Upscaling Process Research Articles

Modelling of macropore flow and transport processes at catchment scale

Macropores play a significant role as a preferential flow mechanism in connection with pesticide leaching to shallow groundwater in clayey and loamy soils. A macropore description based on some of the same principles as those of the MACRO code has been added to the coupled MIKE SHE/Daisy code, enabling a physically based simulation of macropore processes in a spatially distributed manner throughout an entire catchment. Simulation results from a small catchment in Denmark suggest that although the point scale macropore processes have no dominating effect on groundwater recharge or discharge at a catchment scale, they will have significant effects on pesticide leaching to groundwater at a catchment scale. The primary function of macropores in this area is that they rapidly transport a significant part of the infiltrating water and solutes from the plough pan at 20 cm depth some distance downwards before most of it flows back into the soil matrix. This has a very significant effect on the leaching of pesticides from the surface to the groundwater table, because some of the pesticides are transported rapidly downwards in the soil profile to zones with less sorption and degradation. It is concluded that the spatial variations of macropore flows caused by the variation in topography and depth to groundwater table within a catchment are so large that this has to be accounted for in up-scaling process descriptions and results from point scale to catchment scale.

Combining Gradual Deformation and Upscaling Techniques for Direct Conditioning of Fine-Scale Reservoir Models to Interference Test Data

Summary Reconciling multiscale data for reservoir characterization is a crucial issue, because different data types provide different information about the reservoir architecture and heterogeneity. It is essential that reservoir models preserve small-scale property variations observed in well logs and core measurements and capture the large-scale structure and continuity observed in global measures such as well-test and production data. In this paper, we present a new methodology to directly update fine-scale geostatistically-based reservoir models by combining gradual deformation parameterization for the fine-scale geostatistical model, and an upscaling technique for the coarse-scale flow simulation model. As consequence, both fine- and coarse-scale models are updated by dynamic data during the history matching process. The proposed methodology includes: Perturbation of the fine-scale geostatistical model using the gradual deformation parameterization. Gradual deformation ensures the preservation of the overall geostatistical properties of the fine model. Generation of the coarse-scale flow simulation model by upscaling the fine-scale geostatistical model. Fluid-flow simulation and sensitivity computation of the flow simulation results with respect to the fine-scale parameterization. This sensitivity computation is analytical and takes into account the upscaling process. Direct updating of the fine-scale geostatistical model using classical optimization process. Direct updating ensures consistency between the fine- and coarse-scale models. The accuracy of the proposed methodology was improved by calibrating the flow simulation model. The objective of this calibration is to reduce the error introduced by the upscaling step during the flow simulation. We applied successfully our methodology for fine-scale reservoir characterization process by integrating permanent downhole gauge measurements directly into a 3D-geostatistical model containing about two million gridblocks. This test is designed to highlight several key issues of the proposed methodology: Efficiency of the upscaling step, coupled with gradient-based optimization to speed up history matching. Usefulness of the calibration step for a correct integration of upscaling techniques in history matching. Capability of the methodology for maintaining consistency and coherency between fine-scale and coarse-scale models. Improvement of the reservoir characterization process by integrating dynamic data at both fine geostatistical scale and coarse simulation scale.

Status of the SOFC Development at Haldor Topsøe/Risø

The Consortium of Haldor Topsoe A/S and Riso National Laboratory is focusing on the development of cost-effective anode-supported cells and SOFC stacks for operation at intermediate temperatures. The cell production pilot plant with a capacity of more than 1 MW per year has now been in operation for more than one year. A fully up-scaled production process for the anode-supported cells has been established and uniform cells are now produced routinely for test and stack development. The cell manufacturing technology has three major processing steps: Tape casting, spray moulding and co-firing. Optimisation of the composite cathodes has led to a significantly higher cell performance at low operation temperature and to a reduction of the stack cost. The fracture strength of the cells is about 280 MPa in oxidised as well as in reduced state. Mechanical robustness and operation durability of the cells and stacks are prioritised. Stacks include ferritic steel interconnects, ceramic coatings and glass seals. Theoretical stack and system modelling is used to optimise the operation conditions and design. By year 2004, the development program aims at the demonstration of SOFC stacks and systems in the 5 kW size range operating below 850°C.

Cupiagua: Modeling of a Complex Fractured Reservoir Using Compositional Upscaling

Summary The first application of compositional upscaling to the routine modeling of a major reservoir is described. The reservoir— Cupiagua, in Colombia—is a rich gas condensate field. Given that Cupiagua falls rapidly below dewpoint and produced gas is recycled, the main recovery process is the vaporization of liquid components into the gas phase, in which they are transported to producers. Therefore, the process is compositional, but flow is dominantly in one phase. Cupiagua is a heterogeneous reservoir dominated by natural fracture corridors that provide more than 80% of the permeability in some areas. It is not possible to represent these features explicitly within the full-field model (FFM), nor do they fit a conventional dual-porosity representation. Therefore, an upscaling process is required. The process described is the use of alpha-factor compositional upscaling functions, which modify the velocities of individual pseudocomponents. We show how fine-grid cross-section modeling, with a range of sensitivities, may be used to generate an appropriate set of alpha-factor functions, which are validated against detailed sector models and may then be used as the principal history-match parameter in the FFM.

Production of carbon nanotubes: the light approach

In this article we present an overview about the current state of the art using highly concentrated light in the production process of carbon nanotubes. Firstly, the most common approaches using laser light or solar radiation are described and their production possibilities are compared. Secondly, important growth parameters and their complex interactions are discussed. It is shown that a key issue in the production of nanotubes is the creation of the proper temperature conditions. This concerns the temperature of both the target surface and the gas-phase. While the first controls the number and kinetics of evaporated species, the second affects the assembling of nanotubes in the gas-phase. Thirdly, the problem of obtaining high-quality nanotube materials in an up-scaled production process is addressed. Here, a solution may be related to the finding of advantageous light–target interactions.

An Implicit Treatment of Upscaling in Numerical Reservoir Simulation

Summary This paper presents a multiscale computational model for multiphase flow that implicitly treats upscaling without using pseudofunctions. The model overcomes some practical difficulties related to use of traditional pseudocurves by executing the upscaling and solution processes in one step and taking into account changes in the numerical model in an adaptive manner.

Computer assisted scale up from analytical HPLC to preparative MPLC for the separation of phenolic compounds

A computer assisted method for the scale up of a column liquid chromatographic separation from the analytical to preparative scale is successfully proposed to make the up-scaling process easier and faster. The test sample consisting of six phenolic compounds was chromatographed on an analytical HPLC column using two different gradient runs. Based on the chromatographic data achieved from these initial analyses, elution behaviour of compounds could be simulated for alternative conditions using the DryLab program. A simulative replacement of the analytical column with a preparative scale medium pressure LC (MPLC) column allowed the determination of gradient profile to allow sufficient separation in the preparative scale. A test run carried out in suggested simulated conditions matched well with expected elution times. Furthermore, this upscaling procedure was successfully applied to a plant extract.

Production of human interleukin-8 expressed in Escherichia coli: From a laboratory scale for in vitro tests via a technical scale for animal studies to a process scale for a GMP-compatible production

An Escherichia coli K 12 strain has been constructed for efficient expression of recombinant biologically active human IL-8 (Interleukin-8). The development of a fermentation and purification process from the laboratory scale (cells from 15 l fermentation broth) to a production scale (cells from 200 l fermentation broth) is described. Material obtained from the laboratory scale was used for initial in vitro studies and for the development of a biological assay. An upscale purification process starting from 80 l fermentation broth resulted in larger amounts of IL-8 needed for preclinical studies. This process includes a fully automated control of the initial affinity chromatography step. Finally, a production process which differed markedly from the small-scale processes was tailor-made for GMP conformity and economic considerations. It consists of a cell disruption step followed by two crossflow diafiltrations with different molecular weight cut offs and filtration rates, one cation exchange chromatography and a final dialysis step. In order to enhance the overall yield of biologically active IL-8, conditions for a resolubilisation of insoluble IL-8 present in the remaining pellet after cell disruption were worked out.

Symbiotic Relation between Planetary and Synoptic-Scale Waves

Abstract It is hypothesized that the low-frequency planetary scale waves and the high-frequency cyclone-scale waves in an equilibrated state of the atmosphere are symbiotically dependent upon one another. This is demonstrated with an analysis of a dissipative atmospheric model driven by a zonally symmetric forcing. Under a geophysically relevant parameter condition, the synoptic scale waves in the equilibrated state of this system intermittently extract a sufficient amount of energy from the modified instantaneous zonal flow to compensate not only for their own dissipative loss of energy but also for a net supply of energy to the planetary scale waves through the upscale energy cascade process. The planetary scale waves gain this energy in the barotropic form. The planetary scale waves, in turn, create localized strong baroclinic regions whereby the synoptic scale waves may preferentially intensify downstream of the model planetary jet streams. Such cyclone scale eddies collectively give rise to two model...