Only by either 1) making your own fractures via fraccing or 2)...

Only by either 1) making your own fractures via fraccing or 2) finding somewhere they aren't mineralised.

1) is expensive and 2) is very difficult because mineralisation is very difficult to predict. It comes and goes according to the geochemical conditions and fluid flow regime through the rock over geological time.

It's just one of the pitfalls of fractured reservoirs. Mapping where fractures should be is a fairly well-understood science, provided you have enough subsurface data, particularly seismic. But guaranteeing those fractures will be open and unmineralised is basically just trial and error. In this case mostly error!

If I were CTP I'd go ahead with drilling the second Stairway well in a different part of the reservoir. Conditions may be sufficiently different that the fractures are open.

But if the second well also came up mineralised I'd probably pack it in and look at fraccing, or focusing on other fields. As WC Fields said, "If at first you don't succeed, try, try again. Then quit. No use being a damn fool about it."