活动大陆边缘盆地地热模拟及烃的形成以新西兰Taranaki盆地为例

Ｔａｒａｎａｋｉ盆地是新西兰目前已发现商业性油气藏的唯一一个盆地。烃主要来自上白恶统和古新统－始新统的煤层。盆地大部分地区平均地温梯度一般为２９℃／ｋｍ，在不同地区地温梯度变化范围在２２－２３℃／ｋｍ之间。地热及成烃吸是根据盆地不同地区有代表性的并模拟得出的。

盆地模拟技术在地热资源勘探开发中应用

目前国内、外盆地模拟技术已取得了一定的发展,特别在石油勘探开发业得到广泛应用。地热资源勘探开发与石油勘探开发具有相似性和相容性,故可以将现行的盆地模拟软件通过部分的增删、修改和扩充就可以运用到地热资源勘探开发中。

盆地地热场模拟在地热资源勘探中的应用

地热资源是一种新型无污染能源,具有极高的开采价值,已经受到世界各国的关注.盆地因其特殊的地质条件,内部往往蕴涵着丰富的地热资源,且具有易开采、利用的特点.但目前地热资源勘探的手段和研究方法单一,制约着地热资源的开采与开发.而盆地地热场模拟技术已经较为成熟,并在油气成藏模拟中广泛应用.我们可以在已有的技术手段下结合盆地地热模拟技术来提高勘探的精度.本文还探讨了以地温控制方程与地下热水水流方程相结合来建立模型,模拟盆地地热资源.

西藏伦坡拉盆地地热史模拟

伦坡拉盆地位于青藏高原的唐古拉山南侧藏北湖区 ,为早第三纪狭长断坳叠置盆地 ,存在丁青湖组和牛堡组两套含油气系统。在地史模拟的基础上 ,选取适当地热史参数 ,对盆地地热史进行模拟。模拟结果反映了其地温场具有高热流值、高地温梯度的特征。现今地温梯度在 5 .0～ 7.0℃ /( 1 0 0 m) ,古地温梯度略低 ,高地温场延续时间长 。

边界层湍流垂直混合强度对局地热对流模拟影响的个例研究

针对弱环境场下局地对流性降水难于准确预报问题,本文以长江下游地区两次局地对流性降水过程为例,通过调整WRF模式中两类边界层参数化方案(YSU和ACM2)的湍流垂直混合强度,探究改善降水预报准确度的一种可行途径。结果表明:在模式默认的垂直混合强度下,YSU方案模拟的对流发展较缓,对流触发时间略晚;ACM2方案则由于垂直混合过强,模拟的对流弱于YSU方案,对流触发时间晚于观测1~2 h。无论是YSU还是ACM2方案,减弱边界层内垂直混合强度能够更准确模拟对流触发及其发展演变。不同垂直混合主要通过影响边界层内位温、水汽混合比、风的垂直分布和能量输送来影响对流过程模拟:减弱垂直混合后,对流前期边界层内更湿冷,风速和垂直风切变增大,同时对流有效位能(Convective Available Potential Energy,CAPE)增加,这些因素利于更早触发对流,模拟的对流强度也更强。

盆地超压层段非幕式突破期的地热场模型数值解法

盆地超压层段的地热场模拟对超压成因研究及油气生成、排放机理分析有重要意义 ,但求解超压层段的热传递方程的数值解法至今仍没有被很好地解决 .问题的关键在于确定超压流体速度场 .由于超压流体发生幕式突破之前的排出速率极低 ,其速度场v =vxi+vzk近似满足条件 vx/ x + vz/ z =0 ,可以将其近似地视为稳定的不可压缩的无源流体 ,利用这一条件及相应的边界压力条件 ,可使整个计算过程得到简化 .在此基础上所建立的地热场模型有限元数值解法和模拟软件 ,能够实现对含油气盆地在幕式突破之前的超压层段地热场进行动态模拟 .

Alternate operation characteristics of a solar-ground source heat pump system

In order to investigate the alternate operation characteristics of a solar-ground source heat pump system（SGSHPS）,various alternate operation modes are put forward and defined.A two-dimensional mathematical model with freezing/melting phase changes is developed for the heat transfer analysis of the soil.Based on the numerical solution of the model,the variation trends of underground soil temperature of the SGSHPS operated in various alternate operation modes are discussed.The results indicate that,for the day-night and short-time interval alternate operation modes without solar energy,the operation time fraction of a solar heat source should be confined to from 50% to 58% when operated in an alternate period of 24 h.Meanwhile,the disadvantages of a natural resumption of soil temperature can be overcome effectively by solar energy filling,and an optimal operation effect can be achieved by integrating the mode of solar energy filling with other alternate modes.In addition,the accuracy of the presented model is verified by the experimental data of borehole wall temperatures.The conclusions can provide a reference for the optimization operation of the SGSHPS.

Numerical simulation on heat transfer performance of vertical U-tube with different borehole fill materials

Heat exchange performance of vertical U-tube heat exchanger was studied with two different borehole fill materials and CFD software. Borehole surface temperature and water temperature distribution were simulated on the condition of continuous operation for 8 h in winter with inlet water temperature being 10℃. The results show that there is no obvious difference on heat exchanger performance between the two different borehole fill materials.

Physical modeling of failure process of the excavation in horizontal strata based on IR thermography

In order to capture the mechanism of roadway instability in deep mines, a new approach of Physically Finite Elemental Slab Assemblage (PFESA) is proposed in order to construct a large-scale physical model simulating the geologically horizontal strata. We carried out physical modeling on the deformation and failure processes of roadways subjected to a plane loading scheme. Our laboratory tests were based on work which incorporated infrared (IR) detection, IR radiation temperature (IRT) statistics, image feature extraction and 2D Fourier transformation, from resulting thermographies. The IRT characterizes the mechanical responses from the roadway after loading with two stages, i.e., IRT evolving at higher levels corresponded to shallow mining (≤500 m) during which the roadway deformed gradually (referred to as the "steady deformation stage"); IRT evolving in a quasi-cyclical manner with multiple peaks corresponded to deep mining (800–2600 m), in which the failure mode for the roadway are dominated by breakage and collapse (called the "unsteady deformation stage"). The IR images and 2D Fourier spectra illustrate detailed information in terms of initiation, nucleation and coalescence of the damage to rock masses and the eventual failure of roadways subject to external loading.

Numerical simulation and analysis of moisture-heat coupling of soft rock tunnels in the cold regions

With the western development in China, more problems with rock and soil engineering in cold regions will be encountered. To study the stability of rock mass under the frost and thaw condition is of far significance. We attempt to simulate and analyze the temperature and moisture field in the surrounding rock of Dabanshan tunnel at its exit KI06＋025 in the cold region by software Femlab. First, introduced the common numerical solution to the moisture and heat coupled about the soft rock in tunnels of cold region. Then gave emphasis on simulation of the law of temperature distribution coupled temperature-moisture field and draw a parallel between temperature fields with different coefficient of percolation. In the course of simulation we considered the problem of caloric receptivity, thermal conductivity and critical heat varying with temperature.

Unsteady temperature field of surrounding rock mass in high geothermal roadway during mechanical ventilation

To explore the spatial-temporal evolution law of rock mass temperature in high geothermal roadway during mechar^ical ventilation, a series of experiments were conducted based on the physical simulation test system of thermal and humid environment in high geothermal roadway, which is a method independently developed by China University of Mining and Technology. The results indicate that during ventilation, the disturbed region of the temperature extends gradually from shallow area to deep area in the surrounding rock mass of the roadway. Meanwhile, the temperature increases as the exponential function from shallow area to deep, with steady decrease of the temperature gradient and heat flux. As the ventilation proceeds, the relationship between dimensionless temperature and dimensionless time approximately meets Hill function.

Heat calculation and numerical simulation in steam mining of permafrost gas hydrate

Steam mining method was injecting hot steam into the borehole to heat the hydrate strata at the same time of depressurization mining,which could promote further decomposition and expand mining areas of gas hydrate. Steam heat calculation would provide the basis for the design of heating device and the choice of the field test parameters. There were piping heat loss in the process of mining. The heat transfer of steam flowing in the pipe was steady,so the heat loss could be obtained easily by formula calculation. The power of stratum heating should be determined by numerical simulation for the process of heating was dynamic and the equations were usually nonlinear. The selected mining conditions were 500-millimeter mining radius,10 centigrade mining temperature and 180 centigrade steam temperature. Heat loss and best heating power,obtained by formula calculation and numerical simulation,were 21. 35 W/m and 20 kW.

Thermal performance of a single U-tube ground heat exchanger:A parametric study

In this research,the thermal performance of a single U-tube vertical ground heat exchanger is evaluated numerically as a function of the most influential flow parameters,namely,the soil porosity,volumetric heat capacity,and thermal conductivity of the backfill material,inlet volume flow rate,and inlet fluid temperature.The results are discussed in terms of the variations of the heat exchange rate,the effective thermal resistance,and the effectiveness of the ground heat exchanger.They show that the inlet volume flow rate,inlet fluid temperature,and backfill material thermal conductivity have significant effects on the thermal performance of the ground heat exchanger,such that by decreasing the inlet volume flow rate and increasing the backfill material thermal conductivity and inlet fluid temperature,the outlet fluid temperature decreases considerably.On the contrary,the soil porosity and backfill material volumetric heat capacity have negligible effects on the studied ground heat exchanger’s thermal performance.The lowest inlet fluid temperature reaches a the maximum effective thermal resistance of borehole and soil,and consequently the minimum heat transfer rate and effectiveness.Also,multilinear regression analyses are performed to determine the most feasible models able to predict the thermal properties of the single U-tube ground heat exchanger.

THE INFLUENCE OF THE ZHOUSHAN ARCHIPELAGO TERRAIN ON THE TROPICAL CYCLONE TODD (NO.9806) BY NUMERICAL SIMULATION

Taking Tropical Cyclone (TC) No.9806 (Todd) as an example, the effects of Zhoushanarchipelago terrain on landfall TC are investigated by use of numerical simulation. Results show that, undertopographic influences of Zhoushan Islands, the westward-moving landfall TC deflects. And, small orographichighs and enhanced rainfall caused by climbing airflow on the windward slope of main mountains of theseislands are a result of effects of Zhoushan Islands. These results display some particular laws of effects ofsmall-sized islands on the landfall of TC.

Widening and weakening of the Hadley circulation under global warming

The Hadley circulation is one of the most important atmospheric circulations.Widening of the Hadley circulation has drawn extensive studies in the past decade.The key concern is that widening of the Hadley circulation would cause poleward shift of the subtropical dry zone.Various metrics have been applied to measure the widening of the tropics.What are responsible for the observed widening trends of the Hadley circulation? How anthropogenic and natural forcings caused the widening? How the widening results in regional climatic effects? These are the major questions in studing the widening of the Hadley circulation.While both observations and simulations all show widening of the Hadley circulation in the past few decades,there are no general agreements of changes in the strength of the Hadley circulation.Although some reanalysis datasets show strengthening of the Hadley circulation,it was shown that the strengthening trend could be artificial,and simulations show weakening of the Hadley circulation for global greenhouse warming.In the present paper,we shall briefly review the major progresses of studies in trends in width and strength of the Hadley circulation.We address answers to these questions,clarify inconsistent results,and propose ideas for future studies.