OCTAVE cainv3.m - Perform Kelvin-Voigt analysis for damping and stiffness from down-hole data
cainv3 prompts for:
Pick Minimum
and Maximum Frequencies for analysis (GUI mouse 2 Clicks)
Choose C1 (stiffness m^2/s^2) and C2 (damping m^2/s), #
interations (GUI Entry Box)
Default values usually good start, estimated from data
Choose Data Weighting (1/var | 1/stdev | none) (GUI Click
Box)
Choose Balance (Velocity/Decay) 0.5 is equal weighting (GUI
Entry Box)
Inversion runs displaying progress in plots until maximum
iterations completed
PLOT REQUESTS
Least Square Error Plot (LSQE)? [ Yes | No ] (GUI Click Box)
Chi^2 Plots (Velocity, Atten) [ Yes | No ] (GUI Click Box)
Save Results to Disk? [ Yes | No ] (GUI Click Box)
PopUP GUI Relaxation Time Computed (msec) display (GUI Click
OK)
Basic Seismic Utilities (BSU) program run in Octave or Matlab. Within an octave session, type cainv3 and a GUI pops up, use mouse to pick low and high frequency brackets for the analysis. This can be done in any of the 3 plots shown. The next GUI shows estimates of the stiffness and damping coefficients (C1 and C2) and setting for number of iterations to conduct. The next GUI requests choice of data weighting (reciprocal of variance, standard deviation, or none). Weighting by variance or standard deviation weights less uncertain data more than uncertain data. The next GUI requests balance to weight the velocity and amplitude decay blocks of the problem. A value of 0.5 weights them equally. A value of 1.0 only inverts on phase velocity. A value of 0.0 only inverts on amplitude decay, and is not recommended. Values less than 0.1 will tend towards divergence from a solution.
Requires two
files from execution of bvas and bamp programs:
bvas.his
bamp.his
Plots of
observed and computed (solid line) estimates of phase
velocity, decay, semblance.
(above plots refresh after each step in inversion)
Plot of LSQE
Plot of Chi-squared
Display of Relaxation Time in msec (C2/C1)
FILES:
casol.dat, caoutc.dat caouta.dat calsqe.dat cadeld.dat
cachi2.dat
These files are available for input into caplot3.m.
bvas.his
bamp.his
bamp(1) bvas(1) caplot(1)
No known bugs.
Copyright © 2017 by Paul Michaels
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
P. Michaels, PE. <pm@cgiss.boisestate.edu>