More than $1 billion a day. That’s how much value a Permian Basin pipeline crunch wiped out from the explorers most focused on the booming U.S. shale region in two weeks. Eight of the Permian’s so-called pure-play drillers lost $15.6 billion in combined market value in the 15 days through Tuesday, as shipping constraints devour the profit they can fetch for a barrel of crude. Parsley Energy Inc. shares wilted 16 percent in that time; Diamondback Energy Inc. has been defanged, down 18 percent. As oil prices slumped over that span, their losses were far worse than declines for other producers — including more diversified shale drillers Occidental Petroleum Corp. and EOG Resources Inc., majors like Exxon Mobil Corp. […]