Advanced Materials Research Vols. 287-290

Abstract: Building envelope is a typical porous medium. The internal accumulation of moisture will not only affect the structural strength, but also cause the growth of bacterial in the structure, which can seriously affect the indoor air quality. In this work, the modified Luikov coupled heat and moisture transfer equation is derived by using finite difference method. A FORTRAN computer code is developed based on the supplied experiment conditions. The effect of various parameters (include temperature gradient, sorption isotherm, specific humidity etc.) on the coupled heat and moisture transfer and the relationship between the temperature gradient and the moisture gradient are discussed. The results show that the simulation results agree well with the experimental data.

Abstract: This study uses the relative tensile strength of weld and base metal as a quality factor for the Taguchi analysis in laser beam welding of stainless steel. The result shows that the optimum process parameters can be obtained reasonably even in the case of the base metals have a larger property variation or the operation setup is not controlled well properly.

Abstract: Multi-dimensional grey model is effective in building construction poor information system with multiple influence factors. Base on its features, this paper builds multi-dimensional grey deformation prediction model to research on complex non-linear deformation system’s prediction accuracy. This paper uses the deformation data of a certain dam to perform instance demonstration, through comparative analysis, concludes the model’s data requirement, processing pattern and accuracy inspection method. The usage scope of this model is analyzed both theoretically and practically; the result proved that multi-dimensional grey model is an effective deformation prediction model.

Abstract: Carbonate reservoir, widely distributed in china, is an important resource of oil and gas. Most of carbonate reservoir are very tight and need to be stimulated to increase the permeability for the flowing of oil/gas. Acid treatment is a kind of stimulation. However, the ordinary acid system cannot stimulate carbonate reservoir effectively because of the heterogeneity among formations. Based on a novel visco-elastic surfactant, this paper develops a self-diverting acid system (DCA) for carbonate formations. This system had been applied in the treatment of carbonate reservoirs successfully. Experiments studying the diverting mechanism had been conducted with HTHP Rheometer, parallel core flooding system and MRI Scanning system. The results indicate that: the viscosity of reacted acid can reach to 200 times higher than that of fresh acid. The injecting pressure of DCA is 20 times higher than that of ordinary acid (HCl) during the parallel core flooding experiment. MRI scanning images of the cores after acid flooding show that DCA can stimulate the cores with middle and low permeability more effectively. In middle and low permeability cores, the length of wormhole created by DCA is 4-8 times longer than that created by ordinary acid. At the same time, the relationship between flooding pressure and core permeability is also studied. This paper reveals the diverting mechanism of DCA through these experiments.

Abstract: In the construction of the conductor casing and surface casing cementing, due to the low bottom hole circulating temperature(BHCT), the compressing strength of oil well cement development slowly, waiting on cement(WOC)need a long time, an increase of drilling costs, could easily lead to annular gas channeling, and have a bad effect on cement job quality and safety of operations. For the type of current domestic oil well cement early strength agent are few, The effective of some early strength agent are not satisfied. Some are Corrosive to the casing, and have a great influence on slurry rheology and other issues. Laboratory selected a new compound early strength agent with on chlorine and containing crystal seed.The thickening time, compressive strength, settlement stability properties, anti-gas channeling ability and other parameters of the slurry are tested. The results show that: There are some advantages of the cement slurry like right-angle-set, low temperature rapid strength, excellent settlement stability properties, and strong ability of anti-gas channeling and form a low density cement slurry which density range from 1.30 to 1.90g/cm³, it provide a reliable guarantee to cementing operation in shallow well with low-temperature under the different reservoir pressure.

Abstract: 3D finite element mesh for a 270m high CFRD was generated with advanced grid discretion technology. Adopting EI-Centro seismic wave with maximum horizontal acceleration 0.277g, dynamic response of this 270m high concrete faced rockfill dam was obtained by equivalent linearization method. Using residual strain model, the permanent deformation of the dam was obtained. Calculation results showed that the maximum acceleration and displacement of dam body, dynamic stress of face slab and deformation of joints are all within normal range. Therefore, the safety of dam would be guaranteed when it is subjected to 7 degree earthquake.