The burial, thermal maturation, and fracture history of the Upper Devonian Rhinestreet Shale, western New York State.

摘要

This thesis focuses on four aspects of the Rhinestreet Shale; (1) The Rhinestreet's stratigraphy (2) compaction strain, (3) burial and thermal maturation, and (4) fracture history. The author measured the internal stratigraphy of the Rhinestreet Shale along Eighteenmile Creek, Erie County, New York. The Rhinestreet is composed of gray shale intervals, discontinuous diagentic carbonate horizons, and carbonate concretions that can also be recognized in the subsurface of western New York State, and northwestern Pennsylvania. Diagenetic carbonate concretions, which formed perhaps within a meter of the sediment-water interface, preserve the original thickness of the sediment and thus can be used to determine the maximum compaction strain the Rhinestreet Shale was subjected to. Results suggest that mechanical compaction of the Rhinestreet Shale ceased well before its modeled burial depth. Indeed, comparison of estimated Rhinestreet Shale porosities (op = 37.8%) to published compaction curves suggests the Rhinestreet reached its maximum burial induced compaction between 690 m and 1380 m. The burial and thermal maturation history of the shale has been modeled. The Rhinestreet carries as many as five joints; the main systematic sets being oriented NS (352°-007°), NW (298°-313°) and ENE (060°-075°). The oldest NS joints show a very strong affinity for the tops of gray shales immediately beneath black shale units in the Upper Devonian shale succession. Indeed, the author has found these joints at the top of the Hanover, Angola, and Cashaqua shales, in addition to the grey shale intervals within the Rhinestreet Shales. These fractures formed as a consequence of thermoelastic loading resulting from the passage of a peripheral bulge early in the tectonic cycle of the Alleghany orogeny. Later, as the Rhinestreet was buried deeper and passed into the oil window, NW and ENE natural hydraulic fractures formed as a result of catagenesis.