【作者】 武苗；

【导师】 李波； 吴来杰；

【作者基本信息】 中国地质大学 ， 控制理论与控制工程， 2010， 硕士

【摘要】 海底热流数据是开展海洋油气资源综合评价的一个重要参数。利用测量的海底热流数据,结合盆地演化认识和数值手段,可以获得各烃源层所经历的温度史,借助有机质成熟模型,有望揭示有机质的成熟历史,从而指导油气的勘探开发。海底热流值也是准确评价和预测天然气水合物资源潜力的重要依据。海底地热研究包含海底温度、沉积物热导率、地温梯度等多项地热参数的测量与计算。海底沉积物的热导率测试方法通常有两种,一种是原位测量,另一种是室内测量。前者在测量过程中,要求海上作业,难度很大,设备极易损耗；后者是在实验室完成,可以减少海上作业时间,设备损耗的风险也可以大大降低,并且对比发现,两种方法测量获得的热导率基本一致。但是,现阶段,高精度热导率测量设备试验时间长,效率低,并依赖国外进口。因此,研究开发高效率高精度的热导率测量设备非常必要。本研究主要针对多通道热导率测试设备研究开发上位机软件。理论模型是本测量系统的基础,选择合适的理论模型对测量系统最终的成败非常关键。热导率的测试方法有很多,在分析各种热导率理论原理的基础上,本文最终确定了非稳态测试方法中的一种——线热源法。线热源法在实际应用中有几种测量模型：单探针脉冲加热、双探针持续加热、单探针持续加热。结合试验条件和研究的实际需求,本文选择单探针持续加热模型,该方法理论模型较为简单,实验效率相对较高,在海底沉积物测量中应用较多。按照单探针持续加热模型的测量原理,设计开发的多通道热导率测试仪主要由上位PC机、下位机、Agilent 34411数字万用表、测量探针(封装了加热丝、热敏电阻)组成。上位机主要负责测量过程的控制、数据采集和处理、分析测量结果以及影响因素。下位机主要解析上位机命令,激发电流,切换通道,测量各通道相关参量。上位机软件选用Visual C++6.0开发平台。为方便使用,上位机软件分为两个部分：测量软件和评估软件。前者负责控制测量过程、数据采集、数据解算与处理；后者负责分析测量结果和影响因素。测量软件分为测量参数设定模块、检测模块、数据采集和保存模块、数据显示模块,数据处理模块等几个模块。评估软件分为各次测量结果分析模块和单次测量结果分析模块。显示在用户与测控仪器的交互中起到很重要的作用,它的设计既要有美学内涵又能方便用户使用,本文的设计采用经典的微软窗口化设计。在测量软件界面中既方便控制测量过程,也便于用户观察测量的情况,如温度的漂移、加热过程的实时曲线和对应的温度值。评估软件,以点状图、柱状图等形式可以方便的对比各次测量的结果,分析评价测量的影响因素。数据采集主要是靠Agilent 34411A数字万用表实现的,它与上位机之间的通信选用USB通信方式,支持IVI仪器驱动,利用该驱动可以方便的对它进行访问。该驱动程序支持多种开发环境,并支持COM编程,实现了VC环境里,使用IVI仪器驱动对Agilent 34411A数字万用表的控制。数据处理和评估是软件系统开发的关键部分。按照方案设计要求,上位机从安捷伦万用表中读取当前测量通道的数据后,要运用适当的R-T转换算法,把电阻值转换成为温度值。本研究主要讨论了"Steinhart-Hart"的公式拟合法和插值法,两种方法各有优缺点,在测量中可根据需要选择使用。转化后的温度值可形成当前通道的加热曲线,在实际应用中,选择合适的时间段是比较困难的。在加热的最初阶段,热源与全无限空间的接触电阻对热源温度的影响比较大,在简单近似使用中,所得数据需要剔除。而在加热的最后阶段,由于线热源实际长度有限,边界效应影响增加,数据也不能使用。这时,选择一种合适算法,选取合适的时间段来计算热导率值,并能够自动确定加热曲线最优部分就非常重要。本文最终选用高阶近似逼近线热源持续加热代替了一般的一阶近似,该方法简称为SAM算法。它用高阶近似逼近线热源持续加热曲线,考虑到了在传统方法中忽略的一些因素,能够取合适的时间段来计算热导率值,并能够自动确定加热曲线最优部分,得到较真实的热导率。经过该算法处理得出的数据保存在文件中,评估软件将这些数据以点状图、柱状图等的形式表现出来,能更直观、更方便的分析实验数据和评价实验质量,由于环境温度测量的结果的影响很大,所以在每次测量之前,系统要判断实验环境的温度是否稳定,即判断温度漂移是否满足要求。因此,温漂的判断方法也很重要。本文对该方法的选择也做了讨论。整个系统设计完成后,通过实验完成了细沙、泥土等介质的热导率测量,并通过多次实验对系统的设计进行完善。为检验仪器的测量精度,对国际上通用的热导率标定样品石英标准样进行了测定,实验结果显示,研制的热导率测试仪能实现八个通道的测量,精度达到3%,满足海底沉积物热导率的测量及评估要求。研究成果申请了一项发明专利——多通道热导率测量的硬件电路系统；一项实用新型专利——基于线热源原理的微型探针及制作工艺方法。论文研究成果在高效率、高精度的沉积物热导率多通道测量技术及沉积物热导率的多通道测量的数据处理技术上有所创新,为热导率测试工作的进一步展开奠定了基础。更多还原

【Abstract】 Submarine geothermal research is critical to the comprehensive evaluation of the marine oil and gas resources. Combing with the knowledge of the basin evolution, it can help us to understand the temperature history of hydrocarbon source beds, even the organic matter mature history, which is important to the exploration of the marine oil and nature gas. Submarine geothermal research is also important for the accurate evaluation and prediction of the natural gas hydrate resources. It consists of the measurement and calculation of the submarine temperature, the sediment thermal conductivity and the geothermal gradient, et al.There are two kinds of test methods for sediment thermal conductivity, the first one is in-situ measurement, the other one is Indoor measurement. In the former measuring process, marine operation is required, which is very difficult and the equipment is easy to wear and tear; the latter is done in the laboratory, which could reduce the time for maritime operations and the risk of damaging the equipment. After the comparison of these two methods, two ways of measuring the thermal conductivity was almost the same. However, at this stage, the time of thermal conductivity test time is long and inefficient high-precision measurement equipments dependence on imports. Therefore, it is necessary for development of highly efficiency and precision equipment for measuring thermal conductivity. This paper is focuses on the software development of equipment.Choosing a suitable theoretical model, which is the basis of this measurement system, is very critical. In wide ranges of approaches for measuring thermal conductivity, line source method which is one kind of unsteady method is selected in this paper. In practice, there are several measurement models:Pulse Infinite Line Method, dual-probe heat-pulse measurement theory, single-probe continued heating method. The theory of single-probe continued heating method is used in the equipment’s design because it is simple & high efficiency.Based on the theory, multi-channel thermal conductivity meter, which is mainly composed of four parts, is designed. It’s composed of PC, one-chip computer module, Agilent 34411 and measuring probe (packaged heating wire and thermistor). PC is employed in measurement controlling, data processing and analysis of results. One-chip computer module is employed in analysis of host computer (PC) commands, excitation current, switching channels. Agilent 34411 is employed in data acquisition.Software developed in Visual C++6.0 platform is divided into two parts:the measuring software & evaluation software. The former is employed in controlling measuring process, data acquisition, data calculation and processing. The later is employed in result analysis. Measuring software has several modules:measurement parameter setting module, detection module, data acquisition modules, data processing and save module, and so on. Evaluation software has been divided into analysis for each measurement modules & analysis for single measurements module.Human-computer interaction, which has been designed to be not only aesthetic but also user-friendly, plays an important role in the software. In the measuring software, it is convenient for user to control measurement and observe the situation of measurement, such as the drift, real-time temperature curve in the heating process. In the evaluation software, point-like diagram, histogram and other forms is used; it can be easily to compare the results of the measurements.Data acquisition was mainly achieved by Agilent 34411A digital multimeter, which uses USB to communication with the PC and IVI instrument drivers is supported. Therefore, it is easily to use multimeter.Data processing and evaluation is a key part of the software system. In accordance with design requirements, the resistance value gathered by multimeter must be converted into temperature value by suitable algorithm. Curve fitting ("Steinhart-Hart" formula) and interpolation are used in this paper on account of their own advantages and disadvantages.The measuring principle is based on heating a cylindrical source with infinite length, finite radius, and infinite thermal conductivity in a homogeneous and isotropic sample full space with constant heating power for a finite measuring time. Thermal conductivity then is determined from the temperature rise in the source. In practice, the correct choice of the time interval is difficult. In the early stage of heating the source temperature is strongly affected by the contact resistance between source and full space (not accounted for in the simple approximation used).In the later stages of heating, the influence of boundary effects caused by the actually finite length of the line source (assumed infinite in the theory) increases. Inbetween is a time interval in which the source temperature is dominated by the thermal conductivity of the full space and which should be used for the calculation. It is important to choose a method to examine different time intervals for their suitability for thermal conductivity determination. Then the SAM method is selected because it ensures that only results of physical significance are considered. Then the evaluation module uses the data processed by the algorithm. This enables the user to assess the measurement quality and the reliability of the obtained thermal conductivity values.All the above, the work laid a foundation for further researches.更多还原