ARTICLE | doi:10.20944/preprints202304.0700.v1
Subject: Environmental And Earth Sciences, Geophysics And Geology Keywords: Geophysical survey; Semi-airborne electromagnetics; Inversion; Mineral exploration
Online: 21 April 2023 (09:03:37 CEST)
As semi-airborne mineral exploration has limited budgets, it is critical to design experimental procedures that generate data maximizing the desired information We investigate the effects of transmitter-receiver geometries for a variety of anomalies and semi-airborne layouts. Our simulations indicate that 200 m flight line spacing and 100 m point distance are the optimal trade-off between coverage and survey progress for various targets. Based on the target size and distance between the transmitter and the target, the transmitter length should be at least equal to the length of the target and for more than 1 km, at least two or three times the target size. Likewise important are the location and direction of the transmitter cables, which can have great impact on the result of inversion and should be parallel to the target strike. By using more than one transmitter, better results are obtained. If the strike of the target is known, transmitters should be parallel to each other and if not, it is better to use perpendicular transmitters. Results showed that the optimal distance between transmitters is 3 km. Our simulations show that it is even possible to recover targets just below the transmitter in corresponding areas of masked data.
ARTICLE | doi:10.20944/preprints202311.1403.v1
Subject: Environmental And Earth Sciences, Remote Sensing Keywords: oilfield deformation; MSBAS-InSAR; the Qaidam Basin; geophysical models
Online: 22 November 2023 (07:32:43 CET)
Time series ground deformation monitoring and reservoir parameter inversion are crucial for the dynamic assessment of oilfield resources and sustainable exploitation in an oilfield. As one of the regions with the richest oil reserves in China, the oilfield areas in the western Qaidam Basin are selected as a typical study area. Firstly, we used SAR images collected by the Sentinel-1A satellite from January 2021 to December 2022 and applied the Multidimensional Small Baseline Subset (MSBAS) method to obtain vertical and east-west deformation measurements. On this basis, a nonlinear Bayesian inversion method was applied to model the shallow reservoir in a series of complex deformation areas, based on a single-source model and a multi-source model, respectively. As a result, the ground deformation monitoring results obtained by long time series InSAR clearly reflect the uneven ground deformation caused by the oil extraction and water injection operation process. There is slight subsidence in the Huatugou oilfield, while significant uplift deformation occurred in the Ganchaigou oilfield and the Youshashan oilfield, with a maximum uplift rate of 48 mm/year. Further analysis indicates that the introduction of the 2D deformation field helps to improve the robustness of oilfield reservoir parameter inversion. Moreover, the dual-source model is more suitable than the single-source model for inverting complex deformation reservoir parameters. This study not only fills the blank of InSAR deformation monitoring for the oilfields in the western Qaidam Basin but also provides a theoretical reference for model and method selection of reservoir parameter inversion in other oilfields.
ARTICLE | doi:10.20944/preprints201705.0150.v1
Subject: Physical Sciences, Fluids And Plasmas Physics Keywords: Geophysical Fluid Dynamics; Geostrophic flows; Thermal forcing; Analytical model
Online: 19 May 2017 (16:33:10 CEST)
Starting with a hypothetical geostrophic zonal current in an unbounded ocean, the investigation points out the response of this simple system to a thermal forcing, applied to the free surface and consistent with the maintenance of the geostrophic balance. The main result is the formation of a meridional component of the current, according to the Sverdrup relation, such that the full velocity vector rotates clockwise for heating and anticlockwise for cooling to adjust eventually in the initial zonal direction for large depths.
ARTICLE | doi:10.20944/preprints202303.0327.v1
Subject: Physical Sciences, Astronomy And Astrophysics Keywords: habitable planets; exo planets; advanced life; M stars; geophysical conditions
Online: 17 March 2023 (13:48:16 CET)
Using a simple model for internal heat evolution and mass-internal heat relations found for rocky exo planetary objects in the inner solar system we have inferred the phases of volcanism at earth ( EA) or host star ages (SA) in 52 potentially habitable rocky exo planets. We have also calculated the internal tidal heat contributions and magnetic moments of these exo planets. Based on these results we have inferred the probability of existence of life favouring geophysical conditions in the above exo planets at EA and SA. In M star associated exo planets, occurrences of super flares and long night periods may pose problems for the development of advanced life
ARTICLE | doi:10.20944/preprints201811.0595.v1
Subject: Physical Sciences, Nuclear And High Energy Physics Keywords: muon radiography; cosmic rays; tracking detectors; imaging; geophysical prospection; mining
Online: 26 November 2018 (14:09:10 CET)
Muon radiography is an imaging technique based on the measurement of the absorption of cosmic ray muons. This technique has recently been used successfully to investigate the presence of unknown cavities in the Bourbon Gallery in Naples and in the Cheops Pyramid at Cairo. The MIMA detector (Muon Imaging for Mining and Archaeology) is a muon tracker prototype for the application of muon radiography in the Archaeological and Mining fields. It is made of three couples of X-Y planes each consisting of 21 scintillator bars with silicon photomultiplier read-out. The detector is compact, robust, easily transportable and has a low power consumption: all of that makes the detector ideal for measurements in narrow and isolated environments. With this detector we have performed a measurement from inside the Temperino mine in the San Silvestro archaeo-mining park in Tuscany. The park includes about 25 km of mining tunnels arranged on several levels that have been excavated since the Etruscan time. The measured muon absorption was compared to the simulated one, obtained from the information provided by 3D laser scanner measurements and the cartographic maps of the mountain above the mine, in order to obtain information on the average density of the rock. This allowed to confirm the presence of a partially accessible exploitation opening and gave some hints on the presence of a high density body within the rock.
ARTICLE | doi:10.20944/preprints201805.0384.v1
Subject: Engineering, Civil Engineering Keywords: fracture grouting; cement-silicate grout; geophysical prospecting; seepage; Yellow River Embankment
Online: 28 May 2018 (05:45:00 CEST)
Fracture grouting has been a widely used mitigation measure against seepage in the Yellow River Embankment. However, there is currently a lack of systematic investigation for evaluating the anti-seepage effectiveness of fracture grouting employed in this longest river embankment in China. Therefore, in this work, laboratory and in-situ experiments are carried out for investigating the reinforcement effect of fracture grouting in the Jinan Section of the Yellow River Embankment. In particular, firstly, the laboratory tests concentrate on studying the optimum strength improvement for cement-silicate grout by varying the content of backfilled fly ash and bentonite as admixtures. Flexural strength and Scanning Electron Microscope photographs are investigated for assessing the strength and compactness improvement. Subsequently, based on the obtained optimum admixtures content, in-situ grouting tests are carried out in the Jinan Section of the Yellow River Embankment to evaluate the anti-seepage effectiveness of fracture grouting, where geophysical prospecting and pit prospecting methods are employed. Laboratory results show that, compared with pure cement-silicate grouts, the gelation time of the improved slurry is longer and gelation time increases as fly ash content increases. The optimum mixing proportion of the compound cement-silicate grout is 70% cement, 25% fly ash and 5% bentonite, and the best volume ratio is 2 for the investigated cases. Geophysical prospecting using the Ground Penetrating Radar and High Density Resistivity methods can reflect the anti-seepage effectiveness of fracture grouting on site. It shows that the grouting material mainly flows along the axial direction of the embankment. The treatment that is used to generate directional fracture is proved to be effective. The injection hole interval distance is suggested to be 1.2 m, where the lapping effect of the grouting veins is relatively significant. For the investigated cases, the average thickness of the grouting veins is approximately 6.0 cm and the corresponding permeability coefficient is averagely 1.6 × 10−6 cm/s, which meets the anti-seepage criterion in practice.
ARTICLE | doi:10.20944/preprints202301.0329.v1
Subject: Environmental And Earth Sciences, Geophysics And Geology Keywords: Geological; Geophysical; Shale; Dolerite; Calcareous Sandstone; Asu River Group; Eze-Aku Formation
Online: 18 January 2023 (08:50:58 CET)
The Lokpaukwu Uru Quarry was examined geologically, geophysically, and core-wise. The location is between 5056.149'N and 5056.193'N and 7028.312'E and 7028.356'E. The study location may include the Asu River Group and the Eze-Aku Formation. This area has five rock units. In the eastern research region, siltstone forms a "CAP" on the shale. Shale underlies half of the study area. The west has calcareous sandstone. The eastern part of the area is dolerite, the main rock that spans siltstone and shale. The region's geological matter contains iron. Two geological sections were analysed and interpreted to identify the five rock units and their outcrops in the study area. electroresistivity in geophysical research Schlumberger found that the western, northwesterly, and central sections of the research region had a thick sedimentary sequence, whereas the eastern half has an igneous body, the project's main component. Sandstone, siltstone, and shale follow the high-resistivity rock in this location. The rock unit in the region was found in eleven core samples from the east half of the study area. Nine rock-unit core samples were found near Obichioke. The Lokpaukwu area's core data shows the rocks' positions, kinds, minerals, and strengths. Geologic mapping shows that a major fault separates the viable Uru end from the unviable Obichioke lot. Recrystallization dominates the fault track (alcitic matter). Thus, prior to quarrying igneous (basic) units, comparable investigations are advised.
ARTICLE | doi:10.20944/preprints202212.0314.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: cultural heritage; Roman Mosaic; geomorphological hazard; geophysical survey; geomorphological methods; vulnerability zoning
Online: 19 December 2022 (03:40:17 CET)
Heritage monuments are religious, historical, strategic or civil edifices and could be deteriorated, even damaged due to their exposure to natural and human induced processes. The Roman Edifice with Mosaic (II-IV A.D.), the largest one in Eastern Europe is an ancient civil edifice built on the steep cliff in the western part of Black Sea, Constanța, Romania and being exposed to geomorphological and hydrogeological processes is affected by degradation. The main objective of this paper is to assess the current state of this ancient historical site in relation with the environmental instability in order to offer scientific support for rehabilitation process through interdisciplinary and non-destructive methods. Geophysical methods had been applied to analyze comparatively the spatial variations and flows of groundwater around Roman Mosaic over 10 years. Geomorphological hazards had been inventoried and mapped. The results emphasize the state of degradation of the roman mosaic pavement and ancient walls mainly through high variations of the deposits moisture due to poor maintenance which caused suffusion, slip processes, bring the mosaic into highly vulnerability range. Zoning vulnerability map of the Roman Mosaic environment is a necessary tool for continuously improvement of risk management because emphasize clearly the sectors which still confronting with hazards.
ARTICLE | doi:10.20944/preprints202011.0605.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: parameter-free spectral clustering; Lagrangian Coherent Structures; clusters; geophysical flows; unsupervised machine learning
Online: 24 November 2020 (09:25:02 CET)
In Lagrangian dynamics, the detection of coherent clusters can help understand the organization of transport by identifying regions with coherent trajectory patterns. Many clustering algorithms, however, rely on user-input parameters, requiring a priori knowledge about the flow and making the outcome subjective. Building on the conventional spectral clustering method of Hadjighasem et al (2016), a new parameter-free spectral clustering approach is developed that automatically identifies parameters and does not require any user-input choices. A noise-based metric for quantifying the coherence of the resulting coherent clusters is also introduced. The parameter-free spectral clustering is applied to two benchmark analytical flows, the Bickley Jet and the asymmetric Duffing oscillator, and to a realistic, numerically-generated oceanic coastal flow. In the latter case, the identified model-based clusters are tested using observed trajectories of real drifters. In all examples, our approach succeeded in performing the partition of the domain into coherent clusters with minimal inter-cluster similarity and maximum intra-cluster similarity. For the coastal flow, the resulting coherent clusters are qualitatively similar over the same phase of the tide on different days and even different years, whereas coherent clusters for the opposite tidal phase are qualitatively different.
ARTICLE | doi:10.20944/preprints202310.0548.v1
Subject: Environmental And Earth Sciences, Geophysics And Geology Keywords: strike-slip; hydrocarbons; geophysics; basement; West Siberian oil and gas province; geophysical data interpretation
Online: 10 October 2023 (08:15:47 CEST)
The paper presents the results of geological interpretation of the set of geophysical data with substantiation of geological-geophysical and structural geological criteria of oil and gas potential of the sedimentary cover deep levels and the upper part of the consolidated basement in the central West Siberian oil and gas basin. Gravity, magnetic and seismic data are used. The character of manifestation of the regional Pai-Khoi–Altai strike-slip zone covering an area up to 200 km wide is shown. The study provides a basis for assuming a spatial genetic relationship between the conditions for localizing hydrocarbon traps and the extensional and strike-slip and thrust structures of the zone that form so-called "flower structures". The substantiated structural geological criteria were applied to solve the problem of pattern recognition with training, highlighting the environments favourable for localization of hydrocarbon fields.
ARTICLE | doi:10.20944/preprints202304.0629.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: accretion; adaptive responses; Bangladesh; erosion; floods; geophysical; hazards; river basin; river channel migration; resettlement.
Online: 20 April 2023 (08:01:29 CEST)
This study posits that for appropriately explaining the complex charland (mid-channel island) processes and formulating policy and planning measures, a comprehensive understanding of the dynamic characteristics of the geomorphological, ecological, and human systems holistically is essential. This is also valid for the territorial and maritime areas of Bangladesh. The objectives of this study are: (i) to analyze the salient features and characteristics of the geomorphological and riparian systems of the Bengal Delta; (ii) to analyze the evolutionary discourse of the legal systems concerning eroded (diluvion) and accreted (alluvion) land in Bangladesh; and (iii) to assess characteristics of coping and adaptation strategies of the charland inhabitants. The findings reveal that the delta-building processes, characterized by the dynamic shifts of river channels, and erosion and accretion of charlands have made the land and water systems of the territory very dynamic and unstable – resulting in consistent displacement of settlers and serious deterioration of their socioeconomic status. The historical evolution of land laws and regulations concerning the accreted land favoured vested interests. As no effective institutional framework and structure presently exists in Bangladesh for resettlement planning, formulation of a comprehensive national resettlement policy is therefore urgently needed.
ARTICLE | doi:10.20944/preprints201811.0612.v1
Subject: Environmental And Earth Sciences, Geophysics And Geology Keywords: geophysical signal processing; pattern recognition; temporal convolutional neural networks; seismology; deep learning; nuclear treaty monitoring
Online: 29 November 2018 (03:37:48 CET)
The detection of seismic events at regional and teleseismic distances is critical to Nuclear Treaty Monitoring. Traditionally, detecting regional and teleseismic events has required the use of an expensive multi-instrument seismic array; however in this work, we present DeepPick, a novel seismic detection algorithm capable of array-like performance from a single trace. We achieve this directly, by training our single-trace detector against labeled events from an array catalog, and by utilizing a deep temporal convolutional neural network. The training data consists of all arrivals in the International Seismological Centre Catalog for seven seismic arrays over a five year window from 1 Jan 2010 to 1 Jan 2015, yielding a total training set of 608,362 detections. The test set consists of the same seven arrays over a one year window from 1 Jan 2015 to 1 Jan 2016. We report our results by training the algorithm on six of the arrays and testing it on the seventh, so as to demonstrate the transportability and generalization of the technique to new stations. Detection performance against this test set is outstanding. Fixing a type-I error rate of 1%, the algorithm achieves an overall recall rate of 73% on the 141,095 array beam picks in the test set, yielding 102,394 correct detections. This is more than 4 times the 23,259 detections found in the analyst-reviewed single-trace catalogs over the same period, and represents an 8dB improvement in detector sensitivity over current methods. These results demonstrate the potential of our algorithm to significantly enhance the effectiveness of the global treaty monitoring network.
ARTICLE | doi:10.20944/preprints202308.1471.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: underground coal gasification process; gasification reactor; gasification zone; combustion cavity; geophysical methods; borehole ground-penetrating radar
Online: 21 August 2023 (11:52:02 CEST)
In this study, the shape and size of a combustion cavity with a fracture zone in the gasified coal seam was determined with use control boreholes and a ground-penetrating radar (BGPR) test. The underground coal gasification (UCG) field-scale experiment was performed in Carboniferous strata in coal seam 501 at a depth of approx. 460 m in the Wieczorek hard-coal mine in the Upper Silesian Coal Basin, Poland. After the termination of the UCG reactor, five coring boreholes were drilled to identify the geometry of the resulting combustion cavity and the impact of the UCG process on the surrounding rock mass. Borehole ground-penetrating radar measurements were performed using a 100 MHz antenna in three boreholes with a length of about 40-50 m. This enabled the identification of the boundaries of the combustion cavity and the fracture zone in the coal seam. The fracture zones of rock layers and lithological borders near the control borehole were also depicted. As a result, the cavity was estimated to have a length of around 32 m, a width of around 7 m and a height of around 5 m. The analyses performed with the control boreholes and the BGPR provided sufficient information to determine the geometry of the combustion cavity and the fracture zone.
ARTICLE | doi:10.20944/preprints202012.0248.v1
Subject: Environmental And Earth Sciences, Geophysics And Geology Keywords: cryolithozone; geophysical monitoring; pulsed electromagnetic sounding; cross-well exploration; vector finite-element method; numerical simulation; high-performance computing
Online: 10 December 2020 (10:39:26 CET)
The paper is dedicated to the topical problem of examining permafrost state and the processes of its geocryological changes by means of geophysical methods. To monitor the cryolithozone, we propose and scientifically substantiate a new technique of pulsed electromagnetic cross-well sounding. Based on the vector finite-element method, we created a mathematical model of the cross-well sounding process with a pulsed source in a three-dimensional spatially heterogeneous medium. A high-performance parallel computing algorithm was developed and verified. Through realistic geoelectric models of permafrost with a talik under a highway, constructed following the results of electrotomography field data interpretation, we numerically simulated the pulsed sounding on the computing resources of the Siberian Supercomputer Center of SB RAS. The simulation results suggest the proposed system of pulsed electromagnetic cross-well monitoring to be characterized by a high sensitivity to the presence and dimensions of the talik. The devised approach can be oriented to addressing a wide range of issues related to monitoring permafrost rocks under civil and industrial facilities, buildings and constructions.
CASE REPORT | doi:10.20944/preprints202107.0469.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: Research Infrastructures (RIs); Engineering Geological conditions; Integrated geophysical methods; Daya Bay Neutrino Laboratory (DBNL); China Spallation Neutron Source (CSNS)
Online: 21 July 2021 (08:17:01 CEST)
Research Infrastructures (RIs) are essential to achieve excellence in innovative scientific research. However, because of limited land availability and specific geological requirements, evaluating the viability of a site for a new RI can be a challenging task. Stringent safety construction requirements include developing site-specific architectural and geoengineering solutions, minimizing construction disturbances, and reinforcing rock and soil in a timely fashion. For successful development of the RIs in China, such as the Daya Bay Neutrino Laboratory (DBNL), and the China Spallation Neutron Source (CSNS), an integrated approach of joint geophysical methods including the electrical resistivity tomography (ERT), controlled-source audio-frequency magneto telluric (CSAMT)), gravity and seismic refraction methods, and geological mapping and surveys were carried out. Geophysical parameters, such as electrical resistivity, density, and seismic velocity show inverse proportion to the degree of rock fracturing or weathering. The results show that the low values of geophysical parameters suggest the weathered/fractured rock, while high values reveal the fresh bedrock. The Engineering Geological Suitability Index (EGSI) value can represent the individual EGSI values at a constant and summed over varying depths. EGSI methodology is an improvement on the existing siting process, and has been applied this to CSNS. Our integrated approach provides clearer insight of the subsurface for site suitability of RIs in challenging engineering geological conditions, and removes any ambiguity caused by a single geophysical parameter. The obtained geological knowledge of the area not only provides engineers with much-needed information about the construction conditions of a potential site, but also gives scientists the opportunity to explore the local geology. In this study, we demonstrate our innovative approach for siting RIs, as demonstrated by the synthetic evaluation of the site location and utilization for two established RIs (DBNL and CSNS).
Subject: Environmental And Earth Sciences, Geophysics And Geology Keywords: mineral physics; ultrasonic interferometry; resonant ultrasound spectroscopy; law of corresponding states; equations-of-state; Columbia University; American Geophysical Union
Online: 29 March 2019 (07:54:57 CET)
From 1964 to the early 1970s, Orson Anderson led a research program at the Lamont Geological Observatory in the newly-emerging field of “mineral physics”. In collaboration with colleagues Edward Schreiber and Naohiro Soga, Orson exploited the techniques of physical acoustics to study the behavior of the sound velocities of minerals at elevated pressures and temperatures. This research program also included semi-empirical studies of relationships between the bulk modulus and the molar volume of solids and the use of lattice dynamics to calculate the elastic moduli of cubic structures as a function of pressure to predict instabilities, as well as theoretical investigations of the Lagrangian vs. Eulerian formulations of finite strain equations of state.