BEEKMANTOWN (CAMBRO-ORDOVICIAN) GAS RESERVOIR POTENTIAL IN EASTERN NEW YORK STATE

The pore types in the Beekmantown Group (Cambro-Ordovician) of New York include vuggy, intercrystalline, and fracture porosity. Study of both outcrop sections and subsurface cored borings shows that subaerial exposure produced karst breccia caps on almost each of the stacked cyclic parasequences. Porosity occurs at the top of shallowing-upward depositional units, where peritidal dolomites and inferred evaporites accumulated. Authigenic quartz, length-slow chalcedony, and pseudomorphs of nodules (former anhydrite nodules) indicate the former presence of anhydrite in the Beekmantown Group. Dissolution of evaporites generated dissolution-collapse breccia, including angular clasts of dolostone and limestone, which formed when evaporites underlying continuous strata of Beekmantown carbonates were dissolved and the strata collapsed.

A well in eastern New York State found three kinds of petroleum indications: (1) a show of gas (even though noncommercial), (2) oil zones in the pores of some layers 410 ft thick, and (3) kerogen samples which indicate that the organic matter has been heated to the point where natural gas can be expected.