1. School of Earth Science, Institute of Disaster Prevention Science and Technology, Langfang 065201, China 2. Data Processing Interpretation Center of Well-Tech, China Oilfield Services Limited, Langfang 065201, China 3. Department of Geological Survey, No. 203 Research Institute of CNNC, Xianyang 712000, China 4. Geophysics and Information Technology Academy, China University of Geosciences, Beijing 100083, China
The time-lapse resistivity method can be applied to engineering and environmental problems such as monitor groundwater contaminant transport, measure slope stability. In this paper, the normalized data inversion result of the time-lapse resistivity method was used to identify the subsurface structure of small resistivity changes. First, the data ratio normalization was adopted in which the initial data serve as the background data to normalize the data at other times. Next, the separate nonlinear conjugate gradients (NLCG) inversion result of initial data, time-lapse data and normalized time-lapse data were implemented. The same inverted parameters and homogenous half space model that was taken as the reference model were applied in all synthetic data examples. The inversion results show that the normalized data inversion results can effectively distinguish the small changes of resistivity relative to the background, but the conventional resistivity inversion almost cannot recognize it.
Loke M H, Dahlin T, Rucker D F . Smoothness-constrained time-lapse inversion of data from 3D resistivity surveys[J]. Near Surface Geophysics, 2014,12(1):5-24.
[2]
Nimmer R E, Osiensky J L, Binley A M , et al. Electrical resistivity imaging of conductive plume dilution in fractured rock[J]. Hydrogeology Journal, 2007,15(5):877-890.
[3]
Kuras O, Pritchard J D, Meldrum P I , et al. Monitoring hydraulic processes with automated time-lapse electrical resistivity tomography (ALERT)[J]. Comptes Rendus Geoscience, 2009,341(10-11):868-885.
[4]
Ogilvy R D, Meldrum P I, Kuras O , et al. Automated monitoring of coastal aquifers with electrical resistivity tomography[J]. Near Surface Geophysics, 2009,7:367-375.
[5]
Adeyemo I A, Omosuyi G O, Adelusi A O. 3Geoelectric soundings for delineation of saline water intrusion into aquifers in part of eastern Dahomey Basin, Nigeria[J]. Journal of Geoscience and Environment Protection, 2017, (3): 213-219, 221-232.
[6]
Travelletti J, Sailhac P, Malet J P , et al. Hydrological response of weathered clay-shale slopes: water infiltration monitoring with time-lapse electrical resistivity tomography[J]. Hydrological Processes, 2011,26(14):2106-2119.
[7]
Xu D, Hu X Y, Shan C L , et al. Landslide monitoring in southwestern China via time-lapse electrical resistivity tomography[J]. Applied Geophysics, 2016,13(1):1-12.
[8]
Steelman C M, Klazinga D R, Cahill A G , et al. Monitoring the evolution and migration of a methane gas plume in an unconfined sandy aquifer using time-lapse GPR and ERT[J]. Journal of Contaminant Hydrology, 2017: 12-24.
[9]
Legaz A, Vandemeulebrouck J, Revil A , et al. A case study of resistivity and self-potential signatures of hydrothermal instabilities, Inferno Crater Lake, Waimangu, New Zealand[J]. Geophys. Res. Lett., 2009,36:L12306.
Liu C H . Monitoring the solute transport with active time constrained time-lapse electrical resistivity tomography[D]. Beijing: University of Science and Technology of China, 2016.
[11]
Chang P Y, Chang L C, Hsu S Y , et al. Estimating the hydrogeological parameters of an unconfined aquifer with the time-lapse resistivity-imaging method during pumping tests: Case studies at the Pengtsuo and Dajou sites, Taiwan[J]. Journal of Applied Geophysics, 2017: 134-143.
[12]
Daily W, Ramirez A, LaBrecque D,, et al. Electrical resistivity tomography of vadose water movement[J]. Water Resources Research, 1992,28(5):1429-1442.
[13]
LaBrecque D J, Yang X J . Difference Inversion of ERT Data: a Fast Inversion Method for 3-D in Situ Monitoring[J]. Journal of Environmental and Engineering Geophysics, 2001,6(2):83-89.
[14]
Daily W, Ramirez A, Binley A , et al. Electrical resistance tomography[J]. The Leading Edge, 2004,23(5):438-442.
[15]
Miller C R, Routh P S, Brosten T R , et al. Application of time-lapse ERT imaging to watershed characterization[J]. Geophysics, 2008,73(3):G7-G17.
[16]
Cassiani G, Bruno V, Villa A , et al. A saline trace test monitored via time-lapse surface electrical resistivity tomography[J]. Journal of Applied Geophysics, 2006,59(3):244-259.
[17]
Giordano N, Arato A, Comina C , et al. Time-lapse electrical resistivity imaging of the thermally affected zone of a Borehole Thermal Energy Storage system near Torino (Northern Italy)[J]. Journal of Applied Geophysics, 2017: 123-134.
[18]
Lesparre N, Nguyen F, Kemna A , et al. A new approach for time-lapse data weighting in electrical resistivity tomography[J]. Geophysics, 2017,82(6):E325-E333.
[19]
王家映 . 地球物理反演[M]. 北京: 高等教育出版社, 2002.
[19]
Wang J Y. Inverse theory in geophysics[M]. Beijing: Higher Education Press, 2002.
[20]
Spitzer K . A 3-D finite-difference algorithm for DC resistivity modeling using conjugate gradient methods[J]. International Journal of Geophysics, 1995,123(3):903-914.
