Appendix 12

Pinnacle Reefs

The pinnacle reefs in the Michigan Basin Salina-Niagaran Formation are underground "towers". Denser rock encases the remains of ancient coral reefs formed in a time when Michigan was a shallow tropical sea. Oil and/or natural gas bearing porous stone often exist in these reefs. Back to the nesting bowls of raisin bran analogy of the Michigan Basin, imagine a high, narrow, pile of juicy raisins that force their way up through "home bowl" into higher bowls. Now try to pierce the small top of the tower (where the raisin juice accumulates) with your jeweler's drill. If you miss the tower, you're going to miss the "pay." In more traditional oil and gas fields there is the opportunity to drill into a group of oil and gas deposit "raisins" housed under a dome that underlies a large geographical area and produces oil from several wells. Although a single 40 acre surface area accessing a Niagaran pinnacle reef may have the same oil and gas reserves as a huge acreage "traditional" field, pinnacle reefs often allow only "one shot" for discovery and the production of oil or natural gas.