Rujun Chen

Verified

Rujun verified their affiliation via an institutional email.

Learn more

Verified

Rujun verified their affiliation via an institutional email.

Learn more

• Doctor of Philosophy
• Professor (Associate) at Central South University

In induced polarization surveys, the raw data are usually distorted significantly by the presence of ElectroMagnetic (EM) interferences including cultural noise. Several methods have been proposed to improve the signal-to-noise ratio of these data. However, signal processing in an electromagnetically noisy environment is still a challenging problem...

Trend drift is an annoying background interference in induced polarization (IP) exploration, which has great influence on the final calculation of apparent complex resistivity spectrum at low frequency (< 0.1 Hz). This paper proposed a modified empirical mode decomposition (EMD) detrending technique for multi-period induced polarization data. The m...

Disseminated ores in porous or fractured media can be polarized under the application of an external low-frequency electrical field. This polarization is characterized by a dimensionless property that is called the “chargeability”. Induced polarization is a nonintrusive geophysical sensing technique that be used in the field to image both the elect...

In audio magnetotellurics (AMT) sounding data processing, the absence of sferic signals in some time ranges results in a lack of energy in the AMT dead-band, causing unreliable resistivity estimations. To address this issue, we propose a deep convolutional neural network (CNN) to automatically recognize sferic signals from redundantly recorded data...

Non-invasive geophysical exploration methods a play key role in the exploration of ore deposits. In the present study, the audio-frequency magnetotelluric (AMT) method was applied to metallic mineral exploration. The metallic mineral deposit targeted was the recently discovered super large lead–zinc deposit of the Zhugongtang mining area of Hezhang...

Kadanwari Gas Field (KGF) is located in the Middle Indus Basin (MIB), Pakistan is characterized by a variety of heterogenous sedimentary facies, and unique reservoir architecture. These factors make the area more challenging with respect to identification of hydrocarbon potential. Several studies were conducted to delineate the true potential of th...

Models of subsurface structures are important for successful deposit exploration, but are challenged by the need to integrate data from different geophysical methods. In the present study, we evaluated a method of joint inversion in which audio-magneto telluric (AMT) and dual frequency induced polarization (DFIP) data sets are inverted simultaneous...

The Pab Sandstone, a significant and heterogeneous hydrocarbon development target in Pakistan’s Lower Indus Basin, offers a unique opportunity to investigate diagenetic and depositional controls on reservoir quality. A substantial uncertainty in reservoir quality assessment pertains to diagenetic effects. An integrated approach, including detailed...

Geophysical exploration for disseminated chromite deposits has always been challenging because the ore body does not exhibit significant geophysical anomalies. An understanding of petrophysical rock parameters can make the interpretation of geophysical data more accurate. The spectral induced polarization (SIP) method emerged as a promising techniq...

The complex resistivity (CR) measurement constitutes a practical methodology for investigating the internal structures of rocks and ores alongside their mineralogical compositions and the chemical properties of fluids. However, during complex resistivity testing, particularly at high frequencies, the leakage current caused by the distributed capaci...

Ophiolites are the best archives of the evolutionary history of the Earth, especially the ocean basins from their rift–drift to subduction initiation and final closure. The studies of ophiolite have brought together diverse groups of scientists and professionals all through the world on a regular basis far more than any other topic in geology. Ophi...

Pore pressure is a decisive measure to assess the reservoir's geomechanical properties, ensures safe and efficient drilling operations, and optimizes reservoir characterization and production. The conventional approaches sometimes fail to comprehend complex and persistent relationships between pore pressure and formation properties in the heterogen...

The current research deals with the petrophysical analysis of a collection of Chromite and associated host rock samples from the Dargai Complex Heru-Shah, NW, Khyber pakhtunkhwa (KP), Pakistan. Geophysical exploration for disseminated chromite deposits always proves difficult, as these deposits do not manifest significant geophysical anomalies. How...

An essential resource, groundwater is necessary for the maintenance of human activity, agriculture, and ecosystems. Finding the sources of groundwater leaks is crucial for effective water management and the avoidance of any environmental risks. In the karst region of Fuquan, Guizhou, China, the use of Spread Spectrum Induced Polarization (SSIP) as...

The gradual decline of production of the major fields of the Indus Basin has influenced the field pressure. Therefore, the prospects need to be assessed by the petro-elastic relationship. This study highlights the value-addition for identifying gas pockets within the E-Sand of the Lower Goru Formation through estimating and populating petro-elastic...

Citation: Ahmad, J.; Chen, R.; Ahmed, I.; Yaseen, M.; Shah, S.A.; Rahim, O.A.; Ullah, F.; Fahad, S.; Rui, L. Spread Spectrum Induced Polarization (SSIP) Survey for the Qiushuwan Copper-Molybdenum Deposits in Southern Henan Province, China. Minerals 2024, 14, 934. https://doi.org/10.3390/ min14090934 Academic Editor: Michael S. Zhdanov Abstract: The...

As critical minerals in low-carbon economies, rare-earth elements (REEs) are crucial for modern industry, technology, and medicine. The largest known REE resource in the world is the Bayan Obo (BO) deposit in northern China. However, BO features as complicated mineral compositions and has experienced several geological events. As a reuslt, controve...

The Qiushuwan Cu-Mo deposit is located in the East Qinling molybdenum belt and is an important mining location known for its medium-sized molybdenum resources. In order to enhance our comprehension and discover supplementary mineral deposits, it is essential to carry out a comprehensive investigation of the deep and peripheral areas. This study spe...

In the present study, we evaluated a method of joint inversion in which audio-magnetotelluric (AMT) and dual frequency induced polarization (DFIP) data sets are inverted simultaneously to produce a consistent 2D resistivity model to show a clear image of subsurface structures. To achieve the objectives, we conducted AMT and DFIP surveys first on th...

The growing expansion of the economy and population has resulted in an increased inclination towards the utilization of groundwater resources. Conducting a geophysical survey is a widely employed method for subsurface mapping and the detection of groundwater. A geophysical study was conducted in Nanshan township, Huarong County, located in the Huna...

Successful geophysical exploration projects in the Gucheng-Yaxi area located in Gaochun District, Jiangsu Province, China, have been limited partly due to the complex geological conditions of the area and high artificial noise in data acquired using electrical and electromagnetic methods. In this study, we deployed the new anti-interference spread-...

The growing expansion of the economy and population has resulted in an increased inclination towards the utilization of groundwater resources. Conducting a geophysical survey is a widely employed method for subsurface mapping and the detection of groundwater. A geophysical study was conducted in Nanshan township, Huarong County, located in the Huna...

The growing expansion of the economy and population has resulted in an increased inclination towards the utilization of groundwater resources. Conducting a geophysical survey is a widely employed method for subsurface mapping and the detection of groundwater. A geophysical study was conducted in Nanshan township, Huarong County, located in the Huna...

Models of subsurface structures are important for successful deposit exploration but are challenged by the need to integrate data from different geophysical methods. In the present study, we evaluated a method of joint inversion in which audio-magnetotelluric (AMT) and dual frequency induced polarization (DFIP) data sets are inverted simultaneously...

The Qiushuwan Cu-Mo deposit, located in the East Qinling molybdenum belt, which is a major mining site recognized for its enormous reserves of medium-sized molybdenum. In order to enhance our comprehension and ascertain supplementary mineral resources, it is critical to conduct an in-depth investigation of both the deep and peripheral regions. The...

Successful geophysical exploration works in Gucheng-Yaxi area located in Gaochun District, Jiangsu province, China, have been limited partly due to complex geological condition of the area and high artificial noise in data acquired using electrical and electromagnetic methods. In this work, we deployed the new anti-interference spread spectrum indu...

Unconventional hydrocarbon exploration is needed in the current oil and gas crisis scenario. Therefore, the development of conditions for unconventional hydrocarbon exploration is needed. In the Upper Indus Basin (UIB), Pakistan, the Patala Formation is one of the potential candidates for this unconventional exploration. It is a proven source rock...

In the exploration of ocean resources, the submarine electric field signal plays a crucial role through marine electromagnetic methods. However, due to the field signal’s low-frequency and weak characteristics, it often encounters interference from the instrument’s own 1/f noise during its acquisition. To address this issue, we developed a low-nois...

Research on the electrical properties of rocks and ores plays a crucial role in the development of geophysical electromagnetism methods. However, currently available instruments suffer from high power consumption, a limited number of electrodes, inaccurate measurements, poor portability, and a limited ability to measure the electrical parameters of...

Geothermal resources are a sustainable and valuable source of energy that offers considerable economic and social advantages. The present investigation centers on the accessibility of geothermal reservoirs in Reshi Town, Taoyuan County, Changde City, located in the Hunan Province of China. Geophysical exploration techniques are of paramount importa...

Non-intrusive geophysical exploration methods play a major role in ore deposit detection. This study aimed to characterize the subsurface electrical resistivity structure across the recently discovered super-large Zhugongtang lead-zinc deposit in north-western Guizhou province of China, using audio magnetotellurics (AMT) method. The results of this...

Chromite is the only mineral that is a commercial natural source of chrome. Chromite deposits are subdivided into podiform and stratiform (layered) types based on the geometry of the ore bodies and their host rocks. The podiform chromite deposits are always developed in ophiolite complex. Geophysical exploration for podiform chromite deposits is di...

Tetrahedrite-(Ni) (IMA2021-031), ideally Cu6(Cu4Ni2)Sb4S13, is the first natural Ni-member of tetrahedrite group mineral found in Luobusa chromite deposit, Tibet, China. The new species occurs as anhedral grains 2 to 20 μm in size, associated with gersdorffite, vaesite, and chalcostibite, which are disseminated in a matrix of dolomite, magnesite, q...

Lithium is a critical metal widely used in Li-ion batteries for energy storage. The demand for lithium resource in a low-carbon economy is immense and rapidly growing, where a jump between 2015 to 2050 is predicted by Science. Currently more than half of lithium production comes from pegmatite lithium deposits. However, due to similar rock property...

The new mineral tennantite-(Ni), Cu6(Cu4Ni2)As4S13, has been discovered from the Luobusa Chromitite, Tibet, southwestern China. Tennantite-(Ni) occurs as anhedral grains ranging from 2 to 20 μm in size. In reflected light microscopy, tennantite-(Ni) is isotropic and appears yellow-greenish grey. The reflectance data for the four COM wavelengths for...

Drinking water shortage is a major concern in villages across southern Jiangxi, and this has impacted economic and social development. In order to address this challenge, groundwater prospecting was carried out in the villages under the support of Drinking Water Safety Project of China Geological Survey. In this study, we present two example sites...

This paper designs a new distributed time synchronization system without GPS restriction to help geophysical instruments perform distributed prospecting in an environment where there is no GPS signal at all, such as in the mine or the tunnel. In order to solve the problem that geophysical instruments can also perform distributed prospecting in unde...

Induced polarization (IP) is a widely used geophysical exploration technique. Continuous random noise is one of the most prevalent interferences that can seriously contaminate the IP signal and distort the apparent electrical characteristics. We propose a noise separation algorithm based on deep learning to overcome this issue. The standard IP sign...

In the audio magnetotellurics (AMT) sounding data processing, the absence of sferic signals in some time ranges typically results in a lack of energy in the AMT dead band, which may cause unreliable resistivity estimate. We propose a deep convolutional neural network (CNN) to automatically recognize sferic signals from redundantly recorded data in...

Shallow conductive heterogeneity can lead to a static shift in the apparent resistivity sounding curve of controlled-source audio-frequency magnetotellurics (CSAMT). The static effect will shift the apparent resistivity curves along with log-log coordinates axial. Such an effect, if not properly processed, can distort the resistivity of the rock fo...

The invention provides a rock ore specimen impedance measurement signal source generation circuit and device. The circuit comprises an intelligent mobile device; the integrated instrument is connected with the intelligent mobile equipment through a wireless network, and a first electrode interface, a second electrode interface, a third electrode in...

The invention provides a rock ore specimen impedance remote measurement system and method. The method comprises the following steps: step 1, establishing wireless network connection between an intelligent mobile device and a specimen impedance tester through a wireless communication module; step 2, performing collection parameter setting and specim...

IMA No. 2021-031 Tetrahedrite-(Ni) Cu6(Cu4Ni2)Sb4S13 Luobusa deposit, about 16 km northeast of Qusum County, Tibet, China (29°10’58.0” N, 92°17’47.6” E). Yanjuan Wang, Rujun Chen, Xiangping Gu*, Zenqian Hou, Zhusen Yang, Guochen Dong, Hu Guo and Kai Qu. *E-mail: guxp2004@163.com Tetrahedrite group Cubic: I-43m; structure determined a = 10.3478(...

IMA No. 2021-018 Tennantite-(Ni) Cu6(Cu4Ni2)As4S13 Luobusa deposit, about 16 km northeast of Qusum County, Tibet, China (29°10’58.0” N, 92°17’47.6” E) Yanjuan Wang, Rujun Chen, Xiangping Gu*, Zhusen Yang, Zenqian Hou, Guang Fan, Lijuan Ye and Kai Qu *E-mail: guxp2004@163.com Tetrahedrite group Cubic: I-43m; structure determined a = 10.2957(9) Å 4....

The continuous development of Internet of Things technology and computer technology has provided a technical foundation for the development of geophysical instruments, and at the same time, it has realized the remote acquisition and control of the instruments, and has also become the guarantee of the high quality and high performance of the instrum...

The spectral induced polarization (SIP) method is developed on the basis of the induced polarization method. According to the imaginary and real parts of the measured apparent complex resistivity, the amplitude and phase values are obtained to determine the physical characteristics of the underground anomaly. The frequency range of the traditional...

In near surface electrical exploration, it is often necessary to estimate the Cole-Cole model parameters according to the measured multi-frequency complex resistivity spectrum of ore and rock samples in advance. Parameter estimation is a nonlinear optimization problem, and the common method is least square fitting. The disadvantage of this method i...

Potential electrode space is an important factor in induced polarization exploration to balance the signal strength and resolution. How to choose an appropriate space is a difficult task because both the level of noise interference and the size of subsurface structure are unknown. By testing numerical model and acquired data, we found that, IP data...

The responses characteristic of transient electromagnetic in detecting shallow karst is studied focusing on the engineering and environmental problems caused by karst collapse. The shallow karst is generalized to be two types of geophysical models. The three dimensional finite difference time domain method is used to simulate the transient electrom...

We applied the principal component geostatistical approach (PCGA) to the inversion of time-domain induced polarization data in terms of resistivity and chargeability distributions. The PCGA presents two major advantages over standard methods: (1) It avoids the storage of the usually large covariance matrix, which contains the geostatistical informa...

The exploration of podiform chromites in the Indus Yarlong Zangbo suture zone of southern Tibet has proved difficult because most known deposits pinch out and then reappear in the same direction. Several ground-based geophysical approaches such as gravity, magnetic, and controlled-source audio-frequency magnetotelluric (CSAMT) methods have been app...

Time domain induced polarization (TDIP) and frequency domain induced polarization (FDIP) synthetic models, incorporating three-dimensional (3D) anisotropic medium, were tested. In TDIP modeling, both resistivity and chargeability of the medium were anisotropic, and the apparent chargeability values were calculated by carrying out two resistivity fo...

In this paper, we proposed a method to identify the frequency response of the system directly by the circular cross-correlation method, which is different from the conventional method of identifying the impulse response of the system, and can be used in geophysical spectrum induced polarization method. The specific method is: using the coded source...

Shale gas is a particularly important research target on Chinese energy resources, especially in the upper Yangtze region. Complex topography and geological conditions challenge seismic exploration of shale gas in this area, and ground-based electromagnetic (EM) methods are employed to aid to recognize the favorite reservoirs. However, the electric...

Induced polarization (IP) methods are effective approaches in exploration and environmental geophysics. In practice, the earth electrical conductivity shows anisotropy, which will also influence the IP response. However, only a few researches have studied this issue. In this paper, we modeled and analyzed the induced polarization response in the an...

Southwestern Tibet plays a crucial role in the protection of the ecological environment and biodiversity of Southern Asia but lacks energy in terms of both power and fuel. The widely distributed geothermal resources in this region could be considered as potential alternative sources of power and heat. However, most of the known geothermal fields in...

Audio-frequency magnetotelluric (AMT) exploration and control sources audio-frequency magnetotel-luric (CSAMT) exploration is widely used in China for mineral exploration, geothermal exploration, and engineering geophysics. However, the data quality and data density are limited because of few data acquisition units used for above exploration. This...

AMT method is widely used in China for mineral exploration. The resolution of 2-D inversion is usually poor because of static shift and topography effect. Because mineral resources is usually located in mountain area, topography effect may cause serious problem for near-surface exploration. To evaluate the performance of 3-D AMT inversion, we carri...

We developed an ultra-low power, high precision magnetotelluric (MT) data acquisition system based on ZigBee network and GPS. This system is composed of 100 MT data acquisition units, and a control center. Each MT data acquisition unit is composed of power supply and management subsystem, GPS timing and sync subsystem, embedded computer based on AR...

Considering traditional mean stack and digital filtering method can't reduce impulse noise effectively in the data processing of induced polarization based spread spectrum signal. The impact of impulse noise will remain in the complex resistivity spectrum, which will influence the calculating of induced polarization parameters. Objective of this pa...

In this paper, we investigated the robust processing of noisy spread spectrum induced polarization (SSIP) data. SSIP is a new frequency domain induced polarization method that transmits pseudo-random m-sequence as source current where m-sequence is a broadband signal. The potential information at multiple frequencies can be obtained through in meas...

Data processing in strong interference environment was investigated and coherence analysis was applied to do it for multi-frequency IP exploration. The coherence of potential difference and transmitting current for each period is relative to the data quality and the signal-to-noise ratio (SNR). SNR of data with coherence more than 0.5 can be high e...

Spectral induced polarization (SIP) or complex impedance measurement of ore and rock samples is widely studied in recent years. However, few attention is paid for the nonlinear effect in SIP measurement. We find that this effect is easily happened for low impedance sample measurement when a fixed voltage (for example, 5 volts) is given to current e...

Complex impedance measurement of sample in laboratory is the base for the research and application of spectral induced polarization (SIP) method or electro-physics of rocks and minerals. A lot of problems are faced if we measure complex impedance or SIP response of high impedance samples. We need the instruments with high input impedance, and the d...

Introduce the encoding source spectrum induced polarization method and how to decoupling electromagnetic coupling effect in SIP.

Introduce the encoding source spectrum induced polarization method and how to decoupling electromagnetic coupling effect in SIP.

It is generally accepted that a major phase of the Earth's upper mantle is represented by ultramafic rocks, including olivine pyroxenites, dunites, and peridotites. Studies on the electrical conductivity of ultramafic rocks continue to attract a great deal of interest, and much progress in the study of the electrical conductivity of rocks and miner...

Induced polarization (IP) is a powerful tool in metalliferous ore exploration. However, there are many sources, such as clay and graphite, which can generate IP anomaly. Spectral induced polarization (SIP) measures IP response on a wide frequency range. This method provides a way to discriminate IP response generated by metalliferous ore or other o...

Spectral induced polarization method (SIP) or complex resistivity method is increasing its application in metalliferous ore exploration, hydrocarbon exploration, underground water exploration, monitoring of environment pollution, and the evaluation of environment remediation. And the measurement of complex resistivity or complex impedance of rock/o...

Although most of transient electromagnetic (TEM) apparatuses in China and abroad have taken various methods to suppress noise and improve SNR, noise may still remain in TEM data after stacking of all the periods. Stacking samples in time windows is an important technique for TEM data after stacking of all the periods. This paper proposes that Robus...

CannyTEM is a ground based high-resolution transient electromagnetic system, which is based on mobile technology and artificial intelligence for easy operation and good quality data acquisition. This paper presents the design, realization, and testing of CannyTEM. CannyTEM is composed of a transmitter, a receiver, two induction coils, and a smart p...

CannyTEM is developed and tested based on new material for sensor, new electronics (ultra-low noise amplifier, DSP, CPLD, ARM) for data acquisition, and new information technology (mobile technology, artificial intelligence). 1.2 MHz dB/dt sensor is developed with low noise and high dynamic range. 6-channel TEM data acquisition unit is developed wi...

CannyTEM is a ground based high-resolution transient electromagnetic system, which is based on mobile technology and artificial intelligence for easy operation and good quality data acquisition. This paper presents the design, realization, and testing of CannyTEM. CannyTEM is composed of a transmitter, a receiver, two induction coils, and a smart p...