Open AccessThe importance of a small wall deformation in the three‐dimensional acoustic logging results
Author(s) -
Godinho Luís,
Tadeu António
Publication year - 2002
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1046/j.1365-246x.2002.01792.x
Subject(s) - borehole , geology , deformation (meteorology) , rotational symmetry , position (finance) , seismic wave , dipole , acoustics , mechanics , seismology , geotechnical engineering , physics , oceanography , finance , quantum mechanics , economics
Summary A variety of seismic techniques use fluid‐filled boreholes to host detectors and seismic sources. The complexity of the wavefield generated depends on the position of the receivers and the source, frequency excited, type of formation and type of source. In the present paper the boundary element method is used to study the wavefield elicited by monopole or dipole sources within a fluid‐filled cylindrical cavity drilled through an unbounded elastic formation. This model is used to assess the effects of the existence of a small, localized wall deformation on the response. Such a deformation may occur through the mechanical action of the drill string, rock failure adjacent to a drilled borehole, plastic deformation and washing out of the borehole in soft or poorly consolidated rocks. In addition, the effect of a source–receiver tool, placed in an off‐centre and/or tilted position inside the fluid‐filled borehole, on the propagation of both axisymmetric and non‐axisymmetric wave modes, are studied.