Evaluation of the Petroleum Potentials and Prospect of the Chad Basin Nigeria from Heat Flow and Gravity Data

2016 ◽  
Author(s):  
Cyril N. Nwankwo ◽  
G. O. Emujakporue
Keyword(s):  
Heat Flow ◽  
Gravity Data ◽  
Chad Basin

Integrated modelling based on shallow cross-gradient joint inversion and deep petrological approach on 2D/3D data in the Western Carpathians

2020 ◽  
Author(s):  
Ján Vozár ◽  
Vladimír Bezák ◽  
Miroslav Bielik ◽  
Javier Fullea ◽  
Max Moorkamp
Keyword(s):  
Heat Flow ◽  
Lithospheric Mantle ◽  
Joint Inversion ◽  
Gravity Data ◽  
Thermal Studies ◽  
Western Carpathians ◽  
Integrated Modelling ◽  
Geophysical Modeling ◽  
3D Data ◽  
Mineralized Water

<p>We present the integrated geophysical modelling based on magnetotelluric (MT) method included in the crustal joint inversion with gravity data performed by JIF3D code and geophysical-petrological LitMod3D thermaly-selfconsistent mantle modelling. Performed geophysical modeling is primarily based on MT and regional gravity data with supporting information from seismic methods and geothermal data like Moho and lithospheric-asthenospheric boundary (LAB) depth used for building of the starting models. The integration among geophysical models is provided by the cross-gradient coupling method for the crustal structures and in the mantle, the coupling is provided petrological relationship based on compositional, temperature and pressure distribution information. The case study is focused on 3D modelling of the seismic 2T profile in central Slovakia crossing the major Carpathian tectonic units and the contact zone between European platform and Inner Carpathian block, which coincide with Carpathian Conductivity Anomaly (CCA).</p><p>The geoelectrical models from the 3D integrated modeling image the CCA in depths of about 10 - 20km and shows great improvement in comparison with 2D MT models. The CCA exhibits 3D features represented by the offset, along the fault, in the northsouth direction in the northern part of the modelled area. The four basic segments were identified in the crust structure of the central Slovakia part of the Western Carpathians. The southernmost physically distinctive segment with high full crust conductivity caused by young volcanic activity shows the presence of the partial melt, with high geoelectrical conductivity, in the middle and lower crust caused by higher heat flow. These structures are situated to the southwest from the profile and finger type conductors indicate its penetration in northeast direction. These volcanic processes in the south are not connected with CCA presence and its origin, which is supposed to be the presence of graphite or mineralized water in mylonitized rocks on the sheer contact zones of European platform and Inner Western Carpathians.</p><p>For mantle part of the integrated models, we studied different mantle compositions and fluid content within the lithospheric mantle to explain differences in electrical and seismic LAB. The calculated petrological conductivity model shows sensitivity of MT data on the LAB depth change, the correct input of composition parameters of lithospheric mantle and thermal field. The thermal steady state approximation was used to calculate surface heat flow in the area is lower than measured and estimated values from previous thermal studies. The differences between calculated and measured heat flow is primarily caused by high radiogenic production within the crust and not by the contribution from mantle.</p>

Temperature, strain rates, and rheology: the key parameters controling strength variations in the Australian lithosphere

2020 ◽  
Author(s):  
Magdala Tesauro ◽  
Mikhail Kaban ◽  
Alexey Petrunin ◽  
Alan Aitken
Keyword(s):  
Heat Flow ◽  
Seismic Tomography ◽  
Seismic Velocity ◽  
Gravity Data ◽  
Geophysical Methods ◽  
The Other ◽  
Crust And Upper Mantle ◽  
Large Variability ◽  
Other Hand ◽  
Australian Plate

<p>The Australian plate is composed of tectonic features showing progression of the age from dominantly Phanerozoic in the east, Proterozoic in the centre, and Archean in the west. These tectonic structures have been investigated in the last three decades using a variety of geophysical methods, but it is still a matter of debates of how temperature and strength are distributed within the lithosphere. We construct a thermal crustal model assuming steady state variations and using surface heat flow data, provided by regional and global database, and heat generation values, calculated from existing empirical relations with seismic velocity variations, which are provided by AusREM seismic tomography model. The lowest crustal temperatures are observed in the eastern part of the WAC and the Officer basin, while Central and South Australia are regions with anomalously elevated heat flow values and temperatures caused by high heat production in the crustal rocks. On the other hand, the mantle temperatures, estimated in a previous study, applying a joint interpretation of the seismic tomography and gravity data, show that the Precambrian West and North Australian Craton (WAC and NAC) are characterized by thick and relatively cold lithosphere that has depleted composition (Mg# > 90). The depletion is stronger in the older WAC than the younger NAC. Substantially hotter and less dense lithosphere is seen fringing the eastern and southeastern margin of the continent. Both crustal and mantle thermal models are used as input for the lithospheric strength calculation. Another input parameter is the crustal rheology, which has been determined based on the seismic velocity distribution, assuming that low (high) velocities reflect more sialic (mafic) compositions and thus weaker (stiffer) rheologies. Furthermore, we use strain rate values obtained from a global mantle flow model constrained by seismic and gravity data. The combination of the values of the different parameters produce a large variability of the rigidity of the plate within the cratonic areas, reflecting the long tectonic history of the Australian plate. The sharp lateral strength variations are coincident with intraplate earthquakes location. The strength variations in the crust and upper mantle is also not uniformly distributed: In the Archean WAC most of the strength is concentrated in the mantle, while the Proterozoic Officer basin shows the largest values of the crustal strength. On the other hand, the younger eastern terranes are uniformly weak, due to the high temperatures.</p>

scholarly journals Effects of Near-Surface Air Temperature on Sub-Surface Geothermal Gradient and Heat Flow in Bornu-Chad Basin, Nigeria

2021 ◽  
Vol 4 (1) ◽  
pp. 95-102
Author(s):  
Andrew A. Tyoh ◽  
Etim Daniel Uko ◽  
Olatunji S. Ayanninuola ◽  
Onengiyeofori A. Davies
Keyword(s):  
Heat Flow ◽  
Surface Temperature ◽  
Surface Air Temperature ◽  
Geothermal Gradient ◽  
Passive Margin ◽  
Mean Annual Temperature ◽  
Surface Solar Radiation ◽  
Near Surface ◽  
Chad Basin ◽  
The Mean

A study of the effect of near-surface temperature on fields of subsurface geothermal gradient and heat flow has been carried out in the Bornu-Chad Basin, Nigeria, using corrected Bottom-Hole Temperatures (BHTc) lithologic-log data from 9 oil wells. The geothermal gradient using only BHTs ranges from 15.9oCkm-1 to 38.2oCkm-1 with an average of 26.9+/-3.5oCkm-1, while that computed with mean annual temperature and BHTs ranges from 28.2oCkm-1 to 51.5oCkm-1with an average of 37.5+/-2.5oCkm-1. The geothermal gradient using the mean annual temperature and BHTs in the Bornu-Chad is higher than using only BHTs by 7.0oCkm-1. Heatflow ranges from a minimum of 61 mWm-2 to a maximum of 114mWm-2 with an average of 68+/-5.89mWm-2. The isotherm maps exhibit an increasing SW-NE trend. An average heat flow of 68+/-5.9mWm-2 deduced from Bornu-Chad basin is normal for a continental passive margin with age of about 100My. Geothermal gradient results show a distinct and direct relationship with near-surface conditions. There are indications that surface heat flow is controlled by lithology, geothermal gradient and near-surface solar radiation conditions in the Bornu-Chad basin. Consequently, it is recommended that the mean surface temperature be used in geothermal gradients and heatflows estimations. The knowledge of geothermal properties is very important in the search for geothermal energy in the area of study.

Composition model of the crust beneath the Ordos basin and the Yinshan mountains in China, based on seismic velocity, heat flow and gravity data

2014 ◽  
Vol 634 ◽  
pp. 246-256 ◽  
Author(s):  
Yongqian Zhang ◽  
Jiwen Teng ◽  
Qianshen Wang ◽  
Fuyun Wang ◽  
Qingtian Lü
Keyword(s):  
Heat Flow ◽  
Seismic Velocity ◽  
Gravity Data ◽  
Ordos Basin ◽  
The Ordos Basin

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.

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