Depth point 1 A study of the effects of early critical angle crossings. From data I (Paige) had previously processed to check out my sonic log synthesis logic. The green line approximates the deep mute I used to avoid the obvious noise we will discuss. On the first pass please click through rapidly, just to see the consistency of the problem.

Depth point 11 A study of the effects of early critical angle crossings. From data I (Paige) had previously processed to check out my sonic log synthesis logic. Note the over-corrected refraction spawned after the critical angle is passed. Earlier ones had occurred but this strong one is obvious through the whole in-line.

Depth point 21 A study of the effects of early critical angle crossings. From data I (Paige) had previously processed to check out my sonic log synthesis logic. Because all vertical travel was truncated at the critical angle crossing a “reflection energy void” was created below, allowing point source refractions, and other noise to take over. The consistency of these noise events is interesting. The point of this study was to see if removing them would help.

Depth point 31 A study of the effects of early critical angle crossings. From data I (Paige) had previously processed to check out my sonic log synthesis logic. As you move through the examples on this in-line, note that everything below the hypothetical blue line seems to belong to a different world/ It is obviously noise, by I do not currently understand what causes the separation. It is obvious however, that many of the outside traces were a waste of effort.

Depth point 41 A study of the effects of early critical angle crossings. From data I (Paige) had previously processed to check out my sonic log synthesis logic. To detect noise events, the best tool is the arrival pattern. Refractions patterns are linear, and the obvious stage to identify them is before moveout is applied. I did not have that option here so the current logic was developed to try to simulate that by playing with the curvature.

Depth point 51 A study of the effects of early critical angle crossings. From data I (Paige) had previously processed to check out my sonic log synthesis logic. Because of the break in downward traveling energy, we probably cannot depend on the center of the curvature pattern remaining below the energy source. This probably explains some of the odd (after moveout) patterns we see. It certainly complicates noise removal.

Depth point 61 A study of the effects of early critical angle crossings. From data I (Paige) had previously processed to check out my sonic log synthesis logic. But back to the void caused by cutting off the down wave. What you see in this study is just a display of the gather input from the original volume. This eliminates goofs that could explain the last gather traces. Normal ray tracing does not apply after the cutoff so we need open minds.

Depth point 81 A study of the effects of early critical angle crossings. From data I (Paige) had previously processed to check out my sonic log synthesis logic. A few more selections for study.

Depth point 101 A study of the effects of early critical angle crossings. From data I (Paige) had previously processed to check out my sonic log synthesis logic.

Depth point 121 A study of the effects of early critical angle crossings. From data I (Paige) had previously processed to check out my sonic log synthesis logic.

Depth point 131 A study of the effects of early critical angle crossings. From data I (Paige) had previously processed to check out my sonic log synthesis logic.

Depth point 151 A study of the effects of early critical angle crossings. From data I (Paige) had previously processed to check out my sonic log synthesis logic.

Depth point 161 A study of the effects of early critical angle crossings. From data I (Paige) had previously processed to check out my sonic log synthesis logic.

Depth point 181 A study of the effects of early critical angle crossings. From data I (Paige) had previously processed to check out my sonic log synthesis logic.

Depth point 201 A study of the effects of early critical angle crossings. From data I (Paige) had previously processed to check out my sonic log synthesis logic. Click here for basic noise stuff. Or here for bigger study. Or here for basic de-noising of Vibroseis. Or here for a Gulf Coast example. Give them plenty of time to load.