Subsurface thermal and hydrothermal characterization based on geothermal resources map, drill hole thermal gradients, Curie point depths and hypocenter distribution — Examples of Tohoku district, Japan

2006 ◽  
Vol 89 (1-3) ◽  
pp. 389-393 ◽  
Author(s):  
S. Tamanyu ◽  
T. Sato ◽  
M. Kato
Keyword(s):  
Curie Point ◽  
Drill Hole ◽  
Thermal Gradients ◽  
Geothermal Resources ◽  
Hypocenter Distribution

scholarly journals Spectral Induced Polarization Survey with Distributed Array System for Mineral Exploration: Case Study in Saudi Arabia

Minerals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 769 ◽  
Author(s):  
Fouzan A. Alfouzan ◽  
Abdulrahman M. Alotaibi ◽  
Leif H. Cox ◽  
Michael S. Zhdanov
Keyword(s):  
Effective Medium Theory ◽  
Coupling Effect ◽  
Pilot Project ◽  
Drill Hole ◽  
Induced Polarization ◽  
Effective Medium ◽  
Inductive Coupling ◽  
Geothermal Resources ◽  
Spectral Induced Polarization ◽  
Distributed Array

The Saudi Arabian Glass Earth Pilot Project is a geophysical exploration program to explore the upper crust of the Kingdom for minerals, groundwater, and geothermal resources as well as strictly academic investigations. The project began with over 8000 km2 of green-field area. Airborne geophysics including electromagnetic (EM), magnetics, and gravity were used to develop several high priority targets for ground follow-up. Based on the results of airborne survey, a spectral induced polarization (SIP) survey was completed over one of the prospective targets. The field data were collected with a distributed array system, which has the potential for strong inductive coupling. This was examined in a synthetic study, and it was determined that with the geometries and conductivities in the field survey, the inductive coupling effect may be visible in the data. In this study, we also confirmed that time domain is vastly superior to frequency domain for avoiding inductive coupling, that measuring decays from 50 ms to 2 s allow discrimination of time constants from 1 ms to 5 s, and the relaxation parameter C is strongly coupled to intrinsic chargeability. We developed a method to fully include all 3D EM effects in the inversion of induced polarization (IP) data. The field SIP data were inverted using the generalized effective-medium theory of induced polarization (GEMTIP) in conjunction with an integral equation-based modeling and inversion methods. These methods can replicate all inductive coupling and EM effects, which removes one significant barrier to inversion of large bandwidth spectral IP data. The results of this inversion were interpreted and compared with results of drill hole set up in the survey area. The drill hole intersected significant mineralization which is currently being further investigated. The project can be considered a technical success, validating the methods and effective-medium inversion technique used for the project.

scholarly journals Estimation of Geothermal Gradient and Heat Flow for Determination of Geothermal Energy Sources in Monguno Area of Northeastern Nigeria

2019 ◽  
pp. 1-8
Author(s):  
B. C. Udochukwu ◽  
M. Akiishi ◽  
A. A. Tyovenda
Keyword(s):  
Heat Flow ◽  
Curie Point ◽  
Geothermal Energy ◽  
Geothermal Gradient ◽  
High Heat ◽  
Curie Point Depth ◽  
The South ◽  
Geothermal Resources ◽  
North East ◽  
Curie Depth

The aeromagnetic data of Monguno area northeastern Nigeria have been used to estimate Curie point depth, geothermal gradients and heat flow using spectral analysis. These geothermal parameters were subsequently employed to identify areas of geothermal resources. First order polynomial fitting was applied in Regional-residual separation. The Curie point depth obtained in this area ranges from 10.318 to 24.476 km with an average of 13.387 km, the geothermal gradient of the area varies from 23.697 to 56.212°C /km, with an average of 46.195°C /km, while the heat flow ranges from 59.242 to 136.176 mWm-2, with an average value of about 112.364 mWm-2. It was also observed that the deepest Curie depth in the area is identified in the south, while the shallow depth is located in the northeast and spread toward the southwest. On the other hand, the highest geothermal gradient in the area is identified in the northern part of Moguno, while in the south,                    the lowest, geothermal gradient is located. The highest heat flow in the area is seen in the south-west and north-east, while the lowest heat flow is observed in the south. The high heat flow and geothermal gradient in the area show that geothermal energy could be found in Monguno region of the northeastern Nigeria.

Curie point depths of the Island of Kyushu and surrounding areas, Japan

Geophysics ◽  
1985 ◽  
Vol 50 (3) ◽  
pp. 481-494 ◽  
Author(s):  
Y. Okubo ◽  
R. J. Graf ◽  
R. O. Hansen ◽  
K. Ogawa ◽  
H. Tsu
Keyword(s):  
Heat Flow ◽  
Least Squares ◽  
Curie Point ◽  
Power Plants ◽  
Gravity Data ◽  
Depth Map ◽  
Curie Point Depth ◽  
Geothermal Resources ◽  
Regional Geology ◽  
Least Squares Fit

As part of a comprehensive, nationwide evaluation of geothermal resources for Japan, the first of the Curie point depth maps, covering the island of Kyushu, has been prepared. The map was created by inverting gridded, regional aeromagnetic data. Two satisfactory algorithms were developed to invert the gridded data based upon a distribution of point dipoles. The first algorithm estimates [Formula: see text],[Formula: see text], and [Formula: see text], the coordinates of the centroid of the distribution, by computing a least‐squares fit to the radial frequency of the Fourier transform; the second algorithm estimates centroid depth only by computing a least‐squares fit to the squared amplitude of the frequency estimates. The average depth to the top, [Formula: see text] of the collection of point dipoles, was estimated by a variation of the second algorithm. The depth to the bottom of the dipoles, inferred Curie point depth, is [Formula: see text]. The depth estimates are hand contoured to produce the final map. The Curie point depth map is then compared to regional geology and heat flow data, and to a limited set of gravity data. Good correlations are found between the Curie point depths and the heat flow and regional geology. A spatial correlation observed between gravity and Curie point depths is considered a secondary, structural effect. Locations of the currently operating geothermal power plants correspond to the shallowest Curie point depths. Based on these comparisons, we conclude that the methods provide geologically reasonable results which are usable in a nationwide geothermal assessment program.

Analysis of aeromagnetic measurements from the Cascade Range in central Oregon

Geophysics ◽  
1983 ◽  
Vol 48 (3) ◽  
pp. 376-390 ◽  
Author(s):  
G. Connard ◽  
R. Couch ◽  
M. Gemperle
Keyword(s):  
Heat Flow ◽  
Curie Point ◽  
Hot Springs ◽  
Magnetic Anomalies ◽  
High Heat ◽  
Cascade Range ◽  
Thermal Gradients ◽  
Tectonic Structures ◽  
Basin And Range Province ◽  
Lateral Offset

Shallow Curie‐point isotherm depths, indicated by the analysis of magnetic anomalies, young silicic volcanism, hot springs, and high heat flow mark the Cascade Range of central Oregon as a potentially important geothermal resource area. Aeromagnetic measurements in the central Cascades between 43°00′ and 44°15′N latitude and 121°00′ and 122°30′W longitude exhibit predominant northwest‐southeast lineations and less prominent north‐northeast by south‐southeast lineations. Longer wavelength components of the magnetic anomalies (greater than 25 km), possibly related to deeper sources, trend approximately north‐south parallel to the Cascade Range. Magnetic anomalies show a right‐lateral offset of the High Cascades Volcanism at 43°30′N latitude, which is consistent with the tectonic structures of the Basin and Range province southeast of the area. Magnetic source depth calculations show that the High Cascades occupy a structural depression or graben on the eastern side of the Western Cascades. Spectral analysis of the magnetic anomalies suggests that the High Cascades are underlain by Curie‐point isotherm depths as shallow as 9 km. These shallow Curie‐point isotherm depths imply thermal gradients greater than 50°C/km and surface heat flow greater than [Formula: see text].

Petroleum data: leading the search for geothermal resources in Western Australia

2009 ◽  
Vol 49 (1) ◽  
pp. 365 ◽  
Author(s):  
K. Ameed Ghori
Keyword(s):  
Heat Flow ◽  
Drill Hole ◽  
Petroleum Exploration ◽  
Geothermal Resources ◽  
Geochemical Conditions ◽  
Stress Orientation ◽  
Data Compilation ◽  
Australian Continent ◽  
Petroleum Wells ◽  
Western Australian

In Western Australian basins, subsurface drill-hole data, primarily from petroleum exploration, allows the identification of regions of high temperature at depth that may be potential geothermal resources. The extent and economic viability of such resources remain poorly known and require further study. Observed temperatures at depths up to 4.5 km reach 150°C in parts of the Canning, Carnarvon and Perth basins, indicating low-enthalpy resources related to regional heat flow. The greatest potential for hydrothermal resources is in the Perth Basin where subsurface temperatures of 65–85°C are reached at 2–3.5 km depth. Heat-flow modelling of 170 Perth Basin wells shows a range of 30–140 mW/m2, with the highest surface heat-flow values in the northern part of the basin. The median value of 76.5 mW/m2 for this basin exceeds the average reported for the Australian continent—64.5 mW/m2. Potential hot rocks resources are present in parts of the Canning, Carnarvon and Perth basins where the depth to 200°C is less than 5 km. Knowledge of high subhorizontal stress conditions that can enhance geothermal water flow from engineered reservoirs are based on data mostly from petroleum wells in the Perth Basin. A systematic quantitative assessment of geological, hydrogeological, geophysical, stress orientation and geochemical conditions is required to further delineate and prove these resources. Progressive compilation, validation and interpretation of subsurface data from more than 800 wells is underway, and includes temperature logs of 47 shallow water bores and 30 new thermal conductivity measurements of Perth Basin wells. Data compilation from 580 wells in the Canning, Carnarvon and Perth basins is complete. To date the greatest number of wells indicating high geothermal gradients and temperatures are in the Carnarvon Basin.

scholarly journals Determination of The Curie Point Depth, Thermal Gradient and Heat Flow of Parts of Central And North-Eastern Nigeria Using Spectral Analysis Technique

2020 ◽  
Author(s):  
George Idena Odidi ◽  
Abu Mallam ◽  
Naeem Nasir
Keyword(s):  
Heat Flow ◽  
Curie Point ◽  
Geothermal Gradient ◽  
Mean Value ◽  
Centroid Method ◽  
Geothermal Resources ◽  
Analysis Technique ◽  
North Eastern ◽  
Data Points

Abstract Radially power spectrum was applied to the aeromagnetic data covering an area 36,300km2 and bounded by latitudes 7.5o N and 11.5o N and longitudes 7.5o E and 10.5o E., divided into 35 square blocks (with 50% overlapping and approximately 64 by 64 data points) and each block analysed using the spectral centroid method to obtain depth to the top, centroid and bottom of magnetic sources. The result shows that the curie point depths, range from 17.711km to 34.34km, with a mean value of 26.21km, geothermal gradient, range from 16.89 0C km-1 to 32.75 0C km-1, with a mean value of 22.83 0C km-1 and heat flow, range from 42.22 mWm-2 to 81.87 mWm-2, with a mean value of 57.07 mWm-2. These results correlate with the existing geothermal and geo-tectonic signatures of the area. Hence, the possibility of the existence of geothermal resources in the study area and its possible exploration is not far fetch.

Fission Gas Bubbles in Fractured UO2

1968 ◽  
Vol 26 ◽  
pp. 286-287
Author(s):  
O. M. Katz
Keyword(s):  
Electron Microscopy ◽  
Thermal Gradient ◽  
Gas Bubbles ◽  
Inert Gas ◽  
Thermal Gradients ◽  
Fission Gas ◽  
Beam Heating ◽  
Limited Application ◽  
Bubble Characteristics ◽  
Electron Beam Heating

The swelling of irradiated UO2 has been attributed to the migration and agglomeration of fission gas bubbles in a thermal gradient. High temperatures and thermal gradients obtained by electron beam heating simulate reactor behavior and lead to the postulation of swelling mechanisms. Although electron microscopy studies have been reported on UO2, two experimental procedures have limited application of the results: irradiation was achieved either with a stream of inert gas ions without fission or at depletions less than 2 x 1020 fissions/cm3 (∼3/4 at % burnup). This study was not limited either of these conditions and reports on the bubble characteristics observed by transmission and fractographic electron microscopy in high density (96% theoretical) UO2 irradiated between 3.5 and 31.3 x 1020 fissions/cm3 at temperatures below l600°F. Preliminary results from replicas of the as-polished and etched surfaces of these samples were published.

ELASTIC CONSTANTS OF IRON IN THE VICINITY OF THE CURIE POINT

1971 ◽  
Vol 32 (C1) ◽  
pp. C1-415-C1-416 ◽  
Author(s):  
L. ALBERTS ◽  
M. BOHLMANN ◽  
H. L. ALBERTS
Keyword(s):  
Elastic Constants ◽  
Curie Point
Sign in / Sign up

Export Citation Format

Share Document