Drilling locations

From Wikimarcellus

Drilling locations are, when possible, organized into rectangular tracts, called units, that are usually about 640 acres in size (the number of acres in a one mile by one mile plot).

In northeastern Pennsylvania Marcellus shale is typically best mined, or fraced, when the horizontal drill bit direction is driven north-northwest or south-southeast (i.e. approximately 10-15 degrees to the west of due north or, reciprocally, 10-15 degrees to the east of due south.) Mining can be done in other directions, too, but the north-northwest and due opposite direction are considered optimal.

Each 640 unit contains a well pad, or operations area, approximately 5 acres in size. The well pad supports drilling and gathering, or pipeline, activity. Each pad generally supports approximately six individual wells that are drilled vertically to about 5,000 feet (if drilling the Marcellus) before turning horizontally. Horizontal or lateral legs tend to range from 3,500 feet to 5,000 feet in length, although new technology has supported legs that are up to 9,000 feet long. A variety of considerations, including geology, shale thickness, and costs related to the amounts of gas produced by the wells determine lateral lengths.