Geophysical well - log correlations along various cross-sections of the Cerro Prieto geothermal field

The Comisión Federal de Electricidad of Mexico and Lawrence Berkeley Laboratory of the United States are currently conducting joint investigations of the Cerro Prieto geothermal field, located approximately 35 km south of the city of Mexicali, Baja California, Mexico. Based on the geophysical well logs, transversal cross sections were constructed. This study consists mainly of correlating electrical markers observed in the logs. Temperature logs were also used to assist in the differentiation of what we call reservoirs A and B.In this article the stratigraphy observed in the cross-sections, the faults, and the identified producing layers will be described. Finally, the usefulness of this type of study for planning new wells, for selecting producing intervals, as well as for the development of the geologic model of the field will be presented.     

New correlations to predict fracture conductivity based on the formation lithology

Acid fracturing is one of the most important well stimulation methods. Acid fracture conductivity, which represents the available capacity of the fluid pass in fractures, is one the main parameters for designing acid fracturing process. The volume of dissolved rock, rock strength, and closure stress on the fracture are the effective parameters on the acid fracturing conductivity. In this study, regarding above parameters and formation lithology, Genetic Algorithm was used to develop a robust intelligent model to estimate the fracture conductivity by considering experimental data of different formations. Results showed that formation lithology plays a considerable role in fracture conductivity prediction.     

基于数值计算的U型地埋管井群换热器计算模型研究

针对U型地埋管换热器的特点,在分析单井换热器换热量的基础上,考虑到多井换热器井与井之间传热的相互干扰,提出了一种用于U型地埋管井群换热器数值计算的9井模型,这种模型在数值计算时既能代表一般井群换热的规律,又便于计算机处理,为实际工程中分析井群换热规律提供了很好的理论依据。     

New correlations for the weighted-sum-of-gray-gases model in oxy-fuel conditions based on HITEMP 2010 database

Oxy-fuel combustion is one of the promising options for carbon dioxide capture in future coal power plants. Radiative properties of combustion gases and heat transfer characteristics inside oxy-fuel furnaces are different from those found in air-fired furnace. Nowadays, few publications provide appropriate radiation property correlations for oxy-fuel conditions. The available correlations are based on previous versions of HITRAN database, which is not accurate for prediction of spectral intensities at high temperature in combustion applications or above 1000 K. This paper considers the determination and evaluation of new correlations for the weighted-sum-of-gray-gases model to predict the radiative transfer in gases under oxy-fuel conditions. The new correlations are fitted from emittance charts calculated from the up-to-date HITEMP 2010 database for molar ratios of water vapor to carbon dioxide between 0.125 and 4, temperature range of 400–2500 K, and pressure path-length varying from 0.001 to 60 bar m. The new correlations are validated by comparing the radiative source term with line-by-line calculations from HITEMP 2010 database for a one-dimensional slab system. The radiative transfer equation is solved with the discrete ordinate method.     

基于CFD的填砾抽灌同井数值模拟

文章根据已有的填砾抽灌同井砂箱实验台,建立了两种不同尺寸的多区域耦合三维CFD模型,选取了热源井的抽水温度、逐时取热量和累计取热量进行模型验证。热源井抽水温度实验值与模拟值的吻合度较高,两种模型25 min内热源井累计取热量的相对误差分别为3.28%和5.56%。分析结果表明:砂箱的几何尺寸会对含水层流场和温度场的变化造成影响;回填砾石区会发生流贯通,中间隔断区的宽度与抽、回水区的间距会影响回水进入抽水区的速率,因此,应增大回水区与砂箱上顶板之间以及热源井与砂箱四壁之间的距离;应当增大中间隔断层的宽度以及抽、回水区的间距,以此来延缓流、热贯通的形成。     

Modeling and simulation of solar cells quantum well based on SiGe/Si

In recent years, the development of quantum well solar cells QWSCs (Quantum Well Solar Cells) has generated a great deal of interest. These configurations have shown good promise to optimize the low conversion efficiency of conventional solar cells because of the high rate of absorption losses present in them. In this work, we are interested in modeling and simulation of two different structures of solar cells, a simple solar cell based on silicon Si and a quantum well solar cell SiGe/Si. When a solar cell is compared to 80 quantum well layers of Si_0.8Ge_0.2with a pin solar cell based on Si. The short circuit current J_sc increases from 23.55 to 37.48 mA/cm² with a relative increase of 59.15% found. In addition, the limit of the absorption band of the lower energy photons extends from 1100 nm to 2000 nm.     

基于储能飞轮的油井发电机功率补偿与节能应用

基于油田供电系统,研究了负载增减频繁和负荷冲击值较大情况下,发电机的功率响应不足问题.基于储能飞轮的技术特点,利用储能飞轮对绞车的功率需求进行功率补偿.本工作针对存在的问题做出目标优化设计,提出了绞车功率斜率分配调节方案,并搭建具体的实验平台进行验证.实验结果表明,投入飞轮可以使发电机的功率曲线得到较好地平滑,减少了机...     

Mathematical modelling of silica deposition in Tongonan-I reinjection wells, Philippines

Mathematical models of silica deposition are derived using the method of characteristics for the problem of variable rate injection into a well producing radially symmetric flow. Solutions are developed using the first order rate equation of silica deposition suggested by Rimstidt and Barnes (1980). The changes in porosity and permeability resulting from deposition are included in the models. The models developed are successfully applied in simulating the changes in injection capacity in some of the reinjection wells in Tongonan geothermal field, Philippines.     

基于组态软件的供暖锅炉监控系统设计

工业锅炉是采暖供热系统的核心设备,它的主要任务是安全可靠、经济有效地把燃料的化学能转化为热能,进而将热能传递给水,生产出满足需要的蒸汽或热水。     

热力学第二定律与冷库微机控制节能

冷库微机控制与常规自动控制相比 ,其优越性在于它可根据库温变化自动地调整其制冷剂的蒸发温度 ,并使得其制冷剂和蒸发温度与冷库温差总是处于最小值。根据热力学第二定律 ,在其他条件不变的情况下 ,此时制冷装置的能耗最小。     

Lift-off of jet diffusion flame in sub-atmospheric pressures: An experimental investigation and interpretation based on laminar flame speed

This paper reveals lift-off behavior of jet diffusion flames in sub-atmospheric pressures less than 100 kPa, in view of that the current knowledge on this topic is limited for normal pressure conditions. Physically, the variation of ambient pressure may have significant influence on the lift-off behavior of jet diffusion flames due to the change of some critical parameters such as laminar flame speed. In this work, experiments are conducted in a large pressure-controllable chamber of 3 m (width) × 2 m (length) × 2 m (height) at different sub-atmospheric pressures of 60 kPa, 70 kPa, 80 kPa, 90 kPa as well as at normal pressure of 100 kPa. Axisymmetric turbulent jet diffusion flames are produced by nozzles with diameters of 4 mm, 5 mm and 6 mm using propane as fuel. It is revealed that the lift-off height increases as the pressure decreases and being much higher than that in normal pressure condition. The laminar flame speed with its dependency on pressure is introduced to interpret such behavior based on classic Kalghatgi model. It is found theoretically that the lift-off height has a power law dependency on pressure by P¹⁻ⁿ, where n is overall reaction order of the fuel which is usually larger than 1 indicating a negative power law function with pressure (for example p^−0.75 for propane as n = 1.75) as well verified by the experimental correlation. Finally, a global model is proposed by including such pressure dependency function into the Kalghatgi model, which is shown to well collapse the experimental results of lift-off heights of different sub-atmospheric pressures.     

Chemical stimulation techniques for geothermal wells: experiments on the three-well EGS system at Soultz-sous-Forêts,France

Rock matrix stimulation is a method of enhancing well production or injection within a broad range of challenging environments, varying from naturally fractured limestones to sandstones with complex mineralogy. A common and often successful stimulation option, matrix acidizing, utilizes acids that react and remove mineral phases restricting fluid flow. Reviewed is the technology of chemical treatments available for oil, gas and geothermal wells and the key elements and results of the chemical reservoir stimulation program at the Soultz-sous-Forêts, France, Enhanced Geothermal System Project.     

Note on the interpretation of electroluminescence images using their spectral information

We show how to use the reciprocity between electroluminescence and solar cell quantum efficiency for the simulation and interpretation of electroluminescence images. The analysis of the spectral properties of the electroluminescence images obtained by using different short- and long-pass filters yields information about surface recombination velocity, bulk diffusion length and reflection of the back side in flat and textured solar cells.     

基于ECE法规的依维柯某车型前后制动力分配研究

基于ECE法规,提出根据质心位置和重心高度可方便地得到满足ECE法规的制动力分配方法。结合依维柯某车型的基本技术参数,分析了结构参数对制动力分配的影响,确定该车型拥有良好制动方向稳定性时,实际制动力分配系数取值范围,检验结果说明其实际制动力分配满足ECE法规。     

General correlations for estimating the monthly total and direct radiation incident on horizontal surfaces in Yunnan,China

Yunnan Province, China, has the climatic characteristic of evident dry and wet seasons in November to April and May to October, respectively. Utilizing the meteorological data of these two seasons and the observed solar radiation data in seven meteorological stations in Yunnan Province, the general correlations for estimating the monthly total and direct radiation incident on any horizontal surfaces in Yunnan Province are obtained by a linear regression technique, namely Although these correlations are only applicable for estimating H and H_b in areas of Yunnan Province, it is believed that if the number of stations is large enough the general correlations can be found, which can be applied to the estimation of H and H_b in any area.     

Effect of end plates on the performence of a wells turbine for wave energy conversion

In order to improve the performance of the Wells turbine for wave energy conversion,the effect of end plates onthe turbine characteristics has been investigated experimentally by model testing under steady flow conditions.The end plate attached to the tip of the original rotor blade is slightly larger than the original blade profile.Thecharacteristics of the Wells turbine with end plates have been compared with those of the original Wells turbine,i.e.,the turbine without end plate.As a result, it has been concluded that the characteristics of the Wells turbinewith end plates are superior to those of the original Wells turbine and the characteristics are dependent on the sizeand position of end plate. Furthermore, the effect of annular plate on the turbine performance,which encircles theturbine and is attached to the tip,was investigated as an additional experiment.However,its device was not effec-tive in improving the turbine characteristics.