Seismic Exploration Methods Research Articles

The Chemerpil gravimagnetic anomaly as a modern reflection of the unique Precambrian volcanic-plutonic magnetite-gold mineralisation structure of the Ukrainian Shield (Middle Bug area)

The article is devoted to the peculiarities of genesis and mineralogical potential of Chemerpol iron-magnetite structure, its difference from other similar objects of Central Bug area. As an independent geological-geophysical object it was established according to the data of gravimetric and magnetometric survey of medium scale as a complex localised maximum of subisometric shape with diameter of 1.7 km and area of 2.8 km2. In regional structural and tectonic terms, this maximum is confined to the Sinitsiv block of the Golovanovsk suture zone. As of today, the Chemerpol structure has been sufficiently investigated by mapping drilling and various geophysical methods at the level of the crystalline basement surface. Based on the obtained data, the main petrophysical complexes involved in its structure have been determined. The industrial and mineralogical potential of the Chemerpolska structure is estimated at 100 million tons of magnetite quartzites and carbonate formations, as well as 2 tons of exogenous gold in the weathering crust. No estimates have been made of the underlying gold deposits. Copper mineralisation, represented by the natural copper, chalcopyrite and chalcosine, has been identified in the weathering crust and crystalline basement. By structural and tectonic features, petrophysical and mineralogical diversity, the Chemerpolska structure can be attributed to local pipe volcanic-magmatic objects. Its closest well-studied geological analogues may be such Precambrian "stratified" iron-oxide-gold-copper deposits as Solobot and others of the Carajas ore district in Brazil. For geological verification of new conclusions about the peculiarities of the Chemerpol structure and its actual ore potential, it is necessary to continue its study based, first of all, on the data of targeted structural exploration drilling and deep seismic and electrical exploration methods. The economic efficiency of extraction of the main mineral components of the Chemerpolska structure - gold and magnetite iron - can be increased due to the accompanying use of non-metallic calcifiers for the manufacture of sintering flux, soil deoxidation, raw materials for road pavement.

Geophysical exploration strategy for Cu-Ni-Co deposits in China: A review

Nickel (Ni) and Cobalt (Co) deposits are important mineral resources, and China is the largest consumer of these resources. Magmatic, hydrothermal, sedimentary, and meta-sedimentary ore-bearing rocks are the most significant Co-Ni deposit types in China, accounting for 98% of the Co production. Thus, exploring the Chinese Co-Ni resources and reserves is beneficial for promoting its economic development. We have analyzed the metallogenetic geologic model and the physical characteristics of the rocks and ores of magmatic Co-Ni sulfide and hydrothermal Cu-Co deposits and the sedimentary and meta-sedimentary rocks that host the Cu-Co ore deposits to develop an effective geophysical exploration technology system. For magmatic deposits, the small ore-forming intrusion is the main detection target; in general, gravity, magnetic, and seismic exploration and artificial-source electromagnetic methods are widely used to determine the precise location of the ore-forming intrusion. For hydrothermal deposits, ore-controlling structures and favorable positions for mineralization (e.g., alteration belts) are the main exploration targets, and the combination of hyperspectral remote sensing, gravity, magnetic-excitation, chemical prospecting, and artificial-source electromagnetic detection techniques can help locating such ore body types. For sedimentary and meta-sedimentary ore-bearing deposits, a combination of soil debris geochemical exploration measurement, induced polarization (IP) scanning, gravity method, IP sounding, and the transient electromagnetic method has been used to scan and locate the ore-controlling and ore-bearing layers. Finally, upon selecting the Xiarihamu magmatic Co-Ni deposit in the East Kunlun orogenic belt as our study area, we have conducted controlled-source electromagnetic exploration and obtained reliable results. Our study can serve as a reference for determining the most effective geophysical technique for the exploration of Cu-Ni-Co deposits in China.

Research on Body Wave Extraction Technology of Mixed Active Source Ambient Noise

In complex surface environments, active source seismic exploration methods are difficult to stimulate and costly, while ambient noise detection technology is fast and convenient, with a little environmental damage and low cost. Therefore, it has aroused extensive research by scholars at home and abroad. At present, the use of passive source surface wave method for subsurface medium imaging has become mature. However, due to the low content and weak energy of the body wave signal in the actual ambient noise, it is particularly difficult to extract body waves using seismic interferometry. At the same time, body wave exploration has larger exploration depth and higher resolution. In this paper, we propose an ambient noise detection technology of mixed active sources, namely, imposing artificial seismic sources in the continuous ambient noise data acquisition process. We refer to the ambient noise of mixed active sources as "mixed ambient noise". It is found that the virtual refraction wave obtained by the ambient noise detection method of mixed active sources has high signal-to-noise ratio, strong anti-interference ability, and can obtain the real velocity information of the deeper subsurface medium, but cannot reflect the accurate time information. Supplementing the active source signal in the far field can obtain virtual refractions with higher signal-to-noise ratio, while effectively reducing the mixing phenomenon of surface wave and surface interference waves in the virtual common-shot record.

Three-component Seismic Data Acquisition System Base on STM32 and ADS1285

In the three-component seismic VSP seismic data acquisition, high-resolution and low-power seismic wave acquisition is an important research content of seismic exploration methods. In view of the problems of insufficient resolution and signal attenuation of existing geophones, which lead to distortion of seismic signals collected in complex strata. A digital downhole digital three-component detector based on ADS1285 is proposed. The design uses STM32F405 as the microcontroller, ADM2582E as the RS485 transmission chip, and uses the PPP communication protocol to achieve high-speed communication with the host computer. Experimental results show that the dynamic range of the data acquisition system based on ADS1285 is 135dB, and the average analog-to-digital conversion equivalent noise level is below 0.5μV, which can effectively improve the acquisition accuracy of field seismic exploration.

Information model of a geoinformation system for studying the geometry of rock massif based on seismic survey data

This scientific article explores the development of an information model for a geospatial information system (GIS) to manage data on the geometry of rock formations using seismic exploration methods. The main objective of the research is to analyze the key data clusters, identify separate data repositories, and develop efficient tools for visualization and analysis of geospatial data. Additionally, the application of distributed databases for ensuring fault tolerance and improving system performance is discussed. The study examines the usage of tools such as ezdxf and ABViewer and their application for three-dimensional visualization of heterogeneous rock formations data.

Seismic Exploration Methods for Structural Studies and for Active Fault Characterization: A Review

In this paper, seismic exploration methods are reviewed with a particular emphasis on the use of the reflection seismology to investigate the subsurface structures and characterize active faults. The paper provides a descriptive overview, intended for a non-specialist audience, of the methods and of their recent developments aimed at improving the resolution, accuracy, and computational efficiency of seismic imaging. Techniques such as seismic ray tomography, full-waveform inversion and pre-stack depth migration are briefly introduced, highlighting their potential applications in structural geology studies. The main seismic attributes that have become increasingly important in the interpretation of faults and fractures are also presented, along with some examples of application. Finally, some case studies of active fault characterization are discussed. From these examples, the crucial role played nowadays by the seismic exploration methods for structural studies and for active fault characterization is evident.

Mathematical modeling of a new method for processing a seismic signal on the example of a section of the Saratov right bank. Part 2

This paper presents a new method of seismic exploration with two buried receivers on the same vertical, which helps in comparing the experimental seismogram cleared of non-vertical signals with the calculated theoretical seismogram, which depends on the parameters of the layered structure, such as the thickness of the layers, their density, velocity of propagation of longitudinal acoustic waves in rock, and seismic quality factors of media. The method of least squares aided in the search for the global minimum of the discrepancy function of the calculated and experimental seismic pulse waveforms. The implementation of the algorithm for solving the inverse seismic problem was carried out in the MatLab software package. The construction of a theoretical seismogram includes the calculation of the spectrum of the input impulse, calculation of the frequency dependences of the reflection coefficients and the passage of waves at the interfaces of rocks with different physical parameters, the calculation of the shape of the seismic impulses received by the receivers. A comparison of the calculated and real parameters of the geological structure obtained in the COMSOL Multiphysics software package shows that the developed algorithm results in obtaining a seismogram that practically coincides with the experimental seismogram corresponding to the real rock section, with appropriate geological parameters of media, such as thickness, density and propagation velocity of acoustic waves, as well as quality factors.

Three-dimensional P-wave model of the shallow crustal structure, a complementary method for detecting a trapped hydrocarbon: a case study in the DehDasht region, SW Iran

Abstract Local P-wave tomography is an efficient method to study geologically complex areas where the seismic exploration methods are not ideal for unraveling the shallow crustal heterogeneity due to the great thickness of evaporitic deposits. Despite the complex geological features in the salt-rich DehDasht region, SW Iran, we used >11 000 micro-earthquake events, which have been recorded by a temporary seismic network (deployed between 18 October 2016 and 1 July 2017), to derive the three-dimensional velocity structure based on the first arrival time. We selected a subset of events (1571 micro-earthquakes) by various strict criteria for our processing, and then the 1D velocity model was calculated by the computer program VELEST. Afterward, the 3D initial model of the inversion procedure with 1.5-km horizontal and 1-km deep intervals was parametrized using the calculated 1D model. Finally, the observed data (first arrival P-wave traveltimes and events locations) was inverted with an optimum regularization parameter and iteration using the computer program SIMULPS14. Our tomographic results indicate the DehDasht Basin as a relatively low-velocity zone filled out dominantly by the Gachsaran Formation and surrounded by the high-velocity Asmari-Pabdeh-Sarvak Formations. The basin has a bowl shape that is elongated in the NW–SE direction or an oval on a horizontal view. The depth of the basin varies between 3 and 5 km and contains many folding-faulting systems, which lead to locally low-velocity patches. Moreover, some evaporate deposits, which are overlying the Gachsaran Formation, emerge as a thin low-velocity layer (e.g. Aghajari, etc.).

Three-Dimensional Processing of Reflections for Passive-Source Seismology Based on Geometric Design

Passive-source exploration is a method of seismic exploration that has loose requirements on the conditions of the surface, is cheap, and does not require excitation by an active source. The ambient seismic signals collected from the field over an extended period of time can be used to generate virtual-shot seismic records similar to those obtained from the seismic exploration of an active source based on the relevant correlations, and this can in turn yield information on the underground structure through a series of conventional methods of processing seismic data. Three-dimensional (3D) processing can mitigate the influence of the azimuth of random noise to yield a more representative underground structure, but requires intensive computation. In this paper, we propose a 3D method to compute reflections of a passive source based on the geometry of seismic exploration. Assuming a high quality of imaging, we use information on the predesigned geometry to choose and correlate noisy synthetic data on the reflections by a seismic body to create virtual shot data, and subsequently capture images of the 3D data on passive reflection. The use of the predesigned geometry ensures that only the important and useful parts of the dataset are used for correlation and imaging, where this reduces the cost of computation. The proposed method can thus efficiently generate high-quality 3D synthetic data.

Mathematical modeling of a new method for processing a seismic signal on the example of a section of the Saratov right bank. Part 1

The paper presents a new method of seismic exploration, which includes two receivers of acoustic signals, deepened into the rock one under the other at some distance. These receivers record seismograms which are the acoustic signals, the source of which can be the natural seismic activity of the Earth’s crust or targeted sources of acoustic signals, such as an explosion. Simulation of the direct problem of seismic exploration was performed using the COMSOL Multiphysics and MatLab software packages. The seismograms obtained during the simulation are combined and added with each other with the on the delay time shift of the input seismic pulse between the receivers. In this case, the signals that came along the vertical, “amplify” each other on the total seismogram, and non-vertical signals are damped. The correlation function of seismograms was obtained for mathematical simulation. The results of modeling the propagation of an acoustic wave in rocks and an example of processing seismograms according to the proposed algorithm are given. The presented results show that the new method of receiver location and the method of processing seismograms make it possible to obtain a cleared seismogram that can be used to solve the inverse problem of determining the parameters of the geological environment.

Denoising and wavefield separation method for DAS VSP via deep learning

Distributed acoustic sensing (DAS) vertical seismic profiling (VSP) is, a new combined method of borehole seismic exploration, that has the advantages of low cost, high resistance to temperature and pressure, and high sampling rate. However, the collected data generally suffer from high noise, detracting from the potential high-precision imaging benefits and limiting the full application of the technique. The quality of wavefield separation is also crucial to VSP processing. To mitigate the various problems, a regularized residual channel attention network (RRCAN) is proposed for improved denoising and wavefield separation. Based on two prediction tasks, the networks are built (i.e., RRCAN_1 and RRCAN_2) by adding a regularization term to the loss function. To reduce the loss of effective signals during the denoising process, a wavefield separation method that includes secondary effective information extraction is adopted. The final separation results reflect the denoised and removed noise data, a total of 500 geological models are constructed using a random method and RRCAN_1 is trained with synthetic and field noise data. The conventional plane-wave destruction method is improved by using velocity information, and high-precision separation results for upgoing and downgoing waves are obtained for RRCAN_2 training. The test results obtained for the synthetic and field data show that the proposed network effectively suppresses DAS VSP noise while yielding excellent separation results for downgoing and upgoing waves. Therefore, denoising and wavefield separation methods based on RRCAN provide effective high-precision DAS VSP imaging.

Research on comprehensive detection and visualize of hidden cavity goaf

At present, the research on goaf at home and abroad mainly focuses on four aspects: detection technology, stability evaluation technology, governance technology and quality control technology. The most important of the above four aspects is goaf detection technology. In order to ensure the accuracy and precision of exploration, many geophysical methods and high-density geological drilling are usually used for exploration. In case of complex terrain, this method will increase the workload rapidly, and can not achieve a good balance between exploration cost and exploration quality. Goaf exploration methods are still in the development stage, and each geophysical exploration method has its limitations. This study makes full use of the existing detection technology to detect the complex mined-out area of East Open-pit Mine, 9 inferred mined-out areas and 9 suspected mined-out areas were found by using 3D seismic exploration method, transient electromagnetic method is used to delineate 223 abnormal areas at different elevations within the exploration range. 58 drilling holes are arranged in the suspected mined-out area of East Open-pit Mine. Combined with geological software, 3D model map of mined-out area is drawn, and the causes of formation of mined-out area are classified and analyzed. Using 3D laser scanning technology to study the visualization of hidden mined-out areas, the hidden mined-out areas are divided into three types through visualization research, and its formation mechanism is analyzed. It can be applied to detection of open-pit mines which have small underground coal mines and many mined-out areas with complex geometric shapes and has great significance to the proposal of stability treatment scheme of mined-out area. The novelty of this study is prove the area, shape, roof thickness and height of the mined-out area by using joint detection method and the hidden mined-out area is visualized by 3D laser scanning technology.

Investigation on geological structure and geothermal resources using seismic exploration

Seismic exploration was used to investigate geological structure and potential location of geothermal resources in Xian County, North China. The velocity structure survey near surface was conducted by micro-logging and small refraction to determine the observation system and static correction models. Two test sections and many of test points were designed to get the best experimental parameters. The static correction was used to eliminate surface differences accompanied with deconvolution to improve resolution, and the high-precision velocity analysis and three-dimensional Monte Carlo high-precision residual static correction were used to obtain a better signal-to-noise ratio (SNR). The imaging section was converted into geological model in the working area by seismic interpretation technologies. The general morphology and buried depth of the main interfaces in each layer were obtained by using the seismic exploration methods. The potential location of geothermal resource was predicted mainly in Jixianian of Proterozoic of the Middle Upper and the Cambrian Ordovician of Paleozoic and the favorable location of two exploration boreholes were calibrated based on these analyses.

Joint Obn and 3D Das-Vsp Data Acquisition and Processing in the East China Sea

Borehole and surface joint seismic exploration is a 3D seismic exploration method formed by the combination of surface seismic and VSP survey simultaneously. Using the 3D DAS-VSP data, accurate time-depth relationship, formation velocity, deconvolution operator, spherical diffusion compensation factor, absorption attenuation factor, anisotropy parameters and high-resolution structural imaging around the wellbore can be obtained. These parameters can be used to significantly enhance the surface 3D seismic data processing. This paper describes the 3D DAS-VSP data acquired by a downhole armoured optical cable simultaneously with an OBN data acquisition project in East China Sea, and the results of 3D DAS-VSP data imaging processing. The usual 3D VSP data imaging processing steps include: observation system definition, preprocessing, first arrival picking, static correction, amplitude compensation, deconvolution, wavefield separation, velocity analysis and imaging. Based on the characteristics of offshore 3D VSP downgoing multiples, the offshore 3D VSP downgoing multiple imaging technique has been innovatively developed. This greatly expands the 3D DAS-VSP imaging range and improves the overall 3D DAS-VSP imaging quality. The 3D DAS-VSP downgoing multiple reflection wave imaging shows significant imaging quality improvement in comparison with the vintage 3D OBC data imaging. The detailed structure, tracing of the reservoir and formation tops becomes easier and less ambiguous using both new OBN data imaging and 3D DAS-VSP data imaging when compared with the vintage 3D OBC data imaging.

Identification and Evolution of Different Genetic Types of Deep Karst Caves Controlled by Faults—A Case Study in Huanjiang Sag, Guangxi Province, South China

In recent years, it has become more and more common to drill deep karst caves as a part of deep shale gas resource exploration and engineering construction in South China. However, the amount of research on the genesis and development mechanism of deep karst caves is relatively low. Based on drilling core karst morphology analysis and two-dimensional (2D) seismic and wide-field geophysical exploration methods, it is revealed that the deep karst in the Huanjiang area is mainly composed of net cracks, holes expanding along cracks and dolomite honeycomb pores, and that large karst caves are also developed, which are related to NW-trending faults. The deep karst is developed in the hanging wall of the fault, with a width of 500 m and a height of 1500 m, and a linear distribution along NW faults in the region. Based on Th-U dating, inclusion testing and rare earth elements from cave fillings, it is revealed that the development of deep karst space is related to two deep karst genetic types: The first is the hypogene hydrothermal karst, which developed in the Yanshanian period and is related to regional magmatism. The second is the groundwater deep circulation karst, mainly developed after the Himalayan period, which is related to the deep circulation of meteoric water. The genesis of deep karst space is the result of multi-stage karst superposition and is mainly controlled by faults. It is difficult to determine the specific time points of these two types of deep karst transformation, but according to regional tectonic evolution, we speculate that the Yunnan-Guizhou Plateau has been uplifted since the Himalayan period (>3.54 Ma), and the Carboniferous carbonate rocks and early faults in the Huanjiang area have been exposed, leading to the change and evolution of deep karst. Through comprehensive analysis, a fault-controlled hypogene hydrothermal karst pattern and a meteoric water deep karst pattern are established. The genetic pattern of deep karst provides theoretical support for predicting this kind of karst in southern China and for avoiding drilling deep karst caves as a part of resource exploitation.

A Metallogenic Model for Bauxite Deposits and Geophysical Prospecting Methods: Using the Sedimentary Type in Northern China as an Example

An ideal metallogenic and prospecting model has important guiding significance for aluminum ore development and geophysical exploration. Previous research in this field only focused on ore body evaluations and metallogenic belts. Selection of reasonable geophysical methods for exploration of bauxite deposits is still challenging. To solve these problems, a new metallogenic model based on the new geological information is established firstly. The ore-bearing rock and ore bodies of sedimentary bauxite deposits are strictly controlled by the paleo-topographic conditions. The undulating shapes of the paleo-topography control the scales and shapes of ore-bearing rock series and bauxite ore bodies. Then, different geophysical methods applied for exploration of bauxite deposit are analyzed based on the petrophysical measurement. For the areas with thick overburden and large buried depths, it was found that fixed-loop transient electromagnetic (TEM), high-precision gravity, and seismic exploration methods were most effective. In regard to the areas with thin overburden and small buried depths, direct current (DC) sounding, high-precision gravity, seismic exploration, and TEM methods were considered to be effective. However, for the areas with very shallow buried depths, DC sounding and seismic exploration methods were deemed to be more suitable. This study selected the actual exploration processes of the Wanggudong bauxite mining area in western Henan as an example, and the application of a DC sounding method for sedimentary-type bauxite was successfully introduced.

Metallic mineral exploration by using ambient noise tomography in Ashele copper mine, Xinjiang, China

Rapid advances in the seismic exploration method have allowed its application in metallic mineral exploration. However, 2D seismic profiles are often insufficient to describe the shape and areal extent of ore-bearing rock masses away from survey lines. Although more complete, collecting 3D seismic data is expensive, time consuming, and may require considerable investment in surface access. The combination of ambient noise tomography and 2D seismic reflection exploration methods can produce acceptable results relatively quickly and at a low cost. The enormous Ashele copper deposit in northwest China is a typical deposit formed by volcanic eruption. It is rich in resources and possesses good prospecting potential in its deeper and peripheral areas. We performed ambient noise tomography to investigate a near-surface 3D S-wave velocity ([Formula: see text]) structure above a depth of 0.7 km in the Ashele mining area (approximately 8 × 12 km) using 25 days of continuous ambient noise data. From the combined interpretation of the 3D [Formula: see text] structure and the existing 2D seismic reflection profile, we infer that there may be ore-bearing rock masses in the western and northern sides of the research area. We report the discovery of an ancient volcano at a depth of 500 m on the western side of this region. The banded velocity anomalies and the existence of the ancient volcano signify the formation process of a bimodal volcanic rock association. It has been proven that the combination of ambient noise tomography and 2D seismic reflection exploration methods can produce important results in metallic mineral exploration. Therefore, ambient noise tomography can be used as an economical, convenient, and efficient method for future explorations, complementing the 2D seismic reflection exploration method.

Characterization of Soil Profile Using Dispersion Curve Analysis

Research has been carried out on the seismic refraction exploration method by utilizing piles on the construction project of the Geomatics Campus II FTSP ITS Surabaya as a source of vibration. Rayleigh waves are one type of surface wave that is good for identifying layered structures near the earth's surface because 67% of the energy The total amount released by the seismic wave source is transmitted in the form of Rayleigh waves. In the layered medium, Rayleigh waves have dispersive properties, speed as a function of frequency. This property can be used to determine the structure of the earth's layers based on the shear wave velocity (Vs) with depth (h). The inversion process is carried out to match the measurement dispersion curve and the model. The result of the inversion process is the shear wave velocity (Vs) function of depth. This research is expected to identify and characterize the soil profile at the research site. On the track, there are three layers indicated as clay layers, in the first layer 0-6 meters with an average speed of 250 m/s, the second layer 6-19 meters with an average speed of 971 m/s, and the third layer 19-57 meters with an average speed of 1564 m/s

Seismic interpretation and data management by using opendtect and qgis: case study in the North Sea, Netherlands

Seismic exploration method is one of the most important geophysical methods widely applied in the survey of deep geological structures. The seismic wave diagram is related to the acoustic impedance characteristics of the rock environment to help reflect the images of geological objects below. Effective management of the resulting data before and after seismic interpretation will help scientists have an overview in assessing geological objects to be studied. This management process is demonstrated by the need for information to be arranged in a unified manner and the need to quickly update and extract the resulting information. In this paper, our interest is in analyzing seismic data to highlight geological features including gas chimneys and geological fault systems in the North Sea region, the Netherlands. I will conduct two phases of analysis to serve the data management process. First, seismic properties such as entropy and homogeneity composition properties are applied to clarify the position of gas chimneys and geological faults in three-dimensional space. The second process is to extract the interpretation results of these two features into an open source geographic information system. As a result, each feature will be represented on a geographic map through their coordinate value along with images of the object's seismic properties.

Analysis of High-Resolution Seismic Exploration in Coalfield Geological Exploration Methods

In the field of coalfield geological research, the era of traditional geological research has basically ended. At present, it is in the period of earth system scientific research. Starting from the main factors affecting high-resolution seismic exploration and combining with some examples of high-resolution seismic exploration in coal exploration,.this paper analyzes and discusses the middle and high-resolution seismic exploration methods in coal exploration, mainly discusses several key links of high-resolution seismic exploration in the field data acquisition process, and makes a brief summary and induction of seismic wave excitation, seismic wave reception, demonstration of acquisition methods and noise suppression.