“Like an oil lease, you’re easily disposable,” the villainous J.R. Ewing quipped to his beauty queen wife in the 1970s television series Dallas . Readers of the latest edition of the Federal Reserve Bank of Dallas’s quarterly southwest economy publication might want to keep that quote in mind. News from the oil patch — the 11th Fed district that encompasses the shale heartland — is not encouraging, as it reveals a sharper rise in souring energy-related loans. “The persistence of relatively low oil prices has begun taking a toll on district bank customers,” the Dallas Fed said in its report . “Oil-price hedges become less effective the longer prices stay low, and the cushion built by energy firms during the good times gets thinner. Cash flow becomes stretched and collateral loses its value, […]