delta petroleum announces discoveries in the parad, page-15

Zinc,

I haven't looked at the specifics of deltas seismics, though do note that the various formations, though in the same order (if present) throughout paradox, are differing thicknesses. Leadville is much shallower at the Lisbon field and may also be for delta. This may be why Lisbon was drilled decades ago (shallower resource = cheaper drilling = less risk). Remember oil and gas were several times cheaper in real terms when Lisbon was drilled and having to drill deeper would really eat into profits.