Shallow Exploration Research Articles

Navigating the tides of change: The local dynamics of China’s marine economic policy

Local governments are playing a key role in policy formulation and implementation because of the shifting tide during China’s marine economic expansion. This study employs all-encompassing methodologies, including policy quantification, policy networks, and topic modeling, to analyze 4241 marine economic policy texts from 11 coastal regions in China. It reveals the spatiotemporal evolution characteristics of local government marine economic policies (LGMEPs). The main results show that: (1) Overall, since 1956, the number and power of LGMEPs have continued to grow and emerge in four stages: initiation, shallow exploration, rapid development, and optimized adjustment. Significant differences can be found in the marine economy policies among regions. Some eastern and southern regions revealed more quantity and power in their policies. (2) The number of institutions involved in marine economy policy formulation has been increasing, and complex and close joint issuance networks have been formed. Only the regions of Shanghai and Hainan formed coordinated joint issuance networks, while other regions lacked either core institutional leadership or collaborative institutional links. (3) Marine economy policy topics have shifted from traditional marine industry to safe operations, modern marine industries, and marine ecological environmental protection. The resource base and development goals of each region led to marked variations in marine economic policy topics. The findings here provide local governments with a reference for crafting marine economic strategies and policies.

C-RIA: RESISTIVITY DATA INTERPRETATION AND ANALYSIS IN CLOUD MODE

Geophysical methods generally require one or several processes before interpretation is carried out. This process usually requires software that requires fast computer technology. The better the computer device, the faster data can be processed. We propose a new approach in processing and interpreting and integrating geophysical data, especially resistivity data, using cloud technology. This technology is generally able to increase the speed of processing and interpreting geophysical data, which really requires devices with fast capabilities. Not to mention, if there is a lot of data being processed, it will take a long time just to process the data. Therefore, by using cloud technology the work can be done efficiently because it uses computers with modern and fast technology. In this research we apply this technology to geophysical data that is most often used for shallow exploration, namely the resistivity geoelectric method. With this research, we hope that data processing and geophysical data inversion will be more efficient and effective and the data will be safer.

Hydrogeochemical processes as a conditioner of freshwater lenses associated with coastal deposits

AbstractThe aim of this work was to study the processes and factors conditioning the hydrochemistry of freshwater lenses associated with Holocene coastal deposits in an area of the Argentinean Atlantic coast. For this purpose, geomorphological units were mapped and a shallow groundwater monitoring network was established, including pre‐existing boreholes and shallow exploration wells. During the construction of the shallow exploration wells, sediment samples were extracted to determine the texture and mineralogical characteristics. Four samplings were carried out to measure in situ physicochemical parameters and to determine majority ions in the water. The chemical data were analysed considering the associated geomorphology, lithology, water balance and hydrodynamics. The geomorphological and lithological characteristics are the combined factors that favour the preferential rainwater recharge processes. Geoforms with greater topography and extension (continental and coastal dunes) tend to store freshwater lenses, while those with lower topography and little areal extension (sand sheets and beach ridges) have very thin lenses and tend to become salinized. Climate and local water balance are factor that determines that groundwater recharge occurs preferentially in winter. This causes increases in groundwater levels and a decrease in the groundwater EC. On the other hand, mineralogy is a factor that conditions the geochemical processes associated with the water–sediment interaction. Within the main geochemical processes, the dissolution and/or mineral weathering, the dissolution of CO2(g) and ion exchange determine the presence of different hydrochemical facies, where Ca‐HCO3 facies dominates in elevated geoforms, while Na‐Cl in lower ones. The results obtained in this work have provided an understanding of the factors and processes that condition groundwater chemistry in coastal deposits, being of vital importance for the management of water resources.

Improved NSGA-II algorithms for multi-objective biomarker discovery.

In modern translational research, the development of biomarkers heavily relies on use of omics technologies, but implementations with basic data mining algorithms frequently lead to false positives. Non-dominated Sorting Genetic Algorithm II (NSGA2) is an extremely effective algorithm for biomarker discovery but has been rarely evaluated against large-scale datasets. The exploration of the feature search space is the key to NSGA2 success but in specific cases NSGA2 expresses a shallow exploration of the space of possible feature combinations, possibly leading to models with low predictive performances. We propose two improved NSGA2 algorithms for finding subsets of biomarkers exhibiting different trade-offs between accuracy and feature number. The performances are investigated on gene expression data of breast cancer patients. The results are compared with NSGA2 and LASSO. The benchmarking dataset includes internal and external validation sets. The results show that the proposed algorithms generate a better approximation of the optimal trade-offs between accuracy and set size. Moreover, validation and test accuracies are better than those provided by NSGA2 and LASSO. Remarkably, the GA-based methods provide biomarkers that achieve a very high prediction accuracy (>80%) with a small number of features (<10), representing a valid alternative to known biomarker models, such as Pam50 and MammaPrint. The software is publicly available on GitHub at github.com/UEFBiomedicalInformaticsLab/BIODAI/tree/main/MOO. Supplementary data are available at Bioinformatics online.

Anti-Inflammatory Function of Plant-Derived Bioactive Peptides: A Review.

Inflammation is considered to be a crucial factor in the development of chronic diseases, eight of which were listed among the top ten causes of death worldwide in the World Health Organization’s World Health Statistics 2019. Moreover, traditional drugs for inflammation are often linked to undesirable side effects. As gentler alternatives to traditional anti-inflammatory drugs, plant-derived bioactive peptides have been shown to be effective interventions against various chronic diseases, including Alzheimer’s disease, cardiovascular disease and cancer. However, an adequate and systematic review of the structures and anti-inflammatory activities of plant-derived bioactive peptides has been lacking. This paper reviews the latest research on plant-derived anti-inflammatory peptides (PAPs), mainly including the specific regulatory mechanisms of PAPs; the structure–activity relationships of PAPs; and their enzymatic processing based on the structure–activity relationships. Moreover, current research problems for PAPs are discussed, such as the shallow exploration of mechanisms, enzymatic solution determination difficulty, low yield and unknown in vivo absorption and metabolism and proposed future research directions. This work aims to provide a reference for functional activity research, nutritional food development and the clinical applications of PAPs.

A Dual-Air-Core Coil Sensor With Wide Bandwidth and Large Effective Area in Electromagnetic Exploration System

Air-core coil sensors are widely used in geophysical electromagnetic exploration because of their ease of production, high sensitivity, and broadband. In order to increase the bandwidth of the air-core coil without reducing the number of turns, a new type of dual-air-core coil sensor was proposed for the shallow exploration in the electromagnetic method. The design principle of the dual-air-core coil sensor was introduced, consisting of a low-bandwidth coil and a high-bandwidth coil. The output voltage of the high-frequency coil is used as a linear reference to obtain the amplitude-frequency response data of the low-frequency coil, and the fitting model is constructed to extract the equivalent inductance and distributed capacitance of the low-frequency coil, so as to realize the correction of the system response. In addition, the crosstalk model between air-core coils was established, and a method to suppress crosstalk was proposed. In order to prove the feasibility of the dual-air-core coil sensor, in-laboratory and field test platforms were set up. The experimental results show that the crosstalk between the coils can be eliminated by adjusting the relative position of the coil. The fitting method can effectively increase the bandwidth of the low-bandwidth coil, so that it exceeds the high-frequency coil used, and it is shown to have better performance. The effective area is 59.5 m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , the amplitude bandwidth of −3 dB is 200 kHz, the phase bandwidth with the error less than ±5° is 220 kHz, and the noise level is 18 fT <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\cdot $ </tex-math></inline-formula> Hz <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-1/2}$ </tex-math></inline-formula> at 1 kHz.

Processing of seismic diffractions from carbonate nodules in clay formations

The problem of localizing small (relative to wavelength) scatterers by diffractions to enhance their use in identifying small-scale details in a seismic image is extremely important in shallow exploration to identify interesting features such as fractures, caves, and faults. The conventional approach based on seismic reflection is limited in resolution by the Rayleigh criterion. In certain acquisition geometries, such as crosswell surveys aimed at obtaining high-resolution signals, the availability of suitable data sets for effective migration depends on the spatial extent of the available source and receiver data intervals. With the aim of overcoming the resolution limits of seismic reflection, we study the detectability, response, and location of meter- and possibly submeter-dimension carbonate concretions (septaria) in the Boom Clay Formation (potential host rocks for radioactive waste disposal) by diffraction analysis of high-frequency signals. We investigate diffraction wavefields by signal separation, focusing, and high-resolution coherency analysis using the multiple signal classification method and semblance. The investigation is performed for two different surveys in Belgium, a shallow and high-resolution reverse vertical seismic profile (RVSP) and a near-offset crosswell application at Kruibeke and ON-MOL-2 sites, respectively. The data analysis is supported by synthetic wavefield modeling. The multioffset RVSP provides the appropriate geometry to observe and investigate the septaria diffractions from depth and the surface. The crosswell approach, calibrated using synthetic data in the analysis of wavefield patterns in 2D, indicates promising imaging results with field data of a selected diffraction zone in the interwell area.

The study of applicability of the very shallow geophysical exploration method for the strike-slip fault (part 2; S-wave shallow seismic reflection survey and two-dimensional electrical resistivity survey): the case study of the Go-mura fault zone and Yamada fault zone

The study of applicability of the very shallow geophysical exploration method for the strike-slip fault (part 2; S-wave shallow seismic reflection survey and two-dimensional electrical resistivity survey): the case study of the Go-mura fault zone and Yamada fault zone

Surface Magnetic-Field Enhancement Technology With a Double-Polarization Coil for Urban Hydrology Quantitative Survey

Electromagnetic geophysical methods are widely applied in urban shallow exploration, considering their convenience and noninvasiveness. As one of the emerging techniques, polarizing surface nuclear magnetic resonance (SNMR) shows significant potential for water-based target detections. However, problems involving weak signal response and strong noise interference are challenging to avoid. Therefore, numerous studies focused on suppressing the electromagnetic interference and improving the effective electromagnetic control accuracy to achieve high-precision shallow imaging. On this basis, we proposed a new magnetic-field enhancement technology that explored double-polarization coils, instead of the single loop, to improve the applications of polarizing SNMR. By controlling the current for double-polarization coils, the magnetic field, which is twice as strong as the single coil, could be provided. As a result, the sensitivities and signal responses for subsurface detection sensitive areas with the same power consumption were further enhanced. Considering the SNMR research, we also identified that this new configuration with double-polarization coil can effectively improve the resolution of the shallow depth because it compensates for the magnitude of the static magnetic field in the center. Based on the theoretical analysis, we developed the instrument and, for the first time, realized the accurate interpretation of the real ground soil in an urban environment, verifying the effectiveness of the proposed configuration and the reliability of the system.

Petrography and reservoir quality controls in shallow transitional marine Cretaceous-Paleogene deposits in the Dahomey Basin, Nigeria

Upper Mesozoic and Early Cenozoic sedimentary rocks are of great significance to the petroleum geology of the Eastern Dahomey Basin as they are valuable prospects for hydrocarbon reservoirs. Diagenesis and reservoir quality (porosity and permeability) controls are deduced from core samples recovered from six shallow exploration wells in the onshore area of the Eastern Dahomey Basin using petrographic, petrophysical and mineralogical tools. The studied lithostratigraphic intervals consist of limestone, calcareous siliciclastic sandstone (Ewekoro and Araromi Formations), quartz arenite and clay-matrix supported sandstone (Afowo Formation) which were deposited within a shallow marine depositional environment.Siliciclastic samples of the Ewekoro Formation consist predominantly of calcareous sandstone and limestone, which are classified as packstone and wackestone. The porosity values in the sandstones range from 5 to 36% whereas permeability ranges from 0.006 to 109 mD. Ewekoro Limestone porosity ranges from 7 to 32% and permeability ranges from 0.003 to 13 mD. Samples of the Araromi Formation exhibit a porosity of 4 to 45% with permeability between <0.001 and 1764 mD in sandstones whereas a single limestone sample has 8% porosity and permeability of 0.03 mD. Porosity in quartz arenitic sandstones of the Afowo Formation ranges from 15 to 47% with permeability of 0.05 to >10,000 mD, while in the clay-matrix supported sandstones, the values range from 18 to 42% and 0.05 to 5 mD for porosity and permeability, respectively. The main pore-occluding authigenic minerals are carbonate cements (Fe-dolomite, Fe-calcite, siderite and dolomite), iron oxide, kaolinite, and illite-smectite mixed layer clays. The best reservoir quality is observed in the quartz arenitic sandstones of the Araromi and Afowo Formations, except for the low permeability, clay-matrix supported sandstone facies.The most significant controlling factors in sandstones are clay mineral matrix contents and the presence of carbonate cements. Fe-calcite, Fe-dolomite and kaolinite formation occurs during early diagenesis in the studied lithologies and has helped to reduce the effect of compaction. The results of this study indicate fair to good reservoir quality in the shallow marine sedimentary rocks of the Eastern Dahomey Basin, which could be targeted in further exploration campaigns in the region.

Design of an airborne concentric frequency-domain electromagnetic induction system for shallow subsurface geophysical exploration

For the exploration of shallow and small subsurface targets, rigid-beam helicopter-borne electromagnetic systems are often inconvenient or costly, whereas man-portable or ground-based systems are difficult to operate in complex terrain. An airborne concentric frequency-domain electromagnetic system with an unmanned rotorcraft as a flying platform is proposed to avoid the problems of low security in conventional helicopter-borne electromagnetic method and low efficiency in ground-based electromagnetic method for the exploration of shallow subsurface targets. Compared with the series mode of man-portable system, the currents of transmitting and bucking coils are assumed to be separately and continuously adjustable, which can reduce sensitivity of the small errors of the system. In this paper, the principle of canceling the primary magnetic field is analyzed. The design index of the physical parameters of the sensor is determined. The simulation experiment of layered earth model is carried out to verify the feasibility of the proposed system.

Amplitude-Preserved Wave Equation: An Example to Image the Gas Hydrate System

Natural gas hydrate is an important energy source. Therefore, it is extremely important to provide a clear imaging profile to determine its distribution for energy exploration. In view of the problems existing in conventional migration methods, e.g., the limited imaging angles, we proposed to utilize an amplitude-preserved one-way wave equation migration based on matrix decomposition to deal with primary and multiple waves. With respect to seismic data gathered at the Chilean continental margin, a conventional processing flow to obtain seismic records with a high signal-to-noise ratio is introduced. Then, the imaging results of the conventional and amplitude-preserved one-way wave equation migration methods based on primary waves are compared, to demonstrate the necessity of implementing amplitude-preserving migration. Moreover, a simple two-layer model is imaged by using primary and multiple waves, which proves the superiority of multiple waves in imaging compared with primary waves and lays the foundation for further application. For the real data, the imaging sections of primary and multiple waves are compared. We found that multiple waves are able to provide a wider imaging illumination while primary waves fail to illuminate, especially for the imaging of bottom simulating reflections (BSRs), because multiple waves have a longer travelling path and carry more information. By imaging the actual seismic data, we can make a conclusion that the imaging result generated by multiple waves can be viewed as a supplementary for the imaging result of primary waves, and it has some guiding values for further hydrate and in general shallow gas exploration.

Excitation performance enhancement based on optimization of structural parameters of precision-controllable vibrator

This paper focuses on solving the problem of poor excitation performance of precision- controllable vibrator leading to shallow exploration depths, which cannot fully meet the current demand for deep oil and gas resources exploration. For this purpose, the evaluation parameters of the excitation performance of the precision-controllable vibrator are clarified, an optimization model of the structure parameters of the precision-controllable vibrator is established. Particle swarm algorithm and Pareto optimization logic are used to integrate the solution set to optimize the structure of precision-controllable vibrator and enhance the excitation performance of precision-controllable vibrator.

Spatial autocorrelation method for reliable measurements of two-station dispersion curves in heterogeneous ambient noise wavefields

SUMMARYThe microtremor survey method (MSM) is used to estimate S-wave velocity profiles from microtremors or ambient noise. Although array-based MSM analyses are usually used for shallow exploration purposes because of their robustness, the extraction of numerous phase-velocity dispersion curves by two-station microtremor analysis is attractive because those dispersion curves can be used to construct high-resolution phase-velocity maps by solving a least-squares problem. However, in exploration studies (&amp;gt;1 Hz), the reliability of two-station microtremor analysis can be affected by short data acquisition times and heterogeneous noise distributions mainly caused by anthropogenic noises. In this study, we propose a new approach to estimate surface wave dispersion curves between station pairs considering a heterogeneous ambient noise distribution based on the spatial autocorrelation method. We first estimated azimuthal variations of noise energy from the complex coherencies between all station pairs in a receiver array, and then estimated dispersion curves between station pairs. Our field example demonstrates that modelling the azimuthal noise energy distribution allows us to use not only the real parts of complex coherencies, but also the imaginary parts, which are usually neglected when assuming a homogeneous noise field. The simultaneous use of the real and imaginary parts of complex coherencies improves the reliability and continuity of phase-velocity estimations between station pairs. Because the stability of phase-velocity estimations depends on the azimuths between station pairs, we carefully selected between-station azimuths that produce stable phase velocities. Selected phase velocities at 8 Hz can be used to construct high-resolution phase-velocity maps with least-squares inversion. Because our approach does not require a regular receiver interval for two-station analysis, it allows for more flexible seismic array geometries. This is particularly important for MSM analyses in urban areas, where limited space is available to install seismic stations. We conclude that our proposed approach is effective in reconstructing high-resolution shallow structures in heterogeneous ambient noise fields.

Identification of seawater intrusion using geoelectrical resistivity method in the Goa Cina Beach Malang Area, Indonesia

Seawater intrusion can cause groundwater that is looked fresh initially but becomes brackish and even salty. It makes decreasing the quality of groundwater in the area. The Goa Cina Beach, Malang has a geological structure of rock in limestone, sand, and gravel. These rocks have greater porosity, so that the potential to pass water or water infiltration is also quite large, both freshwater and saltwater. Starting from these problems, it is needed to identify groundwater distribution that is not affected by the seawater intrusion process. The geoelectric method effectively determines geological parameters such as depth of bedrock, minerals, fluids, and shallow exploration to identify groundwater aquifers. Data acquisition was carried out using the geoelectrical resistivity method with Wenner configuration with three measurement points. Furthermore, the data processing used Res2dinv Software. The results showed that the measured resistivity value between 0.01000-501 Ωm with a maximum depth of 19.9 meters. The seawater intrusion distribution is assumed to be on lines 1 and 2 at an average depth of 10-19.9 meters with a resistivity value of 0.01000-0.230 Ωm. At the same time, the area that is not expected to experience seawater intrusion is on Line 3. The making of wells for coastal areas needs to consider the distance from the shoreline and rock porosity for minimizing the potential for seawater intrusion.

Early time data processing in shallow AEM exploration

For shallow exploration, high-frequency pseudo-random binary sequence is used in the time-domain airborne electromagnetic system. This system is working in the on-time and the earth response could be derived from system identification, which is different from the previous time-domain electromagnetic systems. The early time data is crucial for obtaining a detailed resolution. It could be severely disturbed by the primary field, the receiver response and noise. Here we present an approach for removing the primary field by matching subtraction in transformation of correlation calculation. The noise is suppressed as not correlated with the pseudo-random binary sequence. This approach is proved efficient by applying to simulation data based on forward modeling. The receiver influence is analyzed through the response of the equivalent electronic circuit. The 1D inversion results indicate that critical damping state and high cut-off frequency could reduce the adverse effect on the resolution of shallow exploration.

One-dimensional data analysis for aquifer layer in Pancuma Village, Tojo Una-Una, Central Sulawesi

The need for water resources continues to increase from year to year to meet various needs. The availability of water resources is increasingly limited due to seawater intrusion or water pollution. Pancuma Village is one of the coastal areas where it is necessary to study the potential of groundwater, especially during the dry season. One way to determine the presence of the groundwater aquifer layer is by using the resistivity method. This method is an effective geophysical method for shallow exploration so that it can be used to determine the structure beneath the earth’s surface. The configuration used in this study is the Schlumberger configuration. Research in Pancuma Village aims to determine the subsurface stratigraphy of the study area based on the resistivity value and to determine the distribution of groundwater aquifers in the study area. The results obtained from this study are that there are four types of subsurface layers in the study area, namely topsoil, claystone, iron sand, and alternating sandstone with conglomerates which are the aquifer layer in the study area. The resistivity value estimated at the aquifer layer ranges from 119 Ωm - 529 Ωm with a thickness of up to 45 meters.

Comparative phenomics of annual grain legume root architecture

AbstractSuboptimal water and P availability are primary limitations to grain legume production. Root architecture influences water and P acquisition, but tradeoffs need to be better understood and mitigated. We hypothesized that tradeoffs in root class investment and resource acquisition strategy would be observable in a variety of grain legumes. Diversity panels of common bean (Phaseolus vulgaris L.), tepary bean (Phaseolus acutifolius A. Gray), cowpea [Vigna unguiculata (L.) Walp.], soybean [Glycine max (L.) Merr.], chickpea (Cicer arietinum L.), groundnut (Arachis hypogaea L.), and single accessions of other legumes were phenotyped in the field. We identified inverse relationships among investments in different root classes in most species, and between indicators of deep and shallow exploration in all species. Bean and tepary bean showed particularly strong tradeoffs in investment patterns among root classes, whereas chickpea and groundnut show less pronounced tradeoffs. We found that legume root architectural phenotypes can be placed on a root system architecture (RSA) spectrum, and that root phenotypes of epigeal and hypogeal taxa present distinct adaptive mechanisms. These life strategies integrating resource acquisition, use, and phenology are exemplified by contrasting chickpea, with many root axes, to tepary bean with few root axes and a contrasting water use strategy. We propose several RSA ideotypes and highlight how dimorphic root architecture may co‐optimize resource acquisition.

Seismic exploration device based on time-frequency space algorithm

Among the exploration methods of oil and gas resources, one of the most important exploration methods is seismic exploration. Due to economic development, the previous shallow exploration has been unable to meet the needs, and it is necessary to conduct exploration in deep geological layers. However, as the depth increases, the signal of the geophone gradually weakens and the noise interference increases, which makes the denoising work of seismic exploration more important. Aiming at the above problems, this paper proposes the research of seismic exploration equipment based on time-frequency space algorithm, and uses different window lengths for processing based on the time-frequency peak filtering algorithm. Through simulation experiments on seismic exploration data with different frequencies, the results show that the method proposed in this paper improves the effective signal amplitude maintenance by more than 11%, and the amplitude maintenance is higher than 88%. The signal-to-noise ratio also improved from -8dB before filtering to 12.13dB. This shows that the method proposed in this paper can better meet the needs of seismic exploration signal processing.

Research on the fracture structure and activity of the Qinling Mountains thrust nappe system in western Hubei

The Western Hubei section of the Liangyun fault is an important structural belt of the southern Qinling Mountains thrust nappe system. As the significant activity of the Liangyun fault since the Quaternary has led to high seismic risk in the surrounding area, the research on the characteristics and activity of fault structure is of great significance for deepening the construction of a seismic safety system in this area. In this study, we conducted a field geology survey combined with quartz optical stimulated luminescence dating, scanning electron microscopy dating, and thermoluminescence dating results and comprehensive application of shallow seismic reflection and high-resolution refraction) to analyze the activities of the Liangyun fault in the Quaternary period. Sediment optical stimulated luminescence dating results of samples from the breakpoint were 134.99 + 15.52 and 160.95 + 16.88 ka. Combined with the seismic profile, outcrop observation, and previous dating results, we conclude that the new era is in fault activities in the early Pleistocene to late Pleistocene (Q2–Q3). The combined application of shallow seismic reflection and high-resolution refraction method can confirm each other’s measured results, providing more parameters for the interpretation of seismic data under complex conditions and ensuring the accuracy of data interpretation at the same time. At present, the seismic experiment scheme is less used in the field of active fault detection, since its good detection effect and the application of the trial to shallow geophysical exploration has a certain application value and global scalability.