The 3,992 wells drilled in the Permian Basin in 1963 represent a 14 percent decrease from 1962. Exploratory tests averaged 32 percent, and development drilling 88 percent successful, resulting in new Pennsylvanian reserves. Pecos County led the area in number of discoveries, and now has the world's deepest production. On the basis of reserves, potential productive area, and geology, 61 of the 359 successful exploratory tests are considered significant. Geophysical activity increased 6 percent in crew-weeks for seismic; gravity decreased 67 percent.