Expectations are high in the Marcellus Shale. Operators expect prolific yields of gas and legislators expect strict environmental compliance with cementing policies in a trend that stretches across the state of Pennsylvania. Operational challenges (mud removal, cementing and completion) abound; the greatest issue, sustained casing pressure (SCP), can surface before and after completion. The FlexSEAL advanced flexible expanding cement system (FECS) has been developed to combat SCP. Four wells in the Northern Marcellus were selected for initial field testing using the new FECS technology. The job was executed successfully and the design objectives were achieved. Fair to good cement coverage was reported from 3480 to 4050 feet. Good to excellent cement coverage was estimated from 4050 feet down to the bottom of the FECS placement. No SCP has been observed in over a year since the FECS was applied to the Marcellus wells.