Pore scale network modelling of residual oil saturation in mixed-wet systems

The prediction of residual oil saturation (Sor) and relative permeabilities after waterflooding in mixed-wet systems is a very challenging task. These are important parameters which must be estimated for a full field simulation of waterflooding. The Sor also defines the target oil for any proposed EOR process after an initial waterflood. Pore-scale network modelling can be used to estimate relative permeabilities, and the amount and nature of the trapped residual oil if the correct physics of oil displacement are properly included. During the waterflooding of mixed-wet systems, oil may drain down to relatively low residual saturations. Such Sor levels can only be calculated correctly when oil layers in pore corners are included in the pore-scale modelling. van Dijke and Sorbie (J. Coll. Int. Sci. 293 (2006) 455) obtained an accurate thermodynamically derived criterion for oil layers’ existence in pores with non-uniform wettability caused by ageing, which is more restrictive than the previously used geometrical layer existence criterion. This thermodynamic criterion has been included in a newly developed two-phase pore network model to calculate realistic Sor values for mixed-wet sandstones. A new ncornered star pore shape characterization technique has also been implemented in this model since the precise description of the pore shape was found to be important. Two unstructured networks, derived from Berea sandstone have been used for a number of sensitivities of the Sor and relative permeabilities with respect to wettability conditions. It is shown that Sor is lower for the more strongly oil-wet cases, while the water relative permeability curves increase gradually with oil-wetness at the higher water saturations. It has also been shown that pore shape approximations and oil layers collapse criterion have a significant impact on the Sor and the relative permeabilities. In particular, the thermodynamic oil layer existence criterion gives higher and more realistic Sor compared to previously used geometrical criterion. The network modelling has been used to match experimental data for water-wet and mixed-wet systems. In particular, the good agreement with mixed-wet systems strongly indicates that using the correct oil layer existence criteria is a significant step forward in the reliable prediction of Sor

Information-Analytical System for Design of New Inorganic Compounds

The principles of design of information-analytical system (IAS) intended for design of new inorganic compounds are considered. IAS includes the integrated system of databases on properties of inorganic substances and materials, the system of the programs of pattern recognition, the knowledge base and managing program. IAS allows a prediction of inorganic compounds not yet synthesized and estimation of their some properties

Photocatalytic reduction of CO2 over TiO2 nanowires catalyst

TiO2 is one of the most common photocatalysts at the moment. One-dimensional TiO2, which has a high specific surface area, is of particular interest. The properties of such nanowires will largely depend on the phase composition, which affects the width of the optical band gap. This paper presents the results of a study of the photocatalytic activity of TiO2 nanowires depending on the phase composition using the reduction of CO2 to methane and methanol as an example. The formation of TiO2 nanowires was carried out using a hydrothermal synthesis method from a commercial TiO2 powder. After synthesis, the nanowires were thermally treated in air to obtain nanowires with different phase compositions. The morphology and phase composition of TiO2 nanowires were studied. The resulting nanowires had a size of about 8 μm and a diameter of about 330 nm

Spectrum of Andreev bound states in Josepshon junctions with a ferromagnetic insulator

Ferromagnetic-insulator (FI) based Josephson junctions are promising candidates for a coherent superconducting quantum bit as well as a classical superconducting logic circuit. Recently the appearance of an intriguing atomic-scale 0-pi transition has been theoretically predicted. In order to uncover the mechanism of this phenomena, we numerically calculate the spectrum of Andreev bound states in a FI barrier by diagonalizing the Bogoliubov-de Gennes equation. We show that Andreev spectrum drastically depends on the parity of the FI-layer number L and accordingly the pi (0) state is always more stable than the 0 (pi) state if L is odd (even).Comment: 6 pages, 5 figures, Invited Report on the Moscow International Symposium on Magnetism MISM201

Design, Performance, and Calibration of CMS Hadron-Barrel Calorimeter Wedges

Extensive measurements have been made with pions, electrons and muons on four production wedges of the Compact Muon Solenoid (CMS) hadron barrel (HB) calorimeter in the H2 beam line at CERN with particle momenta varying from 20 to 300 GeV/c. Data were taken both with and without a prototype electromagnetic lead tungstate crystal calorimeter (EB) in front of the hadron calorimeter. The time structure of the events was measured with the full chain of preproduction front-end electronics running at 34 MHz. Moving-wire radioactive source data were also collected for all scintillator layers in the HB. These measurements set the absolute calibration of the HB prior to first pp collisions to approximately 4%

Synchronization and Timing in CMS HCAL

The synchronization and timing of the hadron calorimeter (HCAL) for the Compact Muon Solenoid has been extensively studied with test beams at CERN during the period 2003-4, including runs with 40 MHz structured beam. The relative phases of the signals from different calorimeter segments are timed to 1 ns accuracy using a laser and equalized using programmable delay settings in the front-end electronics. The beam was used to verify the timing and to map out the entire range of pulse shapes over the 25 ns interval between beam crossings. These data were used to make detailed measurements of energy-dependent time slewing effects and to tune the electronics for optimal performance

Energy Response and Longitudinal Shower Profiles Measured in CMS HCAL and Comparison With Geant4

The response of the CMS combined electromagnetic and hadron calorimeter to beams of pions with momenta in the range 5-300 GeV/c has been measured in the H2 test beam at CERN. The raw response with the electromagnetic compartment calibrated to electrons and the hadron compartment calibrated to 300 GeV pions may be represented by sigma = (1.2) sqrt{E} oplus (0.095) E. The fraction of energy visible in the calorimeter ranges from 0.72 at 5 GeV to 0.95 at 300 GeV, indicating a substantial nonlinearity. The intrinsic electron to hadron ratios are fit as a function of energy and found to be in the range 1.3-2.7 for the electromagnetic compartment and 1.4-1.8 for the hadronic compartment. The fits are used to correct the non-linearity of the e pi response to 5% over the entire measured range resulting in a substantially improved resolution at low energy. Longitudinal shower profile have been measured in detail and compared to Geant4 models, LHEP-3.7 and QGSP-2.8. At energies below 30 GeV, the data, LHEP and QGSP are in agreement. Above 30 GeV, LHEP gives a more accurate simulation of the longitudinal shower profile

Design, Performance, and Calibration of the CMS Hadron-Outer Calorimeter

The CMS hadron calorimeter is a sampling calorimeter with brass absorber and plastic scintillator tiles with wavelength shifting fibres for carrying the light to the readout device. The barrel hadron calorimeter is complemented with an outer calorimeter to ensure high energy shower containment in the calorimeter. Fabrication, testing and calibration of the outer hadron calorimeter are carried out keeping in mind its importance in the energy measurement of jets in view of linearity and resolution. It will provide a net improvement in missing \et measurements at LHC energies. The outer hadron calorimeter will also be used for the muon trigger in coincidence with other muon chambers in CMS

Design, Performance and Calibration of the CMS Forward Calorimeter Wedges

We report on the test beam results and calibration methods using charged particles of the CMS Forward Calorimeter (HF). The HF calorimeter covers a large pseudorapidity region (3\l |\eta| \le 5), and is essential for large number of physics channels with missing transverse energy. It is also expected to play a prominent role in the measurement of forward tagging jets in weak boson fusion channels. The HF calorimeter is based on steel absorber with embedded fused-silica-core optical fibers where Cherenkov radiation forms the basis of signal generation. Thus, the detector is essentially sensitive only to the electromagnetic shower core and is highly non-compensating (e/h \approx 5). This feature is also manifest in narrow and relatively short showers compared to similar calorimeters based on ionization. The choice of fused-silica optical fibers as active material is dictated by its exceptional radiation hardness. The electromagnetic energy resolution is dominated by photoelectron statistics and can be expressed in the customary form as a/\sqrt{E} + b. The stochastic term a is 198% and the constant term b is 9%. The hadronic energy resolution is largely determined by the fluctuations in the neutral pion production in showers, and when it is expressed as in the electromagnetic case, a = 280% and b = 11%

Design, Performance, and Calibration of CMS Hadron Endcap Calorimeters

Detailed measurements have been made with the CMS hadron calorimeter endcaps (HE) in response to beams of muons, electrons, and pions. Readout of HE with custom electronics and hybrid photodiodes (HPDs) shows no change of performance compared to readout with commercial electronics and photomultipliers. When combined with lead-tungstenate crystals, an energy resolution of 8\% is achieved with 300 GeV/c pions. A laser calibration system is used to set the timing and monitor operation of the complete electronics chain. Data taken with radioactive sources in comparison with test beam pions provides an absolute initial calibration of HE to approximately 4\% to 5\%