Priddis pulse/probe experiment: still ambiguous
David C. Henley
It has been conjectured that exciting the earth with a strong, stationary acoustic field will change the relative impedance of rock layer interfaces due to the induced motion of the pore fluids relative to the rock matrix, and that these changes in impedance should be detectable as changes in seismic reflectivity. A small seismic survey experiment to test this theory was conducted in 2008 at our Priddis test site; but the resulting analysis of the data yielded ambiguous results. The present report describes further analysis of those data. Specifically, we contrasted comparably processed CDP stacks of the survey data set acquired with dynamite only and the data set acquired with dynamite in the presence of a constant-frequency acoustic field in the earth. Comparisons were done using both straight subtraction and least-squares subtraction. We conclude from our analysis of those data that the results are still ambiguous, and the conjecture unconfirmed.