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Effects of metal casing on multi-component cross-hole electromagnetic responses |
WEI Baojun1, LI Xiaoqiang2, REN Guangqiang1, JIA Yilong1, WU Kangkang1, DANG Feng3, LIU Fuping4
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(1.College of Science in China University of Petroleum(East China), Qingdao 266580, China;2.Tuha Branch, China Petroleum Logging Company Limited, Shanshan 838200, China;3.China Petroleum Logging Company Limited, Xi 'an 710077, China;4. Beijing Institute of Graphic Communication, Beijing 102600, China)
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Abstract: |
The multi-component cross-hole electromagnetic field 's responses were simulated using an analytical expression of dyadic Green 's functions in cylindrically stratified anisotropic media.With the transmitter borehole encased with a metal casing, the effects of metal casing on different components of cross-hole electromagnetic signals were analyzed systematically.The results show that the existence of metal casing will lead to amplitude attenuation and phase delay for all components of cross-hole electromagnetic signals. Under the condition of fixed casing parameters and frequency,the amplitude attenuation and the phase delay variations remain constant for different components, the coil position and the formation 's conductivity. The amplitude attenuation and phase delay caused by the metal casing become more obvious for higher frequency, larger casing thickness and larger casing permeability and conductivity. In the case that the transmitter borehole and/or the receiver borehole are encased with metal casing, the effects of metal casing can be corrected by this analytical method before inverting the cross-hole electromagnetic measurements. |
Key words: cross-hole electromagnetic responses metal casing multi-component dyadic Green 's functions |
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