Patent ID: 6611761
Filing Date: 2003-08-26
Classification: G01V

Abstract:
A method for determining a radial profile of sonic shear velocity of formations surrounding a fluid-containing borehole, comprising the steps of:suspending a logging device in the borehole; transmitting sonic energy from said logging device to establish flexural waves in the formation; receiving, at said logging device, sonic energy from said flexural waves, and producing from the received sonic energy, measurement signals at a number of frequencies; determining, at each of said number of frequencies, the flexural wave velocity in the formation; deriving sonic compressional and shear velocities of the substantially undisturbed formation; deriving sonic compressional velocity of the borehole fluid; and determining the radial profile of sonic shear velocity from the derived compressional and shear velocities of the substantially undisturbed formation, the derived compressional velocity of the borehole fluid, and the flexural wave velocities at said number of frequencies.