固井质量的测井评价及影响因素分析

在石油天燃气勘探开发中,油气井能否充分利用、正常生产及寿命长短关键在于固井质量的好坏。随着油气勘探开发的深入,超深井、水平井、厚套管井及"三高(高温、高压、高含硫)"气井,给固井质量测井评价技术提出了新的要求。采用多层套管完井,最多可达四层(13-3/8" +9-5/8"+7"+5")套管的四川气井埋藏深度一般在2500～6500米左右。本文主要介绍固井质量的用途及优缺点,声波变密度测井评价,固井声波变密度测井主要影响因素分析。     

基于灰色关联度法的管道临界屈曲应变影响因素分析

在基于应变的管道设计方法中,临界屈曲应变是一个重要指标。对现有文献和标准中临界屈曲应变预测公式的不足做了分析说明。根据现有的临界屈曲应变试验数据,对影响临界屈曲应变的主要因素进行了分析,采用灰色关联度法对4个影响因素进行了定量计算和排序,提出了对现有临界屈曲应变预测公式的改进建议。     

高台子加密调整地区的多学科治理研究与应用

文章以萨南油田高台子油层加密调整实验区为例,通过在该区块开展多学科油藏综合治理研究,搞清了区块剩余油潜力大小和分布状况,实现了各沉积单元剩余油的定量化描述,为在该区块进行综合治理提供了科学依据。文章对加密调整地区的油藏地质条件和开发现状进行了综合分析,在治理过程中应用多学科单砂体剩余油分布研究成果和单井生产历史拟舍曲线,采取多种方法进行现场验证,使区块取得了较好的开发效果,对其它区块的综合治理具有指导意义。     

Frontiers in NDE research nearing maturity for exploitation to ensure structural integrity of pressure retaining components

In this paper, research and developmental efforts that demonstrate high sensitivity detection and characterization of defects and assessment of microstructural degradation, residual stresses and fatigue damage in materials using different non-destructive evaluation (NDE) techniques, have been discussed. Applications of eddy current techniques for quantitative defect characterization and for generalized applications, and remote field eddy current technique for inspection of steam generator and heat exchanger tubes have been discussed. Advanced ultrasonic methods such as time of flight diffraction, synthetic aperture focusing technique, phased array and signal processing for detection, characterization and imaging of defects have been discussed. Applications of ultrasonics and magnetic Barkhausen emission techniques for characterization of microstructures and residual stresses have been discussed. Applications of acoustic emission and infrared thermography techniques for weld quality evaluation of critical nuclear components as part of intelligent processing of materials (IPM) work have been discussed. Application of acoustic emission technique for integrity assessment of pressurized components has been discussed. Development of a software called assets and infrastructure management system (AIMS), for storing and retrieving information for various materials, components and systems, has also been highlighted. The techniques and applications discussed are result of systematic and innovative R&D efforts in the multidisciplinary areas of physics, materials, instrumentation, sensors and softwares for providing solutions to various challenging problems.     

Three-dimensional finite element analysis to predict the effects of SAW process parameters on temperature distribution and angular distortions in single-pass butt joints with top and bottom reinforcements

Achieving adequate top and bottom reinforcement is important to minimize angular distortions in single-pass submerged arc welded (SAW) butt joints. This is achieved in the present work by using a reusable flux-filled backing strip and proper SAW process parameters without resorting to costly distortion mitigation techniques. The butt joints were made without edge (square butts) preparation. The process was also modeled by using three-dimensional finite element analysis by incorporating the top and bottom reinforcements into the modeling. Filler material deposition was also simulated. Temperature distributions and angular distortions obtained from the modeling closely matched with the experimental values. Thus, the cost effective experimental methodology established in the present work can be utilized for minimizing angular distortions in SAW square butts. The modeling methodology adopted can be used for predicting the angular distortions in SAW square butts with top and bottom reinforcements.     

Transient analysis of a PV power generator charging a capacitor for measurement of the I–V characteristics

Measuring the I–V characteristics is of high importance since it can be considered as a quality and performance certificate for each PV generator. The most precise and inexpensive measuring method is represented in capacitor charging by the PV generator. Using the equivalent circuit of the PV generator with a capacitor as load and applying transient analysis on the circuit, we obtain the capacitor charging voltage and current as a function of time, as well as their differentials as a function of short circuit current and capacitor size. The derived equations facilitate the calculation of proper capacitance size for measuring the I–V characteristics, and considers the acquisition speed of the measuring system as demonstrated through two measurement samples in this paper. The capacitor size is directly and indirectly proportional to the short circuit current and open circuit voltage of the PV generator, respectively. Accordingly, the paper presents a capacitance calculation chart, which enables selecting the correct capacitance for measuring the I–V characteristics by a computerized data acquisition system.     

Probabilistic capacity of a grid connected wind farm based on optimization method

This paper proposes a new method to find the capacity of a future wind farm regarding several limits of the grid system: voltage stability limits, thermal limits, voltage limits, load tap changing limitation and generator power output limitation. The method combines the optimization method and a probabilistic analysis to maximize the number of the wind turbines subject to those limits. Two types of wind farms are modeled in this paper: fixed speed wind farms and variable speed wind farms. It is concluded that the proposed method is a fast and accurate method to deal with the uncertainty of wind energy in the planning of wind farm capacity.     

Nodal analysis of a Stirling engine with concentric piston and displacer

To reduce the external volume of Stirling engines and to increase the specific power per unit volume, a novel mechanical arrangement is used where the power cylinder is concentrically situated inside the displacer cylinder. The inner heat transfer surface requirement and the thermodynamic performance characteristics are predicted preparing a nodal analysis in FORTRAN, where the inner volume of the engine is divided into 103 cells. Variation of the temperature in cells is calculated using the first law of thermodynamics, given for unsteady open systems, after arranging the enthalpy inflow and outflow terms. Volumes of cells are calculated using kinematic relations devised for the driving mechanism.The analysis indicates that the heats received from and delivered to the regenerator are not equal to each other. Therefore, the ends of the regenerator should be coupled with a heater and a cooler. The maximum thermal efficiency appears at the minimum mass of working fluid as the minimum thermal efficiency appears at the maximum mass of working fluid. The work increases up to a certain value of working fluid and then decreases. The thermal efficiency increases until a certain value of regenerator area and then decreases as well. Fluid temperature in the hot volume and cooler differs from the wall temperature at significant rates.     

小波灰度图在汽轮机组远程诊断专家系统中的应用研究

利用转子试验台故障试验数据,研究了小波灰度图在汽轮机组典型振动故障识别中的应用,并进一步研究了表征小波灰度图的定量指标———灰度矩对故障的区分度,确定了典型故障的标准灰度图及相应灰度矩取值区间。在此基础上开发的小波诊断模块,已应用在某省级网络化汽轮机组远程监测及故障诊断系统中,该模块作为常规频谱分析模块的辅助诊断工具,对提高远程汽轮机故障诊断的准确度和诊断效率起到了积极的作用。     

支持向量机回归模型在径流预测中的应用

为了探索提高径流中长期预测精度的有效途径,尝试建立了基于支持向量机的径流预测模型,并应用于西江流域梧州站的年、月径流预测中,取得了很好的效果。并与神经网络预测进行对比,结果表明该模型的预测精度要高于人工神经网络模型。