Estimation of the thermal conductivity anisotropy of rock with application to the determination of terrestrial heat flow

1994 ◽  
Vol 99 (B11) ◽  
pp. 22087-22091 ◽  
Author(s):  
David Deming
Keyword(s):  
Thermal Conductivity ◽  
Heat Flow ◽  
Conductivity Anisotropy ◽  
Terrestrial Heat Flow

scholarly journals A Method for Measurement of Terrestrial Heat Flow Density in Water Wells

2018 ◽  
Vol 4 (2) ◽  
pp. 45
Author(s):  
Janilo Santos ◽  
Valiya M. Hamza ◽  
Po-Yu Shen
Keyword(s):  
Thermal Conductivity ◽  
Heat Flow ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Flow Density ◽  
Heat Flow Density ◽  
Terrestrial Heat Flow ◽  
The Mean

ABSTRACT. A simple method for measurement of terrestrial heat flow density in wells drawing groundwater from confined aquifers is presented. It requires laboratory determination of thermal resistance but the field work is simple, being limited to measurement of temperature of water at the well mouth during pumping tests.The aquifer temperature (Ta) is calculated from the measured temperature at the well mouth (Tw), the mass flow rate (M) and the depth to the top of the aquifer (H) using the relation(Tw – To) / (Ta – To) = M'R [1 – exp(–1/M'R)]where To is the mean annual surface temperature, R a dimensionless diffusion parameter and M' = MC/KH is the dimensionless mass flow rate, C being the specific heat of water and K the thermal conductivity of the rock formation penetrated by the well. The heat flow density (q) is then calculated from the relationq = (Ta –To) / ∑ n (i=1) Pi Zjwhere Pi is the thermal resistivity of the jth layer of thickness Zi and n the number of layers. The procedure also allow corrections for the influence of thermal conductivity variations oi the wall rocks.This method was used for the determination of heat flow density values for thirteen sites in the northeastern part of the Paraná basin. The mean value obtained is 62±4 mW/m2 in good agreement with the mean of 59±9 mW/m2 obtained by the conventional method for thirteen sites in the Paraná basin. Though similar in principle to the bottom-hole temperature method used in oil wells, the present technique has some inherent advantages. lt is potentially capable of providing a wider geographic representation of heat flow density (being not limited to petroleum fields) and is relatively free of the sampling problems normally encountered in working with oil companies. 0n the other hand the present method may provide unreliable values in the case of wells drawing water from more than one aquifer. RESUMO. Apresenta-se neste trabalho, um método simples para a determinação do fluxo geotérmico em poços em atividade de bombeamento de água subterrânea. O método requer a determinação em laboratório da resistência térmica total das camadas atravessadas pelo poço mas, o trabalho de campo é simples, limitando-se à medida da temperatura da água na boca do poço durante ensaios de bombeamento.A temperatura do aquífero (Ta) é calculada a partir da temperatura da água (TW), medida na boca do poço da vazão (M) expressa em massa  de água produzida pelo poço por unidade de tempo e, da profundidade do topo do aquífero (H) usando-se a relação(Tw – To) / (Ta – To) = M'R [1 – exp(–1/M'R)]onde TO é a temperatura média anual da superfície, R é um parâmetro adimensional de difusão, M' = M C/K H é a vazão adimensional do poço, C é o calor específico da água e, K é a condutividade térmica da rocha atravessada pelo poço. O fluxo geotérmico (q) é calculado pela relaçãoq = (Ta –To) / ∑ n (i=1) Pi Zjonde Pi é a resistência térmica da i-ésima camada de espessura Zi e, n é o número de camadas.O método permite também a introdução de correções da influência das variações de condutividade térmica das paredes do poço.Este método foi utilizado na determinação do fluxo geotérmico em treze localidades no nordeste da Bacia do Paraná. O valor médio obtido foi de 62±4 mW /m2 concordando com o valor médio de 59±9 mW/m2 obtido pelo método convencional de determinação de fluxo geotérmico em treze localidades da Bacia do Paraná. Apesar de ser um método similar ao das temperaturas de fundo de poço usado em poços de petróleo, esta técnica apresenta algumas vantagens. O método é potencialmente capaz de fornecer uma representação geográfica mais ampla do fluxo geotérmico, não estando limitado a campos de produção de petróleo, e é relativamente livre de problemas de amostragem normalmente encontrados quando se trabalha com companhias de petróleo. Por outro lado, este método pode fornecer valores irreais de fluxo geotérmico no caso em que o poço extraia água de mais de um aquífero. 

scholarly journals Present-day geothermal regime of the Uliastai Depression, Erlian Basin, North China

2018 ◽  
Vol 37 (2) ◽  
pp. 770-786 ◽  
Author(s):  
Wei Xu ◽  
Shaopeng Huang ◽  
Jiong Zhang ◽  
Ruyang Yu ◽  
Yinhui Zuo ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Flow ◽  
Thermal Structure ◽  
Rheological Characteristic ◽  
Rheological Parameter ◽  
Lithospheric Thickness ◽  
Terrestrial Heat Flow ◽  
Geothermal Regime ◽  
Mantle Heat Flow ◽  
Erlian Basin

In this study, we calculated the present-day terrestrial heat flow of the Uliastai Depression in Erlian Basin by using systematical steady-state temperature data obtained from four deep boreholes and 89 thermal conductivity measurements from 22 boreholes. Then, we calculated the lithospheric thermal structure, thermal lithospheric thickness, and lithospheric thermo-rheological structure by combining crustal structure, thermal conductivity, heat production, and rheological parameter data. Research from the Depression shows that the present-day terrestrial heat flow ( qs) is 86.3 ± 2.3 mW/m2, higher than the average of 60.4 ± 12.3 mW/m2 of the continental area of China. Mantle heat flow ( qm) in the Depression ranges from 33.7 to 39.3 mW/m2, qm/ qs ranges from 40 to 44%, show that the crust plays the dominant position in the terrestrial heat flow. The thermal thickness of the lithosphere is about 74–88 km and characterized by a “strong crust–weak mantle” rheological characteristic. The total lithospheric strength is 1.5 × 1012 N/m under wet mantle conditions. Present-day geothermal regime indicates that the Uliastai Depression has a high thermal background, the activity of the deep-seated lithosphere is relatively intense. This result differs significantly from the earlier understanding that the area belongs to a cold basin. However, a hot basin should be better consistent with the evidences from lithochemistry and geophysical observations. The results also show the melts/fluids in the study area may be related to the subduction of the Paleo-Asian Ocean. The study of the geothermal regime in the Uliastai Depression provides new geothermal evidence for the volcanic activity in the eastern part of the Central Asian Orogenic Belt and has significant implications for the geodynamic characteristics.

Measurement of the thermal conductivity of thin layers using a scanning thermal microscope

2001 ◽  
Vol 16 (9) ◽  
pp. 2530-2543 ◽  
Author(s):  
Erwin R. Meinders
Keyword(s):  
Thermal Conductivity ◽  
Heat Flow ◽  
Thermal Structure ◽  
Thin Layers ◽  
Heat Diffusion ◽  
Sputter Deposited ◽  
Relative Differences ◽  
Conductivity Of Thin Films ◽  
Change Material

A scanning thermal microscope (SThM) was used to measure the thermal conductivity of thin sputter-deposited films in the thickness range of 10 nm–10 μm. The SThM method is based on a heated tip that is scanned across the surface of a sample. The heat flowing into the sample is correlated to the local thermal conductivity of the sample. Issues like the contact force, the surface roughness of the sample, and tip degradation, which determine to a great extent the contact area between tip and surface, and thus the heat flow to the sample, are addressed in the paper. A calibration curve was measured from known reference materials to quantify the sample heat flow. This calibration was used to determine the effective thermal conductivity of samples. Further, the heat diffusion through a layered sample due to a surface heat source was analyzed with an analytical and numerical model. Measurements were performed with films of aluminum, ZnS–SiO2, and GeSbTe phase change material of variable thickness and sputter-deposited on substrates of glass, silicon, or polycarbonate. It is shown in the paper that the SThM is a suitable tool to visualize relative differences in thermal structure of nanometer resolution. Determination of the thermal conductivity of thin layers is possible for layers in the micrometer range. It is concluded that the SThM is not sensitive enough to measure accurately the thermal conductivity of thin films in the nanometer range. Suggestions for improvement of the SThM method are given.

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