Optimizing Hydraulic Fracturing Performance of the Fractured Utica Shale, New York State

Javad Paktinat¹, Jim Fountaine¹, Gary Lash², and Michael Forgione^3
1Universal Well Services, Meadville, PA
²SUNY-Fredonia, Fredonia, NY
³Great Lakes Energy Partners, Carlton, PA

The principal purpose of stimulating fractured shale reservoirs is the propagation of long fracture that connects natural fracture networks thereby establishing a flow channel to the wellbore. Despite the great interest in the Upper Ordovician Utica Shale, a successful stimulation strategy remains elusive, perhaps a consequences of mineralogy (38% carbonate), entry pressure, and premature pad fluid leak-off. Indeed, stimulation of Utica shale reservoirs with acid alone has not been successful due to the plugging of pore throats by post acid fines and sludge. This study considers new methods of stimulating the Utica shale formation that utilizes low strength acid treatment to reduce entry pressure, followed by gelled acid and crosslinked fracturing fluid treatment. Leak-off efficiencies and adsorption properties of surfactant treatments were investigated by injecting treatment fluids into 4-foot-long Utica shale packed columns.

Specific results of this study include the following: (1) permeability and post frac water recovery was improved by inclusion of clay stabilizer and a three phase microemulsion additive within the fracturing fluid; (2) microemulsion adsorbs the least into the matrix of the Utica Shale, while the fluorosurfactant and cationic surfactant adsorb the most. Moreover, the microemulsion formulation minimizes adsorption enabling the surfactant to penetrate further into the formation; (3) acid solubility experiments reveal that the carbonate fraction of the Utica Shale is dissolves in 5% hydrochloric acid equally as well as higher strength acid; and (4) clays particles and other post frac fines migration, which can reduce the conductivity of the proppant pack by half, can be stabilized with use of KCl and polymeric clay stabilizers.

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas