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《Chinese Journal of Geophysics》 2016-09
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Theoretical simulation of the seismoelectric logging while drilling technique using the dual source

DING Hao-Ran;CUI Zhi-Wen;Lü Wei-Guo;LIU Jin-Xia;WANG Ke-Xie;College of Physics,Jilin University;  
Although the Logging While Drilling(LWD)acoustic technology has been developed over two decades,it still remains challenge to derive compressional-wave transit time from the LWD measurements due to the disturbance of collar waves,especially in relatively weak formation.The results from this study demonstrate feasibility of extracting acoustic parameters(e.g.,compressional-wave transit time)from the measurements of electric field induced by the electrokinetic effect.To investigate the characteristics of seimoelectric waves in LWD environments,Pride′s seimoelectric coupling equations are exploited.By applying the boundary conditions at the borehole wall and mandrel surface,the transient response of seismoelectric wave field can be simulated using real-axis integral.The results show that the seimoelectric conversion ratio in LWD is similar to that in wireline logging.Seimoelectric effect could be useful in LWD.However,it is found that considerable residual collar waves exist in the converted electric field,even most of collar waves are suppressed.To further suppress collar waves,dual transducers are proposed.The distance between transducers and their firings can vary to maximize reduction ofcollar waves.Numerical results show that relative amplitude of collar wave in the full waveforms is significantly reduced.It has shown promising that using dual-transducers in LWD deliver better quality compressional-wave transit time logs than the current LWD technologies.
【Fund】: 国家自然科学基金(40974067 11134011 41474098)资助
【CateGory Index】: P631.81
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