The shaky future of the oil industry in the Philadelphia region took a turn for the better this week, as did the prospects for hundreds of workers whose jobs are linked to oil refineries along the Delaware River.

In what proved to be a double-barreled announcement Monday of corporate takeovers, one unlikely savior literally swooped down from the clouds, as Delta Air Lines became the buyer of the ConocoPhillips refinery in Trainer.

Given its limited presence at Philadelphia International Airport, Delta's move to lock up a reliable source of discounted jet fuel won't mean lower airfares locally. But it's huge for Delaware County to retain a big tax-paying firm and avoid further industrial decline with a shuttered refinery.

With the other deal — the sale of the proud Sunoco brand to a Texas pipeline company — the region finally seems poised to realize more visible benefits from the upstate Marcellus Shale boom beyond low natural-gas prices.

A key attraction for Energy Transfer Partners of Dallas in the $5.3 billion acquisition of the Sunoco refinery and headquarters complex was the Philadelphia icon's 8,000-mile pipeline network.

With so much shale gas flowing in the state, host drilling communities have reaped the most gain. A drilling fee enacted by Gov. Corbett and state lawmakers this year will have limited statewide benefit.

Meanwhile, the potential environmental downside and threat to drinking water resulting from plans to move drilling into the Delaware River watershed represent a major worry for 15 million residents of the tristate region.

So it's good news that shale gas played a role in the prospects for Sunoco's pipeline operations under the new owners, who say they will retain much of Sunoco's workforce in that arm of the business.

There also may be a Marcellus-related role for Sunoco's Marcus Hook property, perhaps as a terminal to load methane onto ships, or maybe as the site for some petrochemical process that uses natural gas as a fuel or as a raw material.

The Sunoco deal, unfortunately, still leaves the fate of the oil company's refinery in the city undecided, since the company plans to spin off refining by late summer despite its sale.

Hopes are riding on a private-equity firm's agreeing to operate it as a joint venture.

Delta's deal also comes at a cost to Pennsylvania taxpayers of $30 million in a grant, but that's contingent on the buyer making substantial investments at the site, as well as maintaining more than 400 jobs for five years.

While the subsidy appears to be $75,000 per job, Corbett aides contend the deal will help save the jobs of 5,000 people at the plant and in related industries. Of course, the important test will be whether state officials monitor and enforce the terms of the pact.