ACOUSTIC BOREHOLE IMAGING TOOL

摘要

A logging system for producing borehole images of acoustic properties of formations penetrated by the borehole. Images of formation compressional wave and shear wave velocities are generated in real time. The system can be a LWD system with a source section that comprises a unipole, dipole, quadrupole or other acoustic source. The receiver section comprises multiple receiver stations disposed at different axial spacings from the acoustic source. The system requires that the source and receiver sections rotate synchronously as the logging tool is conveyed along the borehole. Receiver responses are measured in a plurality of azimuthal angle segments and processed as a function of rotation angle of the tool. Acoustic parameters of interest are obtained from the azimuthal receiver responses at annotated depths along the borehole and used to produce borehole images of the parameters of interest.

主权项

1. A method for determining a borehole image of one or more acoustic parameters of a formation intersecting the borehole, said method comprising:
providing a logging tool with an acoustic source section comprising and acoustic source and a receiver section comprising a plurality of receiver stations disposed at differing axial spacings from said acoustic source wherein said source and said receiver sections are axially aligned; measuring responses of said receivers to energy emitted by said source in a plurality of azimuthal angular segments and stacked said measured responses for a sample time increment thereby forming a full waveform stack for each said azimuthal angular segment; processing said full waveform stacks for each said azimuthal angular segment to determine said one or more acoustic parameters as a function of azimuthal angle; annotating said one or more acoustic parameters as a function of azimuthal as a function of depth of said logging tool within said borehole to form a pixel line at that depth; repeating the measuring, processing and annotating as said logging tool is conveyed along said borehole thereby forming a plurality of pixel lines as a function of depth; and forming said borehole image from said pixel lines as a function of depth; wherein said one or more acoustic parameters include at least one of compressional wave velocity or compressional wave slowness.