Drilling in the Appalachian basin in Pennsylvania has evolved since its inception. Operators have shifted their focus from mere wellbore delivery to delivering wells in the shortest amount of time to reduce risks and costs, as well as drive efficiency. This paper presents a case study in which offline cementing helped improve operation efficiency by reducing drilling times and provided significant cost savings. Offline cementing is not a new concept. In Q4 2015, an operator drilling in the Eagle Ford shale began the movement of their program toward offline cementing of both the surface and production casings. The operator determined that reducing flat time was crucial to create a cost savings (Hsieh 2018). When another operator began their 2018 drilling program in northeastern Pennsylvania, improving efficiencies was discussed with the service company. After quantifying the experience obtained during a previous project, the service company proposed offline cementing because of the economic benefits it could provide. The service company was able to cement both the surface and intermediate casing strings offline while the operator skidded to the next well to begin rigging up. All surface casings were drilled and cemented offline and the rig skidded back to drill for the intermediate casings, which were also cemented offline. Approximately 15 hours was saved by skidding between surface strings, and another 16 hours was saved between intermediate casings. This paper discusses the successful use of offline cementing during drilling operations in northeastern Pennsylvania. The flat time reduction achieved during this drilling program can be quantified into a cost savings of approximately USD 80,000 per well.

"Gas migration" has been the catch phrase of the Appalachian Basin in the northeastern part of the US for years. As demonstrated in a previous study, optimal displacement efficiency can be obtained by rotating casing during the entirety of the cement operation, providing uniform cement coverage and eliminating gas migration. However, while horizontal well lengths continue to increase, the ability to maintain rotation for the entirety of the cement operation can be severely inhibited. Conventional cement slurries are satisfactory for the majority of wells in both the Marcellus and Utica/Point Pleasant. However, while operators are pushing the limit toward a 20,000-ft measured depth, there is a growing need to rely less on industry best practices written at the onset of shale drilling and expand engineering creativity toward implementing new technologies. With rotation off the table, a service company recommended the combined use of two highly enhanced mechanical property cement slurry technologies to bridge the technology gap from a conventional cementing solution to a more "life of the well" solution. Historically, gas migration from either the Upper Devonian and/or the Marcellus Shale has been proven to be troublesome for the northeastern part of Pennsylvania. When the challenge cannot be addressed with historical best practices, deploying new technology on hand is necessary to achieve the goal. With the more robust functionality of a low-Portland cement design and resin composite cement slurry, the service company's design team was able to combine these two technologies to deliver a dependable barrier tailored to achieve zonal isolation. Optimizing the placement of the resin-composite-based cement slurry itself was pivotal; placement across the problem zones and above the landing point of the horizontal section was necessary. Successful elimination of both pre- and post-fracturing gas migration was achieved without casing rotation during cement slurry placement. The wells were put into production, and the operator has not had to perform any costly remediation operations because the reservoir was properly isolated by means of the primary cementing operation. Enhanced mechanical property cements were proven to be vital for alleviating the concerns of gas migration. These cement systems help prevent Upper Devonian and Marcellus wells from being reworked because of primary cement quality post-completion.