Compaction and Quartz Cementation Modeling Applied to the Medina Sandstone in the Appalachian Basin

Scott McCallum and Chris Willan
EQT Production, Pittsburgh, PA, [email protected], [email protected]

The Medina Group has historically been a target for hydrocarbon production in Ohio, Pennsylvania, and New York dating back to at least1880. Numerous researchers have conducted a great deal of work evaluating the character and extents of the various fields within this play. The current study focuses on modeling the compaction and quartz cementation within the Medina group and how these components influence regional porosity variability within the play.

A 3rd order sequence stratigraphic framework has been defined in the Silurian interval and extended throughout the Appalachian Basin. This framework was used as a general guide to define possible depositional environments, specifically during Medina deposition. The depositional environment was used as a method define initial porosity in a given area. Changes in porosity were modeled through time as a function of burial history and temperature. Compaction modeling, as described by Lander and Walderhaug (1999), was utilized as it more readily incorporates point count data from thin-section work. Furthermore, this type of modeling limits the degree of compaction based on the stable intergranular volume. Modeling of quartz cementation followed the procedure described by Walderhaug (1994 and 1996). Quartz cementation is modeled kinetically and the rates of cementation are considered to be largely driven by the temperature history. Published thin section data were used to calibrate the quartz cementation component of the model.

Initial porosity ranged from 42-45% at time of deposition, which was reduced to approximately 25% due to compaction and further reduced to 0-10% due to quartz cementation. Porosity occlusion was greatest in central Pennsylvania near the structural front and occlusion progressively decreased as traced to the northwest. The eastern limit of the present day Medina play correlates closely with the eastern extent of modeled porosity. Based on the trend of modeled porosity reduction, horizontal technology is the best available method for testing and possibly extending the Medina play to the east.

AAPG Search and Discovery Article #90154©2012 AAPG Eastern Section Meeting, Cleveland, Ohio, 22-26 September 2012