@Article{CiCP-7-47,
author = {Xin Zhan, Zhenya Zhu, Shihong Chi and M. Nafi Toksöz},
title = {Elimination of LWD (Logging While Drilling) Tool Modes Using Seismoelectric Data},
journal = {Communications in Computational Physics},
year = {2010},
volume = {7},
number = {1},
pages = {47--63},
abstract = {<p style="text-align: justify;">Borehole acoustic logging-while-drilling (LWD) for formation evaluation
has become an indispensable part of hydrocarbon reservoir assessment [F. Cittá, C. Russell,
R. Deady and D. Hinz, The Leading Edge, 23 (2004), pp. 566-573]. However,
the detection of acoustic formation arrivals over tool mode contamination has been
a challenging problem in acoustic LWD technology. In this paper we propose a new
method for separating tool waves from formation acoustic waves in acoustic LWD.
This method is to measure the seismoelectric signal excited by the LWD acoustic waves.
The LWD tool waves which propagate along the rigid tool rim can not excite any electric
signal. This is due to the effectively grounding of the drill 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 seismoelectric signals. To theoretically understand the seismoelectric
conversion in the LWD geometry, we calculate the synthetic waveforms for the multipole
LWD seismoelectric signals based on Pride&#39;s theory [S. R. Pride, Phys. Rev. B, 50
(1994), pp. 15678-15696]. The synthetic waveforms for the electric field induced by the
LWD-acoustic-wave along the borehole wall demonstrate the absence of the tool mode.
We also designed the laboratory experiments to collect simulated LWD monopole and
dipole acoustic and seismoelectric signals in a borehole in sandstone. By analyzing the
spectrum of acoustic and electric signals, we can detect and filter out the difference
between the two signals, which are the mainly tool modes and noise.</p>},
issn = {1991-7120},
doi = {https://doi.org/10.4208/cicp.2009.08.174},
url = {http://global-sci.org/intro/article_detail/cicp/7619.html}
}