While the natural gas held deep underground in the Marcellus Shale has existed for millions of years, the technology to get it out of the ground economically was only developed within the past decade.
After penetrating the shale, the rock must be hydraulically fractured, or "fraced", to maximize the production of natural gas from Marcellus Shale. A fracture stimulation fluid comprised of fresh water, sand, and additives is injected into the well under high pressure to enhance fractures in the rock and free more gas. These fractures start at the wellbore and extend as much as several hundred feet into the reservoir rock.
Sand, a "propping agent", is pumped into the fractures to keep the rock from closing when the pumping pressure is released, allowing the natural gas to migrate from the rock pores to the surface wellbore. Along with fresh water and sand, the fracture fluid contains three additives. A friction reducer, similar to cooking oil, aids pumping and a bactericide, similar to Chlorine in a hot tub, kills bacteria. These two additives respectively make up 0.5% and 0.025% of the total fluid composition. The fracture fluid also contains a 0.1% portion of a micro-emulsion similar to those found in personal care products and cutting oils. This additive ensures coating of the formation and effective fracture fluid recovery.
