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| THE FINITE ELEMENT ANALYSIS OF MAGNETIC FIELD CHARACTERISTICS OF THE CASED HOLE WITH PULSE SOURCE |
| YU Bing1,2, LIU Di-ren1,2, YU Xin-juan1,2, CAI Ming1,2, ZHENG Zhan-shu1,2, XU Wei1,2 |
1. Key Laboratory of Exploration Technologies for Oil and Gas Resources of Ministry of Education, Yangtze University, Jingzhou 434023, China;
2. School of Geophysics and Oil Resources, Yangtze University, Jingzhou 434023, China |
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Abstract The magnetic field of pulse source in the cased hole was analyzed by the finite element method. The effect of relative magnetic permeability of casing, casing thickness and the pulse width on the magnetic field distribution was discussed. The magnetic field in pulsed cased hole is considered as two parts in time domain: early signal and late signal. The early signal decreases obviously and includes mainly the useless signals and high frequency part of useful signal. The late signal is the low frequency part of useful signal and decreases slowly, thus containing the information of strata. The magnetic intensity is small when relative magnetic permeability of casing is very large. When the relative magnetic permeability of casing is small, the magnetic intensity is large but decreases drastically. The measurement is more favorable for the moderate relative magnetic permeability of casing.
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Received: 10 June 2010
Published: 15 October 2011
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