NATURAL FRACTURES AND MODERN DEPTH IN THE APPALACHIAN PLATEAU

While much research has been devoted to studying fractures, there is still uncertainty concerning where and why fractures form, how they interact with fluids, and what controls the density of fractures in an area. These questions have implications relating to present day fluid transport; for example, groundwater or hydrocarbon wells can be impacted by fluid flow through fractures. This study aims to determine whether a correlation exists between fracture characteristics and modern day depth in the Appalachian basin, and if fracture characteristics and rock type are related in sedimentary rocks. Additionally, the relationships between geophysical data and core observations are investigated.

During this research, core is examined from the Appalachian basin in Pennsylvania, United States. The age of this core ranges from Pennsylvanian to Late Devonian and the rock contained within the core is primarily mudstone, siltstone, and sandstone. Both natural and induced fractures are observed within the core. The dip angle of natural fractures varies from horizontal to steeply dipping. At least six different types of natural fractures are distinguishable, including calcite veins, horizontal fractures with slip, opening mode horizontal fractures, steeply dipping fractures, and small thrust faults. Some natural fractures show evidence of interaction with groundwater. There is a correlation between present day depth and fracture intensity and particular lithologies are very heavily fractured.