studies, In Ukjent Ukjent (ed.),  19th European Symposium on Improved Oil Recovery/IOR Norway 2017.  European Association of Geoscientists and Engineers.  ISBN 978-94-6282-209-2.  130.
• Ould Metidji, Mahmoud; Brichart, Thomas; Bjørnstad, Tor & Ferrando-Climent, Laura (2017). New fluorescent tracers for SWCTT, In Ukjent Ukjent (ed.),  19th European Symposium on Improved Oil Recovery/IOR Norway 2017.  European Association of Geoscientists and Engineers.  ISBN 978-94-6282-209-2.  19th European Syposium.
• Silva, Mario; Stray, Helge & Bjørnstad, Tor (2017). New Potential Tracer Compounds for Inter-well SOR Determination - Stability at Reservoir Conditions, In Ukjent Ukjent (ed.),  19th European Symposium on Improved Oil Recovery/IOR Norway 2017.  European Association of Geoscientists and Engineers.  ISBN 978-94-6282-209-2.  87.
• Silva, Mario; Stray, Helge & Bjørnstad, Tor (2017). Studies on New Chemical Tracers for Determination of Residual Oil Saturation in the Inter-Well Region, In X X (ed.),  SPE Oklahoma City Oil and Gas Symposium. 27–31 March 2017, Oklahoma City, Oklahoma, USA.  Society of Petroleum Engineers.  ISBN 978-1-61399-514-3.  SPE-185085-MS.
• Wangen, Magnus; Sagen, Jan; Bjørnstad, Tor; Johansen, Harald & Souche, Alban Jean-Rene (2016). Models for Calcium Carbonate Precipitation in the Near-Well Zone by Degassing of CO2. Open Petroleum Engineering Journal.  ISSN 1874-8341.  9, s 178- 194 . doi: 10.2174/1874834101609160178 Fulltekst i vitenarkiv. Vis sammendrag

  Calcium carbonate scale formation is a well known problem for water producing wells. Although there are several types of scale forming processes, we investigate the case of calcium carbonate precipitation when the degassing of CO2 causes the calcium equilibrium concentration to decrease towards a production well. We study a simplified system of carbonate chemistry, which allows for analytical expressions for the porosity loss as a function of time. The precipitation process normally goes from flow-limited away from the well to precipitation-limited close to the well. We derive an expression that estimates the transition zone between these two regimes. Furthermore, we present analytical estimates for the porosity reduction at a given radius as a function of time, including an estimate for each of these precipitation regimes. These analytical results are tested against numerical solutions for the porosity loss, which account for the full set of equations of the model. The analytical models give an accurate estimate of the linear porosity reduction with time, until at least half the porosity is lost. Examples of scale formation are given for the two regimes. Reasonable values for the precipitation kinetics indicate that most production operations have a kinetics-limited regime close to the well. The models also show that this type of scale formation takes place very close to the wells, typically within a few well radii from the walls of the well.

• Stamatakis, Emmanuel; Stubos, A; Bjørnstad, Tor & Muller, Jiri (2013). Calcite scale prediction at the near-well region: A radiotracer approach, In Are Haugan (ed.),  TRACER 6 - The 6th International Conference on Tracers and Tracing Methods. Oslo, Norway, June 6-8, 2011.  EDP Sciences.  ISBN 978-2-7598-1005-5.  Paper.  s 03004-p.1 - 04004-p.6 Vis sammendrag

  Effective prediction of calcite scaling requires a reliable thermodynamic model for the prediction of the scaling tendency, a kinetic model for the prediction of scaling rate and a transport model to simulate flow in a porous medium. The accurate prediction of the scale deposition can warn the engineers to “treat” the formation around the wellbore in time. In addition, the prediction of the distribution of the scale deposition can direct the engineers to ensure the placement of the inhibitors into the formation zones where the deposition is expected, thus maximizing the probability of successful prevention of formation damage and minimizing at the same time the amount of the required inhibitors. In this contribution, we present a geochemical computational model that combines existing thermodynamic and kinetic models for CaCO3 precipitation, with treatments of flow and diffusion in electrolyte systems, in an one-dimensional porous medium. The geochemical model has the ability to predict the distribution of scale deposition along and around the production wells, as well as the distribution of formation damage (pore blocking, permeability reduction) around the wells.

• Stavsetra, Liv; Fure, Kristin; Haugan, Are & Bjørnstad, Tor (2013). Development of an oil tracer labelled with Ba-137m. The European Physical Journal Conferences.  ISSN 2101-6275.  50:05002 . doi: 10.1051/epjconf/20135005002
• Samadani, Fereshteh; Alstad, Jorolf; Bjørnstad, Tor; Stavsetra, Liv & Omtvedt, Jon Petter (2010). Development of a SISAK extraction system for chemical studies of element 108, hassium. Radiochimica Acta.  ISSN 0033-8230.  98(12), s 757- 764 . doi: 10.1524/ract.2010.1787
• Eriksen, Dag Øystein; Haugen, Odd Benny & Bjørnstad, Tor (2009). Enhanced oil recovery methods studied by gamma tracer scanning at simulated reservoir conditions. Journal of Radioanalytical and Nuclear Chemistry.  ISSN 0236-5731.  280(2), s 287- 292 . doi: 10.1007/s10967-009-0513-9

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• Bjørnstad, Tor; Borroto Portela, J. I.; Brisset, P.; Chankow, N.; Charlton, J.S.; Conejo Solis, M.A.; Dagadu, C.P.K.; Dash, A.; Diaz Vargas, F.; Ghiyas-Ud-Din, x; Jin, J.-H.; Li, J.; Munoz Anrique, L.; Pinto Ferreira, A.; Palige, J.M.; Roesch, F.; Jung, S.-H. & Vargas, C. (2013). Radiotracer Generators for Industrial Applications. International Atomic Energy Agency.  ISBN 978-92-0-135410-5.  203 s.
• Abidin, Z.; Berne, P.; Bjørnstad, Tor; Jin, J.-H.; Khan, I.H.; Leclerc, J.-P.; Maggio, E.G.; Moreira, M.R.; Olivar, M.V.; Quang, N.H.; Somaruga, C.; Tang, S.H.J. & Zhang, P. (2012). Application of Radiotracer Techniques for Interwell Studies. International Atomic Energy Agency, IAEA.  ISBN 978-92-0-125610-2.  231 s.

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• Ould Metidji, Mahmoud; Krivokapic, Alexander; Silva, Mario; Bjørnstad, Tor; Selvam, Arun & Cathles, Lawrence (2019). Contribution to the study on nanoparticles as oil-reservoir tracers.
• Ould Metidji, Mahmoud; Silva, Mario; Krivokapic, Alexander & Bjørnstad, Tor (2019). Synthesis and Characterization of a Reactive Fluorescent Tracer and its Possible Use for Reservoir Temperature's Data Collection.
• Panneer Selvam, Arun Kumar; Ould Metidji, Mahmoud; Silva, Mario; Viig, Sissel Opsahl; Madland, Merete Vadla & Bjørnstad, Tor (2019). Nanoparticle tracers for petroleum reservoir studies.
• Selvam, Arun; Ould Metidji, Mahmoud; Viig, Sissel Opsahl & Bjørnstad, Tor (2019). Nanoparticle tracers for petroleum reservoir studies.
• Silva, Mario; Ould Metidji, Mahmoud; Stray, Helge & Bjørnstad, Tor (2019). Alkylpyrazines - from the “Dinner Table” to the Oilfield: A New Class of Partitioning Tracers.
• Bjørnstad, Tor (2018). On-line analyses of mass transport using neutrons.
• Bjørnstad, Tor; Ould Metidji, Mahmoud; Krivokapic, Alexander & Viig, Sissel Opsahl (2018). Nanoparticles as oil detectives?.
• Ould Metidji, Mahmoud; Krivokapic, Alexander; Silva, Mario; Cathles, Lawrence & Bjørnstad, Tor (2018). Nanotracers intended for EOR-operations.
• OULD-METIDJI, Mahmoud; Lopes Da Silva, M.H.; Ferrando-Climent, L.; Krivokapic, A. & Bjørnstad, Tor (2018). Future Prospect For Reservoir Tracer Technology: Benefits, Obstacles and Development. Vis sammendrag

  Abstract: Objectives/Scope: This study provides an outlook on the major benefits, advantages and drawbacks encountered with tracers currently used for residual oil saturation (SOR) determination employing single-well chemical tracer test (SWCTT) and partitioning inter-well tracer test (PITT) methods, as well as the strategies designed to rise above the obstacles in the process of new tracer development. Methods, Procedures, Process: Both SWCTT test and PITT have seen slow development since their introduction, while the challenges faced by today’s industries have significantly evolved. Most drawbacks encountered in published field cases with these tests arise from our ability to detect and quantify the tracer compounds and/or their inadequate selection/testing. The present work has been focused on the development of new tracers, their testing and qualification, and improvement of the analytical methods to quantify them. Strategies to reduce the cost of tracer tests, like on-site or online analysis of the tracers, have also been considered. Results, Observations, Conclusions: Typically, in a common SWCTT large amounts of hydrolyzing esters are injected into the well. The results suggest the possibility of significantly reducing the amount of chemicals used in these tests. This will contribute to mitigate the safety hazard of the operation and reduce possible modification of the near-well conditions through in-situ generation of high amount of acids liberated during the hydrolysis of the esters. Furthermore, the hydrolysis rate is pH dependent and is a crucial parameter for the test results interpretation, therefore using a smaller amount of chemicals will reduce possible interferences in the results. On the other hand, more and properly tested PITT tracers with sufficiently sensitive analytical methods (ppb-ppt levels) will contribute for the dissemination of these tests. It is important to note that a PITT tracer should endure the harsh reservoir conditions for long periods of time in the range of months to years. It should also comply with growing restrictive environmental regulations, as for example on the Norwegian continental shelf, where strict limits are imposed regarding the amount and nature of the injected compounds. Novel/Additive Information: A thorough understanding of the tracers’ behavior together with a new generation of tracers will contribute to improve both accuracy and feasibility of SOR determination. This will facilitate the use of tracer tests in the oil-field, thus improving reservoir characterization which is a key-factor in the selection of EOR techniques to maximize economical oil recovery.

• Silva, Mario & Bjørnstad, Tor (2018). Non-Conservative Tracers for Temperature Assessment in the Interwell Region of Oil Reservoirs.
• Vinningland, Jan Ludvig; Valestrand, Randi; Hiorth, Aksel; Bjørnstad, Tor; Klöfkorn, Robert; Viig, Sissel Opsahl; Jettestuen, Espen; Skjæveland, Svein Magne; Zimmermann, Udo; Stavland, Arne; Nævdal, Geir & Madland, Merete Vadla (2018). The National IOR Centre of Norway.
• Bjørnstad, Tor (2017). Can functionalized nanoparticles be used as reservoir tracers?.
• Bjørnstad, Tor (2017). Keynote Lecture: Recent development in nuclear methods for process monitoring. Vis sammendrag

  In many fields of process monitoring, nuclear methods constitute a technically indispensable tool. However, the use of open or encapsulated radioactive sources is increasingly under public scrutiny, often because of misunderstandings or lack of knowledge. In order to sufficiently mitigate these perceived shortcomings and make the use of nuclear monitoring methods acceptable by process owners and the public, one has to substantiate reduction of any unnecessary human or environmental risks associated with such technologies. For open radioactive sources, i.e. mainly in the form of radiotracers (aqueous, organic or particulate), focus are now on increased application of short-lived radionuclides whenever these can be used. Short-lived radionuclides are commonly produced by neutron irradiations in nuclear reactors or by charged particle reactions at particle accelerators. Hence, due to transportation time and logistics, there is an upper practical limit to the distance of their use from the radionuclide production facilities. Typical industrial examples are off-shore petroleum production in remote areas or onshore process industry in countries which do not host such production facilities. Therefore, there is an increasing focus on developing industrial brands of radiotracer generators, which are based on a secular equilibrium between the long-lived mother and the short-lived daughter radionuclides. This presentation will give some examples of such generators and define the status of their development. Additionally, many long-lived encapsulated radioactive sources used in fixed mountings today (two examples are 60Co and 137Cs) may, in principle, be substituted by the use of small neutron generators which can be turned on and off on demand. The recent years’ development and availability of such transportable neutron generators give, in fact, several new technical possibilities, some of which are summarily mentioned here: 1. on site production of short-lived radionuclides for injection into processes, 2. on-line mounting onto transportation pipelines for in-situ and on-line generation of short-lived tracers directly in the process stream, 3. application of prompt gamma-ray spectra from neutron-induced nuclear reactions generated in the process stream (PGNA) for monitoring of specific mass movement, 4. the use of neutron transmission (thermal and fast neutrons) or reflection (thermal neutrons) monitoring of specific mass movement, 5. generation of prompt gammas in external fixed target for gamma transmission experiments (mass density measurements), and more. This presentation will also describe some of these emerging possibilities in some detail. The use of equipment and methods described here leads to reduced radiation exposure and virtually no left-over activity or radio-contamination after the monitoring process is completed.

• Bjørnstad, Tor (2017). Nuclear-Based Monitoring of Industrial Mass Flow I: The potential use of Small Transportable Neutron Generators. Vis sammendrag

  Radiotracers for industrial monitoring are produced mainly by two main methods: 1) Activation in research nuclear reactors (RNR) or at charged particle accelerators, and 2) by radiotracer generators (RG). Both methods face challenges: 1. The production by activation is often difficult from both administrative and technical reasons. Administrative reasons imply that the production of specific radionuclide has to be known and authorized at the irradiation facilities. Technical reasons imply that irradiation facilities are often non-existing in many countries. Where irradiation facilities do exist, there are limitations due to periodical shut downs. Finally, transportation time between irradiation facilities and industrial site limits again the use of short half-life radiotracers. 2. The number of commercially available radiotracer generators for industrial use is rather limited for the moment. Other options for nuclear-based monitoring of industrial mass flow that appear may therefore be interesting to pursue. One such option is the application of recently developed small-sized neutron generators. Two types of neutron generators are available using deuterium-deuterium (DD) reaction (neutrons at 2:45 MeV) and deuterium-tritium (DT) reaction (neutrons at 14:1 MeV). Commercial DT generators may produce neutron outputs of ¡1011 n/s. Unlike isotopic neutron sources, the neutron generators contain no radioactivity (except the inventory of tritium in the DT neutron generator) making them inherently safe (no external radiation) when turned off. This presentation will review the current status of such neutron generators and discussed possible applications for use in industrial in situ or even on-line monitoring processes. The various approaches include on-site production of radiotracer by off-line irradiation of suitable target, on-line and in situ generation pulses of short-lived radiotracers from macroelements in the flow, direct continuous activation of matrix elements in the flow, activation of injected pulse of a stable chemical compound, PGNAA of injected non-radioactive tracer pulse, neutron transmission measurement after pulse injection of a strong neutron absorber and others. The broad industrial use of such techniques is at present in its infancy, and a considerable R&D work remains to be done to ensure the robustness of the different approaches.

• Bjørnstad, Tor; Stavsetra, Liv; Krivokapic, Alexander; Eriksen, Dag Øistein & Vascon, Alessio (2017). Hydrometallurgy in mineral mining and urban mining.
• Ould Metidji, Mahmoud; Kelesoglu, Serkan; Silva, Mario & Bjørnstad, Tor (2017). Laboratory assessment of nanotracers for oil reservoir characterization.
• Silva, Mario; Stray, Helge & Bjørnstad, Tor (2017). New Chemical Tracers for Determination of Residual Oil Saturation in the Inter-Well Region - Initial Studies.
• Silva, Mario; Stray, Helge & Bjørnstad, Tor (2017). PITT Tracer Candidates: Stability at Reservoir Conditions.
• Bjørnstad, Tor (2016). Reactor-produced radionuclides for tracing operations in industry and civil engineering.
• Bjørnstad, Tor (2016). The possible role of nanoparticle tracers in measurements of residual oil saturation in the near-well area.
• Bjørnstad, Tor (2016). Tracer-based reservoir evaluation and SOR determination.
• Bjørnstad, Tor; Brisset, Patrick; Gardner, Robin Pierce; Kuznetsov, Aleksandr & Moreira, Rubens Martin (2016). Neutron Generators for Tracing Applications.
• Bjørnstad, Tor; Silva, Mario; Brichart, Thomas; Krivokapic, Alexander & Viig, Sissel Opsahl (2016). Development of new tracers for SOR measurements in IW and SW application - Some recent results and future plans.
• Bjørnstad, Tor; Stavsetra, Liv; Fure, Kristin; Opel, Karsten; Haugan, Are & Krivokapic, Alexander (2016). Radiotracer-based monitoring of liquid carry-over from gas scrubbers.
• Silva, Mario & Bjørnstad, Tor (2016). Solid-Phase Microextraction as Sample Preparation Technique in Tracer Technology.
• Bjørnstad, Tor (2015). Mineral exploitation and hydrometallurgical methods.
• Bjørnstad, Tor (2015). Radiotracers Applications in Oil Fields: Enhancing the Recovery of Oil.
• Rollwagen, Joe & Bjørnstad, Tor (2015, 15. september). Mapping it out: Tracer technology and the search for oil. [Fagblad].  IAEA Bulletin, September 2015.
• Abdullah, Jaafar; Alami, Rachad; Abdelwahed, Haifa Ben; Bjørnstad, Tor; Calvo, Carlos Sebastian; Dagadu, Christian Priesley Kofi; Dominguez-Catasus, Judith; Gao, Xiang; Gardner, Robin Pierce; Ud-Din, Ghiyas; Kim, Jong-Bum; Leclerc, Jean-Pierre; Moreira, Rubens Martin; Nguyen Huu, Quang; Palige, Jacek Maria; Goswami, Sunil & Stegowski, Zdizlaw (2014). Radiometric methods for measuring and modelling multiphase systems - progress report No.2.
• Bjørnstad, Tor (2014). A flavour of nano-particles as tracer agents for IOR.
• Bjørnstad, Tor (2014). Aspects of how tracer compounds can contribute to optimize EOR/IOR processes.
• Bjørnstad, Tor (2014). Brief about tracer technology and the National Norwegian IOR-Centre.
• Bjørnstad, Tor (2014). Neutron generators in industry and civil society.
• Bjørnstad, Tor (2014). The Role of Tracers in Optimization of EOR/IOR Operations. Vis sammendrag

  After a brief introduction on the general aspects of water- and gas-based oil recovery methods, the presentation is focused on remaining (or residual) oil saturation and potential for recovery by tertiary methods. The concept of Interwell Tracer Technology by simultaneous use of passive and phase-partitioning tracers is then introduced as a means to measure both flooding patterns and remaining (residual) oil saturation in flooded areas between wells. Single-well push-and-pull tracer technology is also covered to measure residual oil saturation in-situ in the near-well zone (5-10 m from the wellbore) by use of reactive tracers, adding some information on recent technology development. The presentation is rounded off by tracer-based methods for depth-differential well fluid in-flow to detect "good and bad" zones in the well, and the potential use of "smart" functionalized tracers to measure properties of the reservoir (salinity, pH, temperature and others) of importance to EOR-operations.

• Bjørnstad, Tor (2014). The use of transportable neutron sources for industrial monitoring.
• Bjørnstad, Tor; Haugan, Are; Stavsetra, Liv & Fure, Kristin (2014). Multiphase flow in separators and scrubers: Condition monitoring.
• Bjørnstad, Tor; Haugan, Are; Stavsetra, Liv & Fure, Kristin (2014). Radiotracer generators for application in process industries.
• Bjørnstad, Tor; Jin, Joon-Ha; Calvo, Wilson Aparecido; Boutaine, Jean-Louis; Charlton, Stuart; Leclerc, Jean-Pierre; Johansen, Geir Anton & Brisset, Patrick (2014). Report on the Consultant Meeting on "The Current Status and Future Trends on Radioisotope Applications in Industry".
• Madland, Merete Vadla; Hiorth, Aksel & Bjørnstad, Tor (2014). Presenting the 2 R&D Themes for The National IOR Centre of Norway.
• Bjørnstad, Tor (2013). Application of neutron generators in industry.
• Bjørnstad, Tor (2013). Beyond Traditional Flow Assurance.
• Bjørnstad, Tor (2013). Brief about Petroleum Activities at IFE.
• Bjørnstad, Tor (2013). The Role of Tracer Technology in Future Reservoir Management.
• Bjørnstad, Tor; Eriksen, Dag Øystein & Omtvedt, Jon Petter (2013). Radiochemistry and hydrometallurgy - two synergetic fields.
• Berg, Øivind; Bjørnstad, Tor; Dahlgren, Sven; Nøvik, Sven; Rondeel, Wilhelm & Totland, Arne (2012). Thorium - en framtidsressurs i Oslofjordregionen?.
• Bjørnstad, Tor (2012). Application of gamma-ray detection equipment in the petroleum industry.
• Bjørnstad, Tor (2012). Monitoring Multiphase Flow in Separators and Scrubbers - Combined Radiotracer and Sealed Source Technique.
• Bjørnstad, Tor (2012). Possible development of nuclear technology for industrial monitoring applications.
• Bjørnstad, Tor (2012). Radioaktivitet i vår hverdag - delvis til ulempe men også til nytte og forbedret helse.
• Bjørnstad, Tor (2012). Tracer Technology for Interwell Reservoir Examination - Achievements and Future Challenges.
• Bjørnstad, Tor (2011). Extraction of Th from Norwegian Mineral Resources.
• Bjørnstad, Tor (2011). Flow Assurance Challenges in Geothermal Energy Production - Mineral Scaling.
• Bjørnstad, Tor (2011). Oljedetektivene - de syngende molekyler.
• Bjørnstad, Tor; Dugstad, Ø.; Hartvig, S.K. & Haugan, A. (2011). SAGD-Related Oil Recovery: Fluid Tracing Challenges.
• Fure, K.; Stavsetra, L. & Bjørnstad, Tor (2011). Experimental Studies on Generation of Short-Lived Radiotracers of Daughter Products from the Nuclear Genetic Relationships 68Ge - 68Ga and 137Cs - 137mBa, -a Progress Report.
• Bjørnstad, Tor (2010). Development of tracer technology for EOR and production optimization.
• Bjørnstad, Tor (2010). Doses, dose effects and safe operations.
• Bjørnstad, Tor (2010). In the climate perspective - what is the role of nuclear power?.
• Bjørnstad, Tor (2010). Mechanisms of mineral scaling in geothermal wells studied by nuclear techniques.
• Bjørnstad, Tor (2010). Oil generation, reservoir assessment and petroleum production – a primary.
• Bjørnstad, Tor (2010). Radioactivity and nuclear characteristics – a primary.
• Bjørnstad, Tor (2010). Reservoir management and enhanced oil recovery – the role of tracers.
• Bjørnstad, Tor (2010). Tracer field operations.
• Bjørnstad, Tor (2010). Tracer technology for geothermal reservoir examination.
• Omtvedt, Jon Petter; Alstad, Jorolf; Bjørnstad, Tor; Dullmann, C.E.; Gregorich, K.E.; Gupta, N.S.; Nilssen, Johannes; Nitsche, Heino; Samadani, Fereshteh; Schädel, Matthias & Schulz, Frøydis (2010). Superheavy Element Chemistry with SISAK.
• Samadani, Fereshteh; Omtvedt, Jon Petter & Bjørnstad, Tor (2010). Liquid Chemistry of Hassium Tetroxide using Osmium in Model Experiments with SISAK.
• Eriksen, Dag Øystein; Haugan, Are; Bjørnstad, Tor; Halvorsen, S.G; Torgersen, H.J.T.; Haugen, Odd Benny & Brattheim, Sigurd (2009). A two-dimensional gamma scanner for performing flooding experiments at oil reservoir conditions. INCS News.  VI(4), s 7- 13
• Bjørnstad, Tor (2009). Mercury in petroleum – technical and HSE challenges.
• Bjørnstad, Tor (2009). The use of radioisotope technology on well operation, oil transportation and process studies of petroleum reservoirs.
• Bjørnstad, Tor; Borroto, J.I.P.; Brisset, P.; Chakravarty, R.; Chankow, N.; Charlton, J.S.; Dagadu, C.P.K.; Pinto, A.F.; Jung, S.-H.; Li, J.; Munos, L.A.; Palige, J.M.; Roesch, F.; Ghiyas-Ud-Din, x & Vargas, C.E. (2009). Evaluation and validation of radioisotope generator-based radiotracers for industrial applications - 2nd progress report.
• Bjørnstad, Tor; Fure, Kristin & Stavsetra, Liv (2009). Development of industrial radiotracer generators at IFE - chemical, toxic and radiotoxic considerations.
• Hassfjell, Sindre; Haugan, Are & Bjørnstad, Tor (2009). 47Ca-aided studies of CaCO3 scaling rates at low saturation ratios.
• Eriksen, Dag Øystein; Haugan, Are; Bjørnstad, Tor; Halvorsen, Sigbjørn Gottskalk; Torgersen, Hans Jakob Texmo; Haugen, Odd Benny & Bratheim, Sigurd (2008). A two-dimensional gamma scanner for performing flooding experiments at oil reservoir conditions.
• Bjørnstad, Tor (2008). Application of tracers in oil reservoir examinations.
• Bjørnstad, Tor (2008). Development of tracer technology for production optimization.
• Bjørnstad, Tor (2008). Exploration and Production R&D at Institute for Energy Technology.
• Bjørnstad, Tor (2008). Impairment of flow in near-well zones by mineral scaling.
• Bjørnstad, Tor (2008). Interwell tracer technology.
• Bjørnstad, Tor (2008). Interwell tracer technology - past, present and future.
• Bjørnstad, Tor (2008). Recent advances in tracer technology for production optimization.
• Bjørnstad, Tor (2008). Tracers and reservoir architecture.
• Bjørnstad, Tor; Eriksen, Dag Øystein & Yan, Gonglai (2008). Studies on separation of tracer concentrations of radiolabelled [Co(CN)6]3- from radiolabelled SCN- in water samples.
• Bjørnstad, Tor; Thomassen, Dag; Nyborg, Rolf & Seiersten, Marion (2008). Some flow assurance issues connected to mineral scaling, hydrates, complex fluids and the use of tracers.
• Eriksen, Dag Øystein; Haugen, Odd Benny & Bjørnstad, Tor (2008). Enhanced oil recovery methods studied by gamma tracer scanning at simulated reservoir conditions.

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