Simulation of the converted electric field during multipole logging while drilling (LWD)

Abstract

PreviousNext No AccessSEG Technical Program Expanded Abstracts 2006Simulation of the converted electric field during multipole logging while drilling (LWD)Authors: Xin ZhanZhihong ChiM. Nafi ToksözXin ZhanEarth Resources Laboratory, Massachusetts Institute of TechnologySearch for more papers by this author, Zhihong ChiEarth Resources Laboratory, Massachusetts Institute of TechnologySearch for more papers by this author, and M. Nafi ToksözEarth Resources Laboratory, Massachusetts Institute of TechnologySearch for more papers by this authorhttps://doi.org/10.1190/1.2370296 SectionsAboutPDF/ePub ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinked InRedditEmail Abstract In the multipole acoustic logging while drilling (LWD), the detection of formation acoustic arrivals over tool mode contamination has been a challenging problem. By measuring the seismoelectric signal (seismoelectric signal refers to the electric field induced by seismic or acoustic waves) converted from the LWD acoustic waves in the borehole, we could effectively eliminate the tool modes. The LWD tool waves which propagate along the rid tool rim can not excite any electric signal. This is due to the effectively grounding of the drilling string during the LWD process makes it impossible to accumulate any excess charge at the conductive tool‐borehole fluid interface. Therefore, there should be no contribution by the tool modes to the recorded LWD seismoelectric signals.In this paper, we confirm the absence of the tool modes in the multipole LWD seismoelectric signal from the theoretical modeling aspect. A theoretical model for the LWD‐acoustic‐wave induced electric field is developed by applying the Pride's equation into the LWD geometry. Both the acoustic pressure and the electric field strength are calculated by matching the acoustic and electric boundary conditions at all the boundaries in the LWD model. The synthetic acoustic and electric waveforms are calculated in a fast formation under monopole and dipole excitation. For the slow formation, the dipole acoustic and electric waveforms are also demonstrated. The absence of the tool modes in the LWD seismoelectric signals is further proven by applying the semblance analysis to the acoustic and electric waveforms.Permalink: https://doi.org/10.1190/1.2370296FiguresReferencesRelatedDetailsCited BySimulation of mononpole seismoelectric logging while drilling using dual sourceHaoran Ding, Zhiwen Cui, Jinxia Liu, Weiguo Lv, and Kexie Wang1 September 2016A review on electrokinetically induced seismo-electrics, electro-seismics, and seismo-magnetics for Earth sciences12 February 2016 | Solid Earth, Vol. 7, No. 1Simulation of the borehole quasistatic electric field excited by the acoustic wave during logging while drilling due to electrokinetic effectGEOPHYSICS, Vol. 80, No. 5Seismo-electrics, electro-seismics, and seismo-magnetics for earth sciences18 September 2015 | Solid Earth Discussions, Vol. 7, No. 3 SEG Technical Program Expanded Abstracts 2006ISSN (print):1052-3812 ISSN (online):1949-4645Copyright: 2006 Pages: 3541 publication data© 2006 Copyright © 2006 Society of Exploration GeophysicistsPublisher:Society of Exploration Geophysicists HistoryPublished: 06 Oct 2006 CITATION INFORMATION Xin Zhan, Zhihong Chi, and M. Nafi Toksöz, (2006), "Simulation of the converted electric field during multipole logging while drilling (LWD)," SEG Technical Program Expanded Abstracts : 446-450. https://doi.org/10.1190/1.2370296 Plain-Language Summary PDF DownloadLoading ...