In order to extract usable harmonics from real 2^(n) sequence pseudo-random data,a technical method is proposed.An equation for predicting the average amplitude of the main frequencies is proposed to guide the choice ...In order to extract usable harmonics from real 2^(n) sequence pseudo-random data,a technical method is proposed.An equation for predicting the average amplitude of the main frequencies is proposed to guide the choice of signal type for different exploration tasks.By the threshold of the amplitude of the transmitted signal,a set of candidate frequencies are first selected.Then,by operating a spectrum envelope method at these candidate frequencies on received data,effective components in data are extracted.A frequency density calculation method is proposed based on a logical number summation method,to reasonably characterize the frequency density in different frequency bands.By applying this method to real data in Sichuan,China,with signal Type 13,75 effective components are extracted,including both main frequencies and harmonics.The result suggests that the number of effective frequencies in the 2^(n) sequence pseudo-random signal can be increased by extracting usable harmonics,without any additional fieldwork.展开更多
Geothermal energy is a clean,abundant,and dependable energy source.Because the formation of a geothermal field is often closely linked to the distribution and development of granite,it is crucial to understand the reg...Geothermal energy is a clean,abundant,and dependable energy source.Because the formation of a geothermal field is often closely linked to the distribution and development of granite,it is crucial to understand the regularity and formation mechanism of granite geothermal resources to advance the field of geothermal energy.Lancang County is located on the southern edge of the Lincang granite,and contains many hot springs.In this paper,we synthesize rock geochemistry,zircon UePb chronology,and other methods to interpret the genesis of granites in Lancang County and their geothermal formation patterns.The study area mainly comprises a Middle Triassic S-type granite with high contents of heatproducing elements.Zircon UePb dating results show that the intrusion time of the Lancang granite was 239 Ma.The granite is rich in light rare earth elements,depleted in heavy rare earth elements,and characterized by a negative Eu anomaly.The 3Hf values range from -20.3 to 13.6,indicating the presence of mantle material in the source area.Igneous rocks in Lancang County likely formed in the background of an active continental margin associated with the subduction of the Tethys Ocean to the east,which formed an intra-land orogeny.High contents of radioactive thermogenic elements in the granite,fracture development,and additional heat sources from metamorphic rocks combined to generate high-temperature geothermal resources in the study area.The hydrothermal geothermal model of the granite has the following characteristics:a near heat source,large drop,water storage in fractures,simultaneous geothermal influence in deep and shallow layers,and hot spring and geothermal distribution along deep and large faults,etc.The geothermal reservoirs in the study area are classified into four types:internal fissures in granite,granite paleo-weathering crust,tectonic nappe fractures,and sedimentary deposits associated with granite cooling collapse.These types are of great significance to the understanding of the formation of hydrothermal geothermal heat in this granite area.展开更多
To make three-dimensional electromagnetic exploration achievable,the distributed wide field electromagnetic method(WFEM)based on the high-order 2^(n) sequence pseudo-random signal is proposed and realized.In this meth...To make three-dimensional electromagnetic exploration achievable,the distributed wide field electromagnetic method(WFEM)based on the high-order 2^(n) sequence pseudo-random signal is proposed and realized.In this method,only one set of high-order pseudo-random waveforms,which contains all target frequencies,is needed.Based on high-order sequence pseudo-random signal construction algorithm,the waveform can be customized according to different exploration tasks.And the receivers are independent with each other and dynamically adjust the acquisition parameters according to different requirements.A field test in the deep iron ore of Qihe−Yucheng showed that the distributed WFEM based on high-order pseudo-random signal realizes the high-efficiency acquisition of massive electromagnetic data in quite a short time.Compared with traditional controlled-source electromagnetic methods,the distributed WFEM is much more efficient.Distributed WFEM can be applied to the large scale and high-resolution exploration for deep resources and minerals.展开更多
The Heishan geothermal area is positioned above the sole Yunnane-Tibet high-temperature geothermal belt,where huge geothermal energy resources are available.Utilizing the characteristics of large exploration depth,ext...The Heishan geothermal area is positioned above the sole Yunnane-Tibet high-temperature geothermal belt,where huge geothermal energy resources are available.Utilizing the characteristics of large exploration depth,extensive coverage,and high precision of the wide-field elec-tromagnetic method,four survey lines were deployed,totaling 29.8 km,to enable a comprehensive analysis of the granite structure and fault distribution.The results indicate that the rocks within the area can be vertically divided into a granite basement and a fractured layer.Moreover,three different zones of resistivity were identified:the granite basement zone has a resistivity range of 2500-20000 U m,whereas the compressional shear zone and the secondary fault zone have a resistivity range of 750-2500 U m,and the extensional fault zone and the main fault zone have resistivity values below 750 U m.The Heishan-Hejian fault and the fault zone formed during its right-lateral strike-slip process,as well as the controlled area of the Qianmaihe fault,are all favorable targets.Of these,the Qianmahe fault possesses a larger-scale heat-conducting and water-controlling structure.In addition,in the secondary fault-controlled area extending to the west,the zone between F2’and F4 exhibits renewed tectonic activity,suggesting a greater potential for geothermal resources.展开更多
Geothermal energy is a renewable energy with large scale and wide distribution.Geothermal resources are abundant in western Yunnan,China,but the work is less.In this study,a widefield electromagnetic method(WFEM)was a...Geothermal energy is a renewable energy with large scale and wide distribution.Geothermal resources are abundant in western Yunnan,China,but the work is less.In this study,a widefield electromagnetic method(WFEM)was applied to geothermal exploration in Sanying Basin,and six survey lines were deployed.On the basis of the inversion results,the paper conducts a progressive study on the four genetic factors of geothermal exploration,including“source,storage,channel,and circulation”.The Sanying Basin has three sets of intrusive rock masses,two kinds of lateral and vertical additional heating modes.Two sets of deep and shallow reservoir systems were identified.Two major strike-slip deep faults were identified as heat conduction channels.Two sets of water circulation systems were established,and the formation mechanism of hot springs was clarified.Anomaly 1 is a favorable target area for hydrothermal development,and invasion II is a favorable target area for hot dry rock.展开更多
As an important component of the exploration and evaluation of geothermal resources,the formation model has unique formation and distribution rule in different regions.Reliable geological models need to be established...As an important component of the exploration and evaluation of geothermal resources,the formation model has unique formation and distribution rule in different regions.Reliable geological models need to be established to help in temperature prediction,favorable area se-lection,and drilling design studies prior to the development of geothermal resources.This paper provides an integrated approach for analyzing the formation models of geothermal resources by combining geological studies and the wide-field electromagnetic method.The resistivity profile is converted into a geologic profile by analyzing the fault distribution,stratigraphic lithology,magmatic rock development,and signal changes of the profile.Comprehensively analyzing the geological elements including the heat sources,water sources,thermal reservoirs,transport con-ditions,cap rock,and preservation conditions,we investigate the matching relationship of the geological elements on the geologic profile and establish a formation model of the geothermal resources.This approach avoids the respective limitations of geological and geophysical methods,and the formation model established by this approach is comprehensive,intuitive,and accurate and can provide support for the development of geothermal resources.展开更多
Geothermal heat flow(GHF)is a crucial metric in the assessment of geothermal reservoirs.To circumvent the high cost of conventional GHF measurement techniques,there is a growing interest in leveraging machine learning...Geothermal heat flow(GHF)is a crucial metric in the assessment of geothermal reservoirs.To circumvent the high cost of conventional GHF measurement techniques,there is a growing interest in leveraging machine learning models to predict GHF based on geological datasets imputed by the Kriging method.However,the spatial distribution of some geological features exhibits complex data patterns and missing values,justifying the need for a more accurate and efficient alternative to the conventional Kriging method.In this study,we present a novel machine learning-based framework for predicting GHF based on sparse geological data.Specifically,a machine learning model(here MissForest)is employed to impute the missing values of geological data.The MissForest model,by leveraging spatial correlations among geological parameters(e.g.,upper crust thickness,Moho depth,and rock type),achieves superior imputation accuracy(R^(2)=0.90 at 20%missing rate)over the conventional Kriging method(R^(2)=0.84).Based on the imputed datasets,machine learning regression models are trained to capture the mapping of geological features to GHF.Our best model achieves a low error of 10.18%for predicting GHF across various regions,surpassing the previous studies.Furthermore,the machine learning-based framework successfully predicts the GHF globally,shedding new light on the distribution patterns of geothermal resources and their exploitation potential worldwide.展开更多
The wide-field electromagnetic method is widely used in hydrocarbon exploration,mineral deposit detection,and geological disaster prediction.However,apparent resistivity and normalized field amplitude exceeding 2048 H...The wide-field electromagnetic method is widely used in hydrocarbon exploration,mineral deposit detection,and geological disaster prediction.However,apparent resistivity and normalized field amplitude exceeding 2048 Hz often exhibit upward warping in data,making geophysical inversion and interpretation challenging.The cumulative error of the crystal oscillator in signal transmission and acquisition contributes to an upturned apparent resistivity curve.To address this,a high-frequency information extraction method is proposed based on time-domain signal reconstruction,which helps to record a complete current data sequence;moreover,it helps estimate the crystal oscillator error for the transmitted signal.Considering the recorded error,a received signal was corrected using a set of reconstruction algorithms.After processing,the high-frequency component of the wide-field electromagnetic data was not upturned,while accurate high-frequency information was extracted from the signal.Therefore,the proposed method helped effectively extract high-frequency components of all wide-field electromagnetic data.展开更多
基金financially supported by the National Key Research and Development Program of China(No.2019YFC0604902)the National Natural Science Foundation of China(No.42004056)the Natural Science Foundation of Shandong Province,China(No.ZR201911010111).
文摘In order to extract usable harmonics from real 2^(n) sequence pseudo-random data,a technical method is proposed.An equation for predicting the average amplitude of the main frequencies is proposed to guide the choice of signal type for different exploration tasks.By the threshold of the amplitude of the transmitted signal,a set of candidate frequencies are first selected.Then,by operating a spectrum envelope method at these candidate frequencies on received data,effective components in data are extracted.A frequency density calculation method is proposed based on a logical number summation method,to reasonably characterize the frequency density in different frequency bands.By applying this method to real data in Sichuan,China,with signal Type 13,75 effective components are extracted,including both main frequencies and harmonics.The result suggests that the number of effective frequencies in the 2^(n) sequence pseudo-random signal can be increased by extracting usable harmonics,without any additional fieldwork.
基金supported by a Key Research and Development Program of Yunnan Province(202303AA080006)a Major Special Project of Yunnan Province(202302AF080001)the National Natural Science Foundation of China(41927801).
文摘Geothermal energy is a clean,abundant,and dependable energy source.Because the formation of a geothermal field is often closely linked to the distribution and development of granite,it is crucial to understand the regularity and formation mechanism of granite geothermal resources to advance the field of geothermal energy.Lancang County is located on the southern edge of the Lincang granite,and contains many hot springs.In this paper,we synthesize rock geochemistry,zircon UePb chronology,and other methods to interpret the genesis of granites in Lancang County and their geothermal formation patterns.The study area mainly comprises a Middle Triassic S-type granite with high contents of heatproducing elements.Zircon UePb dating results show that the intrusion time of the Lancang granite was 239 Ma.The granite is rich in light rare earth elements,depleted in heavy rare earth elements,and characterized by a negative Eu anomaly.The 3Hf values range from -20.3 to 13.6,indicating the presence of mantle material in the source area.Igneous rocks in Lancang County likely formed in the background of an active continental margin associated with the subduction of the Tethys Ocean to the east,which formed an intra-land orogeny.High contents of radioactive thermogenic elements in the granite,fracture development,and additional heat sources from metamorphic rocks combined to generate high-temperature geothermal resources in the study area.The hydrothermal geothermal model of the granite has the following characteristics:a near heat source,large drop,water storage in fractures,simultaneous geothermal influence in deep and shallow layers,and hot spring and geothermal distribution along deep and large faults,etc.The geothermal reservoirs in the study area are classified into four types:internal fissures in granite,granite paleo-weathering crust,tectonic nappe fractures,and sedimentary deposits associated with granite cooling collapse.These types are of great significance to the understanding of the formation of hydrothermal geothermal heat in this granite area.
基金funded by the National Natural Science Foundation of China(No.42004056)the Natural Science Foundation of Shangdong Province,China(No.ZR2020QD052)China Postdoctoral Science Foundation(No.2019M652386)。
文摘To make three-dimensional electromagnetic exploration achievable,the distributed wide field electromagnetic method(WFEM)based on the high-order 2^(n) sequence pseudo-random signal is proposed and realized.In this method,only one set of high-order pseudo-random waveforms,which contains all target frequencies,is needed.Based on high-order sequence pseudo-random signal construction algorithm,the waveform can be customized according to different exploration tasks.And the receivers are independent with each other and dynamically adjust the acquisition parameters according to different requirements.A field test in the deep iron ore of Qihe−Yucheng showed that the distributed WFEM based on high-order pseudo-random signal realizes the high-efficiency acquisition of massive electromagnetic data in quite a short time.Compared with traditional controlled-source electromagnetic methods,the distributed WFEM is much more efficient.Distributed WFEM can be applied to the large scale and high-resolution exploration for deep resources and minerals.
基金supported by research funds of the Guangxi Key Laboratory of Theory and Technology for Environmental Pollution Control(2201K004)the Key Research and Development Program in Yunnan Province,“Research on Key Technologies for Exploration and Development of Deep and Medium Geothermal Energy in Yunnan Province”(No.202302AF080001)+2 种基金“Mineralization laws and Prospecting Technology Research in the Key Mining Cluster Area of Western Yunnan Province”(No.202303AA080006)the Shenzhen Municipal Science and Technology Innovation Committee(JCYJ20220818103010021)the Guangdong Provincial Marine Economy Special Project,GDNRC[2021]57.
文摘The Heishan geothermal area is positioned above the sole Yunnane-Tibet high-temperature geothermal belt,where huge geothermal energy resources are available.Utilizing the characteristics of large exploration depth,extensive coverage,and high precision of the wide-field elec-tromagnetic method,four survey lines were deployed,totaling 29.8 km,to enable a comprehensive analysis of the granite structure and fault distribution.The results indicate that the rocks within the area can be vertically divided into a granite basement and a fractured layer.Moreover,three different zones of resistivity were identified:the granite basement zone has a resistivity range of 2500-20000 U m,whereas the compressional shear zone and the secondary fault zone have a resistivity range of 750-2500 U m,and the extensional fault zone and the main fault zone have resistivity values below 750 U m.The Heishan-Hejian fault and the fault zone formed during its right-lateral strike-slip process,as well as the controlled area of the Qianmaihe fault,are all favorable targets.Of these,the Qianmahe fault possesses a larger-scale heat-conducting and water-controlling structure.In addition,in the secondary fault-controlled area extending to the west,the zone between F2’and F4 exhibits renewed tectonic activity,suggesting a greater potential for geothermal resources.
基金supported by Shenzhen Municipal Science and Technology Innovation Committee“Study on the Genetic Mechanism of Geothermal in Shenzhen”(JCYJ20220818103010021)This work was also supported by the Key Research and Development Program in Yunnan Province“Research on Key Technologies for Exploration and Development of Deep and Medium Geothermal Energy in Yunnan Province”(No.202302AF080001)Guangdong Provincial Marine Economy Special Project,GDNRC[2021]57.
文摘Geothermal energy is a renewable energy with large scale and wide distribution.Geothermal resources are abundant in western Yunnan,China,but the work is less.In this study,a widefield electromagnetic method(WFEM)was applied to geothermal exploration in Sanying Basin,and six survey lines were deployed.On the basis of the inversion results,the paper conducts a progressive study on the four genetic factors of geothermal exploration,including“source,storage,channel,and circulation”.The Sanying Basin has three sets of intrusive rock masses,two kinds of lateral and vertical additional heating modes.Two sets of deep and shallow reservoir systems were identified.Two major strike-slip deep faults were identified as heat conduction channels.Two sets of water circulation systems were established,and the formation mechanism of hot springs was clarified.Anomaly 1 is a favorable target area for hydrothermal development,and invasion II is a favorable target area for hot dry rock.
基金supported by the Major Science and Technology Project of Yunnan Province(Grant No.202302AF080001)the Key Research and Development Program of Yunnan Province(Grant No.202303AA080006)the National Natural Science Foundation of China(Grant No.41927801).
文摘As an important component of the exploration and evaluation of geothermal resources,the formation model has unique formation and distribution rule in different regions.Reliable geological models need to be established to help in temperature prediction,favorable area se-lection,and drilling design studies prior to the development of geothermal resources.This paper provides an integrated approach for analyzing the formation models of geothermal resources by combining geological studies and the wide-field electromagnetic method.The resistivity profile is converted into a geologic profile by analyzing the fault distribution,stratigraphic lithology,magmatic rock development,and signal changes of the profile.Comprehensively analyzing the geological elements including the heat sources,water sources,thermal reservoirs,transport con-ditions,cap rock,and preservation conditions,we investigate the matching relationship of the geological elements on the geologic profile and establish a formation model of the geothermal resources.This approach avoids the respective limitations of geological and geophysical methods,and the formation model established by this approach is comprehensive,intuitive,and accurate and can provide support for the development of geothermal resources.
基金supported by the National Natural Science Foundation of China(Grant No.52576233)Shenzhen Science and Technology Innovation Commission(KCXST20221021111609024,JCYJ20220818103010021)the Hetao Shenzhen-Hong Kong Sci-ence and Technology Innovation Cooperation Zone Project(No.HZQSWS-KCCYB-2024016).
文摘Geothermal heat flow(GHF)is a crucial metric in the assessment of geothermal reservoirs.To circumvent the high cost of conventional GHF measurement techniques,there is a growing interest in leveraging machine learning models to predict GHF based on geological datasets imputed by the Kriging method.However,the spatial distribution of some geological features exhibits complex data patterns and missing values,justifying the need for a more accurate and efficient alternative to the conventional Kriging method.In this study,we present a novel machine learning-based framework for predicting GHF based on sparse geological data.Specifically,a machine learning model(here MissForest)is employed to impute the missing values of geological data.The MissForest model,by leveraging spatial correlations among geological parameters(e.g.,upper crust thickness,Moho depth,and rock type),achieves superior imputation accuracy(R^(2)=0.90 at 20%missing rate)over the conventional Kriging method(R^(2)=0.84).Based on the imputed datasets,machine learning regression models are trained to capture the mapping of geological features to GHF.Our best model achieves a low error of 10.18%for predicting GHF across various regions,surpassing the previous studies.Furthermore,the machine learning-based framework successfully predicts the GHF globally,shedding new light on the distribution patterns of geothermal resources and their exploitation potential worldwide.
基金Project(42004056)supported by the National Natural Science Foundation of ChinaProject(ZR2020QD052)supported by the Natural Science Foundation of Shandong Province,ChinaProject(2019YFC0604902)supported by the National Key Research and Development Program of China。
文摘The wide-field electromagnetic method is widely used in hydrocarbon exploration,mineral deposit detection,and geological disaster prediction.However,apparent resistivity and normalized field amplitude exceeding 2048 Hz often exhibit upward warping in data,making geophysical inversion and interpretation challenging.The cumulative error of the crystal oscillator in signal transmission and acquisition contributes to an upturned apparent resistivity curve.To address this,a high-frequency information extraction method is proposed based on time-domain signal reconstruction,which helps to record a complete current data sequence;moreover,it helps estimate the crystal oscillator error for the transmitted signal.Considering the recorded error,a received signal was corrected using a set of reconstruction algorithms.After processing,the high-frequency component of the wide-field electromagnetic data was not upturned,while accurate high-frequency information was extracted from the signal.Therefore,the proposed method helped effectively extract high-frequency components of all wide-field electromagnetic data.
