1. "Sometimes" being the key word. If the contrast in elastic...

1. "Sometimes" being the key word. If the contrast in elastic properties is not there in the fluids/rocks, it doesn't matter what you do. The thickness of the sand/shale units will also impact what the seismic can see. If there is no amplitude anomaly on the new seismic at the main target level, it won't be the end of the world, but hopefully there is a classic scenario with gas showing an amplitude anomaly that conforms with structure.

Also consider that the current seismic spacing could have missed any potential gas accumulation. The structure with a 1700m vertical relief is enormous, but it would be insane if this is filled anywhere near spill. See the Envoi document, p7 bottom right, and imagine the 2500m contour or smaller, rather than the red one highlighted at 3800m. If you have a 400m column (monstrous), or even 100m (still big), then you can see why finer 2D (at a bare minimum) is required. A discovery at the low end of reserve estimates would still be a fantastic result.

2. A "brute stack" is only a rough QC product. I wouldn't use it for proper interpretation/analysis. The more refined processing will take a little while. How long depends on the budget. Maybe IVZ will go with a quick/cheap option and try to pump something out for each line as it is acquired, but I would wait until acquisition is finished, and then run a standard pre-stack time migration workflow that would take around 2-3 months with no hiccups. There would be data available before it is completely finished that should be fairly good to start working on. There are other options like depth imaging, but this would add significantly more time and cost. After wells are drilled, they might consider rock physics and seismic inversion studies (about 3-4 months). Probably need a discovery to justify that.