Connectivity of the Oriskany Sandstone with the Marcellus Shale; Effects on Shale Gas Operations in North Central Pennsylvania

Abstract

Faults, natural fractures, and hydraulically-stimulated, propped fractures strongly influence production rates of lateral gas wells. This project examines potential hydraulic connections between the Marcellus Shale and the Oriskany Sandstone in North Central Pennsylvania (NCPA) where Marcellus lateral well production rates are low and brine water production rates are high. Many have theorized that Marcellus Shale production operations in NCPA have been adversely affected by connectivity with the Oriskany Sandstone (a popular drilling target for vertical wells in NCPA the 1950-1970's), but thus far, theories and research efforts in NCPA have not been formalized and/or reported. This project examines the relationship of the Marcellus Shale with the Oriskany Sandstone through the following analyses: 1) structural and stratigraphic, 2) water and gas isotope, 3) water chemistry, 4) formation breakdown pressure, 5) lateral well gas and water production, and finally 6) structural complexity using geosteering data. In order to explore the degree of connectivity, published data are combined with water and gas analysis from producing Marcellus and Oriskany wells, water analysis of preserved sections of Marcellus core, and data provided by shale gas operator, EQT. These parallel analyses and data syntheses will allow strong inference on the connectivity of the Marcellus and Oriskany in NCPA. Ultimately, clarification of fluid and gas flux in deep rock formations will improve our ability to develop effective techniques to maximize hydrocarbon recovery while minimizing brine water recovery and environmental impact.

AAPG Datapages/Search and Discovery Article #90291 ©2017 AAPG Annual Convention and Exhibition, Houston, Texas, April 2-5, 2017