地热深井生产过程的井筒传热数值模拟     

单丹丹  闫铁  李玮  薛云龙  张弦  罗鹏飞 《地球物理学进展》2021,36(5):1891-1899

从地热储层中提取热流体的过程中,在井筒流体与周围地层之间存在着热量交换,使得热流温度发生着变化,为探究流体在生产井中的热量损失过程,本文的目的 是开发一种可靠的数值模型用以说明地热井在生产过程中的流动与换热问题,在此选取COMSOL Multiphysics建立了仿真模型,并对模拟结果进行了解析验证.井筒热量损失的表征要素除了温度以外,热损失功率也起着至关重要的作用,为了全面评价地热生产井的热能损失,故对井口水温及热损失功率两项评价指标进行研究,分析得出水的操作参数及环空热导率变化对井筒热损失的影响.研究结果表明:(1)数值模拟中应用TD代数表达式的连续形式与解析模型中应用Ramey定义的f(t)不连续函数表达式进行热流温度的求解时,对于较长的生产时间,数值解与解析解吻合良好.(2)井底水温的线性变化也将带来井口水温和井筒热损失功率的线性变化,井口水温和井筒热损失功率随井底水温的变化直线斜率随时间的增加略有减小,纵截距也略有减小,说明时间越长,井口温度升高的越慢,井筒热损失功率增大的越小,系统越趋于稳定状态.(3)增量为10 kg/s的采出流量与增量为10℃的井底水温相比,对井口水温的升高及热损失功率的减小影响程度均相应减弱,最终也将趋于稳定状态.(4)环空热导率对井口水温和井筒热损失功率的影响呈现相反的效应,即环空热导率增大井口水温降低,井筒热损失功率增大.结论 认为,综合考虑热流温度及井筒热损失功率两项指标对于高效地热能开采,提高热能利用率等方面具有重要意义,并可全面评价井筒的热量损失大小,为地热能开发提供可靠理论依据.  相似文献   

基于四川GPS观测网络的分米级差分GPS接收机     

陈聪  程奕  顾铁 《四川地震》2011,(1):15-19

基于四川GPS观测网络,本文提出采用低成本GPS-OEM板设计分米级差分GPS接收机。介绍四川GPS观测网络的工作原理,应用GPS观测网络改正由GPS轨道误差、电离层、对流层和大气折射引起的误差,将高精度的差分信息通过GPRS发给流动站来提高接收机的定位精度;论证了差分GPS的定位原理;最后提出整个系统的设计方案,用Thales DG14L OEM板处理GPS天线接收到的卫星信息,同时对GPRS天线接收数据中心差分信号进行差分运算。单片机控制软件采用汇编语言和C语言来编写。系统的实验结果表明,差分GPS接收机应用效果好,定位精度高,最重要的是降低了接收机的成本。  相似文献   

东海陆架泥质沉积物中固相Fe形态及其对有机质、Fe、S成岩路径的制约意义   总被引：2，自引：0，他引：2  

吕仁燕  朱茂旭  李铁  杨桂朋  邓霏霏 《地球化学》2011,(4):363-371

利用化学提取法对中国东海具有不同陆源物质的内陆架(0701)和外陆架(0508)泥质沉积物柱样进行的多种形态固相铁含量及其剖面分布研究结果表明,Fe形态及其分布对有机质、Fe和S早期成岩作用具有明显的制约意义.0508和0701两站点柱状沉积物总活性Fe平均含量分别为12.14 mg/g和10.03 mg/g,其中,氧...  相似文献   

Prediction of the run-out distance of the debris flow based on the velocity attenuation coefficient   总被引：2，自引：0，他引：2  

Yongbo Tie 《Natural Hazards》2013,65(3):1589-1601

Our aim is to determine the run-out distance of the debris flow that is crucial in the assessment, prevention and control of the debris flow hazard. Based on the variation characteristic of debris flow velocity in the alluvial fan, this paper proposes the calculation method of the velocity attenuation coefficient of the debris flow. By defining the velocity attenuation coefficient and deducing its calculating formula, this paper puts forward a new method to determine the run-out distance of the debris flow based on the velocity attenuation coefficient, and Gangou debris flow in Luding County, Sichuan Province is selected as a case for calculation and verification. Having 10 m as its measuring spacing, this paper measured 19 sections at the alluvial fan of the Gangou debris flow (among them, 11 sets of data are valid). And based on the measurement, this paper analyzes the characteristic of the velocity attenuation and calculates its velocity attenuation coefficient after the 2005 debris flow. The study indicates that when the velocity of Gangou debris flow at the alluvial fan is greater than 12 % of the initial velocity (at the mouth of gully), the attenuation is quite remarkable. But when the velocity at the alluvial fan is less than 12 % of the initial velocity, the attenuation is quite slow. Besides, when Gangou debris flow rushes out of the gully mouth (the initial velocity is 10 m/s) and when it attenuates to the 32 time, its velocity is less than 0.1 m/s, the debris flow is considered to stop flowing, and the run-out distance of Gangou debris flow is calculated to be 320 m. But the present alluvial fan of Gangou debris flow is measured to be 285 m in length, and the calculated run-out distance is 320 m, which is 35 m longer than its present length. This means when the debris flow runs out in 2005, it blocked up the main river (Dadu River) in some extent. And this finding is generally in accordance with that from the field survey. The findings can be of theoretical and practical significance in the debris flow hazard assessment, as well as its prevention and mitigation.  相似文献   

High-frequency monitoring of the occurrence of preferential flow on hillslopes and its relationship with rainfall features,soil moisture and landscape     

Hongchang Hu  Jie Wen  Zhenyang Peng  Qiang Tie  You Lu 《水文科学杂志》2013,58(11):1385-1396

ABSTRACT

High-frequency monitoring was conducted to quantify the frequency and controlling factors of preferential flow (PF) in a monsoon-influenced sub-humid mountainous catchment (6.48 km²) of Northern China. Rainfall was measured using nine bucket raingauges. Soil moisture probes were set up at 12 sites to observe the PF. Overall, 129 rainfall events were identified during the years 2014–2016. The average PF occurrence was 41%, which increased to 71% during heavy rainfall events (>20 mm) revealing a strong influence of the amount and intensity of rainfall. The study also revealed that the PF increased with antecedent soil moisture. Soil moisture was much higher on flat sites compared to sloping sites, providing evidence that the topography has a strong influence on rainfall infiltration and runoff which, subsequently, influence soil moisture variation and the occurrence of PF. Our findings provide valuable insights into the hydrological processes for studies in regions with similar environmental conditions.  相似文献   

吹填土自重沉淤阶段孔隙水压力消散的试验研究     

宋晶  王清  孙铁  李晓茹  张中琼  焦志亮 《岩土力学》2010,31(9):2935-2940

利用真空预压法处理吹填土时,细颗粒常堵塞排水管,导致土体排水不畅。为提高吹填土固结效率,采用自重沉淤排水与加负压排水固结相结合的方式在室内进行吹填土固结试验。试验第一阶段用排水管作为吹填土自重沉淤的竖向排水通道;第二阶段以装入中粗砂的排水管作吹填土排水通道,同时也是压力传递通道。试验监测到吹填土固结过程中不同位置孔隙水压力的变化,通过监测数据着重研究自重沉淤排水阶段吹填土的固结规律。借助渗流平衡方程确定吹填土在自重沉淤阶段孔隙水压力变化主要由排水管中水位、单位土面积控制,解释自重沉淤阶段孔隙水压力变化机理。同时,为了减小由于排水距离远近造成的固结不均,利用自重沉淤与加压固结结合的方法使吹填土达到较为理想的固结效果,将砂井设计理论与孔隙水压力变化曲线相结合确定排水管有效排水范围等效直径,为实际工程提供排水管间距的设计参数。  相似文献   

景谷M_S6.6、M_S5.8和M_S5.9地震强震动记录初步分析与场地效应研究     

林国良  崔建文  杨黎薇  刘琼仙 《震灾防御技术》2016,11(2):331-341

2014年云南景谷先后发生M_S6.6、M_S5.8和M_S5.9中强地震,云南强震动台网获取了丰富的加速度记录。本文整理了各次地震中固定台和流动台获取的强震动加速度记录资料,分别进行了地震动衰减关系和加速度反应谱分析,结果表明,所观测到的加速度峰值比云南地区地震动衰减关系预测值高,反应谱谱值随震级的增加有增大趋势。最后将益智强震台作为典型台站,分析了该台站在地震中的场地放大效应。  相似文献   

东海沉积物中铁(Ⅲ)氧化物还原活性的动力学表征     

朱茂旭  范长清  杨桂朋  李铁 《海洋学报(英文版)》2012,31(4):67-76

运用还原性溶解动力学实验和活性连续体(reactive continuum)模型表征了东海表层和柱状沉积物中铁(Ⅲ)氧化物的还原活性及反应进程中的动力学行为,通过动力学数据拟合得到了活性铁氧化物理论含量m₀、表观速率常数k'和活性非均匀度γ。结果表明,表层沉积物中铁氧化物的m₀在26.14~60.51 μmol/g之间,变化较小;表征高活性铁氧化物还原动力学行为的标准化初始还原速率(J/m₀=k')变化也较小,最大相差仅7.25倍;但不同站位沉积物中铁氧化物活性的非均匀度变化较大,当铁氧化物溶解达到90%时,其速率与初始速率相差2~4个数量级。表层沉积物中铁氧化物的m₀,k'和γ 3个动力学参数之间不存在相关性;柱状沉积物中m₀,k'和γ 3个动力学参数都随深度的增加呈总体减小的趋势,且三者之间存在良好的线性关系,这是沉积物早期成岩作用中铁成岩循环的结果。与传统的化学提取相比,活性连续体模型得到3个动力学参数(m₀,k'和γ)能从多个角度表征铁氧化物还原活性和动力学行为的细微差别。  相似文献   

断层气测量用于银川地堑隐伏断裂活动性的研究   总被引：1，自引：0，他引：1  

焦德成  潘祖寿  王增光  何开明  班铁 《防灾减灾学报》2012,28(3):41-47

在系统分析银川地堑活动构造、物探、地震及航卫片解译的基础上,对其内部两条主要隐伏活动断裂进行气氡、气汞测量和分析,结合地堑构造环境、地震活动性,对断层气测量结果用于隐伏断裂的活动性做出了分析。  相似文献   

基于多源遥感数据的融合算法变换效果对比研究     

杨佳佳  冯雨林  孙中任  高铁 《地质与资源》2015,24(5):489-495

随着多源遥感影像融合技术的成熟发展,如何提高高分辨率遥感数据的利用效益和使用质量已经成为影响其应用效果的瓶颈问题.针对QucikBird-2高分遥感数据光谱分辨率不足等问题,结合ASTER多光谱遥感数据,引入3种融合方法：主成分分析（PCA）融合、小波PCA融合和基于小波的IHS（色度、亮度、饱和度变换）融合,实现了对多光谱图像和高分辨率图像的融合,得到了多光谱高分辨率影像,使得在增强影像空间分辨率的同时也尽可能地保留了影像的多光谱信息.最后对3种融合方法的结果进行了定性和定量评价.  相似文献