Drilling a Marcellus Shale well begins with a permitting process regulated by state and federal agencies, such as the Pennsylvania Department of Environmental Protection (DEP). The well is drilled far beneath the ground water aquifers and is encased in heavy steel pipe, which is then completely encased in a thick layer of cement to protect ground water supplies. Once the Marcellus formation is reached the drill bore is directed to a horizontal orientation for drilling the well through the Marcellus formation.
The Marcellus formation holds vast amounts of natural gas but the formation is not permeable which makes the extraction of natural gas difficult. Horizontal drilling technology produces greater access to the natural gas held in the formation as compared to traditional vertical gas wells that access a single point in the formation.
Another benefit of using the horizontal drilling process is that many wells may be drilled in different horizontal directions from one single surface location or "pad." For example the configuration may look much like a star fish with multiple arms originating from one body.