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Lanfang He
State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China; Key Laboratory of Seismic Observation and Geophysical Imaging, Institute of Geophysics, CEA, Beijing, China and State Key Laboratory of Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing, China.

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Journal article
Published: 01 March 2018 in GEOPHYSICS
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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 applied to explore for these chromite deposits but have mostly failed to delineate prospective areas. We have evaluated a successful podiform chromite exploration case history that is based on AMT. More than 8000 AMT stations were used in this study within a [Formula: see text] area of the ophiolite belt. Line separations were 80 or 40 m, and the station separation was 20 m. We implemented Bostick conversion and nonlinear conjugate gradient inversions for data interpretation, whereas 2D resistivity sections and 3D resistivity imaging were used to elucidate the inner structure and distribution of rock faces within the Luobusa ophiolite. Results from rock physics and drilling further indicate that resistivity-anomaly domains from these AMT results are correlated with rock faces in terms of fresh harzburgite, altered harzburgite and dunite, and they can thus be connected to concealed deposits. Therefore, we have developed three resistivity-anomaly models for chromite exploration, and we delineated several prospective regions containing exploitable deposits within the Luobusa ophiolite. Seven of the nine verified boreholes discussed in this paper intersected with chromite deposits; one comprises the largest and highest grade chromite deposit in China to date. Our AMT results provide the impetus for future chromite exploration in Tibet and enable a refined understanding of the structure and distribution of rock faces within the Luobusa ophiolite.

ACS Style

Lanfang He; Ling Chen; Dorji; Zhanxiang He; Xuben Wang; Bayi Xiao; Ligui Xu; Xuefang Zhao; Xiaolu Xi; Hongchun Yao; Rujun Chen. Mapping chromite deposits with audio magnetotellurics in the Luobusa ophiolite of southern Tibet. GEOPHYSICS 2018, 83, B47 -B57.

AMA Style

Lanfang He, Ling Chen, Dorji, Zhanxiang He, Xuben Wang, Bayi Xiao, Ligui Xu, Xuefang Zhao, Xiaolu Xi, Hongchun Yao, Rujun Chen. Mapping chromite deposits with audio magnetotellurics in the Luobusa ophiolite of southern Tibet. GEOPHYSICS. 2018; 83 (2):B47-B57.

Chicago/Turabian Style

Lanfang He; Ling Chen; Dorji; Zhanxiang He; Xuben Wang; Bayi Xiao; Ligui Xu; Xuefang Zhao; Xiaolu Xi; Hongchun Yao; Rujun Chen. 2018. "Mapping chromite deposits with audio magnetotellurics in the Luobusa ophiolite of southern Tibet." GEOPHYSICS 83, no. 2: B47-B57.

Journal article
Published: 01 July 2017 in GEOPHYSICS
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Shale gas is a particularly important research target on Chinese energy resources, especially in the Upper Yangtze region. Complex topography and geologic conditions challenge seismic exploration of shale gas in this area, and ground-based electromagnetic (EM) methods are used to aid recognition of the best reservoirs. However, the electrical properties of organic shale (EPOS) and its correlation to shale-gas petrology remain poorly understood. We studied EPOS and their correlation to shale petrology by measuring and analyzing the petrochemical features and complex impedance of rock samples from the Silurian Longmaxi and Cambrian Niutitang Formations in the Upper Yangtze, southwest China. Our study indicates that the organic shale in the Upper Yangtze features low resistivity and high polarizability in terms of a high negative phase, but no obvious low resistivity is observed among shaly sandstone and shales with lower and higher total organic carbon. Pyrite and quartz contents in the organic shale dominantly contribute to the EPOS with different mechanisms. Our result indicates that the EPOS bear relations to the petrology parameters of organic shale, which is essential for shale-gas evaluation and exploration. The correlation between EPOS and the shale-gas petrology promoted a new way for shale-gas exploration with complex geology, topography, and surface conditions in China, especially in the Upper Yangtze region, by using the ground-based EM method to evaluate the parameters of shale gas and to aid to delimit the productive reservoirs (“sweet spots”).

ACS Style

Lanfang He; Ling Chen; Xuben Wang; Zhengjiang Wang; Bing Zhang; Ligui Xu; Xuejun Liu; Weili Li; Rujun Chen. Electrical properties and its correlation to the petrology of the Upper Yangtze organic shales. GEOPHYSICS 2017, 82, D199 -D209.

AMA Style

Lanfang He, Ling Chen, Xuben Wang, Zhengjiang Wang, Bing Zhang, Ligui Xu, Xuejun Liu, Weili Li, Rujun Chen. Electrical properties and its correlation to the petrology of the Upper Yangtze organic shales. GEOPHYSICS. 2017; 82 (4):D199-D209.

Chicago/Turabian Style

Lanfang He; Ling Chen; Xuben Wang; Zhengjiang Wang; Bing Zhang; Ligui Xu; Xuejun Liu; Weili Li; Rujun Chen. 2017. "Electrical properties and its correlation to the petrology of the Upper Yangtze organic shales." GEOPHYSICS 82, no. 4: D199-D209.

Conference paper
Published: 31 May 2017 in International Geophysical Conference, Qingdao, China, 17-20 April 2017
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Shale gas in the upper Yangtze region is important exploration and exploit target in China. Rough topography and complex geological conditions challenge seismic exploration of shale gas, and electromagnetic (EM) methods are employed to aid to recognize the favorite reservoirs in this area. However, apart from some progress on the relationship between electrical properties and the content of pyrite until recently, electrical properties and its mechanism of the organic shale are also incompletely understood. Quartz content acts as critical role in the shale gas exploiting, as well as bears relation to the total gas content in the upper Yangtze organic shale. We studied the electrical properties and their correlation to the quartz content by measuring the complex impedance and analyzing the whole rock mineral content of rock samples. These samples are from the Silurian Longmaxi and Cambrian Niutitang formations in the upper Yangtze, southwest China. Our study shows that there lies correlation between the electrical properties and the quartz content of the organic shale in the upper Yangtze. The resistivity decreases and the phase increases with the increasing quartz content. The results indicates the electrical properties bears relation to the total gas content of the organic shale, and then potentially promotes a new way for shale gas evaluating by the ground-based EM method.

ACS Style

Lanfang He; Ling Chen; Wang Xuben; Zhang Bin; Wang Zhenjiang; Yu Qian; Yanghua Wang; Zhijing Wang. Correlation between the electrical properties and the quartz content of the upper Yangtze organic shale. International Geophysical Conference, Qingdao, China, 17-20 April 2017 2017, 42 -45.

AMA Style

Lanfang He, Ling Chen, Wang Xuben, Zhang Bin, Wang Zhenjiang, Yu Qian, Yanghua Wang, Zhijing Wang. Correlation between the electrical properties and the quartz content of the upper Yangtze organic shale. International Geophysical Conference, Qingdao, China, 17-20 April 2017. 2017; ():42-45.

Chicago/Turabian Style

Lanfang He; Ling Chen; Wang Xuben; Zhang Bin; Wang Zhenjiang; Yu Qian; Yanghua Wang; Zhijing Wang. 2017. "Correlation between the electrical properties and the quartz content of the upper Yangtze organic shale." International Geophysical Conference, Qingdao, China, 17-20 April 2017 , no. : 42-45.

Journal article
Published: 22 October 2016 in Energies
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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 Southwestern Tibet are poorly prospected and currently almost no geothermal energy is exploited. Here we present a case study mapping the Mapamyum (QP) geothermal field of Southwestern Tibet using audio magnetotellurics (AMT) and magnetotellurics (MT) methods. AMT in the frequency range 11.5–11,500 Hz was used to map the upper part of this geothermal reservoir to a depth of 1000 m, and MT in the frequency range 0.001–320 Hz was used to map the heat source, thermal fluid path, and lower part of the geothermal reservoir to a depth greater than 1000 m. Data from 1300 MT and 680 AMT stations were acquired around the geothermal field. Bostick conversion with electromagnetic array profiling (EMAP) filtering and nonlinear conjugate gradient inversion (NLCGI) was used for data inversion. The AMT and MT results presented here elucidate the geoelectric structure of the QP geothermal field, and provide a background for understanding the reservoir, the thermal fluid path, and the heat source of the geothermal system. We identified a low resistivity anomaly characterized by resistivity in the range of 1–8 Ω∙m at a depth greater than 7 km. This feature was interpreted as a potential reflection of the partially melted magma in the upper crust, which might correlate to mantle upwelling along the Karakorum fault. It is likely that the magma is the heat source of the QP geothermal system, and potentially provides new geophysical evidence to understand the occurrence of the partially melted magmas in the upper crust in Southwestern Tibet.

ACS Style

Lanfang He; Ling Chen; Dorji; Xiaolu Xi; Xuefeng Zhao; Rujun Chen; Hongchun Yao. Mapping the Geothermal System Using AMT and MT in the Mapamyum (QP) Field, Lake Manasarovar, Southwestern Tibet. Energies 2016, 9, 855 .

AMA Style

Lanfang He, Ling Chen, Dorji, Xiaolu Xi, Xuefeng Zhao, Rujun Chen, Hongchun Yao. Mapping the Geothermal System Using AMT and MT in the Mapamyum (QP) Field, Lake Manasarovar, Southwestern Tibet. Energies. 2016; 9 (10):855.

Chicago/Turabian Style

Lanfang He; Ling Chen; Dorji; Xiaolu Xi; Xuefeng Zhao; Rujun Chen; Hongchun Yao. 2016. "Mapping the Geothermal System Using AMT and MT in the Mapamyum (QP) Field, Lake Manasarovar, Southwestern Tibet." Energies 9, no. 10: 855.

Conference paper
Published: 01 January 2016 in Proceedings of the 7th International Conference on Environment and Engineering Geophysics & Summit Forum of Chinese Academy of Engineering on Engineering Science and Technology
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ACS Style

Lanfang He; Ling Chen; Xuefeng Xue; Weili Li. Electromagnetism of ultramafic rocks from the Luobusa ophiolite studied at room temperatures and pressures. Proceedings of the 7th International Conference on Environment and Engineering Geophysics & Summit Forum of Chinese Academy of Engineering on Engineering Science and Technology 2016, 1 .

AMA Style

Lanfang He, Ling Chen, Xuefeng Xue, Weili Li. Electromagnetism of ultramafic rocks from the Luobusa ophiolite studied at room temperatures and pressures. Proceedings of the 7th International Conference on Environment and Engineering Geophysics & Summit Forum of Chinese Academy of Engineering on Engineering Science and Technology. 2016; ():1.

Chicago/Turabian Style

Lanfang He; Ling Chen; Xuefeng Xue; Weili Li. 2016. "Electromagnetism of ultramafic rocks from the Luobusa ophiolite studied at room temperatures and pressures." Proceedings of the 7th International Conference on Environment and Engineering Geophysics & Summit Forum of Chinese Academy of Engineering on Engineering Science and Technology , no. : 1.

Journal article
Published: 28 May 2014 in Chinese Science Bulletin
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The Luobusa Ophiolite, Southern Tibet, lies in the eastern portion of Indus–Yarlung Zangbo suture zone that separates Eurasia from the Indian continent. An aeromagnetic reconnaissance survey has revealed an EW-trending Yarlung Zangbo River aeromagnetic anomaly zone, and it is considered to be caused mainly by the Indus–Yarlung Zangbo Ophiolite. The Luobusa Ophiolite reflects the eastern portion of the Yarlung Zangbo River aeromagnetic anomaly zone. Conventionally, the ultramafic rock in the Luobusa Ophiolite is considered as the origin of the high magnetic anomalies. However, results from the surface magnetic survey and the magnetic susceptibility measurements from drill cores indicate that the high magnetic anomalies are distributed inhomogeneously in the Luobusa Ophiolite. In some cases, the susceptibility exhibits more than 30 times difference between two sides of the same sample. A fact emerged that the susceptibility of dunite with serpentinization is higher than that of fresh dunite, harzburgite and chromite when we analyzed the measurement results. In order to understand the origin of the high magnetic anomalies, we measured the density and susceptibility of 17 samples, microscopic and electron probe analyses have been performed as well. The result indicates the presence of dunite with serpentinization containing an abundant of micro-fissures filled with magnetite. Olivine has a susceptibility of about 2.7–351 (×10−5 SI), pyroxene about 16–320, and chromite about 200–800. All these units feature relatively low susceptibility in ultramafic rock, and only the magnetite is characterized by a high susceptibility of about 200,000 (×10−5 SI). Based on these observations, we conclude that the precipitation of magnetite in the process of serpentinization of the olivine caused by the geological process in the Luobusa Ophiolite is the origin of high magnetic anomalies.

ACS Style

Lanfang He; Xiumian Hu; Yabing Zha; Ligui Xu; Yaohui Wang. Distribution and origin of high magnetic anomalies at Luobusa Ophiolite in Southern Tibet. Chinese Science Bulletin 2014, 59, 2898 -2908.

AMA Style

Lanfang He, Xiumian Hu, Yabing Zha, Ligui Xu, Yaohui Wang. Distribution and origin of high magnetic anomalies at Luobusa Ophiolite in Southern Tibet. Chinese Science Bulletin. 2014; 59 (23):2898-2908.

Chicago/Turabian Style

Lanfang He; Xiumian Hu; Yabing Zha; Ligui Xu; Yaohui Wang. 2014. "Distribution and origin of high magnetic anomalies at Luobusa Ophiolite in Southern Tibet." Chinese Science Bulletin 59, no. 23: 2898-2908.

Journal article
Published: 01 July 2012 in GEOPHYSICS
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Hydraulic fracturing is widely used for initiating and subsequently propagating fractures in reservoir strata by means of a pressurized fluid to release oil and gas or to store industry waste. Downhole or surface microseismic monitoring is commonly used to characterize the hydraulically induced fractures. However, in some cases, downhole microseismic monitoring can be difficult due to the limitation imposed by boreholes. Surface microseismic monitoring often faces difficulties acquiring high signal-to-noise ratio data because of the on-site noise from hydraulic fracturing process. Research and field observations indicate that injecting conductive slurry or water into a strata may generate distinct time-lapse electromagnetic anomalies between pre- and posthydraulic fracturing. These anomalies provide a means for characterizing the hydraulic fracturing using time-lapse electromagnetic methods. We examined the time-lapse variation over an hour, one day, one month, and two years of observed audio-magnetotellurics (AMT) resistivity and the 1D and 3D AMT modeling result of the variation pre- and posthydraulic fracturing. There is also a successful case history of applying the time-lapse AMT to map hydraulic fractures. Observed data indicate that the variation of AMT resistivity is normally less than 6% apart from the data of the dead band and some noisy data. Modeling results show the variation pre- and posthydraulic fracturing is larger than 30% at the frequency point lower than 100 Hz. The case history indicates that time-lapse magnetotelluric monitoring may form a new way to characterize the hydraulic fracture.

ACS Style

Lanfang He; Xiumian Hu; Ligui Xu; Zhanxiang He; Weili Li. Feasibility of monitoring hydraulic fracturing using time-lapse audio-magnetotellurics. GEOPHYSICS 2012, 77, WB119 -WB126.

AMA Style

Lanfang He, Xiumian Hu, Ligui Xu, Zhanxiang He, Weili Li. Feasibility of monitoring hydraulic fracturing using time-lapse audio-magnetotellurics. GEOPHYSICS. 2012; 77 (4):WB119-WB126.

Chicago/Turabian Style

Lanfang He; Xiumian Hu; Ligui Xu; Zhanxiang He; Weili Li. 2012. "Feasibility of monitoring hydraulic fracturing using time-lapse audio-magnetotellurics." GEOPHYSICS 77, no. 4: WB119-WB126.

Conference paper
Published: 01 January 2009 in SEG Technical Program Expanded Abstracts 2009
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Induced polarization (IP) is widely used in oil and gas exploration in the former Soviet Union, Russia, and China. Good results from hydrocarbon exploration were achieved in China recently by applying high‐power spectral induced polarization (SIP) with exploration depth exceeding the buried depth of reservoirs. Precision synchronization between the transmitter and receiver is required for the amplitude spectrum and phase spectrum of SIP measurement in the current technology. The synchronization based on the GPS disciplined oven controlled oscillator (OCXO) is the usual method applied in the transmitter and receiver which are used for SIP exploration. The method increases weight and cost of the receiver because the GPS‐disciplined OCXO uses the major part of the power consumption of the receiver. Furthermore, this method can not satisfy the measurement requirements of SIP in ocean‐bottom conditions because of the lack of GPS signal. We put forward a measurement method of relative phase spectrum (RPS) to resolve the above problem. The IP information of a target is acquired by the amplitude spectrum and RPS of the complex resistivity. The method can decrease power consumption of the receiver by 50% because the RPS measurement does not require synchronization circuit between the receiver and transmitter. The RPS curve shape is similar to that of phase spectrum based on comparing typical parameters of the Cole‐Cole model. The RPS owns the same IP information as the phase spectrum. In fact, the RPS formula proposed by here is equal to the phase spectrum formula which is linearly corrected to EM coupling. This was proven through a field experiment. The 3D SIP acquisition can be realized at low cost in the surface, the well, and the ocean‐bottom if the phase spectrum measurement is replaced by the RPS measurement. It may expand the application of SIP in oil and gas exploration.

ACS Style

Rujun Chen; Zhanxiang He; Lanfang He; Xuejun Liu. Principle of relative phase spectrum measurement in SIP. SEG Technical Program Expanded Abstracts 2009 2009, 1 .

AMA Style

Rujun Chen, Zhanxiang He, Lanfang He, Xuejun Liu. Principle of relative phase spectrum measurement in SIP. SEG Technical Program Expanded Abstracts 2009. 2009; ():1.

Chicago/Turabian Style

Rujun Chen; Zhanxiang He; Lanfang He; Xuejun Liu. 2009. "Principle of relative phase spectrum measurement in SIP." SEG Technical Program Expanded Abstracts 2009 , no. : 1.

Journal article
Published: 01 June 2006 in Journal of Environmental and Engineering Geophysics
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A successful case history of applying the high-frequency passive source electromagnetic (EM) method and controlled-source audiomagnetotellurics (CSAMT) to investigate the Qiyueshan (Q) Tunnel route is presented in this paper. The high-frequency EM system (EH-4, with frequency range from [Formula: see text]) and the CSAMT system (V6-A Multipurpose Receiver, with frequency range from [Formula: see text]) were used for the data acquisition. The orthogonal components of the electromagnetic field were measured in the high frequency EM method, while scalar measurements of the electrical and magnetic field components were used in the CSAMT method. The relevant electrical properties of the earth were extracted from the electromagnetic profiles. High frequency EM has high resolution in the shallow earth but a smaller depth of exploration, while the CSAMT method has a powerful signal but a lower resolution in the shallow earth. The integration of the two methods might be effective for the survey of the deep tunnel route. Q Tunnel, located in central south China, has a length of [Formula: see text] and a depth of up to [Formula: see text]. Half of the tunnel goes through karst terrain, where the geologic structures are very complex, due to cavities, underground rivers and faults. The EM mapping results distinguish the electrical resistivity of different rock formations. Five low-resistivity areas and four high-resistivity areas were found and nine faults were verified by the EM method. These findings were very useful for the later engineering design.

ACS Style

Lanfang He; Minghai Feng; Zhanxiang He; Xuben Wang. Application of EM Methods for the Investigation of Qiyueshan Tunnel, China. Journal of Environmental and Engineering Geophysics 2006, 11, 151 -156.

AMA Style

Lanfang He, Minghai Feng, Zhanxiang He, Xuben Wang. Application of EM Methods for the Investigation of Qiyueshan Tunnel, China. Journal of Environmental and Engineering Geophysics. 2006; 11 (2):151-156.

Chicago/Turabian Style

Lanfang He; Minghai Feng; Zhanxiang He; Xuben Wang. 2006. "Application of EM Methods for the Investigation of Qiyueshan Tunnel, China." Journal of Environmental and Engineering Geophysics 11, no. 2: 151-156.