Buoyancy-driven flows are prevalent in a wide range of geophysical and astrophysical systems. In this review, we focus on threepivotal effects that significantly influence the dynamics and transport properties of buoy...Buoyancy-driven flows are prevalent in a wide range of geophysical and astrophysical systems. In this review, we focus on threepivotal effects that significantly influence the dynamics and transport properties of buoyancy-driven flows and may have impli-cations for natural systems. These effects pertain to the role of boundary conditions, the impact of rotation, and the effect offinite size. Boundary conditions represent how the fluid flow interacts with different kinds of surfaces. Rotation, as the Earth’srotation in geophysical systems or the whirling of astrophysical systems, introduces Coriolis and centrifugal forces, leading tothe profound vortical structure and distinct transport property. Finite size, representing geometrical constraints, influences thebehavior of buoyancy-driven flows across varying geometrical settings. This review aims to provide a holistic understanding ofthe intricate interplay of these factors, offering insights into the complex natural phenomena from the perspectives of the threeeffects.展开更多
The Bozhong Sag is the largest petroliferous sag in the Bohai Bay Basin,and the source rocks of Paleogene Dongying and Shahejie Formations were buried deeply.Most of the drillings were located at the structural high,a...The Bozhong Sag is the largest petroliferous sag in the Bohai Bay Basin,and the source rocks of Paleogene Dongying and Shahejie Formations were buried deeply.Most of the drillings were located at the structural high,and there were few wells that met good quality source rocks,so it is difficult to evaluate the source rocks in the study area precisely by geochemical analysis only.Based on the Rock-Eval pyrolysis,total organic carbon(TOC)testing,the organic matter(OM)abundance of Paleogene source rocks in the southwestern Bozhong Sag were evaluated,including the lower of second member of Dongying Formation(E_(3)d2L),the third member of Dongying Formation(E_(3)d_(3)),the first and second members of Shahejie Formation(E_(2)s_(1+2)),the third member of Shahejie Formation(E_(2)s_(3)).The results indicate that the E_(2)s_(1+2)and E_(2)s_(3)have better hydrocarbon generative potentials with the highest OM abundance,the E_(3)d_(3)are of the second good quality,and the E_(3)d2L have poor to fair hydrocarbon generative potential.Furthermore,the well logs were applied to predict TOC and residual hydrocarbon generation potential(S_(2))based on the sedimentary facies classification,usingΔlogR,generalizedΔlogR,logging multiple linear regression and BP neural network methods.The various methods were compared,and the BP neural network method have relatively better prediction accuracy.Based on the pre-stack simultaneous inversion(P-wave impedance,P-wave velocity and density inversion results)and the post-stack seismic attributes,the three-dimensional(3D)seismic prediction of TOC and S_(2)was carried out.The results show that the seismic near well prediction results of TOC and S_(2)based on seismic multi-attributes analysis correspond well with the results of well logging methods,and the plane prediction results are identical with the sedimentary facies map in the study area.The TOC and S_(2)values of E_(2)s_(1+2)and E_(2)s_(3)are higher than those in E_(3)d_(3)and E_(3)d_(2)L,basically consistent with the geochemical analysis results.This method makes up the deficiency of geochemical methods,establishing the connection between geophysical information and geochemical data,and it is helpful to the 3D quantitative prediction and the evaluation of high-quality source rocks in the areas where the drillings are limited.展开更多
Geophysical fluid dynamics(GFD)is an interdisciplinary field that studies the large-scale motion of fluids in the natural world.With a wide range of applications such as weather forecasts and climate prediction,GFD em...Geophysical fluid dynamics(GFD)is an interdisciplinary field that studies the large-scale motion of fluids in the natural world.With a wide range of applications such as weather forecasts and climate prediction,GFD employs various research approaches including in-situ observations,satellite measurements,numerical simulations,theoretical analysis,artificial intelligence,and physical model experiments in laboratory.Among these approaches,rotating tank experiments provide a valuable tool for simulating naturally-occurring fluid motions in laboratories.With proportional scaling and proper techniques,scientists can reproduce multi-scale physical processes of stratified fluids in the rotation system,which allows for the simulation of essential characteristics of fluid motions in the atmosphere and oceans.In this review,rotating tanks of various scales in the world are introduced,as these tanks have been actively used to explore fundamental scientific questions in ocean and atmosphere dynamics.To illustrate the GFD experiments,three representative cases are presented to demonstrate the frontier achievements in the the GFD study by using rotating tank experiments:mesoscale eddies in the ocean,convection processes,and plume dynamics.Detailed references for the experimental procedures are provided.Future studies are encouraged to further explore the utilization of rotating tanks with improvements in experimental design and integration of other research methods.This is a promising direction of GFD to help enhance our understanding of the complex nature of fluid motions in the natural world and to address the challenges posed by global environmental changes.展开更多
The boundary between cratonic and orogenic lithospheres is a significant seismogenic zones marked by intense lithospheric deformation.The Sichuan Craton(SCC),as a key tectonic block bordering eastern Tibetan Plateau,r...The boundary between cratonic and orogenic lithospheres is a significant seismogenic zones marked by intense lithospheric deformation.The Sichuan Craton(SCC),as a key tectonic block bordering eastern Tibetan Plateau,resists the eastward escape of plateau's crustal materials,resulting in the uplift of the Songpan-Ganzi Block(SGB)and crustal deformation of the Longmenshan tectonic belt(LMTB).To elucidate the compressional structures and deformational modes of the LMTB and SCC,it is essential to accurately determine the location and geometry of the SCC'western boundary.To investigate this issue,the lithospheric properties of the obducted SGB,underthrusting SCC,and LMTB were analyzed using various geophysical data,including seismic reflection profiles,magnetotellurics,aeromagnetics,gravity,and seismic tomography.The SGB crust is characterized by low magnetism,seismic velocity,resistivity and Bouguer gravity,whereas the SCC crust exhibits non-uniform high magnetism,seismic velocity,resistivity and Bouguer gravity.The LMTB,as the boundary between the SGB and SCC,exhibits geophysical characteristics similar to those of the SCC in the southern and central segments.The integration of these geophysical observations indicate that the SCC's western boundary is situated west of the Wenchuan-Maoxian fault zone in the southern and central segments,exhibiting distinct westward wedging and underthrusting.However,this boundary aligns with the Yingxiu-Beichuan fault in the northern segment,without significant underthrusting.The irregular geometry of the SCC's western boundary further elucidates the variation in structural deformation along the LMTB.By comparing crustal thickness and lithospheric strength between the SGB and SCC,this study posits that the differing crustal strength between tectonic blocks may control the irregular geometry of the SCC's western boundary.展开更多
Hypergravity can be realized by creating a field imposed by centripetal acceleration in a centrifuge apparatus.Such an apparatus is often used to test soil response in geotechnical engineering problems.Here we present...Hypergravity can be realized by creating a field imposed by centripetal acceleration in a centrifuge apparatus.Such an apparatus is often used to test soil response in geotechnical engineering problems.Here we present the potential usage of a centrifuge apparatus to study various topics in hydrodynamics.The scaling law associated with hydrodynamics is first reviewed,and the advantage of controlling the body force is described.One of the perceived disadvantages in such experiments is the unwanted presence of the Coriolis effect in the centrifuge.However,we propose exploiting this effect to our advantage to study geophysical fluid-dynamic problems that occur particularly in the equatorial region.展开更多
Identification of reservoir types in deep carbonates has always been a great challenge due to complex logging responses caused by the heterogeneous scale and distribution of storage spaces.Traditional cross-plot analy...Identification of reservoir types in deep carbonates has always been a great challenge due to complex logging responses caused by the heterogeneous scale and distribution of storage spaces.Traditional cross-plot analysis and empirical formula methods for identifying reservoir types using geophysical logging data have high uncertainty and low efficiency,which cannot accurately reflect the nonlinear relationship between reservoir types and logging data.Recently,the kernel Fisher discriminant analysis(KFD),a kernel-based machine learning technique,attracts attention in many fields because of its strong nonlinear processing ability.However,the overall performance of KFD model may be limited as a single kernel function cannot simultaneously extrapolate and interpolate well,especially for highly complex data cases.To address this issue,in this study,a mixed kernel Fisher discriminant analysis(MKFD)model was established and applied to identify reservoir types of the deep Sinian carbonates in central Sichuan Basin,China.The MKFD model was trained and tested with 453 datasets from 7 coring wells,utilizing GR,CAL,DEN,AC,CNL and RT logs as input variables.The particle swarm optimization(PSO)was adopted for hyper-parameter optimization of MKFD model.To evaluate the model performance,prediction results of MKFD were compared with those of basic-kernel based KFD,RF and SVM models.Subsequently,the built MKFD model was applied in a blind well test,and a variable importance analysis was conducted.The comparison and blind test results demonstrated that MKFD outperformed traditional KFD,RF and SVM in the identification of reservoir types,which provided higher accuracy and stronger generalization.The MKFD can therefore be a reliable method for identifying reservoir types of deep carbonates.展开更多
Integrated geophysical technology is a necessary and effective means for geothermal exploration.However,integration of geophysical technology for large‐scale surveys with those for geothermal reservoir localization i...Integrated geophysical technology is a necessary and effective means for geothermal exploration.However,integration of geophysical technology for large‐scale surveys with those for geothermal reservoir localization is still in development.This study used the controlled source audio‐frequency magnetotelluric method technology for large‐scale exploration to obtain underground electrical structure information and micromotion detection technology to obtain underground wave velocity structure information.The combination of two detection technologies was used for local identification of geothermal reservoirs.Further,auxiliary correction and inversion constraint were implemented through the audio magnetotelluric sounding technology for maximum authenticity restoration of the near‐and transition‐field data.Through these technology improvements,a geothermal geological model was established for the Binhai County of Jiangsu Province in China and potential geothermal well locations were identified.On this basis,a geothermal well was drilled nearly 3000m deep,with a daily water volume of over 2000m3/day and a geothermal water temperature of 51°C at the well head.It is found that predictions using the above integrated geophysical exploration technology are in good agreement with the well geological formation data.This integrated geophysical technology can be effectively applied for geothermal exploration with high precision and reliability.展开更多
Missing data are a problem in geophysical surveys, and interpolation and reconstruction of missing data is part of the data processing and interpretation. Based on the sparseness of the geophysical data or the transfo...Missing data are a problem in geophysical surveys, and interpolation and reconstruction of missing data is part of the data processing and interpretation. Based on the sparseness of the geophysical data or the transform domain, we can improve the accuracy and stability of the reconstruction by transforming it to a sparse optimization problem. In this paper, we propose a mathematical model for the sparse reconstruction of data based on the LO-norm minimization. Furthermore, we discuss two types of the approximation algorithm for the LO- norm minimization according to the size and characteristics of the geophysical data： namely, the iteratively reweighted least-squares algorithm and the fast iterative hard thresholding algorithm. Theoretical and numerical analysis showed that applying the iteratively reweighted least-squares algorithm to the reconstruction of potential field data exploits its fast convergence rate, short calculation time, and high precision, whereas the fast iterative hard thresholding algorithm is more suitable for processing seismic data, moreover, its computational efficiency is better than that of the traditional iterative hard thresholding algorithm.展开更多
Edge detection is an image processing technique for finding the boundaries of objects within images. It is typically used to interpret gravity and magnetic data, and find the horizontal boundaries of geological bodies...Edge detection is an image processing technique for finding the boundaries of objects within images. It is typically used to interpret gravity and magnetic data, and find the horizontal boundaries of geological bodies. Large deviations between model and true edges are common because of the interference of depth and errors in computing the derivatives; thus, edge detection methods cannot provide information about the depth of the source. To simultaneously obtain the horizontal extent and depth of geophysical anomalies, we use normalized edge detection filters, which normalize the edge detection function at different depths, and the maxima that correspond to the location of the source. The errors between model and actual edges are minimized as the depth of the source decreases and the normalized edge detection method recognizes the extent of the source based on the maxima, allowing for reliable model results. We demonstrate the applicability of the normalized edge detection filters in defining the horizontal extent and depth using synthetic and actual aeromagnetic data.展开更多
Geophysical techniques play key roles in the measuring, monitoring, and verifying the safety of CO2 sequestration and in identifying the efficiency of CO2-enhanced oil recovery. Although geophysical monitoring techniq...Geophysical techniques play key roles in the measuring, monitoring, and verifying the safety of CO2 sequestration and in identifying the efficiency of CO2-enhanced oil recovery. Although geophysical monitoring techniques for CO2 sequestration have grown out of conventional oil and gas geophysical exploration techniques, it takes a long time to conduct geophysical monitoring, and there are many barriers and challenges. In this paper, with the initial objective of performing CO2 sequestration, we studied the geophysical tasks associated with evaluating geological storage sites and monitoring CO2 sequestration. Based on our review of the scope of geophysical monitoring techniques and our experience in domestic and international carbon capture and sequestration projects, we analyzed the inherent difficulties and our experiences in geophysical monitoring techniques, especially, with respect to 4D seismic acquisition, processing, and interpretation.展开更多
The Shuangjianzishan deposit in Inner Mongolia is a typical Ag-Pb-Zn deposit of the southern Great Xing’an Range.Proven reserves of Ag,Pb,and Zn in this deposit have reached the scale of super-large deposits,with fav...The Shuangjianzishan deposit in Inner Mongolia is a typical Ag-Pb-Zn deposit of the southern Great Xing’an Range.Proven reserves of Ag,Pb,and Zn in this deposit have reached the scale of super-large deposits,with favorable metallogenic conditions,strong prospecting signs,and high metallogenic potential.This paper reports a study involving integrated geophysical methods,including controlled-source audio-frequency magnetotelluric,gravity,magnetic,and shallow-seismic-reflection methods,to determine the spatial distribution of ore-controlling structures and subsurface intrusive rock for a depth range of<2000 m in the Shuangjianzishan ore district.The objective of this study is to construct a metallogenic model of the ore district and provide a scientific basis for the exploration of similar deposits in the deep and surrounding regions.We used three-dimensional inversion for controlled-source audio-frequency magnetotelluric data based on the limited memory quasi-Newton algorithm,and three-dimensional physical-property inversion for the gravity and magnetic data to obtain information about the subsurface distribution of ore-controlling structures and intrusive rocks.Under seismic reflection results,regional geology,petrophysical properties,and borehole information,the geophysical investigation shows that the Dashizhai group,which contains the main ore-bearing strata in the ore district,is distributed within a depth range of<1239 m,and is thick in the Xinglongshan ore block and the eastern part of the Shuangjianzishan ore block.The mineralization is spatially associated with a fault system characterized by NE-,NW-,and N-trending faults.The magnetic and electrical models identify large,deep bodies of intrusive rock that are inferred to have been involved in mineralization,with local shallow emplacement of some intrusions.Combining the subsurface spatial distributions of ore-bearing strata,ore-controlling faults,and intrusive rock,we propose two different metallogenic models for the Shuangjianzishan ore district,which provide a scientific basis for further prospecting in the deep regions of the ore district and surrounding areas.展开更多
The inversions of complex geophysical data always solve multi-parameter, nonlinear, and multimodal optimization problems. Searching for the optimal inversion solutions is similar to the social behavior observed in swa...The inversions of complex geophysical data always solve multi-parameter, nonlinear, and multimodal optimization problems. Searching for the optimal inversion solutions is similar to the social behavior observed in swarms such as birds and ants when searching for food. In this article, first the particle swarm optimization algorithm was described in detail, and ant colony algorithm improved. Then the methods were applied to three different kinds of geophysical inversion problems： （1） a linear problem which is sensitive to noise, （2） a synchronous inversion of linear and nonlinear problems, and （3） a nonlinear problem. The results validate their feasibility and efficiency. Compared with the conventional genetic algorithm and simulated annealing, they have the advantages of higher convergence speed and accuracy. Compared with the quasi-Newton method and Levenberg-Marquardt method, they work better with the ability to overcome the locally optimal solutions.展开更多
To study the impact of modern coal mining on overlying strata and its water bearing conditions,integrated time-lapse geophysical prospecting integrating 3D seismic,electrical and ground penetrating radar method were u...To study the impact of modern coal mining on overlying strata and its water bearing conditions,integrated time-lapse geophysical prospecting integrating 3D seismic,electrical and ground penetrating radar method were used.Through observing and analyzing the geophysical data variations of all stages of pre-mining,mining and post-mining as well as post-mining deposition stable period,impacts of coal mining on stratigraphic structure and its water bearing were studied and modern coal mining induced stratigraphic change pattern was summarized.The research result shows that the stratigraphic structure and the water bearing of surface layer during modern coal mining have self-healing pattern with mining time;the self-healing capability of near-surface strata is relatively strong while the roof weak;water bearing selfhealing of near-surface strata is relatively high while the roof strata adjacent to mined coal beds low.Due to integrated time-lapse geophysical prospecting technology has extra time dimension which makes up the deficiency of static analysis of conventional geophysical methods,it can better highlight the dynamic changes of modern coal mining induced overburden strata and its water bearing conditions.展开更多
Integrated gravitational, electrical-magnetic surveys and data processing carried out in the Sanshandao-Jiaojia area, Eastern Shandong Province, northeast China, aim to illuminate the geological characteristics of thi...Integrated gravitational, electrical-magnetic surveys and data processing carried out in the Sanshandao-Jiaojia area, Eastern Shandong Province, northeast China, aim to illuminate the geological characteristics of this shallow-covered area and delineate deep-seated gold prospecting targets. In this region, altogether 12 faults exert critical control on distribution of three types of Early Precambrian metamorphic rock series, i.e. those in the metamorphic rock area, in the granitic rock area underlying the metamorphic rock, and in the remnant metamorphic rock area in granites, respectively. Additionally, the faults have major effects on distribution of four Mesozoic Linglong rock bodies of granite, i.e. the Cangshang, Liangguo, Zhuqiao-Miaojia and Jincheng granites. The Sanshandao and Jiaojia Faults are two well-known regional ore-controlling faults; they have opposite dip direction, and intersect at a depth of 4500 m. Fracture alteration zones have striking geophysical differences relative to the surrounding county rocks. The two faults extend down along dip direction in a gentle wave form, and appear at some steps with different dips. These steps comprise favorable gold prospecting areas, consistent with a step metallogenic model. Six deep-seated gold-prospecting targets are delineated, i.e. Jincheng-Qianchenjia, Xiaoxizhuang-Zhaoxian, Xiyou-Wujiazhuangzi, Xiangyangling-Xinlicun, Panjiawuzi and Miaojia-Pinglidian.展开更多
The Westwood Mine aims to reuse the tailings storage facility #1(TSF #1) for solid waste storage, but,downstream of the Northwest dike is considered critical in terms of stability. This paper uses numerical modeling a...The Westwood Mine aims to reuse the tailings storage facility #1(TSF #1) for solid waste storage, but,downstream of the Northwest dike is considered critical in terms of stability. This paper uses numerical modeling along with geophysical monitoring for assessing the Northwest dike stability during the restoration phase. The impact of waste rock deposition in the upstream TSF #1 is considered. The geophysical monitoring is based on electrical resistivity methods and was used to investigate the internal structure of the dike embankment in different deposition stages. The numerical simulations were performed with SLOPE/W code. The results show a factor of safety well above the minimum recommended value of 1.5. Geophysical monitoring revealed a vertical variation in the electrical resistivity across the dike, which indicates a multilayer structure of the embankment. Without any current in situ data, the geophysical monitoring helped estimating the nature of the materials used and the internal structure of the embankment. These interpretations were validated by geological observation of geotechnical log of the embankment. Based on this study, it is recommended that the water polishing pond be partly filled before waste rock is deposited in TSF #1. In addition, to ensure the stability of the dike, the piezometric head monitoring prior to and during waste rock deposition is recommended.展开更多
The prospects for expanding the mineral resource base in many countries are linked with the exploration of stranded sites localized at unexplored areas with complex natural and landscape conditions that make any groun...The prospects for expanding the mineral resource base in many countries are linked with the exploration of stranded sites localized at unexplored areas with complex natural and landscape conditions that make any ground survey,including magnetic prospecting,difficult and expensive.The current level of geology requires high-precision and large-scale data at the first stages of geological exploration.Since 2012,technologies of aeromagnetic surveying with unmanned aircraft vehicles(UAV)enter the market,but most of them are based on big fixed-wing UAV and do not allow to substantially increase the level of survey granularity compared with traditional aerial methods.To increase the scale of survey,it is necessary to reduce the altitude and speed of flight,for which the authors develop the methodical and technical solutions described in this article.To obtain data at altitudes of 5 m above the terrain even in a rugged relief,we created heavy multirotor UAVs that are stable in flight and may be used in a wide range of environmental conditions(even a moderate snowfall),and develop a special software to generate flight missions on the basis of digital elevation models.A UAV has special design to reduce magnetic interference of the flight platform;the magnetic sensor is hung below the aircraft.This technology was conducted in a considerable amount of magnetic surveys in the mountainous regions of East Siberia between 2014 and 2016.The results of the comparison between airborne and ground surveys are presented,which show that the sensitivity of the developed system in conjunction with low-altitude measurements can cover any geologically significant anomalies of the magnetic field.An unmanned survey is cheaper and more productive;the multirotor-based technologies may largely replace traditional ground magnetic exploration in scales of 1:10,000−1:1000.展开更多
The water depth in Nansha（南沙） waters,which is located in the southern South China Sea,varies from 200 to 2 500 m,with a deep-water（500 m） area of 500 000 km2.In this region,there are many depositional basins wit...The water depth in Nansha（南沙） waters,which is located in the southern South China Sea,varies from 200 to 2 500 m,with a deep-water（500 m） area of 500 000 km2.In this region,there are many depositional basins with various structural features,prone to the accumulation of organic material.The temperature and pressure conditions in the deep-water environment are suitable for the preservation of gas hydrate.At several sites,we have recognized bottom-simulating reflectors（BSRs） from seismic data.Regional geology analyses show that the Nansha waters may have abundant gas hy-drate prospects,especially in localities such as the Nansha trough and other deep-water basins of the central Nansha waters.展开更多
Fluid-rock interactions alter the geochemical, isotopic, petrographic and physical character of host rocks, producing a permanent record of hydrothermal activity. Maps of altered rock properties show regular variation...Fluid-rock interactions alter the geochemical, isotopic, petrographic and physical character of host rocks, producing a permanent record of hydrothermal activity. Maps of altered rock properties show regular variations that disclose master geologic controls and delineate likely sites for geothermal and mineral resources. In many cases, geochemical and stable isotope data re- veal the origins of thermal fluids, and they can also provide estimates of reservoir temperatures and identify zones of fluid recharge.展开更多
Superconducting quantum interference device(SQUID),with the advantages of ultra⁃high sensitivity,low noise,broad frequency bandwidth,and excellent low⁃frequency response,is widely used in several geophysical methods,s...Superconducting quantum interference device(SQUID),with the advantages of ultra⁃high sensitivity,low noise,broad frequency bandwidth,and excellent low⁃frequency response,is widely used in several geophysical methods,such as vector magnetic survey,electromagnetic method,gravity and gravity gradient measurement.In this paper,the latest technological progress of SQUID and SQUID⁃based geophysical precision measurement technology are described.In addition,the advantages,characteristics,and existing problems of each measurement technology are analyzed.Combined with the requirements of current geophysical technology,the future application prospect is discussed and development suggestions are given.展开更多
Determination of rock mechanical parameters is the most important step in rock mass quality evaluation and has significant impacts on geotechnical engineering practice.Rock mass integrity coefficient(KV)is one of the ...Determination of rock mechanical parameters is the most important step in rock mass quality evaluation and has significant impacts on geotechnical engineering practice.Rock mass integrity coefficient(KV)is one of the most efficient parameters,which is conventionally determined from boreholes.Such approaches,however,are time-consuming and expensive,offer low data coverage of point measurements,require heavy equipment,and are hardly conducted in steep topographic sites.Hence,borehole approaches cannot assess the subsurface thoroughly for rock mass quality evaluation.Alternatively,use of geophysical methods is non-invasive,rapid and economical.The proposed geophysical approach makes useful empirical correlation between geophysical and geotechnical parameters.We evaluated the rock mass quality via integration between KV measured from the limited boreholes and inverted resistivity obtained from electrical resistivity tomography(ERT).The borehole-ERT correlation provided KV along various geophysical profiles for more detailed 2D/3D(two-/three-dimensional)mapping of rock mass quality.The subsurface was thoroughly evaluated for rock masses with different engineering qualities,including highly weathered rock,semi-weathered rock,and fresh rock.Furthermore,ERT was integrated with induced polarization(IP)to resolve the uncertainty caused by water/clay content.Our results show that the proposed method,compared with the conventional approaches,can reduce the ambiguities caused by inadequate data,and give more accurate insights into the subsurface for rock mass quality evaluation.展开更多
基金supponted by the National Natural Science Foundation of China (Grant Nos 12202173,12072144,12232010,12372219,and 12302282).
文摘Buoyancy-driven flows are prevalent in a wide range of geophysical and astrophysical systems. In this review, we focus on threepivotal effects that significantly influence the dynamics and transport properties of buoyancy-driven flows and may have impli-cations for natural systems. These effects pertain to the role of boundary conditions, the impact of rotation, and the effect offinite size. Boundary conditions represent how the fluid flow interacts with different kinds of surfaces. Rotation, as the Earth’srotation in geophysical systems or the whirling of astrophysical systems, introduces Coriolis and centrifugal forces, leading tothe profound vortical structure and distinct transport property. Finite size, representing geometrical constraints, influences thebehavior of buoyancy-driven flows across varying geometrical settings. This review aims to provide a holistic understanding ofthe intricate interplay of these factors, offering insights into the complex natural phenomena from the perspectives of the threeeffects.
文摘The Bozhong Sag is the largest petroliferous sag in the Bohai Bay Basin,and the source rocks of Paleogene Dongying and Shahejie Formations were buried deeply.Most of the drillings were located at the structural high,and there were few wells that met good quality source rocks,so it is difficult to evaluate the source rocks in the study area precisely by geochemical analysis only.Based on the Rock-Eval pyrolysis,total organic carbon(TOC)testing,the organic matter(OM)abundance of Paleogene source rocks in the southwestern Bozhong Sag were evaluated,including the lower of second member of Dongying Formation(E_(3)d2L),the third member of Dongying Formation(E_(3)d_(3)),the first and second members of Shahejie Formation(E_(2)s_(1+2)),the third member of Shahejie Formation(E_(2)s_(3)).The results indicate that the E_(2)s_(1+2)and E_(2)s_(3)have better hydrocarbon generative potentials with the highest OM abundance,the E_(3)d_(3)are of the second good quality,and the E_(3)d2L have poor to fair hydrocarbon generative potential.Furthermore,the well logs were applied to predict TOC and residual hydrocarbon generation potential(S_(2))based on the sedimentary facies classification,usingΔlogR,generalizedΔlogR,logging multiple linear regression and BP neural network methods.The various methods were compared,and the BP neural network method have relatively better prediction accuracy.Based on the pre-stack simultaneous inversion(P-wave impedance,P-wave velocity and density inversion results)and the post-stack seismic attributes,the three-dimensional(3D)seismic prediction of TOC and S_(2)was carried out.The results show that the seismic near well prediction results of TOC and S_(2)based on seismic multi-attributes analysis correspond well with the results of well logging methods,and the plane prediction results are identical with the sedimentary facies map in the study area.The TOC and S_(2)values of E_(2)s_(1+2)and E_(2)s_(3)are higher than those in E_(3)d_(3)and E_(3)d_(2)L,basically consistent with the geochemical analysis results.This method makes up the deficiency of geochemical methods,establishing the connection between geophysical information and geochemical data,and it is helpful to the 3D quantitative prediction and the evaluation of high-quality source rocks in the areas where the drillings are limited.
基金Supported by the National Key Research and Development Program of China(Nos.2017YFA0604100,2016YFC1402004,2017YFC1404200)the Program for Innovation Research and Entrepreneurship Team in Jiangsu Provincethe National Natural Science Foundation of China(Nos.41476022,41490643)。
文摘Geophysical fluid dynamics(GFD)is an interdisciplinary field that studies the large-scale motion of fluids in the natural world.With a wide range of applications such as weather forecasts and climate prediction,GFD employs various research approaches including in-situ observations,satellite measurements,numerical simulations,theoretical analysis,artificial intelligence,and physical model experiments in laboratory.Among these approaches,rotating tank experiments provide a valuable tool for simulating naturally-occurring fluid motions in laboratories.With proportional scaling and proper techniques,scientists can reproduce multi-scale physical processes of stratified fluids in the rotation system,which allows for the simulation of essential characteristics of fluid motions in the atmosphere and oceans.In this review,rotating tanks of various scales in the world are introduced,as these tanks have been actively used to explore fundamental scientific questions in ocean and atmosphere dynamics.To illustrate the GFD experiments,three representative cases are presented to demonstrate the frontier achievements in the the GFD study by using rotating tank experiments:mesoscale eddies in the ocean,convection processes,and plume dynamics.Detailed references for the experimental procedures are provided.Future studies are encouraged to further explore the utilization of rotating tanks with improvements in experimental design and integration of other research methods.This is a promising direction of GFD to help enhance our understanding of the complex nature of fluid motions in the natural world and to address the challenges posed by global environmental changes.
基金supported by the National Natural Science Foundation of China(Nos.U22B6002,42422402,41902202 and 42276222)the SINOPEC Key Laboratory of Geophysics(No.FW0399-0029)+2 种基金the Second Tibetan Plateau Scientific Expedition and Research(No.2019QZKK00708)the Development Fund of South China Sea Institute of Oceanology of the Chinese Academy of Sciences(No.SCSIO202207)the Special Fund of the Institute of Geophysics,China Earthquake Administration(No.DQJB22B23)。
文摘The boundary between cratonic and orogenic lithospheres is a significant seismogenic zones marked by intense lithospheric deformation.The Sichuan Craton(SCC),as a key tectonic block bordering eastern Tibetan Plateau,resists the eastward escape of plateau's crustal materials,resulting in the uplift of the Songpan-Ganzi Block(SGB)and crustal deformation of the Longmenshan tectonic belt(LMTB).To elucidate the compressional structures and deformational modes of the LMTB and SCC,it is essential to accurately determine the location and geometry of the SCC'western boundary.To investigate this issue,the lithospheric properties of the obducted SGB,underthrusting SCC,and LMTB were analyzed using various geophysical data,including seismic reflection profiles,magnetotellurics,aeromagnetics,gravity,and seismic tomography.The SGB crust is characterized by low magnetism,seismic velocity,resistivity and Bouguer gravity,whereas the SCC crust exhibits non-uniform high magnetism,seismic velocity,resistivity and Bouguer gravity.The LMTB,as the boundary between the SGB and SCC,exhibits geophysical characteristics similar to those of the SCC in the southern and central segments.The integration of these geophysical observations indicate that the SCC's western boundary is situated west of the Wenchuan-Maoxian fault zone in the southern and central segments,exhibiting distinct westward wedging and underthrusting.However,this boundary aligns with the Yingxiu-Beichuan fault in the northern segment,without significant underthrusting.The irregular geometry of the SCC's western boundary further elucidates the variation in structural deformation along the LMTB.By comparing crustal thickness and lithospheric strength between the SGB and SCC,this study posits that the differing crustal strength between tectonic blocks may control the irregular geometry of the SCC's western boundary.
基金supported by the US National Science Foundation(Grant No.CMMI-1538211)。
文摘Hypergravity can be realized by creating a field imposed by centripetal acceleration in a centrifuge apparatus.Such an apparatus is often used to test soil response in geotechnical engineering problems.Here we present the potential usage of a centrifuge apparatus to study various topics in hydrodynamics.The scaling law associated with hydrodynamics is first reviewed,and the advantage of controlling the body force is described.One of the perceived disadvantages in such experiments is the unwanted presence of the Coriolis effect in the centrifuge.However,we propose exploiting this effect to our advantage to study geophysical fluid-dynamic problems that occur particularly in the equatorial region.
基金supported by the National Natural Science Foundation of China(No.U21B2062)the Natural Science Foundation of Hubei Province(No.2023AFB307)。
文摘Identification of reservoir types in deep carbonates has always been a great challenge due to complex logging responses caused by the heterogeneous scale and distribution of storage spaces.Traditional cross-plot analysis and empirical formula methods for identifying reservoir types using geophysical logging data have high uncertainty and low efficiency,which cannot accurately reflect the nonlinear relationship between reservoir types and logging data.Recently,the kernel Fisher discriminant analysis(KFD),a kernel-based machine learning technique,attracts attention in many fields because of its strong nonlinear processing ability.However,the overall performance of KFD model may be limited as a single kernel function cannot simultaneously extrapolate and interpolate well,especially for highly complex data cases.To address this issue,in this study,a mixed kernel Fisher discriminant analysis(MKFD)model was established and applied to identify reservoir types of the deep Sinian carbonates in central Sichuan Basin,China.The MKFD model was trained and tested with 453 datasets from 7 coring wells,utilizing GR,CAL,DEN,AC,CNL and RT logs as input variables.The particle swarm optimization(PSO)was adopted for hyper-parameter optimization of MKFD model.To evaluate the model performance,prediction results of MKFD were compared with those of basic-kernel based KFD,RF and SVM models.Subsequently,the built MKFD model was applied in a blind well test,and a variable importance analysis was conducted.The comparison and blind test results demonstrated that MKFD outperformed traditional KFD,RF and SVM in the identification of reservoir types,which provided higher accuracy and stronger generalization.The MKFD can therefore be a reliable method for identifying reservoir types of deep carbonates.
基金Geological and Mineral Resources Survey of Metallogenic Belt in the Middle and Lower Reaches of Yangtze River,Grant/Award Number:1212011220540Jiangsu 1:50000 Dingsanwei,Kaishan Island,Yangqiao,Chenjiagang,New Huaihe Estuary,Xiangshui Estuary,Dayou,Xiaojie,DayuJian District,Grant/Award Numbers:Base[2012]02‐014‐009,Base[2013]01‐019‐002,Base[2014]01‐021‐003。
文摘Integrated geophysical technology is a necessary and effective means for geothermal exploration.However,integration of geophysical technology for large‐scale surveys with those for geothermal reservoir localization is still in development.This study used the controlled source audio‐frequency magnetotelluric method technology for large‐scale exploration to obtain underground electrical structure information and micromotion detection technology to obtain underground wave velocity structure information.The combination of two detection technologies was used for local identification of geothermal reservoirs.Further,auxiliary correction and inversion constraint were implemented through the audio magnetotelluric sounding technology for maximum authenticity restoration of the near‐and transition‐field data.Through these technology improvements,a geothermal geological model was established for the Binhai County of Jiangsu Province in China and potential geothermal well locations were identified.On this basis,a geothermal well was drilled nearly 3000m deep,with a daily water volume of over 2000m3/day and a geothermal water temperature of 51°C at the well head.It is found that predictions using the above integrated geophysical exploration technology are in good agreement with the well geological formation data.This integrated geophysical technology can be effectively applied for geothermal exploration with high precision and reliability.
基金supported by the National Natural Science Foundation of China (Grant No.41074133)
文摘Missing data are a problem in geophysical surveys, and interpolation and reconstruction of missing data is part of the data processing and interpretation. Based on the sparseness of the geophysical data or the transform domain, we can improve the accuracy and stability of the reconstruction by transforming it to a sparse optimization problem. In this paper, we propose a mathematical model for the sparse reconstruction of data based on the LO-norm minimization. Furthermore, we discuss two types of the approximation algorithm for the LO- norm minimization according to the size and characteristics of the geophysical data： namely, the iteratively reweighted least-squares algorithm and the fast iterative hard thresholding algorithm. Theoretical and numerical analysis showed that applying the iteratively reweighted least-squares algorithm to the reconstruction of potential field data exploits its fast convergence rate, short calculation time, and high precision, whereas the fast iterative hard thresholding algorithm is more suitable for processing seismic data, moreover, its computational efficiency is better than that of the traditional iterative hard thresholding algorithm.
基金supported by the China Postdoctoral Science Foundation (No.2014M551188)the Deep Exploration in China Sinoprobe-09-01 (No.201011078)
文摘Edge detection is an image processing technique for finding the boundaries of objects within images. It is typically used to interpret gravity and magnetic data, and find the horizontal boundaries of geological bodies. Large deviations between model and true edges are common because of the interference of depth and errors in computing the derivatives; thus, edge detection methods cannot provide information about the depth of the source. To simultaneously obtain the horizontal extent and depth of geophysical anomalies, we use normalized edge detection filters, which normalize the edge detection function at different depths, and the maxima that correspond to the location of the source. The errors between model and actual edges are minimized as the depth of the source decreases and the normalized edge detection method recognizes the extent of the source based on the maxima, allowing for reliable model results. We demonstrate the applicability of the normalized edge detection filters in defining the horizontal extent and depth using synthetic and actual aeromagnetic data.
基金supported by National 863 Program Grant 2012AA050103 and Grant 2011KTCQ03-09
文摘Geophysical techniques play key roles in the measuring, monitoring, and verifying the safety of CO2 sequestration and in identifying the efficiency of CO2-enhanced oil recovery. Although geophysical monitoring techniques for CO2 sequestration have grown out of conventional oil and gas geophysical exploration techniques, it takes a long time to conduct geophysical monitoring, and there are many barriers and challenges. In this paper, with the initial objective of performing CO2 sequestration, we studied the geophysical tasks associated with evaluating geological storage sites and monitoring CO2 sequestration. Based on our review of the scope of geophysical monitoring techniques and our experience in domestic and international carbon capture and sequestration projects, we analyzed the inherent difficulties and our experiences in geophysical monitoring techniques, especially, with respect to 4D seismic acquisition, processing, and interpretation.
基金financial support from the National Key R&D Program of China(2017YFC0601305)the China Geological Survey(DD20160125,DD20160207,DD20190010)the National Natural Science Foundation of China(41504076)。
文摘The Shuangjianzishan deposit in Inner Mongolia is a typical Ag-Pb-Zn deposit of the southern Great Xing’an Range.Proven reserves of Ag,Pb,and Zn in this deposit have reached the scale of super-large deposits,with favorable metallogenic conditions,strong prospecting signs,and high metallogenic potential.This paper reports a study involving integrated geophysical methods,including controlled-source audio-frequency magnetotelluric,gravity,magnetic,and shallow-seismic-reflection methods,to determine the spatial distribution of ore-controlling structures and subsurface intrusive rock for a depth range of<2000 m in the Shuangjianzishan ore district.The objective of this study is to construct a metallogenic model of the ore district and provide a scientific basis for the exploration of similar deposits in the deep and surrounding regions.We used three-dimensional inversion for controlled-source audio-frequency magnetotelluric data based on the limited memory quasi-Newton algorithm,and three-dimensional physical-property inversion for the gravity and magnetic data to obtain information about the subsurface distribution of ore-controlling structures and intrusive rocks.Under seismic reflection results,regional geology,petrophysical properties,and borehole information,the geophysical investigation shows that the Dashizhai group,which contains the main ore-bearing strata in the ore district,is distributed within a depth range of<1239 m,and is thick in the Xinglongshan ore block and the eastern part of the Shuangjianzishan ore block.The mineralization is spatially associated with a fault system characterized by NE-,NW-,and N-trending faults.The magnetic and electrical models identify large,deep bodies of intrusive rock that are inferred to have been involved in mineralization,with local shallow emplacement of some intrusions.Combining the subsurface spatial distributions of ore-bearing strata,ore-controlling faults,and intrusive rock,we propose two different metallogenic models for the Shuangjianzishan ore district,which provide a scientific basis for further prospecting in the deep regions of the ore district and surrounding areas.
基金supported by the 973 Program(Grant No 2007CB209600)Open Fund(No.GDL0706) of the Key Laboratory of Geo-detection(China University of Geosciences,Beijing),Ministry of Education
文摘The inversions of complex geophysical data always solve multi-parameter, nonlinear, and multimodal optimization problems. Searching for the optimal inversion solutions is similar to the social behavior observed in swarms such as birds and ants when searching for food. In this article, first the particle swarm optimization algorithm was described in detail, and ant colony algorithm improved. Then the methods were applied to three different kinds of geophysical inversion problems： （1） a linear problem which is sensitive to noise, （2） a synchronous inversion of linear and nonlinear problems, and （3） a nonlinear problem. The results validate their feasibility and efficiency. Compared with the conventional genetic algorithm and simulated annealing, they have the advantages of higher convergence speed and accuracy. Compared with the quasi-Newton method and Levenberg-Marquardt method, they work better with the ability to overcome the locally optimal solutions.
基金National Science and Technology Supporting Program(2012BAB13B01)National Key Scientific Instrument and Equipment Development Program(2012YQ030126)+2 种基金Coal United Project of National Natural Science Foundation(U1261203)China Geological Survey Project(1212011220798)National Science and Technology Major Project(2011ZX05035-004-001HZ).
文摘To study the impact of modern coal mining on overlying strata and its water bearing conditions,integrated time-lapse geophysical prospecting integrating 3D seismic,electrical and ground penetrating radar method were used.Through observing and analyzing the geophysical data variations of all stages of pre-mining,mining and post-mining as well as post-mining deposition stable period,impacts of coal mining on stratigraphic structure and its water bearing were studied and modern coal mining induced stratigraphic change pattern was summarized.The research result shows that the stratigraphic structure and the water bearing of surface layer during modern coal mining have self-healing pattern with mining time;the self-healing capability of near-surface strata is relatively strong while the roof weak;water bearing selfhealing of near-surface strata is relatively high while the roof strata adjacent to mined coal beds low.Due to integrated time-lapse geophysical prospecting technology has extra time dimension which makes up the deficiency of static analysis of conventional geophysical methods,it can better highlight the dynamic changes of modern coal mining induced overburden strata and its water bearing conditions.
基金the Geological Science and technology foundation of Shandong Provincial Bureau of Geology and Mineral Resources (Grant No. 20080037)
文摘Integrated gravitational, electrical-magnetic surveys and data processing carried out in the Sanshandao-Jiaojia area, Eastern Shandong Province, northeast China, aim to illuminate the geological characteristics of this shallow-covered area and delineate deep-seated gold prospecting targets. In this region, altogether 12 faults exert critical control on distribution of three types of Early Precambrian metamorphic rock series, i.e. those in the metamorphic rock area, in the granitic rock area underlying the metamorphic rock, and in the remnant metamorphic rock area in granites, respectively. Additionally, the faults have major effects on distribution of four Mesozoic Linglong rock bodies of granite, i.e. the Cangshang, Liangguo, Zhuqiao-Miaojia and Jincheng granites. The Sanshandao and Jiaojia Faults are two well-known regional ore-controlling faults; they have opposite dip direction, and intersect at a depth of 4500 m. Fracture alteration zones have striking geophysical differences relative to the surrounding county rocks. The two faults extend down along dip direction in a gentle wave form, and appear at some steps with different dips. These steps comprise favorable gold prospecting areas, consistent with a step metallogenic model. Six deep-seated gold-prospecting targets are delineated, i.e. Jincheng-Qianchenjia, Xiaoxizhuang-Zhaoxian, Xiyou-Wujiazhuangzi, Xiangyangling-Xinlicun, Panjiawuzi and Miaojia-Pinglidian.
基金financially supported by NSERC (Natural Sciences and Engineering Research Council of Canada) Engage grants
文摘The Westwood Mine aims to reuse the tailings storage facility #1(TSF #1) for solid waste storage, but,downstream of the Northwest dike is considered critical in terms of stability. This paper uses numerical modeling along with geophysical monitoring for assessing the Northwest dike stability during the restoration phase. The impact of waste rock deposition in the upstream TSF #1 is considered. The geophysical monitoring is based on electrical resistivity methods and was used to investigate the internal structure of the dike embankment in different deposition stages. The numerical simulations were performed with SLOPE/W code. The results show a factor of safety well above the minimum recommended value of 1.5. Geophysical monitoring revealed a vertical variation in the electrical resistivity across the dike, which indicates a multilayer structure of the embankment. Without any current in situ data, the geophysical monitoring helped estimating the nature of the materials used and the internal structure of the embankment. These interpretations were validated by geological observation of geotechnical log of the embankment. Based on this study, it is recommended that the water polishing pond be partly filled before waste rock is deposited in TSF #1. In addition, to ensure the stability of the dike, the piezometric head monitoring prior to and during waste rock deposition is recommended.
基金This work was supported by the Council on grants of the President of the Russian Federation[Grant Number MK-3608.2018.5].
文摘The prospects for expanding the mineral resource base in many countries are linked with the exploration of stranded sites localized at unexplored areas with complex natural and landscape conditions that make any ground survey,including magnetic prospecting,difficult and expensive.The current level of geology requires high-precision and large-scale data at the first stages of geological exploration.Since 2012,technologies of aeromagnetic surveying with unmanned aircraft vehicles(UAV)enter the market,but most of them are based on big fixed-wing UAV and do not allow to substantially increase the level of survey granularity compared with traditional aerial methods.To increase the scale of survey,it is necessary to reduce the altitude and speed of flight,for which the authors develop the methodical and technical solutions described in this article.To obtain data at altitudes of 5 m above the terrain even in a rugged relief,we created heavy multirotor UAVs that are stable in flight and may be used in a wide range of environmental conditions(even a moderate snowfall),and develop a special software to generate flight missions on the basis of digital elevation models.A UAV has special design to reduce magnetic interference of the flight platform;the magnetic sensor is hung below the aircraft.This technology was conducted in a considerable amount of magnetic surveys in the mountainous regions of East Siberia between 2014 and 2016.The results of the comparison between airborne and ground surveys are presented,which show that the sensitivity of the developed system in conjunction with low-altitude measurements can cover any geologically significant anomalies of the magnetic field.An unmanned survey is cheaper and more productive;the multirotor-based technologies may largely replace traditional ground magnetic exploration in scales of 1:10,000−1:1000.
基金supported by the National Basic Research Programs of China (973 Programs) (Nos. 2009CB2194 and 2007CB411700)the National Natural Science Fundation of China (Nos. 40976029 and 40676039)+2 种基金the Major Knowledge Innovation Program of Chinese Academy of Sciences (No. kzcx2-yw-203-01)the National Program of Sustaining Science and Technology (No. 2006BAB19B00)the Ministry of Land and Resources, China (Nos. GT-YQ-QQ-2008-1-02 and 2009GYXQ06)
文摘The water depth in Nansha（南沙） waters,which is located in the southern South China Sea,varies from 200 to 2 500 m,with a deep-water（500 m） area of 500 000 km2.In this region,there are many depositional basins with various structural features,prone to the accumulation of organic material.The temperature and pressure conditions in the deep-water environment are suitable for the preservation of gas hydrate.At several sites,we have recognized bottom-simulating reflectors（BSRs） from seismic data.Regional geology analyses show that the Nansha waters may have abundant gas hy-drate prospects,especially in localities such as the Nansha trough and other deep-water basins of the central Nansha waters.
文摘Fluid-rock interactions alter the geochemical, isotopic, petrographic and physical character of host rocks, producing a permanent record of hydrothermal activity. Maps of altered rock properties show regular variations that disclose master geologic controls and delineate likely sites for geothermal and mineral resources. In many cases, geochemical and stable isotope data re- veal the origins of thermal fluids, and they can also provide estimates of reservoir temperatures and identify zones of fluid recharge.
基金National Natural Science Foundation of China(Grant No.41704172)the National Key Research and Development Project(Grant No.2017YFC0602000)the National Key Research and Development Project(Grant No.2016YFC0303000).
文摘Superconducting quantum interference device(SQUID),with the advantages of ultra⁃high sensitivity,low noise,broad frequency bandwidth,and excellent low⁃frequency response,is widely used in several geophysical methods,such as vector magnetic survey,electromagnetic method,gravity and gravity gradient measurement.In this paper,the latest technological progress of SQUID and SQUID⁃based geophysical precision measurement technology are described.In addition,the advantages,characteristics,and existing problems of each measurement technology are analyzed.Combined with the requirements of current geophysical technology,the future application prospect is discussed and development suggestions are given.
基金supported by Xinjiang Key Laboratory of Geohazards Prevention(Grant No.XKLGP2022K07)Key R&D Program of Xinjiang Uygur Autonomous Region(Grant No.2022B03001-2)the Third Xinjiang Scientific Expedition Program(Grant No.2022xjkk1305).
文摘Determination of rock mechanical parameters is the most important step in rock mass quality evaluation and has significant impacts on geotechnical engineering practice.Rock mass integrity coefficient(KV)is one of the most efficient parameters,which is conventionally determined from boreholes.Such approaches,however,are time-consuming and expensive,offer low data coverage of point measurements,require heavy equipment,and are hardly conducted in steep topographic sites.Hence,borehole approaches cannot assess the subsurface thoroughly for rock mass quality evaluation.Alternatively,use of geophysical methods is non-invasive,rapid and economical.The proposed geophysical approach makes useful empirical correlation between geophysical and geotechnical parameters.We evaluated the rock mass quality via integration between KV measured from the limited boreholes and inverted resistivity obtained from electrical resistivity tomography(ERT).The borehole-ERT correlation provided KV along various geophysical profiles for more detailed 2D/3D(two-/three-dimensional)mapping of rock mass quality.The subsurface was thoroughly evaluated for rock masses with different engineering qualities,including highly weathered rock,semi-weathered rock,and fresh rock.Furthermore,ERT was integrated with induced polarization(IP)to resolve the uncertainty caused by water/clay content.Our results show that the proposed method,compared with the conventional approaches,can reduce the ambiguities caused by inadequate data,and give more accurate insights into the subsurface for rock mass quality evaluation.
