PRODUCTION AND WATER USE IN PENNSYLVANIA'S ORGANIC SHALES

Thousands of shale natural gas and oil wells have been drilled in Pennsylvania since 2004. In addition to the Marcellus Formation, other organic shales are being targeted, including the Upper Devonian Geneseo and Rhinestreet organic shale members of the Genesee and West Falls formations, and the Upper Ordovician Utica Formation. Shale gas wells have been drilled in 36 of Pennsylvania’s 67 counties.

In general, a positive relationship can be seen between the amount of water used and gas produced. Recycled water is supplementing other water sources being used to frac wells in recent years. More than 90% of the wells completed in 2013 included recycled water in the frac process. The total amount of water used in deviated (horizontal) wells is one the rise, due in large part to longer lateral lengths.

A portion of these frac waters flow back after stimulation, and formation water is also generated after the well has been turned into production. Disposal methods for these waters have been evolving since 2004, when the modern Marcellus play was discovered in Pennsylvania. At first, disposal primarily relied on industrial waste treatment plants or municipal sewage treatment plants. Now, most of the water is reused. The use of injection wells has also increased.