Extracting useful high-frequency information from wide-field electromagnetic data using time-domain signal reconstruction

Abstract

The wide-field electromagnetic method is widely used in hydrocarbon exploration, mineral deposit detection, and geological disaster prediction. However, apparent resistivity and normalized field amplitude exceeding 2048 Hz often exhibit upward warping in data, making geophysical inversion and interpretation challenging. The cumulative error of the crystal oscillator in signal transmission and acquisition contributes to an upturned apparent resistivity curve. To address this, a high-frequency information extraction method is proposed based on time-domain signal reconstruction, which helps to record a complete current data sequence; moreover, it helps estimate the crystal oscillator error for the transmitted signal. Considering the recorded error, a received signal was corrected using a set of reconstruction algorithms. After processing, the high-frequency component of the wide-field electromagnetic data was not upturned, while accurate high-frequency information was extracted from the signal. Therefore, the proposed method helped effectively extract high-frequency components of all wide-field electromagnetic data.

Keywords

wide-field electromagnetic method / crystal oscillator error / time series / signal resampling / signal reconstruction

References

[1] HeJ-S. Theory and technology of wide field electromagnetic method [J]. The Chinese Journal of Nonferrous Metals, 2019, 29(9): 1809-1816(in Chinese)

[2] TongM-HApplication of the wide field electromagnetic method to babaoshan area in Dulan County, Qinghai Province [D], 2018, Changchun, Jilin University(in Chinese)

[3] HeJ-S, LiD-U, DaiS-K. Shale gas detection with wide field electromagnetic method in North-western Hunan [J]. Oil Geophysical Prospecting, 2014, 49(5): 1006-1012(in Chinese)

[4] PENG Yong-hui, LI Di-quan. Study on electric structure in a hydrocarbon accumulation area, Qaidam Basin [J]. Lithologic Reservoirs, 2015(1): 115–121.

[5] LingF, ZhuY-Z, ZhouM-L, et al. . Shale gas potential assessment of Changsan uplift area in southern North China Basin by using wide field electromagnetic method [J]. Geophysical and Geochemical Exploration, 2017, 41(2): 369-376(in Chinese)

[6] HeJ-S. Combined application of wide-field electromagnetic method and flow field fitting method for high-resolution exploration: A case study of the anjialing No. 1 coal mine [J]. Engineering, 2018, 4(5): 667-675

[7] HeJ-S. New research progress in theory and application of wide field electromagnetic method [J]. Geophysical and Geochemical Exploration, 2020, 44(5): 985-990(in Chinese)

[8] TangJ-T, RenZ-Y, ZhouC, et al. . Frequency-domain electromagnetic methods for exploration of the shallow subsurface: A review [J]. Chinese Journal of Geophysics, 2015, 58(8): 2681-2705(in Chinese)

[9] HeJ-S. Wide field electromagnetic sounding methods [J]. Journal of Central South University (Science and Technology), 2010, 41(3): 1065-1072(in Chinese)

[10] TangJ-T, HeJ-S. A new method to define the full-zone resistivity in horizontal electric dipole frequency soundings on a layered earth [J]. Acta Geophysica Sinica, 1994, 37(4): 543-552

[11] MyerD, ConstableS, KeyK. Broad-band waveforms and robust processing for marine CSEM surveys [J]. Geophysical Journal International, 2011, 184(2): 689-698

[12] ZiolkowskiA, WrightD, MattssonJ. Comparison of pseudo-random binary sequence and square-wave transient controlled-source electromagnetic data over the Peon gas discovery, Norway [J]. Geophysical Prospecting, 2011, 59(6): 1114-1131

[13] MittetR, Schaug-PettersenT. Shaping optimal transmitter waveforms for marine CSEM surveys [J]. Geophysics, 2008, 73(3): F97-F104

[14] ConstableS, CoxC S. Marine controlled-source electromagnetic sounding: 2. The PEGASUS experiment [J]. Journal of Geophysical Research: Solid Earth, 1996, 101(B3): 5519-5530

[15] LU Xin-you, SRNKA L J. Logarithmic spectrum transmitter waveform for controlled-source electromagnetic surveying: US7539279 [P]. 2009-05-26.

[16] HeJ-S, LiuJ-X. Pseudo-random multi-frequency phase method and its application [J]. The Chinese Journal of Nonferrous Metals, 2002, 12(2): 374-376(in Chinese)

[17] HeJ-S. Closed addition in a three-element set and 2_n sequence pseudo-random signal coding [J]. Journal of Central South University (Science and Technology), 2010, 41(2): 632-637(in Chinese)

[18] HeJ-SWide field electromagnetic method and pseudo random signal method [M], 2010, Beijing, Higher Education Press(in Chinese)

[19] JiangQ-YStudy on the key technology of wide field electromagnetic sounding instrument [D], 2010, Changsha, Central South University(in Chinese)

[20] HE Ji-shan, YANG Yang, LI Di-quan, et al. Method and system for generating high-order pseudo-random electromagnetic prospecting signal: CN Patent, 20201034473 32 [P]. 2020-08-11. (in Chinese)

[21] HE Ji-shan, LI Fang-shu, WANG Yong-bing. Method and system for hybrid coding of pseudo-random signal: CN Patent, 2018113093182 [P]. 2019-04-05. (in Chinese)

[22] YangY, HeJ-S, LiD-Q. Energy distribution and effective components analysis of 2n sequence pseudo-random signal [J]. Transactions of Nonferrous Metals Society of China, 2021, 31(7): 2102-2115

[23] TANG Jing-tian, XU Zhi-min, XIAO Xiao, et al. Effect rules of strong noise on magnetotelluric(MT) sounding in the Luzong ore cluster area [J]. Chinese Journal of Geophysics, 2012(12): 4147–4159.

[24] DzikunooE A, VignoliG, JørgensenF, et al. . New regional stratigraphic insights from a 3D geological model of the Nasia sub-basin, Ghana, developed for hydrogeological purposes and based on reprocessed B-field data originally collected for mineral exploration [J]. Solid Earth, 2020, 11(2): 349-361

[25] StrackK M, HansteinT H, EilenzH N. LOTEM data processing for areas with high cultural noise levels [J]. Physics of the Earth and Planetary Interiors, 1989, 53(3–4): 261-269

[26] AukenE, ChristiansenA V, KirkegaardC, et al. . An overview of a highly versatile forward and stable inverse algorithm for airborne, ground-based and borehole electromagnetic and electric data [J]. Exploration Geophysics, 2015, 46(3): 223-235

[27] ReningerP A, MarteletG, DeparisJ, et al. . Singular value decomposition as a denoising tool for airborne time domain electromagnetic data [J]. Journal of Applied Geophysics, 2011, 75(2): 264-276

[28] StreichR, BeckenM, RitterO. Robust processing of noisy land-based controlled-source electromagnetic data [J]. Geophysics, 2013, 78(5): E237-E247

[29] MaclennanK, LiY-G. Denoising multicomponent CSEM data with equivalent source processing techniques [J]. Geophysics, 2013, 78(3): E125-E135

[30] JiangF-B, DongL, DaiQ-W, et al. . Using wavelet packet denoising and ANFIS networks based on COSFLA optimization for electrical resistivity imaging inversion [J]. Fuzzy Sets and Systems, 2018, 337: 93-112

[31] LiG, HeZ-S, DengJ-Z, et al. . Robust CSEM data processing by unsupervised machine learning [J]. Journal of Applied Geophysics, 2021, 186: 104262

[32] YangY, LiD-Q, TongT-G, et al. . Denoising controlled-source electromagnetic data using least-squares inversion [J]. Geophysics, 2018, 83(4): E229-E244

[33] JafarnejadR, JannesariA, SobhiJ. Pre-distortion technique to improve linearity of low noise amplifier [J]. Microelectronics Journal, 2017, 6195-105

[34] LeeT H, HajimiriA. Oscillator phase noise: A tutorial [J]. IEEE Journal of Solid-State Circuits, 2000, 35(3): 326-336

[35] PoddarA K, RohdeU L, ApteA M. How low can they go? Oscillator phase noise model, theoretical, experimental validation, and phase noise measurements [J]. IEEE Microwave Magazine, 2013, 14(6): 50-72

[36] ZengX-J, YinX-G, LinG, et al. . Clock of high accuracy implemented by crystal oscillator in synchronism with gps-clock [J]. Automation of Electric Power Systems, 2003, 8: 49-53+89