Temperature-depth Distribution Research Articles

INVESTIGATION OF TEMPERATURE FIELDS DURING LOCAL INDUCTION HEATING OF THE CASING STRING IN THE WELL

One of the important tasks in geophysical studies of operating wells is the detection of behind the casing flows. The traditional complex of geophysical methods (thermometry, flow metering, composition methods, and others) does not always make it possible to detect the movement of fluid behind the well casing. To solve this problem, it is promising to use the method of active thermometry.Research technology using this method involves recording the temperature in the well during induction heating of a small section of metal casing. As a result of heat exchange between the heated section of the column and the liquid flow, a thermal disturbance is created in the annular flow channel. In the presence of behind the casing flow, heat will be carried away from the induction heating region in the direction of liquid movement and will be redistributed in the column above or below the heating interval. By recording the temperature of the casing during induction heating and after turning off the inductor, it is possible to establish the fact of cross-flow and quantify its flow rate.This paper studies the influence of the direction and flow rate of behind the casing flow on the unsteady temperature field in a metal casing during its local induction heating. The problem is solved numerically in the Ansys Fluent software package. The temperature field in the fluid in the wellbore is calculated taking into account free convection.The model temperature distributions obtained for different behind the casing flow configurations (direction, flow rate) can be used for quantitative interpretation, to determine the flow rate in the behind the casing flow channel by comparing actual and model temperature curves. To assess the intensity of behind-the-casing movement, time measurements at a “point” in the induction heating interval are also informative. The direction of flow is determined by the nature of the temperature distribution in depth above and below the induction heating section.

Determination of the coefficient of effective thermal diffusivity of soil under natural changes in environmental conditions

An experimental setup and a data processing technique have been developed to obtain the soil temperature distribution in depth and in time. The results of measuring the soil temperature during 2021 in the city of Ramenskoye, Moscow Region at depths from 0 to 1.475 m are obtained and presented. An analytical solution of the problem of heat transfer in the soil based on the superposition principle is shown and verified. The coefficient of effective thermal diffusivity of soil a = 0.99 · 10−6 m2/s was determined indirectly in a passive experiment. Conclusions are drawn about the coincidence with the results of the experiment of the asymptotic nature of the dependence of the analytical solution for determining the amplitude of soil temperature fluctuations on depth and linear for the phase. An analytical solution is presented to obtain the temperature distribution in the soil with the known law of temperature fluctuations on the surface and the coefficient of effective thermal diffusivity.

Correction of the Temperature of Biological Objects in Thermographic Methods

The proposed correction allows to refine the surface temperature determined by a standard noninvasive thermographic method based on IR images for the human skin with a nonuniform in depth temperature distribution. The nonuniformity is due to the biophysical necessity of normal functioning of the organism, as well as to a possible presence of pathological processes in certain areas of the body. The measured brightness can be spectral or polychromatic. The value of the correction is analyzed depending on the size, shape, and thermal power of the source of pathology, as well as the depth of its location, thermophysical and optical characteristics of the biological environment.

TEMPERATURE MONITORING OF POLYMER FILMS UNDER IRRADIATION BY FAST ION BEAM

A technique for infrared thermometry remote monitoring of temperature of area of a polymer film under ion irradiation is described. Calculation part of the technique takes into account the case when the irradiated area is significantly smaller than the instrument field of view. Temperature measurements were carried out with 20 μm polyimide films irradiated by 1000 to 1600 keV protons, with 1…5 μA/cm2 current density. A model for calculation of temperature depth distribution in the irradiated film is developed. The model is also applicable for the case of ion irradiation in gaseous atmosphere, and takes into account temperature dependence of the polymer substance thermal conductivity, of the emissivity coefficient, and of the convective heat transfer coefficient. The calculated data are compared with the temperature measurements.

Heat flow, depth–temperature, and assessment of the enhanced geothermal system (EGS) resource base of continental China

This paper focuses on a dataset reflecting the potential for the development of enhanced geothermal systems (EGS) in continental China. Depth–temperature profiles, derived from surface heat flow, thermophysical parameters, the thickness of sedimentary layers, and ground surface temperatures, are the basis of EGS resource assessment. According to up-to-date 1230 pieces of heat flow data, we updated the heat flow measurements and depth–temperature distribution maps in continental China. Subsequently, the EGS resources were estimated using volume method with respect to various depth slices, temperature grades, and provinces, respectively. Results indicate that the total heat content within the depth of 3–10 km is 22.9 × 106 EJ (1 EJ = 1018 J), of which recoverable part is equivalent to 1.56 × 104 billion tons coal equivalent by the conservative recovery factor (2%). Under the assumption of 30-year-long production life, 10 °C reduction from the original rock temperature, and 2% as the recoverable factor, the production of electric power in continental China is estimated to be 4.56 × 106 MWe. On the basis of the calculation, we delineated four favorable targets for EGS resources exploration, including South and Northeast Tibet, West Yunnan (Tengchong), the southeast coast of China (Zhejiang, Fujian, and Guangdong), and Northeast China (Songliao Basin and Changbai Mountain).

Parameter estimation of breast tumour using dynamic neural network from thermal pattern

This article presents a new approach for estimating the depth, size, and metabolic heat generation rate of a tumour. For this purpose, the surface temperature distribution of a breast thermal image and the dynamic neural network was used. The research consisted of two steps: forward and inverse. For the forward section, a finite element model was created. The Pennes bio-heat equation was solved to find surface and depth temperature distributions. Data from the analysis, then, were used to train the dynamic neural network model (DNN). Results from the DNN training/testing confirmed those of the finite element model. For the inverse section, the trained neural network was applied to estimate the depth temperature distribution (tumour position) from the surface temperature profile, extracted from the thermal image. Finally, tumour parameters were obtained from the depth temperature distribution. Experimental findings (20 patients) were promising in terms of the model’s potential for retrieving tumour parameters.

ЧИСЛЕННОЕ МОДЕЛИРОВАНИЕ ПРОЦЕССА ОТБОРА ГЕОТЕРМАЛЬНОЙ НИЗКОПОТЕНЦИАЛЬНОЙ ЭНЕРГИИ ГРУНТА

The aim of our research is to study the interaction of energy foundations with the ground mass and to develop methods for their construction on the example of the city of Perm. Field studies of ground were carried out in a specially chosen pilot site to determine temperature distribution in the ground mass, change of ground-water level and physical-mechanical and thermal-physical characteristics of the ground mass. The diagrams of depth temperature distribution in the ground and its seasonal variations were obtained on the results of monitoring, and also the average groundwater level. To carry out numerical simulation, software-complex “GeoStudio” was selected. Its basic differential equation is the fundamental heat conduction equation with an internal heat source. The purpose of the numerical simulation was quantitative evaluation of the thermal energy extracted from different energy foundations under soil conditions in the city of Perm. By results of the spent numerical experiments the equations of regress and nomographs dependences of size of received thermal energy on geometrical parameters of the projected power bases to hydro-geological and climatic conditions of the Perm region are constructed

Numerical Simulation of the Process of the Geothermal Low-potential Ground Energy Extraction in the Perm Region (Russia)

The aim of our research is to study the interaction of energy foundations with the ground mass and to develop methods for their construction on the example of the city of Perm. Ground field studies were carried out in a specially chosen pilot site to determine the temperature distribution in the ground mass, change of the ground-water level and physical-mechanical and thermal-physical characteristics of the ground mass. The diagrams of the depth temperature distribution in the ground and its seasonal variations were obtained on the results of monitoring, and also the average groundwater level. To carry out numerical simulation, a software package “GeoStudio” was selected. Its basic differential equation is the fundamental heat conduction equation with an internal heat source. The purpose of the numerical simulation was the quantitative evaluation of the thermal energy extracted from different energy foundations under soil conditions in the city of Perm. On the basis of the results of the conducted numerical experiments, the equations of the regress and nomograms dependences of size of the received thermal energy on geometrical parameters of the projected power bases for hydro-geological and climatic conditions of the Perm region are constructed.

Numerical simulation of the process of geothermal low-potential ground energy extraction in Perm region (Russia)

The aim of our research is to study the interaction of energy foundations with the ground mass and to develop methods for their construction on the example of the city of Perm. Field studies of ground were carried out in a specially chosen pilot site to determine temperature distribution in the ground mass, change of ground-water level and physical-mechanical and thermal-physical characteristics of the ground mass. The diagrams of depth temperature distribution in the ground and its seasonal variations were obtained on the results of monitoring, and also the average groundwater level. To carry out numerical simulation, software-complex “GeoStudio” was selected. Its basic differential equation is the fundamental heat conduction equation with an internal heat source. The purpose of the numerical simulation was quantitative evaluation of the thermal energy extracted from different energy foundations under soil conditions in the city of Perm. By results of the spent numerical experiments the equations of regress and nomographs dependences of size of received thermal energy on geometrical parameters of the projected power bases to hydro-geological and climatic conditions of the Perm region are constructed.

A Microwave Radio Thermometer for Measuring the Depth Temperatures of Biological Objects by a Noninvasive Method

A new area of medical diagnostics is being actively developed at the present time, based on the complex measurement of physical fi elds and the radiations of electromagnetic waves by the human body in the microwave and infrared ranges of the spectrum during vital activity [1]. By using methods of microwave radiometry, one can carry out noninvasive radio-thermal mapping of biological systems in different spectral bands, from which one can establish the depth temperature distribution profi le. One can determine the temperature distribution of a biological medium as a whole, which is an important characteristic of the function of an organism. To measure the natural radiation of a biological medium in the microwave band, radiometers with applicator-type antennas (radio thermometers) are employed [2], where the unpredictable value of the refl ection coeffi cient at the boundary of the antenna and the biological system has the main effect on the measurement accuracy. In instruments, the effect of the refl ection coeffi cient, like the main error of the measurements, is minimized by different methods: by compensation, by additional temperature stabilization of the antenna system, by processing the signals using complex algorithms, etc. Structural solutions in constructing the input receiver units are used for the same purpose in radiometer systems, the basis of which is the method of producing additional noise on the object being investigated using a reference radiometer signal [3–5]. It is assumed here that part of the radio-wave signal from the object, with an effective noise temperature T at the boundary with the antenna, is refl ected back into the object and has a value TR for a power refl ection coeffi cient R. An adaptive determination by the radiometer of the part of the useful electromagnetic signal, returned back into the object, ensures the property of symmetry and identity of the refl ection coeffi cient both from the side of the object being investigated and from the receiving antenna of the radiometer. Radio thermometers, using the method described above, are incorporated into systems where the additional noise signal is regulated by the change in the temperature of a matched load [6]. The noise signal, generated by the matched load, is equal to its physical temperature in units of the Kelvin scale (in the thermodynamic scheme the matched load is an analog of an absolutely black body). Hence, a heated or cooled matched load may change the noise signal acting on the boundary of the antenna and the medium being investigated from the side of the input unit of the radiometer. This regulation principle uses the analog method.

Numerical calculation of temperature and surface topology during a laser ablation process for ceramic coatings

In this paper a numerical procedure is presented to calculate a laser ablation process for ceramic thick film coatings. The code is required to cover temperature dependent material data, projected beam intensities and inhomogeneous coating–substrate combinations to calculate the hole shape geometry, the temperature distribution under the surface and the ablation rate per pulse. Therefore, the ablation speed was calculated by an Arrhenius equation while the temperature distribution was simulated by means of the heat conduction equation, which is solvable by a finite differences scheme. Hence, an adaptive mesh is used and the expansion of the code to three spatial dimensions enables the simulation of more complex ablation geometries. The simulation time was held low by introducing actualization frequencies, where critical and time consuming steps were only run if necessary. A validation of the numerical simulation was done by comparing the calculated temperature depth distribution and hole geometry with micrographs of experimental ablations.

Modeling of Processes in Co-Based Coatings Exposed to Plasma Jet Irradiation

The model of microstructure of thick (about 300 μm) plasma detonated Co-based coatings on steel substrates is suggested on the basis of experimental research. Computer simulation of temperature distribution in depth from the surface of coatings under plasma jet irradiation was done; and certain parameters for additional treatment by irradiation were proposed. The irradiation was carried out according to the design conditions. It was established that the roughness of the modified coatings decreased by 2 times, microhardness increased on the average by 25 %. There was established the evolution of the structure and phase composition of the coatings after irradiation, which caused the improvement of their strength. DOI: http://dx.doi.org/10.5755/j01.ms.19.3.1903

하이브리드 섬유보강 쉴드터널 라이닝의 온도의존적 열전도도 추정

본 연구는 콘크리트의 열전도 역문제의 해를 통해 온도의존적 열전도도를 추정하는 방법을 제안하였다. 온도의존적 열전도도의 추정은 실물모형 화재실험에서 측정된 하이브리드 섬유보강 쉴드터널 라이닝의 시간 및 깊이별 온도분포 데이터를 이용하였다. 추정된 온도의존적 열전도도는 실험시간이 짧은 시점에서는 상온 영역에서 열전도도의 급격한 감소가 나타나는 것으로 추정되었다. 반면 깊이 25mm 위치에서 최대온도가 측정된 실험시간대에서는 온도에 따른 콘크리트의 특성변화 및 강섬유 혼입 효과를 반영하고 있다. 따라서 온도의존적 열전도도 추정 시 가열면 부근에서 최대온도가 측정된 시점을 기준으로 실험시간을 결정해야 한다. 추정된 열전도도는 유사배합을 사용한 기존연구와 유사한 결과를 나타내고 있다. This study presents estimation method of temperature-dependent thermal conductivity by using solution of inverse heat conduction problem. Time and depth temperature distribution data from full-scale fire test were used for estimating temperature-dependent thermal conductivity on hybrid-fiber reinforced shield tunnel lining. At short heating time, estimated thermal conductivity sharply decreased within <TEX>$100^{\circ}C$</TEX>. On the other hand, it reflected thermal properties of concrete and effect of steel fiber at heating time of measured maximum heating temperature. Thus arbitrary time should be determined to estimate temperature-dependent thermal conductivity in time zone of measured maximum heating temperature. Estimated temperature-dependent thermal conductivity is similar to results of other study.

Assessing the thermal regime of soils in the depressions of the Prebaikalia and Northern Transbaikalia

Long-term data from meteorological stations have been used in assessing the thermal state of the soil layer in large depressions of the Prebaikalia and Northern Transbaikalia. We examine the characteristics of temperature distribution in depth over an annual cycle for seasonally frozen and permafrost soils. For the Baikalian type depressions we carried out a spatial differentiation of the lowest and highest (having regard to the temperature lag) mean monthly soil temperatures. It is concluded that within a single depression the thermal regime of the soil fluctuates over a very broad range. On the other hand, an identical situation with the temperature regime can occur in different depressions.

Heat flow, depth–temperature variations and stored thermal energy for enhanced geothermal systems in Canada

In order to help assessment of enhanced geothermal energy potential in Canada, we constructed a new series of heatflow and depth–temperature distribution maps (down to 10 km). We focus on high-temperature resources (>150 °C) capable of electrical production. Maps presented show large temperature variability, related mainly to heat flow patterns. The highest temperatures occur in western and northern Canada. Here temperatures greater than 150 °C, required for enhanced geothermal systems (EGS), can be reached at reasonable drilling depths of <5 km. Heat flow, by itself however, is not a sufficient tool to predict areas of high energy content. A combination of thick low thermal conductivity sedimentary blankets and moderate to high heat flow areas can generate targets that are as favorable as regions with high conductivity and high heat flow. Some moderate heat flow areas in the deeper parts of the Western Canada Sedimentary Basin have heat content comparable to high heat flow zones of the the Canadian Cordillera. The magnitude of in-place thermal energy available for future heat ‘mining/farming’ was esitmated throughout Canada by calculating heat released through cooling a defined rock volume through a fixed temperature change. These estimates show the first-order appoximation of available geothermal heat content. The fraction of true heat energy available will be as low as 0.02 of these values. However, even this more limited energy production could be large enough to be a considerable future renewable energy resource for Canada.

Quantification of crustal geotherms along with their error bounds for seismically active regions of India: A Matlab toolbox

Determination of the thermo-mechanical structure of the crust for seismically active regions using available geophysical and geological data is of great importance. The most important feature of the intraplate earthquakes in the Indian region are that the seismicity occurs within the entire crust. In Latur region of India an earthquake occurred in the upper crust. In such situations, quantifying the uncertainties in seismogenic depths becomes very important. The stochastic heat conduction equation has been solved for different sets of boundary conditions, an exponentially decreasing radiogenic heat generation and randomness in thermal conductivity. Closed form analytical expressions for mean and variance in the temperature depth distribution have been used and an automatic formulation has been developed in Matlab for computing and plotting the thermal structure. The Matlab toolbox presented allows us to display the controlling thermal parameters on the screen directly, and plot the subsurface thermal structure along with its error bounds. The software can be used to quantify the thermal structure for any given region and is applied here to the Latur earthquake region of India.

Radial Structure of the Temperature Field in Biological Tissue under Irradiation by a Laser Beam

Using the previously developed method, we have obtained analytically the Green function in the time and radial coordinates for the problem on medium heating under external irradiation. On this basis, the radial structure of the temperature field in the biological tissue has been investigated. The influence of the radial diffusion of light on the thermal conditions of the tissue has been estimated, and it has been shown that at fairly large times after irradiation such diffusion can be neglected. Examples of radial and depth temperature distributions at various optical parameters of the tissue are given.

Thermal Structure of the Ionian Slab

We propose a thermal model of the subducting Ionian microplate. The slab sinks in an isothermal mantle, and for the boundary conditions we take into account the relation between the maximum depth of seismicity and the “thermal parameter” Lth of the slab, which is a product of the age of the subducted lithosphere and the vertical component of the convergence rate. The surface heat-flux dataset of the Ionian Sea is reviewed, and a convective geotherm is calculated in its undeformed part for a surface heat flux of 42 mW m−2, an adiabatic gradient of 0.6 mK m−1, a mantle kinematic viscosity of 1017 m2 s−1 and an asthenosphere potential temperature of 1300°C. The calculated temperature-depth distribution compared to the mantle melting temperature indicates the decoupling limit between lithosphere and asthenosphere occurs at a depth of 105 km and a temperature of 1260°C. A 70–km thick mechanical boundary layer is found. By considering that the maximum depth of the seismic events within the slab is 600 km, a Lth of 4725 km is inferred. For a subduction rate equal to the spreading rate, the corresponding assimilation and cooling times of the microplate are about 7 and 90 Myr, respectively. The thermal model assumes that the mantle flow above the slab is parallel and equal to the subducting plate velocity of 6 cm yr−1, and ignores the heat conduction down the slab dip. The critical temperature, above which the subduced lithosphere cannot sustain the stress necessary to produce seismicity, is determined from the thermal conditions governing the rheology of the plate. The minimum potential temperature at the depth of the deepest earthquake in the slab is 730°C.

LA ICP-MS study of fluid inclusions in quartz from the Yuzhna Petrovitsa deposit, Madan ore field, Bulgaria

Major and trace elements contents of individual fluid inclusions in quartz from the Yuzhna Petrovitsa hydrothermal Pb-Zn deposit were analyzed microthermometrically and by LA ICP-MS in order to better characterize the ore-forming fluids and their evolution. We found different trends in T-h vs. depth for fluid inclusions associated with various stages of mineralization, which quantitatively match predictions from published hydrothermal fluid flow simulations. The data indicate that the early quartz-pyrite association formed when the hydrothermal system was still heating up. The somewhat later quartz-galena-sphalerite main ore stage was deposited during the thermal peak under hot hydrostatic head conditions with a temperature-depth distribution representing the fluid's boiling curve, and post-sulphide quartz formed after the thermal peak. Galena and sphalerite precipitated from a slightly acid fluid with a Pb content of about 7-8 ppm and a Zn content of about 33 ppm at the present-day +668 m level, which represents a paleodepth of about -1200 m. Precipitation within the vein structure was mainly the result of cooling from about 310 C to 285 C over the investigated 400 m vertical interval. Ore fluid concentrations of lead and zinc can be used to estimate a minimum time-integrated amount of fluid in the order of 10(2) km(3) that was necessary to form the Madan ore field, which agrees well with typical values for present day hydrothermal systems.

Climate change of the last 2000 years inferred from borehole temperatures: data from Hungary

Ground surface temperature (GST) history, reflecting past climate conditions in Hungary, was evaluated by analysing the excursions left on the present-day temperature–depth distribution measured by precise temperature logging in 20 boreholes. These data were used to assess climatic changes over the last two millennia. We inverted the temperature–depth data using the algorithm by Bodri and Cermak [Global Planet. Change 11 (1995) 111]. Four main episodes can be distinguished: a warm period around 0 AD, extended cold conditions in the 6–16th centuries, a general warming culminated near 1850 and the cooling since then. The verification of the GST assessment was accomplished by independent data from historical sources and the GST reconstructions in surrounding Slovakia and Slovenia. The long cold conditions in the Middle Ages and the absence of the Little Climatic Optimum seem to be generic feature of the climate in Hungary. In their more recent parts, the obtained GST histories are consistent with the meteorological records in the area.