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A physically based generic viscosity model for synthetic polymer solutions has been created. It gives viscosities as a function of shear rates (Carreau curves). The input to the model is concentration, temperature, salinity and molecular weight (polymer type). A model for mechanical degradation of synthetic polymer solutions has also been developed. It calculates the solution viscosity after mechanical degradation by flow through a porous medium. The two models are linked through molecular weight distributions of the polymer solutions.The viscosity model fits very well experimental data from viscometry. The mechanical degradation model also fits available experimental data when utilising a correction factor. The models have good predictive power and can be used for different purposes such as, • estimating mechanical degradation for different plugging scenarios • calculating the added polymer concentration needed to achieve a given in-situ viscosity at a certain level of degradation • calculating the viscosity degradation for a diluted production fluid with known Mw (from analysis) and unknown concentration. • estimating degradation during operation of a well based on the pressure data • choosing the best polymer solution for a specific field • calculating the effects of pre-shearing (before injection) and the optimal degree of pre-shearing • perform case studies to investigate the impact of system parameters on polymer degradationThe models have also been used for further development to estimate polymer injectivity as well as degradation in process equipment. Currently, the model predicts slightly increasing degradation for decreasing water salinity which is opposite the trend indicated by most experimental data. Reasons for the deviation are disussed together with suggestions for possible extention of the model. Figure 1-Basic principle of the models SPE-179593-MS 5

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Various voltammetric methods have been used to study FLINAK (LiF‐NaF‐KF eutectic melt 46.5–11.5–42 mol %) melts containing about 1 mol % niobium‐fluoro and ‐oxofluoro complexes with Nb in oxidation states (V) and (IV) at 700°C and varying amounts of Na2O in the range 04 , all Nb and O added are dissolved. Strong indications of the coexistence of the oxygen rich Nb(V)OF complexes and O2− ions in FLINAK at nOo/nnormalNbo>4 have been found. An equilibrium/sampling/analysis technique was also used to study this system without Nb metal added. The results mainly agree with the results of the voltammetric studies. However, no indications of spontaneous reduction of Nb(V) to Nb(IV) were observed, even after 24 h. © 2000 The Electrochemical Society. All rights reserved.

The article contains sections titled: 1. Introduction 2. Properties 3. Raw Materials 4. Production 4.1. Extraction by Electrolysis 4.1.1. Preparation of Magnesium Chloride Cell Feed 4.1.1.1. Chlorination of Magnesia and Magnesite 4.1.1.2. Dehydration of Aqueous Magnesium Chloride Solutions 4.1.1.3. Dehydration of Carnallite 4.1.2. Electrolysis 4.1.2.1. Technical Data 4.1.2.2. Electrolytic Cells 4.2. Thermic Reduction Processes 4.3. Refining and Casting 4.4. Particulate Magnesium 5. Environmental Aspects 6. Quality Specifications 7. Uses 8. Economic Aspects 9. Toxicology and Occupational Health 10. Safety