As an old, “mostly” retired, exploration geologist, I can say that Rock Man pretty much hit the nail on the head. Even in conventional reservoirs, a fault with vertical displacement frequently does not form a trap. Plus, some types of faults don’t create vertical displacement at all, the rocks slip “sideways.”
We have minerals under four sections in Block 76 PSL in Loving County, which we worked out a development plan with and leased to EOG. Just prior to drilling the first two (horizontal) wells in the Wolfcamp Shale, they shot some tight, localized seismic which identified a disruptive fault. As a result, they had to move the location for one of the wells, just as Rock Man suggested can happen.