Modeling dynamic viscosity of n-alkanes using LSSVM technique

One of the important thermophysical properties is viscosity which expresses the resistance of fluid to flow. The least squares support vector machine (LSSVM) algorithm is proposed as a novel method for prediction of dynamic viscosity of different normal alkanes in a wide range of pressure and temperature. As this study is purely computational, 228 experimental data points were gathered from literature for training and validation of the model. The outcomes of the LSSVM algorithm were compared with the actual data with acceptable average absolute relative deviation and the coefficient of determination (R²) of 1.014 and 0.9968, respectively. The comparisons showed that the predicting model has the potential of prediction of n-alkane dynamic viscosity in terms of pressure, temperature, and carbon number of n-alkane, so this strategy can be used as a simple tool for predicting the behavior of reservoir fluids.     

Horizontal impedance of pile groups considering shear behavior of multilayered soils

The impedances and internal force distributions of a pile and pile groups subjected to horizontal harmonic pile-head loads have been studied. A layered Pasternak model, which overcomes the limitation of the Winkler model, that ignores the shear stiffness of the soil, is developed to describe the reaction of the soil on piles. The differential equation of the horizontal damped vibrations of a pile is solved by the initial parameter method, combined with transfer-matrix formulations, to deal with the layered property of the soil. The superposition approach, based on the interaction factors, is taken to estimate the effects of pile groups. The precision and the applicability of the method are demonstrated through this study. Comparing the results of the Pasternak model and the Winkler model, it is revealed that the role of soil shear has an influence on the impedances of a single pile and pile groups, especially in the case of a low pile–soil modulus ratio.     

母线洞对地下洞室群施工期风流行为的影响研究

基于CFD技术，采用标准k-ε湍流模型，分别建立地下洞室群风流场单相流模型和CO扩散混合模型。对施工期通风风流行为进行三维数值模拟，分析了母线洞贯通前后主厂房的风流场分布和厂房内不同位置CO浓度分布随时间的变化趋势。结果表明：母线洞贯通后使得主厂房内低速涡旋区增大，造成厂房底部施工工作面附近风流场紊乱，在工作面附近区域形成污染物滞留区。这易导致主厂房和主变室之间形成污风循环，对安全施工造成影响。     

RESERVOIR CHARACTERISTICS OF JURASSIC SHAXIMIAO FORMATION,WESTERN SICHUAN BASIN

Our study shows that （ 1 ） the Shaximiao reservoir, western Sichuan Basin, is mainly composed of arkose and lithic ar- kose, and litharenite, feldsparthic and lithic quartz sandstone for the second; （2） the reservoir space includes pore and fracture, and in- tergranular dissolution pore for the main one whereas residual intergranular pore and intragranular dissolution pore for the second ones; （3） the throat type dominantly contains tubular and intergranular fissures, which belong to fine- to micro-throat ones; （4） its porous structure is poor, which is characterized by small pore and shallow throat, small volume of effectively connecting pore, and medium to high drainage pressure; and （5） this reservoir is mostly featured by low to medium porosity and permeability, partly high porosity and per- meability, and strong heterogeneity. In addition, the factors controlling its growth, the sandbedy distribution, and the favorable reservoir belts are further studied. These results may provide an important support for exploration and development of Shaximiao reservoir.     

Induced generalized hesitant fuzzy operators and their application to multiple attribute group decision making

In this paper, we develop a series of induced generalized aggregation operators for hesitant fuzzy or interval-valued hesitant fuzzy information, including induced generalized hesitant fuzzy ordered weighted averaging (IGHFOWA) operators, induced generalized hesitant fuzzy ordered weighted geometric (IGHFOWG) operators, induced generalized interval-valued hesitant fuzzy ordered weighted averaging (IGIVHFOWA) operators, and induced generalized interval-valued hesitant fuzzy ordered weighted geometric (IGIVHFOWG) operators. Next, we investigate their various properties and some of their special cases. Furthermore, some approaches based on the proposed operators are developed to solve multiple attribute group decision making (MAGDM) problems with hesitant fuzzy or interval-valued hesitant fuzzy information. Finally, some numerical examples are provided to illustrate the developed approaches.     

Sensitivity Analysis to Operational Parameters of the Offset Well During Fast-SAGD Process in Naturally Fractured Reservoir

Few studies were done to investigate performance of the Fast steam-assisted gravity damage (SAGD) recovery method especially in naturally fractured reservoirs (NFR). The authors studied some cyclic steam stimulated operational parameters effects on the Fast-SAGD performance in NFR. A synthetic 2D homogenous model was constructed by Computer Modelling Group's (CMG) and simulated using the STARS module. Comparison between SAGD and Fast-SAGD recovery methods in this model shows great increase in the oil production but small increase of thermal efficiency in the Fast-SAGD recovery method. Simulation outcomes represent 17% increment in ultimate recovery factor but small reduction in steam-oil ratio. Results show that increasing the number of offset cycles and injection period yield increment in the oil production. Increasing the offset injection rate causes growth in the oil production, but has an optimal value. By increasing the distance between the offset well and SAGD well pairs up to a certain value, oil production increases but decreases after that point. This is due to the ability of the fractures in making connection between the steam chambers in higher distances. When production bottom-hole pressure decreases, the heated oil in near well region is subjected to more pressure drop and causes more oil to be produced. More offset wells result in higher production but simultaneously lower recovery factors. Increasing and decreasing soak time as the last investigated parameter did not affect the trend of production anyway.     

乌拉泊水库除险加固勘察及其成果分析

制定了乌拉泊水库除险加固勘察工作要点,并对库区进行了实际勘察。通过对勘察成果的详细分析,为乌拉泊水库的除险加固工程提供了重要依据,同时也为该水库的安全运行提供了科学的资料。     

State variable analysis of hydrological systems

The concepts of state and state variables are introduced. From a mathematical point of view the concept of state variables provides the means of transforming a differential equation of any order into an equivalent set of first-order equations. From a physical point of view the state of a system, specified by numeric values of the system state variables at a given time, contains all the relevant information about the system necessary to predict the behaviour of the system in the future. The state variable concept is thus very much suited for analysis of dynamic systems. Examples of the state variable concept applied to analysis of discharge from a reservoir and from two reservoirs operating in series are presented.