In an instant, Chesapeake Energy Corp. will erase the equivalent of 1.1 billion barrels of oil from its books. Across the American shale patch, companies are being forced to square their reported oil reserves with hard economic reality. After lobbying for rules that let them claim their vast underground potential at the start of the boom, they must now acknowledge what their investors already know: many prospective wells would lose money with oil hovering below $40 a barrel. Companies such as Chesapeake, founded by fracking pioneer Aubrey McClendon, pushed the Securities and Exchange Commission for an accounting change in 2009 that made it easier to claim reserves from wells that wouldn’t be drilled for years. Inventories almost doubled and investors poured money into the shale boom, enticed by near-bottomless prospects. But the rule has a catch. It requires that the undrilled wells be profitable at a price determined by […]